Surly Big Fat Dummy Wideloaders

“Wideloaders” are a load-supporting framework that sit level to the rear axle on a cargo bike. They are not made for the Surly Big Fat Dummy, but the frame has fittings to attach them. Here is how I made mine with no special tools or fabrication skills.

The Surly BFD Project Menu
Prologue
Episode 1: 138L (each) Panniers… Seriously?!
Episode 2: Big Fat Dumb Wideloaders (you are here)
Episode 3: Kickstand Kaos
Episode 4: Add a Flight Deck. And a Hangar
Episode 5: Odds and Ends

Do It Yourself (its not like you have a choice)

Wideloaders go hand in hand with the use of XL panniers like Great Big Bags 2.0. If you have wideloaders that your bags sit on, it lets the frame support part of the load directly and increases carry capacity. So, for my Surly Big Fat Dummy, I definitely wanted these.

Big Fat Problem

The Big Fat Dummy is a unique frame design. It is similar to the Surly Big Dummy. There’s a family resemblance to XtraCycle-compatible frames. There are many factory-original and aftermarket options for those bikes, but similar is not ‘identical’ or even ‘compatible’. BFD owners figure this out pretty quick.

The image below shows a bright green Surly Big Dummy frame overlaid onto a Big Fat Dummy frame. The front wideloader mounting points are lined up (look for the frame hole/white circle on the bottom tube extension, aft of the bottom bracket). This overlay makes it clear the rear mount holes don’t match. You need wideloaders designed specifically for the Big Fat Dummy frame.

Image credit: Surly Bikes (click image for original page)

Unfortunately that product doesn’t exist. If you want them, you make them. So I did.

Lets Get Started

Your wideloaders are going to mount in the front and rear hollow tubes that already exist in the frame. These cross-tubes are both 7/8″ Inside Diameter (ID), so you will need to buy 7/8″ Outside Diameter (OD) tubing. Luckily, this is widely available. However you will find a variety of thicknesses, heat treatments and alloys. I’ll pass along what I think is the best to use, and, well, what I used. I’ll let you decide whether or not to follow my lead or make some changes, as what I did turned out to be really REALLY heavy duty, but also heavy for what it is.

What about copper tubes?
You can go a different way and use copper tubing and soldered joints for a very, very cool look. But its no lighter than the alloy and screw-together approach I used, requires semi-permanent solder connections and a whole lot more effort (and money) to put together. It will look incredible when its done though. If you go this route yourself, note that copper tubing is designed to have a specific liquid flow rate, so it is measured via its Inside Diameter rather than Outside. So while I am using 7/8″ tubing, your typical copper tubing that fits is going to be known as 3/4″ tubing. The deciding factor to proper fit will be wall thickness so pay attention when you are doing your buying.

Parts List

27.49  6063-T5 7/8" OD x 7/16" ID (0.219" wall) x 8 ft
43.00  AL7005 22.2mm OD x 1.8mm wall x 1000mm len (qty 4)
43.96  Stainless boat hand rail 90-degree elbow (qty 4)
43.92  Stainless boat hand rail Tee (qty 4)
12.88  Stainless Mil Spec 0.89" ID Washer 10 pak
11.98  2:1 1" heat shrink - 25 ft
14.98  Reinforced 7/8" ID garbage disposal hose
       (10 ft) (qty 2 optional)
 3.00  Stainless steel M5 socket caps
       flat washers
       nylock nuts (2 ea)
29.74  2" x 30" hook/loop cinch straps 6 pak (qty 2)
31.90  Ratchet tubing cutter (optional)
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In original build but replaceable with disposal hose
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12.74  Corrosion resistant sleeve bearing (2)
 6.24  Abrasion-resistant cushioning washer 10 pak

Total project cost (not counting shipping): About $247.00. $277 with the optional tubing cutter.

Notes on the Parts List

6063-T5 Tubing

This is an extreme-duty choice and possibly overkill. With a wall thickness of almost 1/4″, this is heavy freaking tubing. But using two of these as thru-frame cross-pieces, your wideloaders will not bend even with well over 100 lbs of cargo loaded on them. My record is about 160 lbs (72.5 kg) and I have to say I was glad to have this uber-tubing, especially when I was hitting surface imperfections… an overloaded bike that weighs over 500 lbs with the rider onboard is not nimble in any way, and that means you have no choice but to roll over things you would rather not on the ride home.

This tubing is too thick for the tubing cutter so you can either start it with the cutter to make your life a little easier when you switch to a standard-issue hacksaw, or find some other method of cutting this very thick tubing. Me, I used the cutter+hacksaw method which worked fine, but was something of a pain in the ass.

AL7005 Tubing

This stuff is sold in metric measurements since it is coming from a bicycle tubing supplier, but the measurements translate to 7/8″ OD tubing with walls about 0.071″ thick, in individual lengths of 39″. That is roughly the thickness of bicycle handlebars, and as aluminum stock tubing goes, it is still quite thick. Its also much lighter than the 6063 I used for the crossbars. You can substitute two tubes of this material for crossbars less insanely thick than the 6063. They may in fact be plenty strong for you. Since I have a powerful electric mid drive on my bike, the ability to endure severe punishment was valued over weight.

The pipe cutter makes life a whole lot easier.

Stainless Boat Rail Fittings

Being thick stainless steel, these marine boat fittings are all about durability and strength. Also they are heavy as hell for bicycle components. Once again, this is a job where weight weenies need not apply. You put these suckers on and screw down their grub screws into the softer alloy tubing and they will hold fast, regardless of whether or not you forget how wide the bike is and walk it into a stucco wall … in that contest, the wall loses.

hmmm… This piece is not on the parts list

Worth Noting: In many of the pics here, you will see I am using tee and quad-fittings that allow more connections than are necessary for the project in this post. Thats because I was developing this project with an additional integrated center-mount kickstand in mind. We’ll save that for a separate article. Stick to the parts in the parts list to just build the wideloaders.

Garbage Disposal Hose

What in the hell is that doing on this list? Fact is, I didn’t build my wideloaders originally with this in the parts list. You will see many pics here with the older bushings, washers and heatshrink tubing for coating. I got the idea a few months afterwards. Covering the outer tubes in thick tubing permanently dingproofs them and helps protect whatever I lean the bike up against.

Once I found cheap PVC garbage disposal hose, I realized I could further use it to replace almost all of the washers and spacers in the build.

Originally I used 3 layers of cheap heatshrink to cover the tubes, plus bushings and washers. The garbage disposal tubing replaces all of it and saves about $30 on project cost.

Since I had already built mine, I personally only used the disposal hose on the outer facing tubes, leaving the two inner lengthwise tubes covered in heatshrink. However, you could buy two units of the disposal hose, drop the heat shrink from your parts list and sheathe all of your tubing in the disposal hose. Simpler, looks kinda neat and about the same cost.

25 feet of Heat Shrink

The need for this stuff was largely eliminated with the use of the garbage disposal hose. However you still need about 2 feet of it (20″, actually) to line the crossbars inside the frame. In a cruel lesson in Chinese capitalism, 10 feet of 2:1 heat shrink is one cent more expensive than 25 feet. So what the hell lets get some extra. Also, the 3:1 that is widely available in shorter lengths is the marine grade with adhesive glue inside and thats too thick for our crossbar liners. So… maybe its not a bad idea to check your local hardware store before buying this stuff. Its not going to be any cheaper but if you don’t want an extra 23 feet of 1″ heat shrink tubing sitting in a drawer for the next decade, a local buy might fix that.

The Sleeve Bearings and Washers

I used these in my original build and you can see them in all the pics. They were optional then and, later on when I discovered the garbage disposal tubing, were replaceable in the project. The one remnant I would still use regardless are the “mil spec” steel washers. Why milspec? They are cut to closer tolerances than ordinary washers. If you want a really snug fit to your tubing, with a not-gigantic OD to go along with it, these milspec washers are pretty much the best option I could find.

If you use the disposal hose to replace the cushioning washers and bushings for spacing, I would still use the mil spec washers up against the frame to ensure the most solid contact possible.

Set the fastening screws facing UP on your tee fittings. If they come loose you stand a chance of seeing the problem before they become UFOs.

Construction / Assembly

NOTE: While I often go into painful levels of detail, I won’t be specifying measurements on cut dimensions. I don’t want you taking my word for what works on your bike and your fittings. I’ll make one exception to this: The width of the crossbars, since that requires some thought and is worth discussion. We’ll get into that below.

Step 1: Cut the Crossbars to Desired Width

This is maybe your most important decision of this project. How wide are you going to go? You’ll have to put your thinking cap on, because this width will determine what things you will bump into while trying to move the bike around, or smash into as you try and negotiate a narrow passageway (like a shared use path entrance). A good rule of thumb for maximum width is ‘no wider than your handlebars’. That will mean that whatever you are riding thru, if your handlebars fit then most likely the wideloaders will not snag on it, either.

