How To Build An Ebike From Scratch: Final Assembly Day

We’re in the final stretch. All of the big stuff is done, except installing the brakes. Today, the work is mostly about tying up loose ends.

Step 1: Planning
Step 2: Hunting
Step 3: Tinkering
Step 4: Buying
Step 5: Build Day 1
Build Day 2
Build Day 3 (you are here)
Working Handlebar Setup
Test Rides
Custom Motor Settings
Finalize Battery Wiring
Grips On – Finalize Handlebars
Step 6: Perfecting
Tools List

Wrapping It Up!

We accomplished a lot yesterday. What do we have left? Only one major component is left to install – the brakes – and then some final mopping up. We’re almost done.

Put On The Brakes (Literally)

We have already completed a part of this job: We put the brake rotors on with the wheels during Day 1. Now, we add the brake calipers that grab those rotors. We’ll mount calipers to the fork in front, and the frame in back, with the brake hose coming up from each caliper to the handlebars, where the levers are attached. This will be a lot simpler than it could be as hydraulic brake kits ordinarily come as a set with everything attached together already.

For this project, we chose a small 160mm rotor on the front wheel and a 180mm for the rear. A given bike could be built with various combinations of rotors. A brake caliper adapter lets a generic brake kit match up to any rotor size. How to pick the proper adapter is a common question, so let’s take a short detour and explain.

How To Pick A Brake Caliper Adapter

For almost all bikes, there are two different types of adapters: IS (International Standard) and Post. I’m going to ignore some of the fringe products like flush-fit, which you’ll probably never see on an ebike conversion/build.

International Standard mounts have two unthreaded M6 bolt holes, (spaced apart 51mm, center to center) facing horizontally, that pass a bolt through into a threaded adapter. The brake caliper then bolts to two top-down, vertically facing holes. Our project bike has a typical rear IS mount. Here it is, both before and after the brake caliper adapter has been installed.

Figure 1: Rear frame IS brake mounts, bare and with adapter installed.

In the right picture above, that is a Magura brand adapter. They handily have the adapter type printed right on them. You can see the model is QM-10, which is not particularly useful here (its an old part number… I dug it out of my parts pile for this build). What IS useful is the size/type designation under it: ISR-180. That stands for an IS mount type, R = Rear and 180 means it fits a 180mm rotor.

The most important takeaway from this tidbit of knowledge is there is a difference between a front and a rear 180mm rotor adapter for IS mounts. The two are not compatible, and if you try to swap a front adapter to the rear, at the very best you are going to get a bad fit to the rotor. At worst the caliper won’t fit over the rotor at all.

Our project’s front fork is a model-year 2000 Marzocchi Bomber Z2 X-Fly. That old fork has (for 2022) a very unusual disk brake adapter for a suspension fork: an IS mount. Almost all modern suspension forks use Post type mounts.

Figure 2: The IS type brake adapter mount on the Apostate’s model-year 2000 Marzocchi front fork.

Here’s a pic from my Smash’s front fork, which is an MRP Ribbon. You can see where the name ‘Post’ comes from as the two mounts look like posts sticking straight out of the fork at a 90-degree angle.

Figure 3: The arrows are pointing to the post mounts on the fork

A Post mount adapter bolts straight down onto the threaded posts, which are spaced 74mm apart (center to center). Typically, a fork has “160mm posts” which means you can use a 160mm rotor with no adapter. I have seen some forks with 180mm posts, which means you don’t need an adapter with a 180mm rotor, but those are rare. Regardless, you want to KNOW what size your posts are if you have them, both front and rear.

Bolt the caliper directly to the posts on the fork. Just like the IS mounts, M6 bolts are used on Post mounts.

Figure 4: This is a Post mount adapter in the rear. The rotor is 203mm.
What Have We Learned?
  • Brake caliper adapters with IS mounts are specific to the front or rear.
  • If the frame or fork has two unthreaded M6 holes that you put a bolt through horizontally inward across the bike’s wheel, with a 51mm distance (center to center) between the two holes, that is an International Standard (IS) mount.
  • If the frame or fork has two threaded holes facing outward (usually that look like two parallel posts) with a 74mm distance (center to center) between them, then that is a Post type mount.
  • Post adapters are unthreaded. IS adapters are threaded.
  • Pick the adapter that is meant for the rotor size, mount type and front/rear axle that matches your wheel.
One More Thing!

