Dual Motor AWD Electric Bikes – Case Study: Twin Geared Hub Commuter

A big bruiser geared specifically to be pedaled hard at 32-34 mph, this is my commuter workout-workhorse. Don’t want to sweat? Just relax and pedal easy… at 28 mph.

AWD Ebikes Menu
AWD. OMG. WTF!
Case Study – Flatland Fat Bike Commuter. Hub+Hub (you are here)
Case Study – Alpine Road & Trail. Hub+Mid Drive
Case Study – Low-Power Cargo Beast. Hub+Mid Drive

The Great Pumpkin

  • 2 x 750w 80Nm geared Bafang G060 hubs
  • 1 x 52v, 30ah battery with Samsung 30Q cells, 90a continuous BMS
  • 2 x 35a KT brand controllers
  • 2 x KT brand displays
  • 160 Nm total power

The Great Pumpkin remains my fast commuter workhorse. This bike is meant for transportation to and from a destination, not sightseeing. As such it is designed to travel as close to the safe, legal speed limit as possible. Here in California the assist limit is 28 mph, I stay on the street (no shared-use bike paths allowed) and this bike’s gears are made to let me power it up past that 28 mph limit to about 34 mph – if I am strong enough to pull it off.


A note on speeds and our local roads here, and how they influence the design and capabilities of this ebike:  in California the law limits ebikes to 28 mph (45 km/h) of assist.  Thats an assist limit, not a speed limit.   The maximum lawful speed is the posted motor vehicle speed limit, adjusted downward if necessary to maintain safety.  So if you can pedal the bike faster than 28, thats fine so long as doing that is "safe for conditions".  

These speeds seem like a lot to readers in some parts of the world.  But remember here in the USA we've got open roads that are nothing like you see in many urban centers in, for example, the EU.  The two pictures above come from two different places along my 15-mile commute route.  The speed limit signs are in mph not km/h.  Bear in mind drivers regularly exceed these limits by a significant margin so in rush hour traffic a 30 mph bike is by far the slowest thing on the tarmac, with no pedestrian issues to speak of.  So, on streets like this, if I can pedal to 34 mph - and oftentimes I can - thats perfectly legal.  In fact I have been paced and radar'd by police cruisers and motorcycle traffic enforcement many times without incident.

So the secondary purpose of this bike is to enable me to work hard while still transporting me to Point B at a practical speed. You’ve heard how ebikes let you arrive at your destination without getting all sweaty? Well, this one lets you arrive all sweaty on purpose if you like.

The geared hub motors let it accelerate fast in traffic, and despite its necessary lack of suspension, the fat tires (and the suspension seatpost) let it ride well on lousy pavement. It has over 7000 miles on it at present (March 2021), and benefits from all of the learning I got the hard way building its predecessors. In fact, I am using the same set of wheels I had built for my very first AWD ebike: The Colonel. This is a testament to finding a good wheelbuilder at the Local Bike Shop of your choice and have them build you a quality wheel with quality components.

Fresh from the wheel builder in March of 2017. DT Champion 2.0 spokes, 16mm brass nipples, double-wall Weinmann 80mm rims. Still going strong today, three bike builds later.

Motor Choice

The Pumpkin is a flat-country bike. Dual geared hubs are powerful, but hub motors – since they power thru the axle and cannot use gears – are just single-speed. Despite their power and ability to handle lots of current, they can get the bike up steep hillside streets, but they struggle doing it. Riding this bike in the Carmel/Pacific Grove portion of the Monterey Bay Area, where nothing is flat, I found it could climb anything but it lugged its motors mightily doing so, to the point I feared for their long life. But if you live on flat land (and this bike’s permanent home is in the table-flat San Joaquin Valley), this is the design that will gobble up pavement for lunch. It will get you where you need to be safely and quickly as an ebike can legally travel.

Why didn’t I choose maintenance-free direct drive hubs? Because they lack torque, and that means slow acceleration unless I load the bike down with bigger, higher voltage batteries and motors with much more unsprung mass.

Battery

Having done it the wrong way before out of necessity (translation: too expensive) I put in a single big battery on this bike. It has the biggest battery I could fit into the triangle of this XL-sized frame (A Chumba Ursa Major made with chromoly tubing). A 14S9p (52v) pack that uses Samsung 30Q cells to give me about 30ah. That means it takes awhile to charge. But it also takes awhile to drain, and this single battery is placed down in the triangle where it does not reduce the carry capacity of the bike, or screw up its performance with schlocky placement of a battery on the rear rack.

But doing an AWD bike with a single battery means you have to address more than just size. The Battery Management System (BMS) has to be able to handle the amp draw of two motors simultaneously. Looking for batteries out in the wild that can do this… you’ll find almost none that are capable of it.

Initial battery fitment prior to connecting the power and charging cables. The bag hides a multitude of cable-routing sins.

How do you calculate the sort of battery you need? You take the peak output of both of your motors and add them together. Your BMS’ “continuous” power rating has to be more than that peak to ensure your motors never trip the BMS’ limits. If they do, to reset the battery you have to hook it up to a charger, which is unlikely to be handy on the side of any road you’re traveling on.

So, with a 35a rear controller and a 35a front controller, I need a battery with a 70a continuous (or more) BMS, and thats a special order item. In my case, the BMS can handle 80a continuous current.

Controllers and Wiring

The 35 amp KT brand rear motor controller is sitting under the saddle, zip-tied neatly with small clear, low-visibility ties to the seatpost mounting arms of the rear rack. This puts the controller in open air to keep its heat down. It will reach temperatures of 135 degrees fahrenheit if stored enclosed. A home-made fender comprising of an extended commercial mudguard and cut-to-size flexible cutting board provides complete coverage from water coming up off the rear tire.

The front motor controller is an identical 35 amp KT, housed in the handlebar bag. This bag has had reinforced brass grommet holes placed strategically inside and out so cables can pass thru its inside compartments to the outside of the bag, without creating issues of splashing water (here again extended fenders help). The top of the bag is left zipped open and this keeps heat from becoming a problem. The front motor cable travels directly up and into this bag, while cables for pedal assist, brake cutoffs, display and throttle exit out either a grommeted side entry or out the open top of the bag. The bag itself essentially hides all of the front motor cabling rats’ nest, both by housing excess wire inside itself and via natural camouflage, providing a black backdrop to black cables running along and woven into its MOLLE exterior. Cables exiting and entering are carefully bundled together for neatness.

Is that a controller mounted to the front rack? Nope its a 5 amp weatherproof charger, with the cables housed in the dump pouch, just behind it.

The center triangle bag is stuffed mostly full with the custom-sized triangle battery. Like any triangle bag on an ebike, it also serves to hide excess wiring, and given the dual custom splitters for brake cutoff signals and pedal assist (one sensor signal is split off to both motors for simultaneous PAS power) there is plenty of wiring that thankfully remains invisible thanks to this bag, which seldom needs to be opened. The bag has forward and rear-facing cable holes that don’t suffer from water ingestion, again thanks to the fender setup. A capped XT60 charger plug is coming out the front of the bag just behind (and shielded by) the head tube, and this cap is removed and a charger is plugged in here to recharge the battery.

Display/Controls

Ergonomically, the cockpit is very well designed and reflects this being my third or fourth try at doing the job. There is one throttle for each thumb in easy reach, and both throttles are clocked so when fully engaged, the paddle is pointing straight down. If you hit a pothole your thumb doesn’t push thru and break the throttle. It slips off instead. The PAS panel is also one-per-side, and also within thumb reach without losing your grip on the bars. SRAM 9-speed shifters are in use, because a SRAM shifter gives you enough real estate on a handgrip (vs. Shimano) to stack multiple hand controls and still be able to easily reach everything.

Cockpit view. Notice the max speed reading on the top display. I used the gears and got a workout on the ride into the office that day.

Despite the duplicated motors and controllers, the displays are mismatched simply because I am re-using parts from older bikes no longer on the front line (in this case parts came off The Purple Thing). For this build I needed a new display and the KT model LCD8H was available, so I grabbed one. It is the same display as the KT model LCD3 above it, used for the front motor. The LCD8H is just in color and easier to configure.

And in case you noticed… yes this is a bike with Class 3/Speed Pedelec performance that has throttles. Reality is, though, the bike is designed specifically as a pedelec. Pedaling acceleration via PAS is plenty fast and is in fact (thanks to controller settings) a little faster than using the throttles. They are only put into use typically for a split second on take-off from a standing start while I regain my balance on the bike and settle in to pedaling. If I am crossing a 4-lane street, I am off the throttles before I get past the first lane while crossing and won’t touch them again until the next stop at the next intersection.

Power (too hot)

These two 80Nm motors have controllers feeding 35a to each axle provide giggle-inducing acceleration. So much so I found performance needs to be turned down for multiple reasons:

#1 (Safety). Come to a stop at an intersection. Acceleration is so strong from a stop, you leap forward so fast you are always the first vehicle that gets to the other side, and you’d better be hanging on. Thats fine if you meant to do that. If on the other hand you accidentally engaged pedal assist, you could be throwing yourself – literally – into the path of a car.