While you are figuring this width out, know that the center section of the Surly Big Fat Dummy is exactly 10″ wide.

So, the BFD 26″ bike in Bliolet uses Answer ProTaper bars, which are 810mm wide. That works out to almost 32″ of width, give or take. So knock 10″ off of 32″ (the width of the center section) and divide by two. Following the no-wider-than-handlebars limit, that means you would have wideloaders 11″ on each side. The crossbar would be 32″ in total width.

Thats way too wide. Forget about that rule. It sounds like a good thing to have all that room for gear, but it will be VERY ungainly to have that much hanging off the side. Don’t even think about it. Another issue it will create is trying to get the bike thru a door. Think about how much fun it will be to get a bike that is 32″ wide (and almost 8 feet long) thru a doorway that is commonly no more than 36″ wide. And some doors are 32″ wide.

I settled on a bar that is 26″ in length. Subtracting the 10″ center section and dividing the remainder, that means I have an 8″ crossbar extension. The elbow will extend my width a bit more so figure in the end, I have about a 28″ wide rear platform. Here again the dictating factor is getting thru a doorway (I park in a garage every day and bring the bike in thru a normal door that I have to enter from a sharp angle).

If you are unsure, its better to guess on the too-wide side since it is a whole lot easier to file or cut metal off than it is to put it back on again (fun fact: this is also the First Rule of Gunsmithing).

Step 2: Drill And Fit the Crossbars

This part is easy. I took the 26″ cut crossbar and measured it to 13″. Then I used a red Sharpie to mark the center. In the pic below, a test-fit, you can see the red mark coming thru the centered frame hole. Once you have confirmed the spot is in the right place (measure!), pull the tube out and drill a centered hole straight thru at the spot of that marker dot. Drill large enough for an M6 bolt.

Finalize Crossbar Fitment

Once you have drilled that hole you can fit the tubing right inside the 7/8″ ID frame tubing and attach the crossbar, centered exactly to the frame and fixed in place with a stainless M6 socket cap bolt, nylock nut and a washer on each side. However, there will be a small amount of play between the crossbar and the frame, which means these things will rattle. We can’t have that.

  1. Add a length of heatshrink – cut to a 10″ length to the center section of the crossbar. Using your heat gun, shrink the tubing so it sits tight on the very center of the crossbar. The hole you drilled will be a clearly visible depression on the bar.
  2. Get a bit of dishwashing liquid or similar non-permanent lubricant and smear it over the now-snug heatshrink.
  3. Push the crossbar into the frame. It will now be very snug thanks to the added diameter of the heatshrink. The dishwashing liquid will let you push the bar into the hole while leaving the heatshrink attached and placed on the center. You may have to experiment with lesser lengths of heatshrink as it might want to be pushed back by the frame as you get further into the frame and closer to centering it (I had to spiral wrap sandpaper on a wooden dowel and run it thru a few times to debur the interior of the frame. If you already own a cylinder hone of the right size this is a place you might carefully use it).
  4. As you push thru, when you see the depression in the center frame hole where heatshrink sags in under your drilled bolt hole, stop. Now just shove the washer’d bolt into that hole. It will break the heatshrink on its own. Clamp in with the nut on the other side.
  5. Repeat the process with the other bar.
  6. Your crossbars are now tightly fit, will not rattle and are centered and bolted into the frame.

Step 3: Fit the Tee’s and Inner Lengthwise Bars

Now that the crossbars are bolted in, its time to attach the inner bars. What you see in the pic below is a test fit where I hadn’t yet finished Step 1 above. The crossbars aren’t yet bolted in. But the procedure is well-illustrated. Loosen the grub screw on your front tee. Stuff the bar into it until it stops. Measure how far it went in. Position the bar atop the rear tee. Its going to go in the same distance, so measure accordingly. Thats your tube length. Cut to size and if it fits, do one more like it for the other side.

To do the actual fitting once the tube is cut, loosen the grub screws in the tees so they are still in place, but do not intrude at all into their opening (or remove them completely and stash in a safe place). Place the cut tube ends into each of the tees. Make sure the grub screw holes are facing up for both tees. Now slide this assembly over the attached crossbars and slide them inward to their final position. If they do not slide smoothly to the interior – if they hang up halfway down the crossbar for instance – you may have cut your tube a bit too long and need to make a second cut, or do some filing if its a near thing.

This is a good time to mention that for placement on the drive side, you want the inner bar to clear the derailleur when it is on the smallest cog, with some extra room to spare that allows for frame flex (although these wideloaders can’t help but stiffen the frame). Keep this in mind when you are deciding final placement on the drive side inner bar.

When the tees and tube are sitting, unbolted, in place, move on to the next step.

Step 4: Fit the Elbows and Outer Lengthwise Bars.

Repeat the process from Step 3 for the outer bars. This time measure fitment with the 90-degree elbows. In the pic below note I had a tee in place in the rear – I was considering doing an extension out behind. In the end I thought an 8-foot-long bicycle was plenty and squared it up with an elbow.

After cutting the tubes, do the same procedure as in the previous step with regard to placing the bar and elbows onto the frame without permanently attaching anything.

When the tubes are all cut, everything is lined up and you know it all fits, its time for Step 5.

Step 5: Add The Bumpers / Final Assembly

Since you didn’t actually tighten anything down in Steps 3 and 4 above, its easy to take it all back apart. Do so now, leaving only the crossbars, which should already be firmly assembled. Your next moves, in order:

Straighten out Your lengthwise (long) pieces of Disposal Hose

OK this is out of order because you should do this a day or two in advance of your actual build party. You want to give the hose some time to uncurl itself.

Off the shelf the hose is kind of a pain in the ass to deal with, considering between two and four lengths of it need to be cut fairly precisely to a bit under a 3-foot length. I found two ways to deal with this (and used both of them). First, the easiest way:

If you have some long lengths of 1 1/2″ hard PVC pipe laying around, stuff this curved tubing inside of it. Let it sit like this. You can do it with 1 1/4″ PVC but its a tight fit and really tough to get it thru in lengths any longer than about 3 feet.

If you don’t have PVC, use your actual wideloader tubing. If you are following the parts list above you have four individual tubes that are longer than you will need. Work with those. This is going to be a snug fit and require some elbow grease to stuff it on there. I stuffed on a couple of feet, then dripped on some WD40 and let it penetrate (there’s a bit of slack to let it dribble in) and just worked it. Once I had used enough of it (used… not over-used), and let it spread, they slid on and off easily. But it takes a little time and patience. Afterwards, wipe off the tubes. I didn’t worry about the residual WD40 inside the hose itself. Just enough remained to make final assembly straightforward.

I let this sit overnight and added a length of PVC on the still curly side to help straighten the rest of it

Cut spacers for frame-to-inner-tee fitting

You will cut spacers to desired lengths from the disposal hose. On each corner, use one of the milspec washers up against the frame for a total of 4 washers needed. The milspec sizing will give the washer a nice even fit.

On the build you see pictured, I used 1.5″ corrosion resistant bushings in the rear for a nice look and exactly the spacing from the frame I wanted. In the front, I stacked three of the rubber cushioning washers, sandwiched by two milspec washers. This front scheme was a leftover from earlier plans that did not include bolting in the front crossbar. Thats what you get when you plan a build and buy parts before you get the bike in hand to work with directly. You will want to just cut a short length of hose and back it with a washer.

Line the inner lengthwise bars

You are going to do one of three things here:

  1. Line the inner bar with 2 or 3 layers of heatshrink. Do multiple layers in case you scuff or ding the bar. Just one layer is easily torn. This was my initial build because its all I had figured out how to do at the time.
  2. Line the inner bar with a length of garbage disposal hose. to match all the other bars. Using the disposal hose is cosmetic on the inner bar, but it is more durable and will give you a consistent, beefy look. Doing this is almost the same cost as using the comparatively fragile heatshrink. If starting over from scratch, I would go this route.
  3. Do nothing and leave the bar bare. If you like the bare look then great you are done.

Install the inner lengthwise bars

At this point you are ready to do the final install of the inner lengthwise bars. Having attached any desired covering to the bar, loosely reattach the tees to the bar and slide it on just as in Step 3, again making sure the grub screws for the tee fitting are facing up. When in place up against the spacers you cut and installed above, its time to tighten the screws.

This is one of the few times a thread locker is properly in order vs. being a misused crutch. I personally prefer Vibra Tite. The blue gel is easy to apply, never hardens and holds tight regardless of vibration and impacts over time. Goop up the threads of each grub screw and tighten them into the softer alloy tubing until they are roughly flush-fit to the fitting. Nothing is going anywhere once that is done.

Line the remainder of the crossbar

Now you need to line the next section of crossbar if you care to do so. At this point I will say that heatshrink should not be an option – go with the flexible PVC (or do nothing if thats your bag). Cut each length to size and slide onto the tube.