As if the above is not enough, there’s one lesson I have learned that has served me well: Buy an adapter made by the same manufacturer who made your brake calipers. A homebrew brake caliper job often involves using washers here and there as spacers/shims to make up for a slightly wrong/bad fit of the caliper to the rotor face.

I have never had to shim a brake setup since I started matching caliper and adapter manufacturers. Here’s the thing: An adapter is often made with the manufacturer’s calipers in mind. So for example, Avid brakes are mounted with semi-hemispherical washers above and below the caliper (this is used to aid caliper alignment to the rotor). The lower washers take up vertical space. That space is accounted for with a slightly lower rise in an Avid adapter.

Try mounting a different manufacturer’s caliper on one – where that caliper was not intended to be spaced with those washers in mind – and it’ll be too short. You’ll need two or three M6 washers (or dedicated brake spacers, which are a precise thickness) between the adapter and the caliper to make up for that difference.

Or use a matching Magura adapter with your Magura caliper and everything bolts directly together with no messing around.

Speaking of which, rotors are by no means manufacturer-specific, but you may see a slight misalignment when mixing rotor and caliper manufacturers. So there is a case to be made for matching the manufacturer throughout the entire system unless you are willing to do some experimentation off on your own You may suffer through a little trial and error, but you may also find a perfect combination, as I think I have (I normally use Tektro TR-17 rotors but not on this particular project).

So, with all that said, for this project bike I need a front (Magura QM-43) 160mm IS mount, and a rear (Magura QM-41) 180mm IS mount.

Bolt the two adapters on, front and rear. Magura specifies 6Nm for the M6 bolts you will use to do this (they should be included with the adapter you buy). Magura adapters include bolts with a Torx T25 head. 6Nm for an M6 is a good number regardless of what brand(s) you buy.

Attach The Calipers And Levers

Once thats done, you are ready to bolt on the brake calipers. Once again, you use M6 bolts, but the standard 6Nm may not be where you want to be on the torque spec. More on that when we tackle caliper alignment below.

Before you do this, you need to spread the pistons inside the caliper so they are fully retracted. Depending on your brakes, you can do this with a screwdriver, or a brake block that came with your brakeset, or both. The actual procedure for this is illustrated in the Filling / Bleeding Video 2 below. You want those pistons spread wide for that first installation. After you have spread the pistons, if you removed the pads (not really necessary if you just used a screwdriver) put them back in.

Now you can mount the caliper. Do NOT torque it down. Thread down the bolts until there is only a very little play in the caliper. It should be able to slide sideways left to right with fingertip pressure. You need to be able to fudge it around a bit in our next step.

The brakes I am using come pre-assembled – the caliper is connected to the brake hose, and the brake hose is connected to the brake lever that goes on your handlebars, so it is a ready-to-run assembly. The brakeset has hydraulic fluid in the lines already and does not need to be bled unless you cut the hoses to fit your bike. This makes initial installation a lot easier.

After mounting the calipers, your next step is to provisionally bolt the brake lever onto the handlebars (don’t worry about routing the hydraulic hose just now. Thats for later). Since brake levers are manufacturer-specific with their own torque settings and bolt sizes (some are M5, most are M6 and the SRAM brakes that came on my Big Fat Dummy were actually an SAE size) I am not going to get into the bolt or torque spec for the lever. Refer to your manual for yours. Just get the lever on in more or less the right place, and only tighten so its barely held in place. You should be able to rotate it on the bars without effort, which you will need to do later on in the day.

Align The Calipers

With the brakes on the bike but not safe for riding just yet, we need to align the caliper so it doesn’t rub on the rotor, which it will when you do an initial install.

Take up the ‘slack’ in the brake pistons

In the auto racing world, brake pads can wind up getting spaced away from the rotor thanks to the torsion that comes with sharp curves and high speed flexing of the suspension. This gives you something called ‘knock back‘. The cure for knock back is to do some gentle brake pedal depression in advance of that corner you are rushing up to. This tee’s up the pads so they are right up there with the rotor again. Otherwise, your pedal goes to the floor and you need a change of underwear.