#2 – (Safety). Come to a stop at an intersection. Put your feet down, release the bars and take a drink or something. If you engage again (pedal assist or throttle) and forget to put your handlebars straight, your front wheel will shoot off in the direction its pointed in. Typically a bad thing.

#3 – (Fork survival). With this much torque pulling on the front fork, things start to happen that a bicycle was never stressed or designed for. A front fork was never designed to be pulled on hard, for extended periods or in sudden jerks. Especially not day after day for days and weeks stretching into years.

#4 – (Frame survival). This one was unexpected: Even though I am using a highly durable hand-made-in-USA frame, I still found it was straining under the repeated daily stress of stoplight-to-stoplight acceleration from the rear motor. Specifically I started to hear creaks from the rear triangle and dropouts. eek.

#5 – (Safety again for crying out loud!). I use fat street-smoothie tires in summer. Doing that with the motors unrestrained makes for about a half rotation of front wheel spin on full throttle, and maybe a 1/4 spin on pedal assist… and a goodly chirp out of the back, at the least (lots more if the ground is not clean, dry pavement). Thats fun for an afternoon showing off but more than that and its just plain dangerous.

Power (just right)

To slow down the bike so it accelerates at a safe rate on city streets, and doesn’t wear itself out from all the extra stress of doing this day in and day out, I utilize a setting in each of the two KT brand controllers that sets the power curve to ‘slow start’: C5=00 is undocumented on all but the newest KT display manuals. Where it is documented, it is listed as the most restricted of the three ‘slow start’ modes.

What this does is create an acceleration curve slope that is shallow at tip-in but increasingly steep as it continues forward. Here’s the crazy-cool part: Even dialed way down on both motors this bike is still typically faster than anything else crossing the intersection from a standing start. So you aren’t missing out on much in the way of fun if you want to pour on the amps. Its just safe, sane and controllable when its put on a leash.

Torque Arms (!)

I’m not going to get too deep into the specifics of this topic, but I will say if you use hub motors you have to use torque arms. Gotta do it. Thats for any motor that has ‘flats’ on its axle to allow their use (which is almost all of them). It is true many motors do not need torque arms because they are of such low power. I will say having suffered the consequences of not using one, its WAY better to be safe than sorry and just go ahead and install them regardless of motor power.

What could happen? If you don’t use a torque arm, the force of the motor will overwhelm your bicycle’s dropouts and the motor will “spin out”. That means your steel dropouts will not be able to contain the motor’s axle, which will spin (instead of the motor casing spinning) and when that happens the dropouts spread. Your frame or fork is effectively destroyed and unsalvageable at that point. These 750w, 80Nm motors are right on the edge of demanding two torque arms. For sure they need one. I have used two on the front motor and one on the rear, where the stronger rear dropouts are much less likely to have an issue.

Gearing

Last but not least… take a look at the pictures on this page and you will see the biggest front chainring ever on a fat bike. Look to the back axle and you may be looking at the smallest cluster. And the derailleur is a mid-length cage, to boot. Fact is, this bike was geared to be pedaled fast on the street, not overland on trails as is the norm for fat bikes.

The front chainring is a 50T ring, while the rear cluster has an 11T small cog. Frankly I forget the size of the biggest cog because I never use it. Its 28T… Maybe 30. And since the hubs on this bike are the motors, powering the bike thru the axle, not the drivetrain, gearing is largely useless unless I want to pedal faster while going slow. This almost never happens because this bike should not be taken on pedestrian paths or similar where such slow travel is necessary.

Redundancy

For a daily driver bike that is transportation, not recreation, you need to address many areas to ensure reliable, day-in, day-out operation. There are many issues addressed on that topic with this bike, but I’ll only touch on the AWD-specific ones here. In a word: Redundancy. If you do a general overview of this bike’s propulsion systems, you will see almost everything but the battery is a separate, independent system. None of this is accidental or done because I was forced to do so (you can buy controller solutions that reach out to two motors at once, for instance). Its done this way because its better. Dual throttles are better. Setting PAS independently per wheel is better than combining the two. Even two different displays let you focus on different bits of each (although that one I could do without if push came to shove).

Redundancy on a dual motor bike can be a big benefit. I’ve had one unfortunate lesson in this: I went over the handlebars and slammed straight down on the pavement, cracking some ribs. I also bent my front fork (just a little) and smashed my rear throttle, among other things. That broken throttle disabled the rear motor despite all other components being in working order. I was able to limp the bike home without pedaling, which I really needed given the cracked ribs and various and sundry other minor injuries.

This is one more reason by the way, why I want throttles on the bike. If I am physically unable to pedal I want to be able to get me and the bike home, or to the emergency room as the case may be.

Gallery

And THAT is my rain or shine daily driver.

Dual Motor AWD Electric Bikes (the good and bad)

I like to build top-quality-component ebikes from the frame up. Quite a few of them are dual motor or AWD or 2WD or whatever you want to call them. Why would you build an AWD ebike?

AWD Ebikes Menu
AWD. OMG. WTF! (you are here)
Case Study – Flatland Fat Bike Commuter. Hub+Hub
Case Study – Alpine Road & Trail. Hub+Mid Drive
Case Study – Low-Power Cargo Beast. Hub+Mid Drive

In the Beginning…

Well, I could spell ‘ebike’ and that was about it. I had a solid background as a lifelong cyclist, but I went over to the Dark Side and started riding ebikes. I had been working on my own bikes for most of my life and I was pretty good at that part.

So, as an experienced cyclist but a newbie ebike owner I came across a bike built by my (now) friend Houshmand Moarefi, who is the head honcho over at Ebikes USA in Denver. He took the same model of rear-hub-motor ebike I had, upgraded the rear motor, then added a front motor, controller and surrounding bits to make a badass AWD e-fatbike. He posted his creation on the Interwebs.

Figure 1: Houshmand Moarefi’s 2wd Sondors Original. Want to know what dual-motor is good for on an ebike? Just look here. He still rides this bike and you can see it on display at Ebikes USA in Denver.

After seeing the bike online – and peppering Houshmand with questions – I did what everyone on the internet does: shamelessly copied his idea. It is pictured in Figure 2 below. This was taken the night I completed it, moments before I opened that garage door and took my first ride.

Figure 2: AWD by Matt… Version 1.0000. a.k.a. The Colonel (“Colonel Sondors”). How much did I have to learn about doing AWD right? I’ll have to make a list.

Its a good thing I took the picture, as 15 minutes later I broke it. I got it fixed and it gave me years of service, but thats another story entirely. Suffice it to say in that pictured moment, we see triumph and despair occurring almost simultaneously.

What are we in for, building one of these things?

First… “Whhyyy?”

Why put two motors on an ebike? Well… “because we can” works. But lets do better than that.

Is it even possible?

Not so long ago, internet experts in the DIY ebike crafting community would tell you all about how a powered awd ebike could not even function in the first place.

  1. The powered wheels would fight for supremacy between each other.
  2. It is essential to match the power to both wheels but impossible to do so.
  3. Even slight differences in wheel circumference between the two would make terrible things happen.
  4. blah blah blah

So, I was being told it could not be done after having put thousands of successful miles on a bike that could not exist. A lesson on the value of internet experts. Only value the advice of those who have done the work and actually know things.

I don’t want to get too deep into a litany of refutation on common mistakes, but I do want to clear up a couple that come up the most often. All three, really, are more or less re-statements of the same misconception:

Matching Power (current) to the Wheels

This is a common worry, but not a real one as you will discover moments into your first ride. The concern is dissimilar power levels cause problems. They don’t. Tailoring power front to back as conditions change is a major benefit to AWD. In simple clean/dry conditions, all that will happen is the wheel that gets less power doesn’t work as hard.

The easiest way to understand how this is: Geared hubs freewheel forward. So the same thing happens if you have no motor on the back and you are, say, going down a hill with a front motor. The watt output of the front motor decreases as gravity ‘powers’ the speed increase (or you pedal your little heart out on flat ground). Likewise, differences in circumference are a non issue. This is true in bikes with slightly different tire sizes, but is most visibly proven with the in-service bike pictured below.

Figure 3: Different types of motors with perpetually different outputs… and totally different wheel sizes. It still works great.
Contention

Here again, one ride will lay this concern to rest. Two motors will not fight for supremacy with each other despite differing power levels. Partly because of the geared hub’s ability to freewheel. You should take it for granted you will have different power levels on each axle. I commonly keep low power on my front wheel (I will expand on why further on) but for my hub+hub commuter I often just go full blast on each motor and pedal up over top of it. In that instance, with two big motors giving it their all I only very rarely feel a bit of a shift in pull vs. push and it is very minor. Another technique on that bike: 5 levels of PAS on the rear wheel plus 5 on the front means that – in good conditions where I do not vary the power for safety – I have PAS with 5+5=10 levels. As I want more I ratchet up the rear a notch, then the front, then the rear and so on never giving all PAS power to just one wheel.