Line the outer bars (or don’t)

Almost the same procedure as the inners: Affix your elbows to the tube and attach the tube assembly to the crossbars. Now you know how much exposed crossbar there is. measure this and cut your outer bar liner/bumper. Tighten ONE of the elbows onto the outer bar and remove the elbow from the crossbars. Now you are holding the outer bar with one elbow attached. Take your cut liner and slide it down until it is snug against the installed elbow. If you cut the liner to the proper length, it is now installed perfectly centered.

Since I did my bumpers after the initial build, I lined the outer bars first – the inners are bare in this pic.

Install the outer bars

Loosely attach the second elbow to the outer bar. Slide the assembly over the crossbars. Tighten all the grub screws down so there are no gaps, using thread locker and again tightening so the grub screws are roughly flush with the outer wall of the fitting.

We’re almost done .

Step 6: Add the Floor (Straps)

Up to this point we’ve created an empty framework. It needs a floor to help hold up the Great Big Bags that will be sitting on top of it. I opted to use 2″ x 30″ hook-and-loop cinch straps, 4 on each side, which are movable, super lightweight, have some give to them but at the same time are very strong.

I had to buy two 6-packs of straps to get what I want, so I could add more straps, but 4 is enough and more importantly I can space the straps in such a way they work in complement to the four pannier straps I use to provide additional support on heavy loads.

Since the bag straps also have to wrap around the inner bars of the wideloaders, the floor straps have to be out of the way, and what you see is spaced out to let me interleave the bag straps between the floor straps.

A Final Note on the Floor

At around $30, the floor straps added a noticeable bump up in job cost. Is there a cheaper way to do this? Probably. I considered a bunch of ideas including diagonally (super thick) bungee cord widely woven into a floor. I have a spool of the stuff in my garage.

What about more tees and crossbars with the leftover tubing bits? Without question that would look great and be supremely sturdy… but is it necessary? I don’t think so, and I didn’t feel like taking the time, adding the weight or going to the expense. But for sure, it would look great. In the end I felt the straps got me to the finish line immediately and were easiest to manage over time.

The floor straps are spaced so I can interleave two more bag straps between the two center floor straps for extra support with heavy loads.

Job Done. They Work Great!

These pics are from the initial build, and reflect the parts I used for spacers at that time, along with some showing a different strap setup. Your results may vary so the bags you buy or build may dictate a still different approach.

The Pacific Fleet

or… I Have Too Many Damn Ebikes

Since I got back into bikes (thanks to ebikes being a viable platform to let this cardiac-issues ex-cyclist start riding again), I have gotten right back into building bikes up, oftentimes from scratch. At this point I really have to stop simply because I have no more room to park the things.

Up to this point I have only written about my Mongoose Envoy, a very recent arrival, and have just begun getting into my Surly Big Fat Dummy, which is more recent still.

What else is in the stable? I’ll do some very quick mentions here and then over time branch out and describe each more fully in separate posts.

The Great Pumpkin

So named because of its very nice bright candy orange color (done at a local powder coat shop for next to nothing) you can call this one my third generation of 2wd bikes. Twin 35a controllers. A single custom-built 30ah 52v (14S9P) battery with a BMS able to handle 90a continuous current. Twin 750w-rated geared hub motors that commonly peak (each) at over 1700w. This bike accelerates like a bullet if I let it do so. But to keep the frame in one piece and me from being launched into traffic I have toned down both motors. Now I am merely the first vehicle to the other side of the intersection after a stoplight turns green.

It has synchronized dual pedal assist as well as brake cutoffs that individually shut off both motors on application. It has thousands of miles on it; all street commuting. Gearing is set up for 34 mph at about 70 rpm cadence. That is just a bit faster than the motors can power the bike, so if I want to cruise down the street at 30+ mph I have to work at it a bit more than you would think for a fairly high powered ebike. I get a strong workout due to this gearing.

The frame is a chromoly Chumba Ursa Major, with a Surly Ice Cream Truck front fork where the brake adapter on that fork was specially modified to get around the ICT’s rear-wheel brake spacing.

2Fat

While the build of this bike pre-dates The Great Pumpkin, it was actually designed as a next-gen design to follow another 2wd bike (see the Purple Thing below) that pre-dated both bikes. So if the Pumpkin is 2wd 3.0, this one is 2wd 2.0. This one does not have the single unified battery, and its handlebar config is not as well done (two clocked-position throttles are on the left grip instead of one on each thumb… I hadn’t discovered shifters that would allow me to do the latter yet). However, it also sports a 30a, 1750w mid drive powering the back, and has the same fat hub motor as the Pumpkin powering the front. It too has dual pedal assist, but done in a completely different way given the dissimilar motors and controllers. 2Fat was created because of the learned weaknesses of even a powerful dual geared hub design in hill country. 2Fat was designed to climb walls effortlessly, and it will, without issues of overheating or strain.

100mm custom wheels with a DT 350 Big Ride ratchet rear hub and steel cassette body, Lynskey titanium frame is a prototype made along the lines of Chumba’s Ursa Major ti version of that frame. Possibly it was made as part of a pitch by Lynskey to make the frames for Chumba. Its hard to say for sure so essentially, the frame is unique, or close to it. I do know it is visually almost identical to the Chumba production models except the dimensions do not match any of their production frames.

The Smash

A big departure from my usual bikes. The Smash is a 29er … and a bike with no job. With a 3kw Cyc X1 Pro motor, a 50a ASI BAC800 controller and a 20ah 52v backpack battery, this bike is strictly a hot rod. And no, despite those big power numbers its not as powerful as you might think. Certainly it doesn’t tear up trails. This is one of the last alloy frames Guerrilla Gravity made before switching to carbon fiber later in the same month I placed my order. The MRP Ribbon fork on the front is a jewel. Also has a RockShox coil spring, a complete SRAM EX drivetrain and my usual Magura MT5e brakeset.

I’m glad I took these pics right after the build was completed because it will never be this clean again. Ever. Also the pump location and top tube bags only lasted as long as this photoshoot as they violated my ‘festooning’ rule.

The Fixed

An even bigger departure is my Luna Fixed, which despite having custom DT wheels, is largely a factory bike and was bought primarily as a test platform. I fell in love with the design concept (stealth ebike), but it also loved the fact it had an internally geared hub, a Gates belt drive and torque sensing. These were three technologies I had yet to experience and I decided this bike was going to be how I experienced all three on one bike. Its the only ebike I have ever ridden that feels like a road bike from the 1970’s. I re-did the handlebars to a more urban narrow config, added bar ends, changed the stem, saddle and pedals… not a lot else. Its for sale on eBay now as I’m largely done with it, its still effectively new and I never ride the thing.

The Stormtrooper

So named because of its black/white color scheme. The Stormtrooper is just a really nice, simple fat tired ebike – with deep dish 90mm carbon fiber rims. Noteworthy on this bike is that it has plenty of motor and battery cabling running all over the place, but I sheathed the wires (even the brake and shifter lines) in white heat shrink. The matching color effectively hides all the wiring in plain sight for a very clean look. the bike is light and fun, with good range from its mid-sized 12ah potted ‘indestructo’ battery.

This frame was a rescued Motobecane Lurch that was stripped, sand blasted and powder coated.

The Mongoose

One of the few bikes I have written up here, The Mongoose Envoy has its own extensive writeup already. The Pacific Fleet’s first aircraft carrier thanks to the 44″ skateboard deck.

The Big Fat Dummy

The most recent addition to the Pacific Fleet, The Surly Big Fat Dummy is its second aircraft carrier, with a 40″ skateboard deck (and below-deck hangar) putting the length of this behemoth at just over 8 feet. This bike is in the beginnings of its build writeup here on the site.


Sunk

In no particular order, the ships that are no longer in the fleet

Frankenbike

Now in the hands of a friend who needed a ride. Frankenbike was cobbled together from leftover parts from an upgraded electric bike, plus other goodies. It was my first 2-rack cargo-oriented bike. I painted the frame myself using Main Force Pursuit (MFP) Yellow. Google that if you don’t get it. The frame is identical to the Purple Thing, below.

The Stump

Murdered by a careless auto driver who t-boned it and me while I was thoughtlessly riding slow in the bike lane with headlights and after making eye contact. The Stump was a little hotrod that never made it past the initial shakedown cruises before its demise. Paid for by the other driver’s insurance company but left in my possession, I donated the damaged but still fully functional motor to another cyclist who could make good use of it

The Purple … Thing

Essentially this was 2wd 1.5. I transferred my parts from the 2wd 1.0 bike when I cracked the frame, and made a few improvements. Since it was an emergency build to get my daily commuter back on the road, I didn’t do a lot of measuring and took what I could get framewise. It didn’t quite fit me and a year later one of these motors and some of these parts moved to The Great Pumpkin. The frame is still sitting dust-covered in a corner of my garage.