We artificially induced a form of brake pad knock back when we spread the pads during the caliper installation. Now that the caliper is on, we need to undo that. The procedure is the same as with a race car: Squeeze the brake lever a few times, and don’t worry that it goes all the way down to the handlebars on the first couple of pulls. Keep squeezing and proper lever travel will eventually come back.

What follows is the ‘brake whisperer’ version of aligning a bicycle brake caliper. This is a lot more effort than most people go to, but it will yield perfect alignment on even marginal brakes, barring some sort of mechanical defect (like a warped rotor). It is almost a you-have-to-feel-it-to-get-it technique. I will try my best to write it down coherently so you can replicate it yourself. Here goes!

Rear Caliper

Lets align the back wheel first. Toolwise, you need to keep within arm’s reach whatever wrench you need to tighten down the brake caliper. Usually that is an M6 hex key wrench, or a Torx T25.

Either spin the rear wheel by hand or use the crankarms. Get an earful as to how much misalignment there is (your ears will tell you how much real quick). Now grab and depress the brake lever to clamp and stop the wheel. Keep holding the lever down so the brake continues to hold the wheel. Since we left the caliper so it had only light play and could move freely, that caliper is now sitting very close to its natural, proper alignment, and is holding itself there thanks to your hand clamping the brake lever.

Now pick up that wrench you set aside with your other hand. While still holding the brake lever, gently tighten first one bolt, then the other so now the brake caliper is just barely held in place. It is imperative you apply only the gentlest amount of torque to that wrench, because even a bit too much will cause the caliper to move and spoil your alignment.

When done with two gentle tugs on that wrench, spin the wheel again. Does the wheel come really close to rotating without any touch to the rotor? Since we only barely tightened it, you can now move first one side and then the other of the caliper side to side, just a hair, with your fingertips to try and eliminate all contact. The slight tension you put on the caliper via the bolt should still allow you to move it, and that movement will now stick. Fiddle with it front and back, gently, side to side until you have the brake caliper in the perfect spot, so it does not rub at any point in the wheel revolution.

If we have the caliper in a final position, since we have barely any tension on the brake caliper bolts, we need to – again, very slowly and gently – apply more torque, alternating from one bolt to the other. It is a good idea to physically hold the caliper and adapter with your thumb and forefinger, clamping it in place with your fingers while you do small wrench turns – maybe 1/16th of a turn or less (!) at a time at each go. After each adjustment, spin the wheel and see whether the caliper shifted a hair in the wrong direction. If so, try and correct with your thumb and forefinger, or back the bolt off just a touch until you can make an adjustment.

You may have to undo and restart the process a few times. It is not at all unusual for the caliper to rotate on its horizontal axis a hair – even on a caliper not using hemispherical washers. Don’t be discouraged by this. Just take it into account as you try (and likely retry) to get the caliper tightened down sufficiently so it is in place, not moving and not rubbing. Do it precisely enough and you will find that sweet spot.

When you do find it, that bolt is almost certainly nowhere near the 6Nm that is typical for a tight M6 bolt. It will be much less. I do not try to tighten the calipers down that tight. Applying torque like that makes it almost impossible to align the caliper with the kind of fine control I want. I have never had a caliper loosen so, anecdotally, you should be fine too.

Its worth mentioning that this procedure is being used with Magura brakes along the lines of what you see in Figure 4 above: No washers, no spacers. Just direct part-to-part contact. And I am often using 2.3mm thick rotors, which are very thick. Even thicker than the 2.0mm rotors Magura recommends for their calipers, which are in turn thicker than the 1.8mm rotors that are the standard for most of the rest of the industry. So this procedure is used to dial in a very tight system that has very little wiggle room in it. Still, it will work great for any system if you are willing to put the time in. And once its done, its done. It will survive wheel removal and reattachment just fine.

Front Caliper

Aligning the front caliper is the same process as aligning the back. Only one additional observation is necessary that applies to both wheels: given the low torque on the caliper used here, you could be forgiven for coating the threads with Vibra Tite gel (NOT Loc-Tite). I use it if a tube of the stuff is within reach. Otherwise not. So its not something you have to do, but it can’t hurt, right? Don’t lose any sleep if you forget to use the stuff.