One Throttle/Two Motors

You don’t want this. You can have it but you are selling yourself and the platform short if you go to the extra amount of trouble to make it happen. I will get into some real world specifics of why this is later on. The short version is if you unify the throttles or even work harder to unify PAS power levels to the two wheels you will be introducing problems with traction and control. You want to keep your control granular. It won’t be confusing or difficult!

What About Two Direct Drive Hubs With Regen?

What I said above doesn’t apply. If you expect to use regen on a twin-DD-hub AWD bike then you are talking about a whole different animal in terms of two hub motors coexisting. I know its been done, but I have never done it personally. I will let some other pioneer on the trail take the arrows in the back on that one (I suspect: regen can be used on the rear but not on the front… or just don’t do regen at all with DD hubs).

A final point: Years into having AWD bikes in service, there are now numerous commercially-produced examples in plain sight. The arguments that it cannot be done have melted away now that so many have obviously done it.

Figure 4: The Purple Thing. Built after the death of The Colonel (cracked frame not related to AWD)

So YES you can do AWD. The question is are you doing it right? Well, thats a whole ‘nother thing.

Whats the Up Side?

Take a look at Figure 1 for the most obvious example: All Wheel Drive on a bicycle is every bit as good of an idea on a bike for the reasons it is a good idea on a car, truck or ATV. On other vehicles, just putting more power to your back wheels is not anywhere near as good of a solution as putting power down to all wheels. It is the same on a bicycle, but so few have done it, the result is not considered to be the obvious no-brainer it is on other platforms.

If conditions are sub-optimal, as in rain, snow, mud, riverbed rocks, hillsides and whatnot… AWD on a bike gets you through it easier, across the board. If conditions are ridiculously bad, AWD can get you thru things you thought were impossible to ride. Oftentimes so easily you stop, look back and wonder how the hell you just did that.

The range of things that you can ride through just got a lot wider.

If on the other hand conditions are just dandy – say, a smooth, flat, dry paved street – having both wheels deliver power to the ground is again an improvement for all the same reasons it is better on a performance exotic car. Powered traction is distributed across twice as much rubber to the ground. Everything just works better.

And since the improvement makes for a qualitative, but drama-free result, its really hard to describe other than to say ‘everything just works better” or “this is how it was meant to be” … which do not help much when explaining AWD to skeptics. Nonetheless… the nebulous, big-brush-stroke description is accurate.

In terms of acceleration, doing it with AWD vs. RWD is a very different rider experience. You aren’t being pinned to your seat, nor is your body wanting to slide off the back while you hold onto the handlebars for dear life. Instead you get an amazing rate of acceleration, but it is smooth and – again – without drama. The feeling is of it being effortless for the bike to do what its doing.

Mechanically there are benefits as well. If you are keeping tabs on the amount of heat your motor generates, you’ll find gunning one motor around will get so hot you may not be able to touch it for awhile. Not so good for longevity, especially if it has nylon gears inside. But: Run two geared hub motors as a team to achieve the same performance and by some miracle the two don’t even get a fraction as hot as did the one. All of a sudden a motor that was working itself to death isn’t even breaking a sweat, and you’re going at least as fast and as hard.

How is this possible? In May of 2020 Grin Technologies did a detailed technical analysis of multi-motor ebikes. They explain how this is possible, complete with the technical details on why it happens. Its well worth a watch if you are interested in taking a deep technical dive on your AWD ebike options. I have queue’d up the video in the link below to the exact spot where he explains the heat reduction.

Another issue not generally considered is redundancy. With two motors, if something bad happens on your ride and you lose a motor, you still have another and can limp home on it. I learned this the hard way once when I went over the handlebars on my twin-hub Great Pumpkin. I smashed one of the throttles and disabled the rear motor completely. I managed to roll home on the front motor without needing to pedal. With freshly cracked ribs that was exactly what I needed.

Whats the Down Side?

AWD is not all sunshine and roses. There are down sides. Most of them only affect the bike builder. But a few do affect the rider, so we’ll look at the negatives from both perspectives.

For The Builder…

Put simply, AWD on an ebike is one hell of a lot more work. There is so much more you have to keep track of. So many more wires that have to be hidden.

Fig. 5: Custom brake cutoff splitters and extensions for sending signals to 2 controllers

You have to address the issue of brake cutoffs going to two separate motors simultaneously. Pedal-assist to two motors at once is a beautiful thing. But only for the person riding the bike. For the builder it typically means customized controller settings and maybe even a little fabrication to get a sensor signal to two motors at once.

Fig. 6: PAS splitter cable (one sensor –> 2 controllers)

Battery power? You’re going to need a big battery, and it needs to deliver more power than pretty much any regular ebike battery available on the open market. So you either have a single custom pack made or kludge together off-the-shelf packs and suffer through the weight and space issues that go with them.

Fig. 7: Cutout sized, marked and photo sent to the battery builder. All thats left is to drain my bank account.

What does a front motor need in terms of structural support? You’d better think that one through. NEVER use a suspension fork in an AWD build. Your motor can literally pull the thing apart. Whoever designed a bicycle fork never expected a powerful motor would be pulling on it for extended periods, or in sudden jerks. Thats tough on a chromoly fork but they can handle it. Its typically too much for an alloy fork (aluminum is nice and light but doesn’t bend: it breaks) and it is definitely too much for a suspension fork that has 2-piece blades that can be literally pulled apart.

Not to mention fork dropouts. A hub motor must have torque arms attached that prevent the motor from ‘spinning out’ (That is how I broke the Colonel on its maiden voyage; destroying its fork dropouts). You generally cannot use quality torque arms on a suspension fork due to its physical construction. If so, the dropouts have to endure 100% of the punishment and… newsflash … they may survive today but they won’t have the kind of long life they would have had without a motor axle trying to tear thru them.. Internet discussion groups are chock full of pictures of DIY builds where someone used a front hub motor and their suspension fork’s dropouts snapped clean apart. Even with a torque arm.

We’re not done with the front fork yet. Regardless of construction, that pulling on it can loosen your headset at an alarmingly fast rate depending on your power and acceleration levels. If its a problem you have, you will want to think of ways to keep that headset in place (psssst… use two star nuts) and while you are at it, make sure you use a superduty headset with steel races. And a serious mtb stem that clamps the crap out of your steering tube.

You can google “broken ebike fork” or just follow this link (one of many) on Endless Sphere to see more electric motor + fork carnage.

So… How do you get away with using a front suspension fork, then? You see people do it with front-motor bikes. Assuming they thought the job through and are not just future emergency-room visitors, its simple: use a very low power motor. Or neuter a powerful motor and trust the buyer won’t know any better because hey… nobody has any actual experience with these things so you can give them just a little power and they will still be thrilled.

So… to build or sell an AWD bike its a whole lot of work for the same result (a single finished bike). Its no wonder AWD bikes are not common, and when they are up for sale, the seller wants a high price. Assuming they did their job right (never assume), a lot of work went into that bike.

Fig. 8: Wires everywhere. I have to figure out a way to hide all this…

For The Rider…

Fortunately, the downsides of AWD are minimal if all you have to do is ride the bike. But they do exist. All of the negatives can be eliminated if you just realize this bike is a new kind of animal and take it easy when starting out. So… learn how to handle the increased traction, power, and the subtly different behavior.

Dual Throttle

If your bike builder did the job right (I’ve said that two times so far and not by accident), you have two throttles – one for each thumb – to let you apply power granularly to each motor as the needs of the moment come up. Thats a new feature you will need a bit of time to learn how to take best advantage of. The basics of this will be learned by the time you have traveled about one city block. The finer points will take some experience – not a lot – to figure out.

  1. Holding down the front throttle in a turn has the end result of elongating your turn radius (this is about how you naturally ride, not how the bike handles… but it still happens). You cannot take a turn as sharply if applying front throttle, and could wind up smashing into the center median in a right turn in traffic, or the curb in a left turn thru an intersection. There is an easy solution: stop pedaling, release front throttle, turn in, re-engage front throttle just at turn-in so the slight delay will engage the motor right about at the moment of corner exit. Leave rear throttle engaged throughout the turn if you can safely get away with it). That turn procedure all takes place in the space of about two seconds. It will become second nature in short order. But it has to be learned. Now… thats how you hot rod your way thru a turn. You won’t want to do that all the time, and mostly you will go thru a turn no differently than you do on any ebike.
  2. On singletrack/trails, less power to the front wheel is more. Rip down a trail, hit a root and the front wheel bounces up. If it comes down pointed in a different direction than you are headed, your now-powered front wheel will shoot off in that new direction if its going full blast. Keep front motor pedal assist power low – much lower than what you have set for the rear. Then when the inevitable happens its easy to deal with. I’ve found pedal assist dialed down in the 200-250w range is best. If you decide you want more front wheel power at any point, a dab of throttle will do ya. You know you are overdoing it if you get any level of wheel spin in the front.
  3. You are no longer the slowest thing accelerating from a stop at an intersection. So if you are not the first vehicle in the left turn lane, Your instinctive use of full throttles to both motors will rocket you right into the rear bumper of the car in front of you. This is an easy fix. In a left-turn-lane situation, initially use only rear throttle, then add the front when the car in front of you starts to pick up speed. Dial it back again as that car completes their turn and lifts on their own throttle before straightening out. Or you can just hit the front throttle for a split second to get yourself rolling from a stop, then drop it and let PAS manage the rest.