The Colonel

The bike that got me started back on two wheels again and changed my life for the better. A Sondors Original fat ebike whose cost was so low at around $700, I was willing to toss the money out the window and take a chance this whole ebike thing was going to allow me to get back onto a bicycle. By the time my first year was up I had put more than 4000 miles on it. I had also changed out almost every component but the frame, and converted it to 2wd – something you will still see supposedly experienced builders tell you is impossible to properly function for a whole host of reasons that sound smart but are all dumb and wrong, and easily demonstrable as such if you build one with your hands rather than type about one with your fingertips on a keyboard.

The Colonel died with his boots on. After almost 6000 miles on the road, supporting a whole lot more power and speed than it was ever designed to bear by its original Chinese overlords, the rear seatstay cracked at the lower rack boss. My philosophy on frame cracks is not to repair them as where there’s one crack there will likely be more showing up soon. Components were transferred to The Purple Thing along with several upgrades.

Great Big Bags 2.0 – 138L (each) Panniers… Seriously?!

My first set of Big Bags were 77L each, almost the same size as the largest generally available cargo bike pannier (and 1/3 the price). It turns out you can go a lot bigger than that and stay practical.

The Surly BFD Project Menu
Prologue
Episode 1: 138L (each) Panniers… Seriously?! (you are here)
Episode 2: Big Fat Dumb Wideloaders
Episode 3: Kickstand Kaos
Episode 4: Add a Flight Deck. And a Hangar
Episode 5: Odds and Ends

When I put together my first set of Big and Cheap DIY Cargo Bike Bags, I thought two 77L panniers were huge! I fit them onto my Mongoose Envoy cargo bike project, and for several months they have been great, but not quite perfect. Not because of the capacity of the things. They were perfectly sized for that mid tail frame. But there were a few convenience issues … you’ll see below what my solutions were.

Why go bigger?

Well, I liked the Mongoose mid tail so much (it was my first dedicated cargo bike) I decided to jump all in and go for a full sized longtail with as much capacity as I could get my hands on. The Surly Big Fat Dummy was a bike I had *almost* bought before the Mongoose, and I decided with its fat tires, sheer size and very stiff frame it would offer the larger carry capacity and greater versatility I was after.

Going from a mid tail to a long tail meant I had more room for bigger bags. I could do the Rothco 77L canvas bags again, but after quite a bit of shopping around, I found Rothco’s larger, heavy-canvas 34″ long, square zipper’d duffel bag was dimensionally just about perfect to fit the BFD’s rear cargo area.

But, I am getting ahead of myself.

Parts List

$92.00 Rothco Jumbo Canvas Cargo Bag (qty 2)
  7.08 C.S. Osborne #5 5/8" hole Brass Grommets (qty 10)
 44.00 Cross Linked Polyethylene - 2lb, yellow 72"x48
 15.00 7/8" thick hardwood dowel (qty 2)
 20.00 12" soft cargo loops, 6 pak (qty 2)
  7.21 7/8" rubber chair feet 4 pak
 36.00 74" buckled 2" wide luggage strap 2 pak (qty 4)

Total Project Cost: About $221.00.
Result: 276L of pannier space. Two Hundred and Seventy Six Liters.

Notes on the Parts List

Foam
I am sure you can find something cheaper. I wanted something bright yellow so I could see the contents of the bag easily. Cross linked polyethylene is essentially a thin version of gym mat material. Extremely fine-celled. I have used Foam Factory for some esoteric jobs in business for custom cut stuff and found they had what I was after. What you want here is a big single sheet of foam that wraps entirely around the bag interior. The large foam sheet specified here is just over double what you need. Cut it in half, shave a few inches off one side and its a perfect fit. As an alternative you might try a couple of the Therma Rest mattresses that I used in my original bags, and some gorilla tape.

Grommets
You can also use #6 grommets just like I did with the original Big And Cheap Bags. It all depends on what tools you have in your garage. If you have no grommeting tools whatsoever, this #5 size midget grommet kit will give you everything you need – the tool and plenty of grommets. Cost is about $56 and you will have plenty of grommets left over so you can hammer reinforced holes into more things.

The Wooden Dowels
You can go to Home Depot and pay about half what you will at Amazon. Thats what I did, and HD has a handy manual-cut station you can use to cut the rod down if you don’t have a saw (please buy a saw instead). I only put Amazon as a source so there is an online purchase choice.

The Luggage Straps, Part 1
I specified four 2-paks for a total of 8 straps. 4 per side. Generally you only need two. But when carrying really heavy items, like the pictured load below (still in the shopping cart) that weighed about 128 lbs (58 kilos) … you want more straps to help take the burden off of your wideloaders. So, you can buy fewer straps. Or you can buy the max that will fit and toss the spares into your cavernous panniers and forget about them until they are needed. Your choice.

My first shopping trip with these bags was a Costco run. I didn’t realize I had almost 130 lbs in the cart. The duffel in the bottom goes onto the deck was at least another 20 (Just the lock is 15 lbs).

The Luggage Straps, Part 2
Notice in the pic above, and in my previous Big Bag posts, I used 2″ and then 3″ wide velcro straps (a single 3″ above). these hold fine, but in daily use, velcro is… velcro. It is constantly sticking to things it decides to stick to, and generally making my life more difficult. The straps do indeed do their job, but first and foremost just finding 3″ wide straps long enough to work with these bags is very difficult (and a process I will not describe since I abandoned them). Also these 3″ extra-long unicorns are just too damned expensive. Kydex buckled straps unbuckle in an instant, don’t stick to themselves or anything else, fit 4 to a side which is plenty and cost less to boot. Lastly, the luggage straps I am specifying adjust from 40″ to 74″ which is perfect for folding the bags up, empty, and expanding them out when full. Since the excess strap length is captured via a sewn-on sleeve, nothing is ever flopping around.

Whats With The Dowels?

My original Big Bags used hooks, and I went to a fair amount of trouble to make sure they were absolutely planted and rattle-free. And they are all that. But still, I thought there has to be a better way, and I ended up coming up with one.

Using dowels and cargo loops for hanging the bag has major benefits over hooks:

  • It doesn’t rattle
  • It is light weight (lighter still if you use an alloy tube)
  • It is cheap (less so if you go alloy)
  • It distributes the load on the bags evenly across their entire length
  • It holds them fully secure
  • There are no points of excessive wear/rubbing.

And last but not least, they make bag removal and reattachment a snap. The process described in a nutshell:

STEP 1: Loop-tie five cargo loops per side to the Dummy rails, and loop those up thru the deck itself so they drape down. If you are not making bags for a Surly or Xtracycle-compatible cargo bike, use as many loops per side as you can, as well-spaced as you can make them.

Here is one of my early fitments when I was figuring this all out.

STEP 2: Create 5 grommet holes in the top inside edge of each bag. One on each top corner, and the remaining three positioned so they are roughly equally spaced down the side of your rack. the exact positions will vary depending on your rack. I illustrated the whole grommet-creation process in the original bag creation post. But worth noting for these bags I used smaller #5 grommets and I really prefer this smaller size.

STEP 3: Line up your now-holey bag with the dangly loops and, one at a time, put each loop into each corresponding bag hole. As you do this, thread your dowel thru the loop on the inside of the bag.

Here is what this looks like with no bag in the middle


Annnnnd with the bag:

STEP 4: Remember the rubber chair feet? Put one on each end of the wooden dowel. This keeps the bag from rubbing on the edge of a relatively sharp edge of cut wood. Sooner or later it will rub enough to wear thru the canvas. But not if you have a big soft round rubber bumper on that edge.

Note the above pics show a 1.25″ wooden dowel. I downsized to 7/8″ and its much easier to fit the loops thru when putting the bag back on. You can see the smaller version in the pics below. Original concern was the dowel bending, but there are so many cargo loops to suspend it… thats not going to happen.

Spend a few minutes with some fine-grit sandpaper to make the imperfect surface of your dowel silky smooth.

Bag Removal and Re-Attachment

Here it is in a few easy steps. I photographed my first bag removal as you see, and I timed the second one with a stopwatch. It took 30 seconds to remove the bag from the bike and another 15 seconds to toss in the straps and zip the bag back up.

You can forget about making something that fast and easy with hooks.

STEP 1: Unbuckle the two bag straps. Pull the top inside corners of the bag back so each end of the wooden dowel is visible.

STEP 2: Pull off the rubber foot from one side. I removed the rear one this time.
STEP 3: Pull the dowel out from the other side. Its only halfway out in the picture. It will slide out quickly and easily.

STEP 4: DONE. The bag is now free. It is now a big duffel bag with handles you can lug into the house with all its contents. Feel free to use the shoulder strap that came with it.

Did I Mention The Kangaroo Pouch?

Yes really. Just like the original bags, Big Bags 2.0 are typically folded up when empty. The foam liner inside means the folds are fairly thick and a pouch is created in the fold. For bags this big, its pretty deep, too. And almost three feet long. Check out how I almost disappear a 2 lb sledgehammer into it, standing on its end, below.