Route The Brake Hoses

This is effectively the identical process that was described in Day 2 when we routed the shifter cable. Once again the exact process varies greatly by bike, and you’ve already seen how I am going about it on the Day 2 build. So we won’t re-cover the same ground. Below in Figure 5 is a pic showing the anchor points for both brake hoses. Numbers 1 through 3 are identical to the shifter cable that is on the other side. #4 is a simple zip tie wrapped and anchored by crossing the V-brake post. Modern front forks will have some sort of dedicated, manufactured anchor point at roughly the same spot.

Be sure you leave enough slack in the front so there is adequate room to turn the handlebars to their fullest extent without any tugging on the brake hoses. Need an example? Look at another finished bike 😀 . The hoses need to be long but not too long.

The picture below shows the temporary brake routing I used in the first few weeks as initially I did not shorten the brake hoses.

When routing the hoses, they will be longer than necessary. Route them so the excess hose is sticking out in front of the bike. From the caliper forward/upward to the handlebars, the hoses should be tied down as you expect them to stay.

Figure 5: Brake cable anchor points.

Shorten The Brake Hoses

This is luckily one of those times when a video is the best tutorial, and we have a great one here. Again this is tailored to Magura brakes, but the principles hold across all brake marques. Its only 3 1/2 minutes long so watch it now:

VIDEO 1: Specific to Magura brakes, but still a good tutorial on snipping and shortening a hydraulic brake hose.

Here’s what I do differently: I use a different hose cutter as shown in the tool list. I also would put on the cable molding cover, nut and olive BEFORE I stuff on the metal hose barb. The reason for this is when you put the barb in, it often spreads the housing of the cable just enough to make it impossible to thread those fittings over the now-finished hose end. So just put them all on before pushing the end barb in.

My treasured needle driver. Makes a PITA job so simple its worth the $26.

Additionally, I use the specialty tool (brake hose needle driver) that carefully drives the end pin into the hose. Its a lot easier than hammering in the pin. Video 2 makes this process look easy as pie and it is seldom that. If you don’t want to spend the $26 for a specialty tool, yes you will get the job done by using the method shown in the video. For me, I never want to fight with a hose barb again and I’m glad I sprang for the needle driver.

Bleed The Lines

Once you have cut down the hoses, you have air in the hydraulic lines, which is very bad. You have to bleed the brake lines to get the air out. Here are two videos that show ‘the long way’. This is how you should do it at least the first time after cutting the hoses down. I am also showing you Video 3, which is much less messy than the ‘official’ instructions in Video 2. It is worth mentioning that the instructor in Video 3 is a Magura tech specialist. So its not like he is breaking any rules.

VIDEO 2: This is the ‘long’ way to bleed your hydraulic brakes, minus one trick to minimize fluid loss.

The only issue with this next method is you have to remove the caliper, which means you have to realign it per the procedure above.

VIDEO 3: This is the same ‘long way’ to bleed hoses, but with an added trick – remove and raise the caliper to the level of the brake lever.

And now for the short way. Use this method for a touch-up bleed down the road. You can probably get 90% of the efficacy received from a full bleed by doing it this way, which is much simpler and does not involve disconnecting brake lines and spilling fluid. Its also faster.

Note also that when I do ‘the long way’ I just use a syringe stuffed into the reservoir hole like is done below and do not bother with the expensive bleed bottle that is used in Videos 2 and 3 above. I use just a syringe with a hose and screw-on tip, a syringe reservoir and a bottle of fluid. No need for any fancy bleed kit.

VIDEO 4: Yet Another Brake Bleed Video


Its time to start getting the handlebars set up in their final format. Now that the brakes are on, we’ve pretty much got a working bicycle here and all thats left is some tidying up. The only thing we aren’t going to do is put the grips on, and thats because the grips I put on often have to be cut off. So I want to wait until the last second to take that final step. Everything else should be put in its final position.

Brake Levers

These are what you position first. Nothing is more important than being able to easily reach your brakes without having to work at it. So having them set up right is Priority #1. They go closest to the grips. Always. And everything is fit around them. You don’t move your brakes to a sub-optimal position to make up for anything else. It is done the other way around.