Clearly from these examples, manual AWD acceleration (separate from pedal assist) is a learning process. A dual throttle is a big part of getting this down pat without needing to dumb down the bike’s performance.

You can run an AWD bike with a single shared throttle, but doing so means you will be lifting more frequently and when you do its all-on or all-off. You will lose the ability to decide for yourself what happens and the result is more jerky and less refined.

Battery

If your bike builder did the job right (there it is again), its got a single big battery with a high capacity Battery Management System (BMS) capable of handling the peak and continuous loads of both motors running together. For the rider who has such a setup, the only thing necessary is to set aside enough quality time on a charger to get this bike up to snuff to carry the day’s ride.

Fig. 9: The Purple Thing was … Gen 1.5. Rear motor battery in triangle, front motor battery in the rear rack pack. Front controller in the handlebar bag. Rear controller is in open air under the seat on the rack stays (best for cooling).

For the rider not lucky enough to get a proper battery, that means – at the least – putting up with dual batteries in positions that reduce carry capacity. The rear rack typically gets the duty for one battery in a dual-pack system, so whatever your rack’s capacity was, take off 10 lbs and only use the sides. You may also have to deal with charging the two batteries separately, which is a big drag on convenience and turnaround. You *will* have days where you forget to go and switch the charger to the other battery. Speaking personally: Been there, done that.

Fig. 10: One of my Gen 1.0 iterations with the front motor battery in the bag under the handlebars. Don’t ever do this (but the dual kickstand worked *great*).
Maintenance

Two motors = two sets of service intervals. In practice this should not be a big deal, but fair is fair – we have to count this as double the effort on motor maintenance. This is the part where the direct drive hub people all jump up and remind you for the 100th time that they need no maintenance. You will also get slightly faster wear on the front tire, now that its powered.

Commercial Feasibility

I’ve made it pretty clear what I think a proper feature set is for these sorts of bikes, based on the fact I started doing it a while ago, and I’ve had the opportunity to work thru a variety of designs and iterations to find out what works best.

  • Dual throttle
  • Single hi-current battery low and centered
  • Redundant, dual controllers and displays
  • NO front suspension
  • Shared signals from sensors

All you have to do is look at what is out there commercially to see none of the bikes out there adhere to this. When I look, I see the sort of feature sets – and mistakes – from when I first started kludging AWD bikes together. The reality is, though, from a commercial perspective we are unlikely to make much headway forward in the near term. Why?

Money… thats why. What I describe is maximum-cost given its redundancy. Its also darned expensive to build an XL battery with a high capacity BMS, and in addition to that, there is the issue of minimum order quantities from component/battery manufacturers. I don’t see it happening unless a manufacturer goes on a mission to sell a bike that is thoughtfully designed to be a cut above the rest.

More likely to happen: Development of a suspension fork strong enough to withstand the pull of a front motor over the long haul. It remains to be seen if ANY of those in use now on commercial AWD bikes is going to last. We’ll have to see if product liability issues (and injuries) ensue from whats in use now, or whether the sellers have de-tuned the front motors sufficiently to let those forks survive. But down the road, this is definitely something that could successfully evolve.

Something that came on stage right about the time I published this article is the Eunorau Defender-S on Indiegogo. That is a full-suspension bike, so there’s the front-suspension concern. Given its late-2021 delivery date (plenty of time to figure stuff out), the fact that the vendor is going nowhere near any obviously phony claims, and reliable people who know the company are giving it a serious look, this AWD bike may be something of a landmark for the species both in price and thoughtful use of components.

I would be remiss if I did not mention the AWD motorcycles, bikes and ebikes developed by Christini, where they have created a unique, robust, mature – and patented – system to share the power from one motor (rider or electric) to two wheels via mechanical linkage. Lets say that a different way so its clear what they have accomplished: They tap into the power of a single motor (either the rider or a BBSHD) and use that to successfully, reliably power two wheels. Its pretty neat stuff.

What does all this mean for the DIY ebiker? Well, the tools and components are out there for you to build your own, and do it considerably better or less expensively (or both) than anything available in the commercial marketplace.

Fat chance you’ll see a tree-climber like this in stores near you anytime soon.

Wrapping It All Up

The best way to see what good can come from an AWD bike is to look at some representative examples. I have chosen three that work very well for me, and do so in very different ways. Because we’ve gotten to a good place to pause with this post, I’ll do so and point you to the individual case studies that should be linked together in the menu at the top of this post

A Basic (e?)Bike Tool Kit

Rather than looking at the ideal kit, whats the basic everyman version?

Lets Not Get Carried Away Here…

In my previous post, I laid out my idea of an ideal tool kit for my current daily driver/commuter/shopper/cargo bike. That sucker is one big bike, and given its nature, I can carry along a lot of crap with me (like a chair!) without really noticing. I thought maybe it might be a nice idea to toss out a short post supplementing that one, showing what I carry along on a much more normal sized ebike.

So, without further ado, lets see all the stuff:

The Patch Kit

As I noted in the other post, I am using kits I made myself of bulk patches and bigger vulcanizing fluid tubes. I save a little money, can carry more patches in the same space and get a little better container. If you just want to cover this base and aren’t into buying patches 100 at a time, the Rema Large Touring Kit has been on the market for decades, largely unchanged, for a reason (since I was a kid riding in the 1970’s, they improved the sandpaper. Thats the only change). It will suit you just fine.

Rema Large Touring patch kit: The gold standard. Throw away the instructions

The Tire Levers

No discussion of alternatives this time. These Park 6.2 levers are sturdy and thin, so they fit more readily in a small kit. Over time as I mentioned in my other article, I have tried many different levers and settled on these. They’re worth the extra money.

Very thin plastic coating, metal core with smooth exposed metal edges… The best lever I have found, on balance.

A Tire Patch

If you encounter something that puts a major slit in your tire, you need some way to limp home. The Park Tire Boot is basically just a great big gooey glue patch and probably the best overall solution to this. Another one is to pull a dollar bill out of your wallet and line the tire under the slit with it. Still another: Wrap duct tape around the outside of the tire and rim and suffer thru the thumpThumpThump on the ride home (I have done this and it really works). But a tire boot is the cleanest solution and may even be a permanent fix if the tire is not too badly damaged.

A Tire boot is different from duct tape in that the goo on the patch will really stick – forever – on the flexible corded tire surface.

Small Pliers

At minimum, small needlenose pliers. Why? To pull out a bit of stuck metal or glass from your tire. If space permits in your bag, bump that up to a small multitool with a pliers attachment so you can count in a knife, screwdriver etc.

Pocket Knife

If you bumped up to a multi-tool above, you already covered this base.

Stubby Hex Wrenches

I used the long version of the Bondhus hex wrench set in my big kit. But usually I use this shortie version of the same wrench set. If I was REALLY trying to save weight I would pull out all the wrench sizes I don’t use, but you never know when you could use an extra little pry bar or brace ;-D

Short Adjustable Wrench

If you have a hub motor, then you need one of these to remove your wheel IF NECESSARY. While a big wrench is always easier to use as a lever, you should be able to use a small 6″ wrench almost as effectively. Make sure you need one of these for wheel bolts before you bring it along.

Its not big. But its big enough. Check to be sure it will operate in the available space on the frame – in your garage before you need it.

c02 Inflator and cartridges

This is something you will keep in a separate bag of some kind. It is your backup inflation method – that will be your primary in some cases where you need to blast in a lot of air fast to get a tire back up to pressure so the sealant inside can do its job. Usually that means blast in a cartridge, jump on the bike and ride a half block and pray the hole has sealed. If it does, use the pump to get it back up to a rideable volume. I haven’t discussed co2 before so this is what I used:

C02 inflator

There are many out there. I have settled on the Lezyne inflator and have half a dozen of them. You can save a buck or three on something different, but this model has a regulator that doesn’t stick out so it can get bent in your bag. Its reliable over time and multiple uses. Its just a clean, reliable example of the species.

Super small and reliable. Best of breed.

co2 Cartridges

Bring as many as you can figure out how to carry. Especially if you have a fat bike. I use this brand and size (25g) of co2 cartridge… but the price they want for 9 is about what I paid for a pack of 30 of the things. Prices have gone way up on these bulk cartridges in the year or two since I bought them. Shop around and you can get a better price, but not a lot better. For tires that are not fat tires, you can get away with 20g cartridges.