That makes for secure storage of most daily-use items. On a typical day, a small backpack with my work clothes, pouch with my keys and alarm remote and garage door opener, and another with my wallet and phone are all snuggled in one side or the other. Road bounces and vibrations don’t disturb them, and there is enough room left over that I don’t have to open the bags up at all unless I am on a shopping trip. So as big as these things are, if anything they handle small jobs just as well as the the large ones they were designed for.

I used to think the 77L bags were crazy big. I spent a lot of time agonizing over whether I was wasting time and money even attempting to go bigger with these duffel bags. Now, having had some time to live with them and on more than one occasion to stuff them full, I can’t imagine why I would want to go smaller.

The Surly Big Fat Dummy Project

Prologue (you are here)
Episode 1: 138L (each) Panniers… Seriously?!
Episode 2: Big Fat Dumb Wideloaders
Episode 3: Kickstand Kaos
Episode 4: Add a Flight Deck. And a Hangar
Episode 5: Odds and Ends

Less than a year ago, I started the Mongoose Envoy Project. I loved the bike and – after dabbling with fast-carry-stuff ebikes for a few years (that ended up looking more like zombie-apocalypse bikes), it was my first actual purpose-built cargo bike.

The Mongoose Envoy, in its final form with the 44″ skateboard deck, indestructo wheels and big poofy tires

With respect to the cargo platform, I. Freaking. Loved. It. I am not a recreational rider. I never have been since I started riding in the 1970’s. I put in long commute rides, and I try and do as much as I can of my daily errands on a bike vs. uh… one of my automobiles. Yes I have to admit that while I am doing the whole save-the-planet schtick and trying not to drive, its because I love riding bikes and I always have.

I bought a station wagon because i hate bike racks and could put a bike in the back. Things got out of hand.

Anyway, where was I? Right. Cargo bikes. So… I built the Mongoose out until it was truly as perfect as it can be for its intended purpose. Its even a good value and componentwise I would put it up with just about any high end cargo bike. With that said, it has some problems.

  1. It doesn’t fit me quite right. Mostly in the upper body. I have done pretty much what I can to deal with this. A LOT of the problem has absolutely nothing to do with the bicycle and has everything to do with lingering injuries from when I was T-boned by an inattentive driver in a SMIDSY type collision. I did a passable Superman impression on the arc upwards… and a decent impression of Vinko Bokataj for the landing.
  2. It hurts to ride the damn thing. Again, this is all about residual pain from the above-referenced accident and has nothing to do with the bike. My wrists remain in bad shape, probably permanently, and while the Jones bars help by putting my hands at a better angle, I need both a higher upright riding position to take weight off my wrists, and a suspension fork to reduce the impacts that are part of normal street riding.
  3. As the cargo bike platform expanded my idea of what a bike could accomplish, I wanted more than the Envoy, with its mid-tail size and only plus-sized (after upgrading) tires could deliver. Go big or go home as the saying goes, and the Big Fat Dummy is arguably, physically the largest production 2-wheel bike on the planet.
  4. The addition of the larger 2.8″ plus sized tires on the Envoy worked so well, and I have done so much work with the fat tire platform, I wanted to go fat on a cargo bike and take advantage of the added capacity the fat tires give (and since my very first serious Costco run weighed in at a total of over 500 lbs counting me and the bike… good decision!)

So, this section of the blog, of which this page is only a teaser that will eventually house the episode menu, will document the custom work I have done on this bike. What is worth mentioning that is. This is not going to be a rivet-scraping pass over the bike. We’ll just hit the high points.

Planned (so far) Project Episodes

One bike to rule them all? So far yeah. Its all that.

Frankenstein Boots For The Ursus Jumbo

I had an aftermarket kickstand that was too short. Here’s a way to add a tough-as-shoe-leather extension that should last forever.

My Mongoose Envoy received a much-needed upgrade to its kickstand when I upgraded to an Ursus Jumbo, whose much-wider (18″) leg platform keeps the bike stable on uneven pavement or when it was heavily loaded.

The stock Envoy stand works well unless you have 100 lbs of groceries loaded up. Do that and .. oops you gently bumped the bike! Over it goes and boy does your life suck. You’ll have to unload the bags, stand the bike back up, uncrack the eggs and load back up again. Same deal happens when parked on an incline.

The Jumbo solved this problem given its obvious mechanical advantage.

Jumbo on… Skinny tires. Problem solved.

… until I put some big poofy 26×2.8 Vee Speedster tires on the bike, which raised the frame up probably a full inch; maybe more. That meant of the two legs that Ursus kickstand has, only one of them was on the ground at any one time. At first it was kind of fun to be able to lower the stand and roll the bike around, or out of my way with ease. Then I saw what a bad idea it was on a sloping driveway. The bike was happy to tip over. For a cargo bike that will be loaded, that has to change.

Fat tires tall. Fat tires good. Kickstand barely touching ground bad.

A couple of methods presented themselves. The first was to lower the stand by shimming the base. While I would have been able to find a longer M10 bolt to do the job, making a shim that will actually work is a lot more complex than just throwing in some washers and calling it good. Absent a mill and some billet to do some custom fabrication, shimming was a no-go. So, since I can’t make the base longer, that leaves only the legs. I had to make them longer.

Shoe Goo… To The Rescue!

I should be brought up on charges for that header. Couldn’t help myself, and besides its true. Shoe Goo is a shoe repair tool that is essentially replacement shoe leather. Or shoe adhesive to hold your precious Converse All Stars together after they came apart. Or both. For you shade tree mechanics, if you think of it as a hard rubber equivalent of JB Weld … you have it down.

I suggest buying the big tube. I used about one full tube per side.

So what I decided to do is to stick my kickstand upside down in a vise, block off the bottom of each leg with some painter’s tape, fill the resulting cup with goo and let it dry. Peel off the tape and I’ll have a longer kickstand with a new, tough-as-nails rubber foot.

It turned out to be a bit longer than that, and took quite a bit more time to cure. But layering on a bunch of goop to the bottom of the kickstand is the short version of what I did here. And best of all, it actually worked.

Time For Plan B

What you see above is only the first attempt, using green painter’s tape. And while it worked (see photos sans tape) it became clear just by looking at it I could expand the ‘foot’ to a much greater size if I taped off the base and poured in more goo. You can see this in the last two photos where the tape has been removed. the foot of the Jumbo has essentially a large hole in it that you can further tape off, then fill in. this time you need to tape halfway up the leg as that hole runs thru to the front of the stand, and your tape will provide a deep chamber for the goo to fill and harden into.

This time I used silicone tape, which I discovered by accident does not stick to Shoe Goo! Knowing that, I was able to use a scrap of tape to help sculpt the slowly hardening-but-still-pliable glob of goo. That matters because as this stuff dries – and then cures – it shrinks into itself. You will need to come back every couple of days to apply another layer. And when at some point you call the job done, you will want to let this material sit for at least another five days.

So if you are doing the math here, that means this is going to take time. I spent a total of about two weeks applying, filling again after it shrinks down and then letting it cure so its stable with a bike standing on it.

Is it worth the trouble? Well, I spent about $8 on two of the big tubes of goo and another nickel or so on a length of black rubber mastik tape around each foot to pretty them up. When I was done, I had a kickstand that completely solved my problem, and I can expect to be able to use for the life of the bike. If you want, Shoe Goo comes in a black formula that will have a matching look… but it costs more than double what the clear stuff does.

If You Do This…

I felt my way thru this project and learned as I went. The way YOU want to do it is skip the first stage with the green tape entirely. Use the silicone tape to wrap the entire foot. Wrap snugly at the bottom of the channel you want to fill, and as you get to the top – the actual extension to the base – do not wrap that tight, just do it loosely and make sure the tape wrap adheres to itself. Then inject the goo with a narrow nozzle (there are kits out there that have them) deep into the channel you just created, filling it from bottom to top until you have a single large ‘sole’ wrapped in the silicone tape.

Then, walk away from it for 24 hours. Add more goo as it cures and shrinks down. Use a scrap of silicone to pat down the added goo so it forms a nice smooth surface. If it seems solid, remember thats just the outer layer and inside its still like jelly. I went on a week’s vacation after I thought I had it done and it was pretty solid.

So… Wait it out. the results are worth it.

Mongoose Envoy Update – Cargo Deck 3.0

When I originally used a double-kick longboard deck to make an XL cargo carrying top for my Mongoose Envoy project, its 33″ (84cm) length and 10″ (25cm) width seemed really big.  Considering I was coming from a world of ordinary bike racks on normal-wheelbase bikes, it was quite large.

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Deck 1.0, shortly after installation. I try to avoid the word “festoon” to describe a bike build so those two little bags in back went away soon afterwards.