The next most important item on the bars is the shifter. Here again, you must have unrestricted accessibility. You also don’t want to have to change your grip to use it, so the shifter should be directly up against the brake lever. On an ebike, typically you have only a right-side shifter (for the rear cluster).


If there’s a shifter taking up the space adjacent to the brake lever on the right side, that leaves the left side for the throttle. I am assuming a thumb throttle here and will not get into the nuances of a grip or half-grip throttle as I never use them, so I don’t have much to say for them or about them.

One nuance of a thumb throttle that is often overlooked is ‘clocking’ the lever. You want to position the lever so when it is fully engaged, the tip of your thumb is comfortably holding the handlebars, and preferably the paddle is fully extended straight down. The reason for this? When you hit a pothole or similar road imperfection, if you are putting any sort of weight or grip on that fully depressed throttle paddle, your hand/thumb will bounce down thanks to gravity and inertia… and can snap that paddle clean off as a result.

If you clock the throttle so it is pointing down when fully engaged, then your body’s reaction to a terrain impact will just cause your thumb to slip off. The throttle snaps back to zero input. Maybe a bit annoying to have to re-engage, but nothing is broken. Maybe for you straight down is too much. Experiment with it to find out what works for your preferred grip on the bars, while keeping this fail-safe technique in mind.

Once that is done, this is what the bike looks like now.

BAM! This sucker is ready to ride, finally.

Whats with the handlebar bag?

Well, in addition to being a handy way to store wallet, phone and keys, it also hides any excess wiring that I can’t easily get rid of. In this case, even though the wiring harness I am using is a little shorter than normal, it is still probably an extra foot longer than it needs to be. That slack has to get taken up somewhere. Likewise, there are wires connecting to the left brake, the right brake, the display and the throttle. In addition to the usual shifter plus right and left brake hoses. Thats a lotta wires.

I have found a handlebar bag – especially this particular molle deployment bag I am using here – is great at hiding that rats’ nest in addition to being a convenient dump pouch for what is usually in my pockets. The molle loops on the bag are perfect for running excess wire so it is literally integrated into the bag’s surface. In these early build pictures, I am using a leftover brown bag I had in my parts pile. A black bag hides black wires running along its surface much more effectively, and I switched to one later on for that reason.

Test Ride Time

Go on. You’ve earned it. Go for a ride. If you’ve done your job as described here, its ready. Sure, the grips aren’t on yet, but you can hop on and ride around the neighborhood. Start out slow. Engage the pedal assist. Give it some throttle. Figure out how it handles, keep things mellow. Oh, and wear gloves and a helmet. Some of my worst mishaps occurred on test rides that were supposed to be a 5 mph toodle around the neighborhood cul-de-sac and ended up with a faceplant. Right now you are a test pilot. Dress like one. At least a little.

Tailor The Motor Settings

This procedure will vary depending on your chosen motor. For this project, we are using a BBSHD and I have that platform down pat. I know exactly what settings I want and I have a tool to change those settings that I can plug right in.

Here’s the process I use. Once you’ve read thru this article, follow on to the sequel linked at its page top. I plugged in the Version 2 screens in that second article on this bike in a couple of minutes (shown below). These are the most neutered pedal assist settings I have in my toolbag. The gentlest stuff you can find while still retaining the ability to lay on full motor power with the throttle if its ever needed. Look to the linked articles for sterner stuff.

Clean Up The Wiring

OK so you were having fun riding your new bike around. Unfortunately there’s a bit more drudgery to get through. You need to finalize the battery wiring … at least you do on this bike because everything is out in the open. So we need to do something short, strong, neat and tidy that is also color matched so it doesn’t stick out.

Figure 6: The finalized exterior wiring. Bottom wire is AC Power to the motor. Top wire is battery charger input.

Here’s what we are looking at in Figure 6 above. First: the power lead that sends battery power to the motor. A BBSHD comes with two fairly long (roughly 35cm), separate black and red 12-gauge wires, each terminated in an Anderson Powerpole connector. While Anderson connectors are adequate, they are susceptible to water and far from your best choice, which is generally considered to be a water-resistant, spark-resistant XT90S.