Pump

Here again you have multiple choices. If you have a road bike you will want a high-pressure pump. If you have a mountain bike you will want one slanted towards high volume. While I generally like the Lezyne line of portable pumps, I have one of these and its a great alternative. The T handle in particular is worth a lot when it comes to delivering a hundred pump strokes, but also the screw-on chuck and the floor-mounting ability make it a standout. Typically a pump is either in a separate bag or strapped into a mount on one of your water bottle cages. This pump does have a cage mount included.

A Bag to hold all this Crap

I use an under-seat bag, personally. The one I decided I liked that holds all my stuff is found here on EBay and also you can find it on AliExpress, so long as you are willing to take the usual risks associated with buying direct from a Chinese vendor (I did).

I have 4 or 5 of these bags. Cheap, roomy, well-made and they stay put.

There are many other alternatives. This one looks promising. I like velcro as it stays put where adjustable-length snap buckles tend to slip.

Chances are pretty good a bag like this will be large enough to handle more than the tool kit, like your keys for sure and maybe your wallet as well (or a couple-three co2 cartridges!).

The End

I think. We’ll see if people come up with more questions on this subject on the FB groups where posts like this one are used to provide more in-depth answers.

A Proper (e?)Bike Tool Kit

You need to carry tools as a matter of routine. Especially if you ride daily for transportation or commuting. But what do you really *need*?

This is the companion post to “(e)Bike Flat Prevention“. In that post, I talked about how best to prevent the inevitable: Flat tires. Well, since they are inevitable you had better be able to fix one when your luck runs out. Part of that process is having the right tools for typical roadside jobs.

As I mentioned in the initial post on this subject, I ride pretty much every day by choice. Day in, day out. If it is raining I’m riding. Same for when the sun is blazing. I’ve been doing it for many years and over time I have experienced quite a lot in terms of pratfalls, mishaps, bad decisions and just plain rotten luck. One of the benefits of experience has led me to make specific choices with regard to the tools I bring along with me on the road. I see some folks bringing along the kitchen sink, including bandages, spare electrical wire and diagnostic equipment… All kinds of crap. I’ve been there myself, but if something hasn’t been used in my kit in awhile, it gets left at home eventually. The reverse goes for something that totally saved my butt. Its got a spot in the kit for life.

So… what does the kit look like? I’ll use the BIG one on my Surly Big Fat Dummy. It is larger than some of my kits, but not by much. I’ll go over the whys and wherefores of every item and you can decide if whatever it is I am including is something you want to leave off.

Lets See All The Stuff

Whats Missing?

Before I go into all the details, lets talk about what you cannot see.

The Electric Pump

I wrote up a post not too long ago on an emergency electric bike pump that uses the ebike’s battery so it can remain lightweight. That pump is on the It Saved My Ass list so its always included. As you can see in the linked article, I keep it in a cloth pouch and generally it sits at the bottom of one of my panniers.

The Spare Tube

I carry one of these whether I am running tubeless or not. Its the last line of defense between me and trying to carry the bike home. The spare tube on my Surly is located in the ‘basement’ deck at the back, in a ziploc bag. Where it will hopefully remain forever.

One item I am not discussing in this post is seen front-left in the basement: a weatherproof, adjustable battery charger as discussed in this article devoted to showing you how to make one

The Bag Holding All This Crap

Its a straightforward, cheap canvas MOLLE pouch purchased from Amazon. You can see it in the basement in the pic above, held down by a velcro strap and taking up most of the center section.

Yes it is a pretty big bag, but its also a big bike and fits perfectly in the basement rack.

The Chair

Yes thats right. A freaking chair. This is my newest addition and it got included after I had to stand one too many times in a sun-baked parking lot waiting for curbside pickup. A simple folding 3-corner stool, it can be used either as a seat at the (skateboard) table, or anywhere around the bike while I work. Much better than squatting on the ground or kneeling.

The chair tucks in under the side of the deck using the net I’m already using to hold stuff down on top.

This is a luxury that, realistically, is only possible with a larger longtail bike, or at the least one with a rack you can lash a chair to.

A luxury made possible by an 8-ft long cargo bike with a 40″ deck out back.

  1. Tubeless Tire Repair Kit (from Lezyne)
    I use FlatOut as a tubeless sealant and it should seal holes up to 1/2″ (I already have seen it do its job up to about 1/4″). But stuff happens, and a tire plug kit like this (same idea as the ones sold for car tires) is what you use to seal up a tear in your tire that your sealant doesn’t want to plug, or you just feel better about repairing – these plugs are a permanent fix. A tire plug is not going to make up for torn tire casing cords. In all but extreme cases you can use one of these and forget about the damage the hole made to your tire.
  2. Tube Patch Kit (home assembled)
    I make these up myself. You can buy them cheap, but with all the riding I do, it makes more sense for me to buy a pack of 100 patches and stuff about a dozen of them, a snip of flexible sandpaper and an XL tube of cold vulcanizing sauce into an empty prescription bottle. That bottle has an adult-proof cap and a hard shell superior to the plastic boxes the full kits come with.
    Note that generally you would use this kit only if you are running tubes. I keep it along just in case I meet a fellow rider who has flatted on the road, or the off chance I can make use of it myself

  3. The Ridiculous Tire Lever (from a set of 3)
    This is a tool reserved only for when I am desperate. It is in fact meant for a motorcycle and it is a solid piece of steel. A tool like this can easily damage a bicycle rim or tear open an inner tube so while its included in the kit, its there as a last resort only.
  4. Sturdy, Safer Tire Levers
    I have tried many different tire levers. The Park TL-6.2 steel core tire levers I use these days seem to be the sweet spot between sturdiness and usability, and have never bent or broken on me. Before I switched to these I ran Pedro’s tire levers, which are cheap and smooth enough they pretty much never pinch a tube. But on really stout tire/rim combinations, they like to break, so its always smart to carry more of them than you need, and expect to keep buying them to replace broken ones.

    Before I used those levers, I used the Portland Design Works 3Wrencho. I had three and bent two of them. Also the plastic on the lever side likes to tear away (something the Park levers don’t do).

    Since we are ticking off the also-rans, these Schwalbe levers were pretty good, and don’t take up much space. But they are definitely breakable and the edges on the lever can tear into a tube.

  5. 6″ Needlenose Pliers
    These are your basic, garden variety small-ish needlenose pliers. I have them listed as going in the tool bag, but these are actually in another secure location where I can grab them fast. Why? Because when your tire is hissing air, you may or may not be able to remove the foreign object with your fingers. It could be a sharp bit of steel or jagged glass. Pliers will always be a better choice than bare fingers for grabbing that. Since you have to remove larger foreign objects so the tire sealant can do its job… keep pliers handy. You can jump off the bike, pull out a nail, jump back on again and keep riding like nothing happened.
  6. Long T25 Wrench
    Most folks will have no use for this. But, I use Magura brakes. Magura has decided NOT to honor the M6 hex bolt standard used by the entire rest of the industry, and instead uses a Torx T25 for all their fittings. So I have to keep one with me. I keep the green plastic store card on it so its easier to find in the bag.
  7. Pocket Knife
    Bit of string. Handkerchief. Some hard candy. Pocket knife. Gun. Stuff a guy needs on general principles. Tossed onto the pile. No purchase link because of course you already have several.
  8. Chain Pliers
    Nowadays, chains use master links and don’t need chainbreakers (usually). Sure you can use a bit of your shoe string to separate a master link, and there are other tricks to reassemble one… but the right tool for the job weighs almost nothing and takes very little space. The pliers in the picture above are made by Park Tool. But these cheapo chain pliers work just as well at half the cost. I have a few of both. Make sure you buy a pair that can both separate and assemble (some just do one or the other).
  9. Battery Charger Adjustor (#0 phillips screwdriver)
    Since I carry along a portable, adjustable, weatherproof charger on this bike, A little screwdriver is needed to adjust the pots that govern target voltage and current (amps). Even though the one in my kit is inexpensive, an electrician’s insulated screwdriver like this is overkill. You can find something much smaller, like an eyeglass repair kit screwdriver.
  10. Metric Hex Wrenches
    Even though, on a bicycle, you only need about four sizes, I carry the whole set. For this XL bicycle with an XL toolkit, I am using the extra long ball-end wrenches. But for most of my bikes I use the short length wrench set. This is easily the heaviest tool in the kit, but its also the most useful. I like the USA-made Bondhus wrenches because they are a) cheap and b) made of strong tool steel. They will not round off.
  11. Chainbreaker (aka “chain rivet removal tool”)
    With master links now being in common use, a chainbreaker (and the black art of its use) is no longer essential on the side of the road. However, this tool can be the only one capable of fixing chain issues that decide if you are riding or walking. This mini version by Park is a bit more expensive than others, but it is very small – just large enough to use effectively. And it has something a lot of chainbreakers don’t: a second ‘shelf’ that the chosen few know how to use to unfreeze a link.