The XL deck worked *splendidly*.  I had no complaints whatsoever, and I could have left it like that forever.  However…

The board, by virtue of its 33″ length, only used 4 of the 5 available rows of M5 mounting bosses.  So I had definitely left some available space on the table.   In a perfect world, I would have found a longer version of the same board:  Say a 40″ double-kick.  But alas, at the time, I couldn’t find one.  I also could not find another board that had this same 10″ width.  Everything else was more narrow.  But I could get close with what became Deck 2.0: a 40″ x 9.75″ kicktail longboard.

It installed easy enough.  I painted it with Rustoleum truck bedliner to pebble the surface just right so it held onto gear a bit.  I used the same inverted grub-screws for drill guides like I describe in the Deck 1.0 post.   And the rack was now long enough so it used all 10 mounting points on the frame.  It couldn’t be more solid – the board is 8 layers of Canadian maple – and makes a sturdy handle I can use to pick the bike up and move it around from the rear.

And… its 40″ long.  With that solid center mount kickstand, its handy to have a coffee table with you wherever you go.  From a cargo standpoint I could easily net down a 3-foot duffel bag on top and still have room to spare.

Still, It didn’t work out quite the way I planned.  I thought I wanted to move the rack further forward so I could mount gear under the seat.  So I did that and the idea was to take up the otherwise wasted space just behind the seat.  But once I had it set up, I found the space effectively unusable.  I needed to keep some room back there for the Thudbuster to flex as part of its normal duty cycle, and my legs hit whatever was jacked up all the way to the front.

I also missed the front kick on Deck 1.0, which provided a natural slope to keep gear from sliding forward under hard braking.  As a substitute threaded a couple of M6 bolts directly into the M5 holes (no fixing nuts needed) that existed for the nonexistent trucks. These held down a simple 50-cent L bracket wrapped in my favorite padded rubber mastik tape.  It worked but in the end I removed it for aesthetic reasons. 

Lastly, I mounted the board just a hair too far forward, and occasionally I brushed it with my legs during the pedal stroke.  Not a big deal unless you are a perfectionist. I didn’t want to redrill the holes so I could move it back. It was a minor imperfection. So I left the board on for several months and it worked great.

But I did acquire a 44″x9″ kicktail longboard from Magneto, with the intention of using it on the back of a planned Surly Big Fat Dummy build.  That plan went away, and the 44″ board had no home… so what the hell lets put it on the Envoy.

While I was at it, I decided to make a couple of changes.  First of all, the Magneto board comes with an aggressive, highly abrasive grip coating on it.  I took an orbital sander and smoothed it down some so it would not potentially wear thru duffel bags and bits I’ll have netted down on top of it.

Next, I painted it with the same Rustoleum truck bed coating spray.  This took a little more of the harshness off the grip coating and gave the deck a tough finish.  I also decided to two-tone it with some medium gray paint on the underside.  It turns out this is totally invisible unless you are laying on the ground looking up at it.

Also, instead of re-using the 25mm post spacers, I bought new ones 40mm tall. These required longer 75mm bolts.  Having used the rack already for several months with 25mm between deck and frame, I wanted more room to move my hands in and out attaching/detaching net hooks, passing cinch straps thru etc.

It came out great.  This Magneto board is a sandwich of bamboo and maple so it has a touch of flex to it. This made  bolting to the somewhat uneven frame easier.  Its still rock solid despite the now 4″ longer tail out the back, which I do not notice from a convenience standpoint (its not too long, which I worried about).  The 40mm spacers are an absolutely perfect height to let me get my hands in there without being so long they compromise the solidity of the mount.

The board has a front kick, but it turns out it can’t easily be used, for the same reason I couldn’t use the front few inches on the 40″ deck. However it is slightly narrower than the shorter board so even though it is just as far forward, I no longer hit it with my legs.

As a gear-stop/bumper, I wanted something a bit more substantial than the half-assed L bracket I used on the shorter board, so I used a couple of the leftover 25x13mm M5 spacers, plus some 10x10mm spacers I had in my parts bin, to create some ‘electrode’ stanchions fore and aft.  With the large area washers at top, they either provide a bumper for gear stowed on the deck, solid purchase for a hook, or a place for my net to grab onto in the very back. Silicone grip scraps fit right over them to ensure the edges of the top washer don’t bite into my gear.

The two forward stanchions are extended from the deck mounting holes and go all the way thru to the frame.  They use 110mm M5 bolts.  The two in the rear use the rearmost holes drilled for the trucks. These use matching countersunk bolts and finishing washers like those used with all the other mounting hardware.

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A bit of scrap silicone handlebar grip tucks under the rear stanchions to provide a smooth, grippy place for my net to glom onto. You can stretch the net all the way back and over the kicktail, too.

Compare this pic above to the 40″ board and its clearly longer, but functionally, the increased length is no bother.  If I had to fit the bike on a train or bus then this is not the best solution.  At some point, if I need some extra carrying space out back, its available.  At present, I have an extended amount of space for my round 40″ duffel.

… and a bigger coffee table.

The BBSHD: Musical Chainrings

It seems inevitable.  When I build a bike, I go through front chainrings trying to get the gearing just to my liking.  My Mongoose Envoy build has pretty much set the world record for tweaks in this regard.  But gearing wasn’t the problem so much as chain alignment.  Alignment is one of the most talked about issues with mid drives and up to this point I have not had to work too hard to get it right.  This build, not so much but I think I finally got it (like $350 later).

While dealing with this I have fooled around with three different sets of crankarms (160’s, 170’s and 175’s).  Not the subject here so if you notice the different crankarms in the pics, I am ignoring them on purpose.

Sidebar:  When building the Surly Big Fat Dummy, I found exactly the same thing as I did here insofar as chain alignment is concerned.  And used the same solution – the USAMade adapter listed as an Honorable Mention below got pulled out of the parts pile and put to use.

The Right Tool For The Job

The Mongoose build is a first for me in many ways.  One thing in particular:  the BBSHD fits the frame really well.  Its a 68mm bottom bracket with absolutely zero chainstay obstruction for the secondary housing.  So I can butt the motor right up against the bottom bracket.  Further, its a lonnnng way back there so chain alignment and misalignment – an inevitable concern with an HD build – is a lot more forgiving since the angles are gentler thanks to the longer reach.  On this bike, if I want I can even forego the offset non-drive side crankarm and the pedals are still easily centered under me.  So the HD is a great fit here.

About That Job…

The Mongoose is a cargo bike.  So it hauls heavy stuff (usually groceries).  It has a secondary job as an unladen backup commuter, but primarily it needs to be optimized to start from a stop while the entire system – with me – weighs 400-450 lbs (180-204kg).  I have really loaded it that heavily so this is not a theoretical exercise.  So I want a big-ish chainring for when I am pedaling fast and light, and still need to be able to get to the big cogs in the back for when I am loaded up and chugging along like a two-wheeled freight train.

Plan A:  Luna Eclipse (42T)

The Luna Eclipse is one of the best BBSHD chainring setups on the market, with a unique ‘wicked’ tooth profile meant to eliminate the possibility of a chain drop under extreme use.  It also has the most extreme internal offset of any chainring option.  This will do the most to overcome the grief visited upon the BBSHD builder by that drive’s secondary housing sending the chainring way out to right field.

Its also gorgeous.  The gunmetal finish I chose matched beautifully with the dark grey frame.  Unfortunately 42T (which is the standard for full-offset chainrings as any smaller and you can’t clear the secondary housing) was not large enough to keep me from clown-pedaling when riding the bike as a commuter.  There was another problem:  Chain alignment.  Running that smaller 42T ring with the smallest rear cog resulted in, after only a few weeks, a whole lot of wear on the inside.  This is why mid drive builds demand the most out of the builder in terms of thinking things thru.  Time for Plan B.

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Its not ruined yet, but its lifespan sure has been shortened.  this was only a couple hundred miles of wear.

The Eclipse is a proprietary chainring platform, but fortunately other sizes are available.  the largest of which is what I tried next.

Plan B:  Luna Eclipse (48T)

So Plan B was to swap in a Luna 48T ring onto the Eclipse center section to fix the clown pedaling, and to stay the hell off the 12T small rear cog to deal with the alignment issue (I am using a welded together steel cluster for durability and the 12T is alloy and not a part of the welded cluster, so its better to stay off it for the sake of longevity anyway).  I thought that 48T/14T on this bike was the perfect sweet spot.  A small front ring is best when its on cargo duty, and a large one is best when its a commuter.  48T, when used in conjunction with upshifts, gave me pretty much everything I needed.

Pretty much but not everything.  First of all, remember the deep offset of the Luna ring?  It moves the chain inboard 24.8mm which *usually* eliminates the damage the BBSHD does to chain alignment.  Not on the Mongoose, whose narrow bottom bracket effectively papers over all of the sins committed by the motor (at this time I had not yet fully figured this out).  So, as I found with the 42T ring, it was inset too far, even when I stayed off the smallest cog.