It so happens the wireless Luna Wolf pack I am using also has a female XT90S built into itself, so the decision to use the more capable male XT90 is made for us by the battery.

The job was to measure thrice and cut once. I had to shorten the power cables running out of the motor just right so a similarly shortened 10-gauge XT90 pigtail could wrap around the frame at just the right length to be snug, yet removable without being so tight it would break something.

The tutorial on making safe, reliable crimp connections is here and gives you complete details, tools and instructions on doing this exact sort of work.

Since this power cable is in the worst possible place for collecting grit, grime and water, I went overboard on the protection for the connection. I used 3:1 marine adhesive butt-end connectors and surrounded the connection area with thick marine 3:1 adhesive heat shrink. This effectively waterproofed and armor plated the connection. I topped it off with a hand-wrapped spiral of frame-matching red silicone tape to lower the visibility of the thick wire. This also adds more protection and waterproofing. If I could have found a reasonable way to use the same red PEX or PVC tubing to further armor the connection I would have done that too. But as it sits, if something gets through all that its probably going to destroy the bike, too.

The battery cable was made almost the same way. Two short 12 gauge male and female XT60 pigtails were crimped together with marine heat shrink butt end connectors to make a short extension cable. No 3:1 heat shrink this time as I need this cord to be flexible. The loose end that will be attached to the battery charger is tucked into the velcro strap that is helping to lock down the pack onto the frame. What you can’t see in Figure 6 is the open female end of the extension cord is further covered with a waterproof cap made to fit the XT60 like these (also widely available on Ebay). I finished the job with a matching, protective wrap of red silicone tape.

Put The Grips On

My chosen silicone grips are 50/50 in terms of being removable. Half the time they have to be cut off, so they only go on at the last possible moment. That moment is now. We’ve got everything installed, laid out, positioned and generally nitpicked so we can put the grips on without worrying we have to take something back off. Further, we purchased as many parts as possible that use clamshell type attachment (the one exception is the throttle) so those items can be removed without also having to remove the grips.

For silicone grips like those I am using (Wolf Tooth Fat Paw), I have found some drug store denatured alcohol inside and on the grip is the way to go. Here is a video that shows removal and installation of a variety of grip types using various methods, including the use of alcohol.

How To Build An Ebike From Scratch: Assembly Day 2

Assembly Day 1 got us a rolling chassis that looks like a bike. If you squint a little. Lets keep up the pace of progress here on Day 2

Step 1: Planning
Step 2: Hunting
Step 3: Tinkering
Step 4: Buying
Step 5: Build Day 1
Build Day 2 (you are here)
The Wire Harness Tube
Display and Throttle
Shifter, Chain and Derailleur Install and Adjustment
The Speed Sensor
Battery Attachment
Motor Function Testing
Build Day 3
Step 6: Perfecting
Tools List

The Fight Goes On

Well, really its not a fight. We’re moving forward pretty steadily despite a couple of time sinks that came in the form of a failed Tannus Armour installation, and a ‘peat-and-repeat motor installation where it took a bunch of time to get the cable routing off the motor just right. And speaking of motor cable management, thats where we will start.

We’re nowhere near done with the motor, but on this second day we won’t start there.

Since we bolted the derailleur on the bike as our last act yesterday, lets continue with the drivetrain and start today with…

Craft The Wire Tube

This is a component that is unique to this bike. That doesn’t mean it can only be done on this bike. But its an unusual element for an e-bike, so bear this in mind when you are building yours.

Usually (maybe even ideally) when you build an ebike you choose a frame that has ample room in the forward frame triangle for a battery pack. You secure this battery pack in a battery bag (Since we have already repeated the mantra of DIY does not have to mean half-assed enough for it to sink in, I will ignore the fact that some ‘builders’ use duct tape – or worse – to secure a battery in the triangle). Myself personally I really like battery bags, and I use them on most of my bikes.

Battery bags let you secure the pack on multiple sides, nice and tight. They also let you pad the pack so when you are bouncing around, your pack stays protected. You know what else they do?

They hide all the damn wires.