  12. Sized, Spare Chain (with fresh, reusable master links in the bag)
    This is the third and largest of the chain-related tools in this kit. A whole freaking chain! With the number of links needed to serve as a proper emergency substitute. In the case of this 11-speed Surly longtail bike, that means I have to use two chains sectioned together to hold roughly 210 links. If I am using the factory-stock 11-speed drivetrain, that means for normal daily riding I run two 11-speed ebike chains. Not cheap at almost $100 for the pair (thats the COVID shortage price. You should bargain-hunt when you don’t need them. I paid about $28 each for mine).

    Why bring a chain? Because we are using a mid drive for power-assist. Mid drives can eat chains. So just as you carry a spare tube and a patch kit… the smart mid drive rider brings along a spare chain. Goes with the territory.

    Since this is an emergency just-get-me-home chain, I use two KMC X11 chains, which only cost about half of the ‘e’ chain.
  13. 4″ and 6″ Adjustable Wrenches
    You’ll want to look at whether or not you need an adjustable wrench at all on your bike. In my case I do have some hex bolts with nuts. Realistically I can get away with just the 4″ wrench and as such I will probably get rid of the 6″ even though it is not especially large.
  14. Brake Blocks
    These are a good practice to use when pulling off a wheel if you have hydraulic brakes. Depressing the lever when the wheel is off the bike extends the pistons way further than they were meant to go, and that can cause the caliper to leak fluid… onto the pads. Thats a disaster that can even mean replacing the brake caliper. You can also use a popsicle stick, a bit of twig off of a nearby tree or a key from your keychain. But the Magura brakes I buy come with these brake blocks for free so I carry a pair along.

    The fact that these stupid things cost almost $10 each to actually buy is ridiculous. I have a stack of them from owning about 6 sets of brakes so that means I could sell them all on Fleabay for over $200?
  15. Fat Tire Hand Pump
    Now that I have the emergency portable electric pump, this one is a backup. But lordy… trying to use a hand pump to re-inflate a flat fat tire is a nightmare! But this unique Lezyne Micro Drive XL portable pump is a modern miracle. It will turn 400-500 pumps into … well, 200. Thats still awful until you sit down roadside and try and pump up a fat tire with 500 strokes of a normal portable pump. Then… only 200 is freaking great.

    Note you can also use 20g or 25g co2 cartridges – you’ll still need more than one cartridge of either of these expensive XL sizes. I have both. But since I have gone to using the portable electric pump, I have taken the single-use co2 inflators and cartridge piles out of service.
  16. Padding
    All of this junk in the bag does two things: a) it does not fill up the bag and b) it rattles around as I roll over things. So I stuff in some padding to help keep things from rattling. this yellow closed cell padding is extra left over from when I lined my Great Big Bags. It serves a second use: A knee pad for when I am down on the ground. Another excellent candidate for this sort of padding is a sized slice of Thermarest Classic padding.
  17. A Nice Soft Towel
    I roll up my adjustable and hex wrenches, plus the Ridiculous tire lever in the towel. Between the padding and the towel, there’s no rattling in the bag when the bike is going over bumps. Plus, a towel will always come in handy somewhere.

A Word On Tool Use

I try NOT to use tools that are half sized for easy packability, or otherwise downsized somehow (particularly multi-tools). When I work on my bike at home in my garage, I try and always use the tools in this bag. The idea is, if I am used to them – and they are as close to full size as is reasonably possible – then I am not handicapped when sitting on the side of the road, trying to do a job with tools that are half-assed.

Epilogue

So… thats it. All of the tools I carry on the bike. And yes thats plenty. But bear in mind this is a big bike and I am counting things in like pumps and chairs and such that take up a fair bit of space, and ordinarily aren’t looked at when it comes to tool kit inventory. I have plenty of bikes where all of the tools fit into a pouch behind the seat, and a frame pump is attached to a water bottle mount. What you see here is the most complete, more better version that, if you have the capacity, should solve all of your typical problems.

oh, and don’t forget to bring along your phone and at least a debit card 🙂

(e?)Bike Flat Prevention

As a daily rider for decades, I have some thoughts on this subject. Mostly along the lines of “no flats allowed, ever”.

This is Part 1. Part 2 focuses on tools to carry. This post was updated on 27 Dec to report the results of the tubeless installation with FlatOut sealant.

So… I try to ride to work every day. My office is 4.4 miles from my residence, but since I am trying to get as much exercise as I can, I may take up to 15.5 miles to get there. Thats all on city streets, which translates to potholes, nails, staples, steel shards, rabid rats and whatever else the mean streets throw at me.

With one break of about 15 years, ending about 5 years ago, I’ve been doing this since the mid-1970’s, and that includes shopping and errands as much as possible. I do actually own a couple of cars, but I’m trying to completely replace them.

I bought this station wagon factory-stock to carry bicycles without needing a rack… things got out of hand (Location: T8A @ Sonoma Raceway)

As such, I have spent more than enough time on the side of the road, dealing with punctured, flat and damaged tires.

There are five patches on this tube. It lasted until Hole #8 was finally too big to fix.

What Not To Do

Be a weight weenie. If you want the most responsive ride, and are willing to work thru flat tires to get it, fine keep your wheels light weight, your tubes ultralight and your tire casings thin. Thats not me and we’ll be doing the polar opposite of this philosophy: going almost literally for Bulletproof.

What TO Do

Everything described here is about flat prevention. I have tried just about every anti-flat tech there is. I won’t be describing all of it and just focus on where I have evolved to today – probably after trying a lot of other things that you are thinking about trying yourself. I am this kind of guy: I use the best. Not because I can afford to throw money at the problem but … because I need to keep rolling; not walking. Nothing sucks worse than flatting on a cold winter night after work (well, maybe getting hit by a car but you know what I mean). What you see here is what I’d call state of the art to keep me on the road and not on the side of it.

Belted Tires

If you have a bike where such tires can fit, these are the Holy Grail. I have found, for instance, the Continental Contact Plus City tire is to all intents and purposes invulnerable. I found it also wears like iron, so you will get lots of miles out of a set. It is E50 rated so its got a seriously sturdy casing.

It is less expensive than the Schwalbe Marathon Plus (which garners all the mindshare for this class of tire) but essentially the same performance: Flatproof. The Contis are cheaper because in part Continental is fighting to take market share from Schwalbe, and partly because they sell into ebike rental fleets where cost is a big factor.

If you can get this tire on your wheels, consider it seriously. Be aware however that it rides hard. In other words it sort of feels like you are rolling on a smooth rock (full suspension would be a big plus). Thats the price you pay for modern, genuinely flatproof tires so either live with it or look to a different solution.

If you have a fat bike, don’t worry about what flatproof tires would do to your ride comfort because you can’t get them for fat bikes. They would weigh a ton.

Thorn Resistant / tough / Smart Inner Tubes

I’ll make this simple: If using tubes, use thornproofs wherever possible. Always. Here again, if you own a fat bike you don’t have to worry about it because they don’t make them for fat sizes. Again because of the colossal weight.

For fat bike riders, scan the marketplace (it changes by the month) and look for the thickest tubes you can get: 1.2mm is the most I have been able to find, and only sporadically. The thicker the better.

What do I mean by “smart inner tubes”? Well, the tubes aren’t smart but you need to be when choosing the size. This is a little counter-intuitive, but you want to always try and oversize your tubes. If you have a 26×2.8″ tire, a 26×4.0″ tube is perfect for it. Why? Because the tube doesn’t blow up like a balloon inside of the tire. In fact it may not be distended in the slightest.

Try blowing a balloon up full and then barely touch it with a pin. BOOM. Now take another balloon and just put a puff or two of air into it, so its barely stretched out. Tap it here and there with that pin. Different result entirely. That same idea holds for tubes. The trick is if you are doing this, you are going to need to work more carefully to get that tube in under that tire safely without it getting pinched under the bead (top tip: Barely inflate it so it is not sufficient to hold shape… that will happen when you are stuffing the tire onto the bead). Once the tube is safely in and the tire is mounted, you are golden.

Oh and, like I said you need to be smart. So when using oversized tubes don’t overinflate the tire past its rated max. You will find that using a bigger tube means it is capable of tearing your tire apart from the inside. I’ve never seen anyone actually do this. Just Sayin’… don’t be That Guy.

DIY Belts Under Tires

There are many such products, with Mr. Tuffy being the oldest of the bunch and arguably the most effective. I started using Tuffy ages ago when it first came out, on road bike tires. That polyurethane formula was damn near impregnable. You did have to fiddle with it a little to get it centered on the tread, but the result was well worth the effort. Sadly I have found that the new-generation Mr. Tuffy that is made for Plus sized and fat tires (XL thru 4XL sizes) never met a nail it didn’t like. My Tuffy 4XL had a zero percent (0%) effectiveness rating at turning nails. I gave it plenty of chances to redeem itself. Its hard to hate the Tuffy people too much for this as a properly thick belt would (drumroll) weigh a ton. Sound familiar?