So Plan B helped, but it didn’t solve the problem.  After only a couple weeks (I am now checking carefully and frequently) I saw the beginnings of the same wear on the inside of the chainring.  Like the 42T, I had to retire this thing fast so I could use it on some future project.

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Not as bad as the 42T, but still bad.  Both this one and the 42T looked perfect on the other side.

Sidebar: A mid drive chain powered by a 1500w motor is a chain saw when it comes to components rubbing against it.  That is just a reality of a mid drive and you have to deal with it as part of your design/build process.  When you get it right, you are golden for thousands of happy miles.  Get it wrong and you are sawing thru chainrings and cogs like nobody’s business.

Plan C: Lekkie Bling Ring (46T)

So now what?  42T was too small.  48T was more or less just right.  And the chainring offset that lets me use the inner cogs at great alignment still needs to be reduced or I can’t use anything but the lower gears.  Lekkie has a Bling Ring available in 46T.  It has the same internal offset their 42T ring has and, since I use them on two other bikes I know they are top quality.  At 18.3 mm its offset is quite a bit less than the Luna.  So I got a 46T.  I also added a 2mm spacer underneath it, further reducing the chainring offset to 16.3mm.  That is a whopping 8.5mm less than before so I hoped I would be good on the smaller outer cogs and still let me use the big inners.

And, pretty much, it was.  Chain alignment didn’t seem to be much of an issue, although it still wore down a bit more on the inside.   I was also able to shift up to the biggest cogs in the rear for very low gearing options.  Those are important on a full cargo load and if I am dealing with hills.

But… I flat out missed that 48T high gear for commuting.  And I was still seeing – very slight but noticeable – wear on  the inside of the chainring teeth from the chain, which was still visibly angling outboard a fair distance.

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This one was on for a few months and had 8.5mm less offset.  But it still shows signs of premature aging.  This was undesirable but livable.

I decided to try an extreme option I had not previously considered.  But on this bike, where all of the normal chainring offset stuff doesn’t seem necessary, it might actually work.

Plan D: Luna 130 BCD Adapter and Wolf Tooth 48T Ring

BBSHD chainrings are generally all proprietary to the platform.  Not so in the cycling world, where chainrings are universal, needing only to match the proper Bolt Circle Diameter for the chainring bolts.  Match the BCD between crankset and chainring and you are good to go.  There are adapters out there in the world that allow a Bafang motor to use standard 104mm and 130mm BCD chainrings.  The problem is they don’t give you anywhere near as much inward offset.  But given my experience so far, maybe I can live with that.  They should fix my alignment on my ‘commuter’ cogs, but will I still be able to use my ‘cargo’ cogs?

In addition to the LunaCycle 130 BCD adapter, I also chose the Wolf Tooth Drop Stop chainring as those rings are best-in-show for this sort of thing on a mid drive.  Attachment to the adapter was a little different than the usual chainring-to-crank operation in that its backwards.  The chainring bolts onto the inside.  I was able to play some games to good effect:  I reversed the chainring so it is logo-side-inward.  Not as pretty, but doing that lets me take advantage of the countersunk bolt holes on what is normally the outboard side.  The countersinking let me mount a bolt so it is almost flush with the ring, which in turn is butted up almost on top of the secondary motor housing.  With the countersinking it now has plenty of clearance.

Plan D Results

FINALLY.  Everything is working right.  The reduced chainring offset means my 14T cog (still not using the 12T for the reliability issues mentioned above) lines up straight back.  This outboard shift did affect my inner cog alignments but I can still get to all of them but the biggest 32T.  I’m comfortable with the angles on all but the second-largest 30T for long term use, and in a pinch, that 30T will work fine.  I just don’t want to stay on it for a week.  So this 9-speed is now a 7-speed and as DIY mid drives go thats still better than a lot of builds can manage.

And worth mentioning, like a lot of what they do, the CNC-machined Luna adapter is freaking gorgeous, and very precisely manufactured.  So much so it really stands head and shoulders above another adapter I got my hands on and was able to compare it directly to.

Honorable Mention: USAMade 130 BCD Adapter

I was surprised at how well this worked and how nicely it was made.  The part only cost me $29.99 on Amazon.  Still, it was Made in USA, well machined and rock solid.  The only things I didn’t like about it was the fact it was machined a bit too heavily, which meant it placed the chainring a millimeter or two further outboard than was necessary, and in this game millimeters count.  Further, as you can see above I was able to reverse the WolfTooth ring and take advantage of the bolt head countersinks.  That didn’t work with this part as USAMade countersunk the outside edge of their part, which made the bolts too long to allow my trying the same trick on the inside, where I needed it.  For a different build it might work fine so I am keeping it for my parts pile.

As for the Stone chainring seen on the USAMade adapter (scroll up to the title image at the top of the page), thats a Chinese Special that ran less than the godawfully expensive Wolf Tooth.  Its noticeably lighter in construction than the WT and I’m not sure I am sold on the tooth profile.  This ring will sit in my parts pile waiting in the wings as an emergency replacement.

Great Big Bags (an important afterword)

Some time ago I made a post about Big And Cheap: DIY Cargo Bike Bags.  On that post I noted on the build sheet this last item:

Therm-a-Rest Classic Foam Pad        Amazon   29.95

And then never mentioned another word about it.  I still ignored it in the Cheap DIY Cargo Bags: Update follow-on post.

Oops

So, that item is actually sort of a big deal for these bags.  Why?  Because the padding lines the inside of the otherwise floppy ol’ canvas parachute bag and gives it a soft but firm structure.  It also of course pads the interior so your carton of eggs stands a better chance of making it home in the same number of pieces it started out in at the grocery store.

Without further ado:  Here’s a look at the end result:

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And here’s what it looked like before I took a knife to it:

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This is a “Therm-a-Rest RidgeRest Classic Foam Camping Sleeping Pad” in its Large size, which is 77″ long by 25″ wide.  The important measurement is the width:  25″.  Thats only 1″ wider than the measured 24″ width of the Rothco Parachute Bag we are using for this project.  In actual practice, stuffing it into the bag, the width is perfectly sized to the bag.

What about length?  Well, I found all you have to do is cut one of these sleeping pads in half, widthwise.  This will give you two 25″ wide by 38.5″ long pieces.  That 38.5″ is pretty much perfect insofar as lining three sides of the bag (rear, bottom and front face).

Having this sturdy but padded liner inside the bag, you can pile stuff on inside and the bag retains its squared off shape.  Further, when using the straps to lift up the bag off the lower rack, the liner allows those straps to carry some of the bag’s weight without flopping down onto the rack in its center.  Without the pad as a liner, none of that good stuff happens.

Here are a couple of shots of the bags, empty, and folded up.  Here again the pad on the inside gives these monstrous panniers shape so they can fold up and stay neat/tidy.

 

You can see from the pics above how useless those big straps would be without some sort of internal structure (also notice these are still the early 2″ straps).  That internal padding is crucial to making these bags work.  Now lets look at the bags loaded:

 

See that grocery cart in the background?  Well, it was mostly full and now its loaded up into the Mongoose.  Filling both the 25L (each) front panniers and these almost 77L bags in the rear.  Those bags are still well-loaded but as you can see by no means full.   They are loaded mostly with 2L juice bottles, a case of 500ml coca cola bottles and a slew of soup cans and such.  With all that weight, the straps can still hold the bags up and partially off the lower rack and retain their shape (although I did add a third 2″ strap in the center to supplement the two outer 3″ straps… this load was *heavy*).

So… thats why you need the pads.

Finally, what do these bags look like when truly, fully filled out?  Recently I took some old XL sleeping bags out of the house.  A city park was midway to the drop off point and I pulled over for a quick set of pics.

 

 

Heat Sinks For the BBSHD Ebike Mid-Drive

Not so long ago, someone asked whether heat sinks had ever been applied to the BBSHD with any success.  This reminded me to document what I have done for posterity’s sake.  I turned a motor whose casing temp was 165 degrees fahrenheit and reduced it to 135.  Still pretty warm but a 30-degree reduction nonetheless.

Whats The Problem?

Well, there isn’t one, actually, unless you are really beating on the drive.  Even then its only going to be an issue under specific circumstances.  The fact is, these motors are pretty well built and they generally don’t suffer from heat issues.  Unless…

  • You are running the motor on the street, say, on long city blocks, and either laying into a high level of continuous pedal assist, or the throttle

AND

  • You are running the motor on a 52v battery, in its max 30 amp configuration

AND

  • It is REALLY hot outside.  We are talking 100-110 degrees fahrenheit (38-43 Celsius).

So, we’re talking summer commutes or midday shopping runs in Central California on streets like this, where my bike – which I geared for proper pedaling at 28+ mph – is putting out 100% power from the motor, continuously in between stoplights… and its a long way to the next light.