So, the Apostate’s 1999 Intense Tracer frame has the nearly unique and wonderful characteristic that it fits a Luna Cycle Wolf Pack almost as if it was made specifically for it. Not only was no battery bag needed… I couldn’t use one even if I wanted to. In the lead-up to the actual assembly days, during Tinkering, I tried all sorts of alternatives including different batteries (I have several that can either be pulled out of storage or off of another bike), the use of rectangular, strong cordura/molle bags and even jerry-rigged strapping. No alternative worked.

Its not just a perfect fit. Its the ONLY fit.

So that, as they say, is that. I can forget about having the luxury of a battery bag, where I can stuff all my loose wires and just run them thru slots in the bag, back to front with no one the wiser. I had to come up with an alternative.

For the Stormtrooper, I used matching white heatshrink to cover the exposed wiring, effectively hiding it in plain sight.

I couldn’t do what I did with the Stormtrooper above as the most ‘red’ heatshrink I could find looks pink against the deep, fire engine red of the frame.

Now What?

I decided to make a wiring tube – a bit of fixed plastic pipe clamped to the frame. I can run the main motor harness wire and the unused-but-still-dangly shift sensor wire through it.

I bought a 5-foot length of 1/2″ PEX pipe (inside diameter is actually about 0.68″) from Home Depot for a whopping US$2.93. The ‘hot’ version of PEX is red. But not right red. To fix that I spiral-wrapped the pipe with the red silicone tape I had on hand. I affixed the tube to the frame with a combination of careful wraps of more silicone tape, and red zip ties. Yes I hated to use those ties. Topping off the attachment was about 8″ of velcro cinch straps I chose to use to secure the battery as firmly as possible.

Annoyingly, I did not take close-up pictures of the wire tube during the time it was created and attached to the frame. The tool used to cut the PEX pipe to size was a simple hacksaw and the pipe was cut while holding it by hand. The hacksaw went through it like butter.

Here’s a good, close look at the wire tube at the end of my first ‘live’ ride of the finished bike (note the rain water)

This is another instance where a lot of prep time in advance of the actual build day was spent figuring out exactly how to deal with a problem. While cosmetically I wasn’t thrilled with doing it, functionally it worked very well to both hide the wiring and give it strong protection.

I was never happy with the look of the tape-wrapped PEX pipe, or its connection to the frame. Shortly after build completion I placed an order for different parts and did a different, better tube. Since it took weeks for the parts to arrive, many early ride pictures (particularly the ones in the Grand Canyon) show this original PEX pipe. We’ll address its replacement in the Perfecting post.

Run Main Wiring Harness Through Wire Tube

With the wire tube in place, its time to run the wire harness up through it from the motor to the handlebars. Because the connection between the motor side cable and the harness will be in the middle of the tube, and the tube has been affixed to the bike, we need to do this in a particular order.

  1. Feed the harness into the tube from the top, down to the motor. Feed it all the way in until it gets to the knot where the wires separate. This will leave plenty of extra harness wire sticking out, motor-side.
  2. Connect the harness to the motor-side plug. Be careful to line up the little arrows on each plug housing to ensure everything goes together properly. Do this wrong and you can destroy your harness by bending the wire ends inside the plug.
  3. For this build I am not using the shift sensor, which is the wire coming out of the motor with the yellow HIGO/Julet plug. Stuff it into the tube just ahead of the plug you just connected in Step 2.
  4. Feed the harness back up the tube so there is no longer any slack down at the bottom and the wires now feed straight into the tube. Because you stuffed the shift sensor plug in ahead of the wire harness plug, that thick plug, which is almost the width of the inside of the tube, will drag the shift sensor up with it; keeping it safe and snug. When the shift sensor wire has extended fully into the tube you can stop.
  5. You now have a fair bit of extra wire sticking out of the front of the tube. On some bikes, there won’t be a lot of excess. On others there will be a lot. We’ll deal with this on Day 3. Just let it hang for now.
The generic BBSxx wire harness. Green to display, yellow male to throttle, the two yellow females to brake levers. For this project, I am using a harness from California Ebike that substitutes red females for the yellow ones for Magura brakes.