After decades of swearing by Tuffy, on fat tires I was forced to abandon it for what I consider to be its natural enemy…

Tube Sealant (Slime!)

With Mr. Tuffy failing to deliver in fat city riding (maybe it still works on goatheads), I turned to the most widely available and well known alternative: Slime tire sealant.

Remember… I am riding with tubes and not going tubeless. You CAN use tubeless sealant in inner tubes. I suggest you don’t. I have used both Stan’s Tire Sealant and Orange Seal Endurance Formula in tubes. Both did a great job of sealing the tire once the sealant leaked out of the holes in the tube… but the air kept coming out of the tube and leaked thru the spoke holes (that means a LOT of sealant gooshed out along with the air… that is a mess you need a toothbrush and an hour per wheel to clean up).

To be fair, I did have instances where both sealants worked to seal goathead thorn holes on a tubed tire. But after the above catastrophic failure (lots of goatheads… like 50 per tire) I abandoned tubeless sealants in tubes. They just do not have enough fibers to seal more-stretchy tubes with the same level of reliability as tube sealant.

Get the right TUBE sealant not the green-label tire sealant

Where was I? Oh right… Slime. Tubes. Slime worked very well for me, I found if I could hear the hiss-whack-hiss-whack-hiss quickly enough, I could jump off the bike (stopping first) pull the nail, jump back on and get rolling with enough air still in the tire the sealant could plug the hole. If I wasn’t so fast I might need some co2 to give a fast rush of air so I could get that roll on. And if I did have a leak that didn’t seal up completely, many times it slowed the leak enough I could turn and haul ass straight home so I could do my repairs sitting in my garage, with a soda and a sandwich, rather than sitting on a rock, or on the curb in the sun.

Slime was of course, a mess. A huge mess in some instances. But it worked. However it is only rated to work on holes up to 1/4″ in size. Over that and you could be walking. I’ve had that happen more than a few times (we’ll get to tools and roadside repair in the follow-on post to this one).

Slime is rated to last about two years before it dries out. I’ve had it dry sooner (about a year). Once its dry its worthless. You really should just replace the tube at that point as its really heavy and won’t do you any good any more. With respect to dosage: Rule of thumb from user groups (my experience is the same) is to double the recommended dose. A fat tire bike can and should use a full 8 oz bottle of the stuff. Work down in dosage as your tire size decreases.

While Slime has been knocked off of its pedestal by the following product, that product is I think still not quite fully proven. Thats why I am leaving a full discussion of Slime here rather than ignoring it as old news…

Tube Sealant (FlatOut)

So… Slime dries out and it is only good for holes up to roughly 1/4″ in your tube. Is there something better? It seems there is and its called FlatOut. You want to use the Sportsman Formula for a bike.

Unlike Slime and most sealants out there, FlatOut is advertised to last for “10+ years” which translates to “forever”. It doesn’t dry out.

It also advertises itself as working on holes up to 1/2″ wide. Double the size of Slime and other sealants. I’ve only been using it for a few months and a few hundred miles but it has already sealed a few holes for me… one of which was a piece of jagged metal so large I have to wonder if Slime could have handled it at all.

Again… get the right version!

It was enough to make me start believing the 1/2″ hole claim. Time will tell.

The label on FlatOut indicates nowhere that it can be used on bicycles of any type. Hearing that others had been using this but nobody could say for sure if it was fit for purpose, I called FlatOut and asked. I got hold of their product manager responsible for bikes. It turns out the Sportsman formula was tested extensively by a manufacturer who made hunting ebikes: for hunters heading out to game stands and blinds in the boondocks. The recommended dose for a 26″x4.0+ tire is a half bottle (16 oz). The recommended dose for a Plus sized tire is about 12 oz. For smaller tires… figure something out or call them and ask for guidance.

So the dosage for FlatOut is quite a bit more than the amount that you would put in for Slime. On the plus side, its a one-time application that could very well last the entire life of the tire: Set it and forget it.

Tire Armor

This one is kind of a new category unto itself. By and large it has one credible product in the category: Tannus Armour. Basically its just what it sounds like. A barrier that completely surrounds and protects the tire. Flexible enough not to ruin your ride and tough enough to stop stuff from coming thru.

There are a number of sizes. I can say the difficulty of installation can vary widely. My 29er has two slightly different tire sizes, one of which required a trim to fit. Difficulty of installation ranged from difficult to almost impossible. But I got it in. For those two installations I used thornproof tubes underneath and that probably kept me from damaging the tubes during the installation battle. Centering the armour under the tread was also difficult.

For the two fat bikes I have it installed in, both went in much more easily. One bike with 100mm rims and 26×4.8 Vee Snowshoe XL tires went smooth and easy. If anything the Tannus protected the tube completely as I levered the tire bead back onto the rim.

My second installation with 80mm rims and Vee Mission Command 26×4.7 tires was more difficult, but still ok. Part of the reason was the fact the claimed 4.7″ tire size is baloney and the Vee Mission Command is really a 4.3″ wide tire.

A couple of 26×4.0-4.8 Tannus inserts laying out so they flatten after being stuffed in their boxes.

I have heard complaints about the ride with Tannus underneath the tires, but I have not experienced any squishiness or anything else other than an obvious unsprung weight increase.

In the spirit of overkill, I also used FlatOut in the tubes under the Tannus Armour. So far so good no flats. But if you ride long enough you know you can go months with no problems… then your luck changes and you get three flats in a week.

I have also seen photos of Tannus Armour that has, over time and miles, compressed to being paper-thin. I’ll have to see whether that renders its protection less effective. Since as I mentioned above, I like to oversize tubes and the tubes I used under all of my Tannus installations were a bit over. In particular I used Vee 26″ x 3.5-5.0″ tubes which are small enough to work but also capable of fully expanding. So maybe that was a good choice given this potential scenario.

So only time will tell. Still, I have high hopes and believe my expectations are justified.

Tubeless Setup

Running tubeless is a whole different world. Here again, the right choices are simple and for simple reasons. You just have to hear what they are and the benefits should be obvious.

Tubeless Valve Choice

See the metal lip on the bottom of the Versavalve? Valves that don’t have them seem more prone to pull thru or eventually leak.

Any valve with a metal lip on the bottom. There aren’t too many of these on the market. The ones I use are from MBP and the Orange Seal Versavalve. The MBP valves are a bit less expensive but still totally solid on quality. The Versavalves give you more stuff along with the valve. Particularly a valve core remover that screws onto the valve and stays with the wheel permanently, staying right where you could need it as opposed to being *somewhere* but you are not sure what pouch you put it in when you need it.

Why does that bottom lip matter? Because it provides a solid backstop for the gasket that sits on top of it. When you screw down the valve the gasket is smooshed into the rim hole; sealing it to the rim whether it wants to or not. For a different kind of valve with just a rubber gasket glued to the bottom, well if you have to screw it down tight, you could end up pulling the valve clean thru the rim. Also the valve is not held in a vise like it is with a metal lower lip.

Like everyone else on the planet I first tried Stan’s Notubes valves and sealant. I found these valves worked perfectly on the first seal, but over time – especially when adding air down the road – they leaked no matter what I tried (including the standard pliers-on-the-valve-nut bit). Replacing them with MBP or Versavalves solved the problem instantly. Stan’s valves do not have a metal lip on the bottom.

Tubeless Sealant

In the long history of Serious Tubeless Sealant, there are only a couple of mass market players.

Stan’s Notubes Sealant

Ask any internet gathering what sealant to use and you will hear a chorus of “Stans“. And to be fair, the stuff works, and it has been on the market for years reliably keeping people rolling rather than walking. I am one of them. But being the first to market, and not really having noticeably changed over the years, I don’t think its the market leader anymore in terms of performance. You can depend on it, but it has some limitations. For starters, it dries out fairly quickly. The mfr says it will last from two to seven months. Thats not a lot but back in the day it was still a miracle just to have the stuff in the tire with no tubes, and for it to work. In my experience Stan’s lifespan is a lot closer to seven months than it is to two. This may be because I use it in thick-casing mtb tires.

Next, its formula has ammonia in it… and that can be corrosive to your rims. Yes really. Google it for details if you like. Suffice it to say this is not a good thing.

Lastly… remember I mentioned that Stans dries out fairly quickly? Well how it dries is a bit of a subject all to itself. Google “Stan’s boogers” and click on the image results to see what it becomes. This translates to your not only needing to add more sealant, but to also clean out the boogers on occasion.