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I’m riding in the Class 3 lane on the street, not the Class 1/2 shared use path just to the right

Put all of these things together and now you have a motor that gets hot.  How hot?  My Stormtrooper – A rescued Motobecane Lurch frame with carbon fiber 90mm deep dish wheels, 52v 30a BBSHD, and a Luna Lander front air fork – was seeing motor casing temps of 165 degrees.  Yikes.

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The Stormtrooper – Now living the good life in Pacific Grove, CA where it is never hot, unless its on the inside of a freshly baked cheddar bagel.

So…. what can you do?  On this bike, I added a whole slew of 8.8mm x 8.8mm x 5mm heat sinks – purchased with thermal adhesive already applied so they are just peel-and-stick.  Here is a link to the source I used.  You can find them quite a bit cheaper buying direct from China but you will wait a couple of months for them to arrive.  When done, the motor casing looked like this (I completely encircled the motor so there are many more of these things on than you can see here):

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The small heat sinks are placed in rows, 4-across.

Next, I put on another large round heat sink on the end cap.  Since it was sold to me in bare alloy, I used radiator paint (for minimal impact on heat transfer).  I also had to apply my own heat transfer adhesive.  I chose this style as it had the large center area that could be used for adhesive.  Note I also had to fill the very center of the motor where there is a gap thanks to the laser etching for the logo.  I did this with 3+ layers of thermal adhesive, cut to fit flush.

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You can see the thermal adhesive I applied to the center alloy section of the end cap, just at the top.  Hand cutting the adhesive strips to fit was a pain.

Here is a different motor where I used different heat sinks.  These are 8mm x 30mm x 8mm in size.  So they fit – again almost perfectly – in the smooth channel on the BBSHD motor casing.  This time you only need to stack them as they fit the channel 1-across.  Much easier.  Also they are a bit taller, with more room between the fins.  Is that better or worse then the little 5mm units?  I haven’t done any testing so I don’t know.  On this motor, I did the same end cap as pictured above.

IMG_20180630_081347
These 30mm-wide sinks were a lot easier to apply as you only have to go 1-wide all around the motor.

Here is a link to the 30mm heat sinks I used.  I can’t find a domestic source for these so if you decide to go this route you just have to order them from the source … and wait.

By the way, these identical heat sinks work extremely well on a mini-Cyclone… Those motors overheat if you give them a dirty look.  The same combination of 30mm adhesive sinks mounted radially, plus the same end cap.  Takes the surface temperature down to the point where the motor can be used with relative confidence once you learn not to overdo the throttle and cook it… The heat sinks cool the motor from the outside literally as much as is possible under the circumstances.

Cheap DIY Cargo Bags: Update

Recently I posted up about how I made some Big And Cheap DIY Cargo Bike Bags.  Since I made that post, I have made a couple of improvements worth mentioning (including learning to lock my front wheel… look closely at that pic above… doh!).

The Straps

While I discussed them in my original post, my use of 3″ wide straps hadn’t actually happened at that time.  The straps were in transit.  They have since arrived and been installed.  I do prefer the wider size, and the shorter length of just under 60″ (I’m using two 30″ straps connected together).  You can see them in use in the picture above.

It is worth noting the clumsiness I experienced with the longer 2″ x 72″ straps went away with a couple of days’ use.  I simply got used to them, so as I mentioned in my original post, there is nothing wrong with 2″ straps.  1-piece, 2″ x 60″ straps should work just fine, will cost a bit less and be a hair less complicated.  Although they will give a little less support.

The Hooks

Discussing the improvement to the hooks is a bit more involved.

Lets backtrack a step: Originally when planning this project I ordered some AN970 Large Area Washers from Pegasus Auto Racing Supplies.  I intended to use them in conjunction with the M5 mid-frame braze-on bosses on the Mongoose Envoy to permanently anchor the bags to the side of the bike.  Later on as the project matured I decided to just use the straps and not bolt the bags to the bike.  So I never utilized these washers.

I bought the 1/4″ size which have an outside diameter of 1.125″ (28.6mm).  Inside diameter is suitable for an M6 bolt, and usable with an M5.  Washer thickness is 1.6mm so these are very beefy.  Additionally they are made with Grade 8 heat treated steel.  These washers are VERY strong.  I have used the 1/2″ size, unsupported except for a nut, to secure end link bushings on a track (race) car and they held firm without bending in that very extreme job.  If you toss your bike out of an airplane, these washers will probably be the only thing not bent on impact.

So… I have a bunch of unused washers.  So what?  Well, as you can see from the original build, the S hooks fit inside of a fairly large 13/16″ hole.  The hook has plenty of lip to hang on thru bumps and bonks while going down the road, but it still moves and there is a little rattling.  I hate rattling.  When I build a bike it doesn’t rattle.  I don’t care how big of a cliff you ride off of.  No rattles.  So… I took steps.  Afterwards, the bags remain easy to remove from the bike.  You just do it differently.

img_20191201_082723
Fig. 1:  Here’s everything we need to get the first part of the job done (stabilize the connection of the hook to the bag)

Step 1: Attach the big washer

These washers are big.  1 1/8″ wide in fact (essentially the same size as a headset stem cap).  They are so wide they cannot fit inside of the narrow end of the ‘S’ hook unless we spread it a bit.  So lets do that.

Take your pliers and spread the small end of the ‘S’ just barely enough so the washer will fit inside of it.  Fit the washer in and then again being very careful not to over-crimp the ‘S’, take it back to being the same shape (parallel) it was originally.

When you are done, you can stop here and fit the resulting product onto your bag grommet to see what you have accomplished.  You will fix the hook by putting the big end thru from the inside of the bag.  It will look like the picture below.  At this point the connection is much more solid and when on the bike very unlikely to come undone unless you want it to.

img_20191201_083417
Fig. 4:  If you over-crimp the hook it will be too tight and will no longer fit.  If you leave it spread out, it will rattle and move around.  Just put it back the way it was before you put the washer in and everything will be fine.

So, we could stop here, but if you recall, I said no rattling.  So lets take this another step to further solidify the hook into the hole and, as a bonus, make it silent.

Step 2: Add mastic tape to washer

Everyone knows duct tape is a gift from the Gods.  A million uses.  For bicycles and particularly ebikes, 3M Moisture Sealing Tape, Type 2228, is even more useful.  This stuff is available at your local hardware store for about $10 a roll for the 1″ wide stuff.  Its magic comes from the fact it is 65 mils thick (five or six times thicker than what you think tape thickness should be) and is a soft, adhesive rubber that can be stretched, bent, squished and molded as you see fit.  And when it sticks to itself it literally welds together.

For this job, for each hook I snipped three snips of tape, each about 5mm in length.  I didn’t actually measure – no need to be so precise.  I just eyeballed it.  Two of the snips went to the inside side of the washer, pushed inward to hold the hook in place and more or less fully face the washer with thick, soft rubber tape (3 guesses on how that affects rattling).

img_20191201_083921
Fig. 5:  Do a better job than I did here and cut yourself a little more tape so it goes edge to edge on the washer.

Step 3: Add tape to hook

With the above complete, plant the hook in the grommet hole – now you have to do it from the inside of the bag – and use the third snip to wrap around the hook, so the tape is between the hook and the grommet face.  Like so, below.  This will be a snug fit, but the tape’s tendency to weld to itself makes this job certain despite the fumblefingering that will ensue during job completion.  When done, you have this:

img_20191201_085540
Fig. 6: The 3rd strip of tape silences the hook rattling against the grommet.

Repeat the process with all four hooks.  Here’s a peek inside the bag.  Notice the washers completely cover the grommet hole.

img_20191201_090027
Fig. 7:  View from inside.  Pretty sturdy connection compared to poking a hole in fabric with a hook.

The hooks worked fine as conceived in the original build.  But these are now a  more secure, stable mount.  For long term use this is a better way to do the job, and the cost to do it is about 80 cents.

FYI its fine if you don’t use these Grade 8 uber steel washers… look for something similar at your hardware store, probably a 1/4″ zinc fender washer.  Cheaper, too.

Upgrade The Hooks

This is not such a big deal but it works just a little better.  All of the pics above use the black steel hooks that presently retail for $8.99.  These hooks are powder coated so the black is on there pretty good,  But its not going to be perfect, and rubbing paint (bike frame) on powder coat (hook) means you get some rubbing off on both the frame and the hook.  Plus that powder coat isn’t as smooth as polished steel.  These hooks come in a polished steel option for an additional $1 for the 30-hook pack.  I got a pack of these and they seem to fit more smoothly against my frame (where the hook is exactly the size of the frame rails, so fitment is always rubbing-tight).

There is a slight cosmetic difference as they are slightly visible now whereas the black ones were not.  I’ll leave it to you do decide if you care.

These hooks, in the best tradition of Chinese marketing, are described as “premium metal steel” so we’ll have to see whether either behaves differently.  I am using polished on one side and powder coated on the other.  Time will tell if either will rust.