Orange Seal Endurance

The Other Leading Brand (which seems to be slowly replacing Stans as the de-facto recommendation) is Orange Seal. By all accounts, it works a little better than Stan’s to initially seal up stubborn wheels. Depending on who you ask, it either lasts longer. Or not as long. Yay internet! The Endurance formula is advertised to have a lifespan of six months. I have found this 6-month span to be about right. And when it does dry out… no boogers! It dries into a thin, spread-out, easily removable coating on the inside of your tire. Not enough to throw it out of balance. So every few months you add more and you can ignore cleaning it out.

Orange Seal and Stan’s both seem to last longer than advertised. But both have a finite lifespan.

So which is better?

Both work fine but I give the nod to Orange Seal for convenience and no corrosion issues. One thing is for sure: Both of these sealants are more suited to small pinholes (think goatheads) than they are large tears…. jagged metal and your garden variety construction site drive-by pickups. They just aren’t made for that kind of puncture. Even Slime is better at that sort of thing thanks to its thick gooey fibrous nature versus tubeless sealant’s watery liquid latex composition.

There are some new kids on the block, however, that seem to eat the big stuff up.

Black Ox Sealant

This stuff is amazing. Just watch the videos on how it seals tires up. Whats not to love about it? Its brand new on the market and relatively unknown at present. I contacted the mfr and asked them about the product’s longevity. They responded that they are still determining that (like I said… new on the market). For that reason, I’ll keep an eye on it… and wait and see.

FlatOut

Yup… FlatOut Sportsman Formula. Same stuff as was described in the Tubes section above. On the Amazon product page linked here there are videos of ridiculously large holes being nearly instantly sealed by this stuff. When I discussed the product with them, they noted they have versions for military use that seal holes up to 1.5″ wide (not highway safe but doesn’t need to be). I can personally confirm FlatOut sealed a hole on one of my bikes, from a large jagged piece of metal, that I doubt Slime could have handled… Never mind Stans or Orange Seal.

It seems the equal of the Black Ox stuff in terms of sealing hole size, and they say out loud it lasts the life of the tire. FlatOut is also a lubricant so I can see using a bit of it on the lip of the rim helping to mount a tire (instead of the dish soap I use now).

In my discussion with FlatOut I asked about using it as a tubeless sealant… something they had not tried or tested. I had a game plan as a result of that conversation where they suggested to ensure an initial seal at bead seating, paint the bead with FlatOut to ensure that initial pop and seal, then load the tire up thru the valve core as usual.

Did it work? Well, I put it into play the same day this post went live, and here’s the update: Yes. Perfectly in fact. The bead-painting trick was not necessary. the bead was seated as usual with a blast of compressed air, and the sealant added after this just like any other tubeless installation. In the first few days I was losing about a pound of air per day and expecting to need to refill each tire roughly once per week. Since then the air loss has slowed and I have only needed to refill air once in about a month, after the first week. Tires are still holding without any apparent loss.

I’m running 90mm Nextie carbon deep dish rims, 1″ gorilla tape over the center depression (a unique issue with my rims) covered over by 85mm Whisky tape. 26″x4.7″ Vee Snowshoe XL tires on top.

From the looks of it, I have a sealant that never dries out and is capable of handling some of the worst things that can happen to a bike tire.

Exciting!

A Lightweight Electric Emergency Bike Pump

Got an ebike? Use the big battery you are already lugging around to power a small portable pump.

Me personally, I like to ride around on ebikes with fat tires, and I have several of them. The most recent addition to The Pacific Fleet is my Surly Big Fat Dummy. Its a monstrous cargo bike that, for me, doubles as a commuter. A few nights ago, on my way home from work – in the dark – I picked up a piece of twisted metal in my back tire. Part of the reinflation process (I use Flatout tire sealant so you need air in the tires as they spin around and seal the hole) requires air in the tires.

Because I wasn’t paying close enough attention, by the time I got the bike pulled over and the metal removed, my 26×4.3″ tire was flat as a pancake. Fortunately, I had a painless solution in my panniers and that solution is the subject of this post.

Now, when it comes to bicycle commuting this ain’t my first rodeo. I have always carried a Lezyne portable fat bike pump and it makes pumping fat bike tires tolerable. But its still far from ideal. Life sucks while you are putting in those 250+ pump strokes. And it ain’t quick by any stretch. If your tire is leaking air while you are pumping, the pump may not be a workable solution. As a backup I used to carry 25g co2 cartridges. Two of those monsters would blast a fat tire up far enough, fast enough, to be able to jump back on the bike and roll a half block or so to let the tire sealant do its job. Followed by another 250 pumps to get the now sealed but mostly-flat-again tire back up to rideable pressure.

But… you can only carry so many single-use co2 cartridges, and they are very pricey at that large size. Some time ago I came across a better way to deal with this issue.

The Portable Pump Solution

Wouldn’t it be nice if you could just connect a hose to a small portable compressor, flick a switch and pump up your tire? And the compressor pumped fast enough to outpace even nail-sized holes in your tube or tire? Well, portable pumps like that have been around for quite a while. Small automotive ones connect to your cigarette lighter plug in your car (I have this one in mine). Unfortunately they run on 12v DC. Your ebike is running at least 36v DC and likely more. So you can’t use those. There are plenty of pumps available that have their own internal battery… but batteries are heavy and so are those pumps. Besides. You already have a great big battery on the bike. Why can’t you use it?

Well, you can but you need a pump that can run on 48v. Fortunately they do exist but you have to look for them. Here is the one I use, purchased from Amazon.

Yeah yeah. I know. China. If you can find a USA-made portable pump that runs directly on a 48v power source, feel free to drop me a line and I’ll add it in here. As it stands, there are only a very few such pumps readily visible on the market and they are all from the Far East. I have used them a half dozen times without incident. Will they last forever? Good question. I do still carry my hand pump just in case.

DIY a Battery Plug

As you may have noticed from the pictures, the pump has an odd plug on it. What you want to do is plug straight into your main battery. To do that you are going to have to get your hands dirty. From here on, I’ll give a step-by-step on how to make this happen.

Step 1: Snip off the plug

View of the cut off plug and spread pump wires

This one is pretty simple. Take a pair of scissors and snip off the plug.

Step 2: spread and strip the wire ends

You can see the wire strippers I used in the picture above. I used the 18ga hole, and I left about twice as much bare wire as I ordinarily need for a crimp connector. These wires are so thin I want to fold it back so the butt-end connector I will use has more material to grab onto.

Step 3: Determine which wire is hot

Yeah thats right. The plug gives us no indication which is the hot wire, so we have to figure that out for ourselves. What I do is bring out a bike battery and connect a bare XT90 pigtail to its output cord. This in turn gives me a bare, hot lead that I had sure better be careful with, and so must you.

View of the bare hot wire setup
Those are bare live wires on the end of that pigtail! Be careful.

So the next move is to bring the bare, stripped pump wires up to the bare battery wires and – after turning on the pump, touch the wires together to see which combination fires up the pump. Getting it wrong will not hurt anything. Just try the other combination if your first try doesn’t work.

View of the marked hot wire next to the live bare wires
When you know which wire is hot, mark it. I used a bit of red heatshrink pushed over the wire end.

As soon as you have marked your hot wire, disconnect the pigtail so you don’t have bare hot wires waiting to say hi to the cat.

Step 4: Make the connection

My choice for this job is a combination of the following:
1. Marine adhesive butt-end connectors
2. Adhesive heatshrink over the individual wires on each side
3. Adhesive Heatshrink over the butt-end connectors

I’m looking to make a reinforced and solid connection since the wires on the Chinese side are pretty flimsy. Here’s what it looks like after I have crimped the wires together, but before I have done the final heatshrink of first the connectors, and then the sheathing over them.

overall view of the connection prior to heatshrink activation

Notice the different colored rings on each side of the connections?

Closeup view of the wire connectors

I used ‘step down’ connectors because the pump side wire was so much thinner. 18 gauge if we are being generous and probably 20 gauge if we are being accurate. This is why I folded the pump wires over to double them up. Which will only give more material to the crimp itself. The true strength of the connection comes mostly from the connector ends, plus the adhesive sheathing over top of that.

Step 5: Activate the Heatshrink (last step)

Finally, heat shrink the connectors first, then the individual wire sheaths, and finally the connector sheaths that also go over top of the individual small wires. BE CAREFUL on the pump side as the pump wire is very intolerant of heat and will happily melt on you even with mild heat. I use a heat gun set to low. You could get away with a hair dryer. I wouldn’t want to use an open flame due to the fragility of the pump wires.

View of finished plug
The layered heatshrink is not particularly flexible but it greatly strengthens and stabilizes the connection.

Epilogue

View of finished pump
I have added a Presta adapter to the end of the pump hose. Because I opted for a strong rather than a flexible connection, the battery plug no longer folds into the cubby on the pump.

At this point we just toss our pump into a bag to protect it from everyday rummaging, and that bag into our panniers. We’ll all hope we never have to use it, but we will of course.

View of pump inside carry bag