As noted above, most bike builds will not use a wire tube. If you are using a battery bag, you can just run the harness up inside of and thru the bag. You can also use velcro onewrap straps or zip ties to run the harness wire along the bicycle frame tubing. Remember… zip tied cables all over your frame look cheesy. Avoid them as much as possible, but if you must use them, try to use colored ties that are at least in the ballpark of a match to the frame. Even a rough color match sticks out a lot less than say black on red.

Attach Display and Throttle To Handlebars

This step is here simply because it has to happen somewhere. This is a good time to get it over with. Attachment of the throttle, by necessity, involves slipping it over one end of the handlebars since its a single piece, tightened to the bars with a small metric hex socket. Displays tend to be a little more flexible, typically using a hinged attachment that makes them a little easier to install. Usually they tighten up with another small metric hex socket. Sometimes you’re unlucky and its a Phillips head.

For both pieces, just get them onto the bars in roughly their expected final position. Tighten them only so they are snug, but still movable. Do not connect them to the wiring harness yet. We won’t put on the grips and brake levers until tomorrow so what we’re doing here really is just ticking a box, so we can do our motor functionality test at the end of the day.

Attach Chainring To Motor

Here again, we’re just taking a relatively easy step that gets us closer to our goal. We need the chainring on so we can put on the chain, which will let us do a motor test.

Since we’re doing a Bafang mid drive motor, attachment of the chainring involves the use of five short M5 socket cap screws. As always I recommend you visit your hardware store and acquire upgraded stainless steel examples. Also – and this is pretty much true everywhere – DO NOT use button head screws. It is tempting to do so because the low profile button heads give a more finished appearance, but they are a bad choice on a bike for a number of reasons – all of which I learned the hard way.

  • A button head uses a smaller hex socket because of its diminutive size. So when torqueing it down (or removing it after time has passed) it is much easier to strip.
  • If a button head is stripped, you will need a specialty tool to back it out. If instead you had used a socket cap, a small vise grip could clamp onto the socket and has a pretty good chance of working.
  • A socket cap is much less likely to strip in the first place thanks to the larger size hex head.
  • A socket cap is rated to withstand more torque (see above).

The prohibition against button heads used to apply especially to M5 brake rotor screws, and after losing a couple of them I switched to M5 button caps, but in recent years, the industry has fixed that problem by using screws with Torx t25 socket heads, which solves the stripping problem. If you can find longer, stainless steel Torx M5-sized screws, those could be an option for fastening the chainring.

The five mounting screw holes for the chainring.

Tighten the chainring screws in an alternating star pattern. The torque spec you use should vary by the kind of screw you are using. Here is a table showing the different common metric screw material grades, and the Nm settings that represent a maximum for each. Keeping in mind we also don’t want to strip out the threads in the socket, I would not exceed 8Nm. The minimum of 7Nm on the chart should also work just fine.

While I am a big fan of never using a thread locker, as a properly torqued bolt doesn’t back off, this is one place where I have violated this rule. However you need to use the right kind of thread locker. Consider Vibra Tite gel. It is a vibration-resistance product with roots in aviation. It never truly dries. It just goops up the threads sufficiently so they don’t back off. I learned about it participating in shooting sports, where the old hands use it on extremely expensive – and delicate – optics that are subject to repeated, severe recoil impact.

If this thread locker is used, bolts will stay put. They can always be backed off with a simple hand tool without risking a seized bolt or a twisted-off socket cap.

Quick Chain Alignment Check

Do this BEFORE applying final torque to the chainring above: Just snug the chainring bolts. At this point, you can now use your final wheel assembly, complete with rear cluster installed, to check your final chain alignment. There is no need to actually install the chain. Just drape it over the chainring, and back over the rear cluster onto its middle ring. How does it look? This is probably the first time you can see for sure what your bike’s chain alignment is really going to be.

For this project, doing this quick check, I found my chain alignment was too far inboard to the frame. My Lekkie 40T ring provides a bit over 20mm of inward offset. Which is a lot as these things go. Too much in this case. I used a Lekkie 2mm spacer (which was included in my motor cover kit) to bring it out just a bit. I also used slightly longer M5 screws to make up for the spacer moving things outboard.

This fits between chainring and motor to move the ring 2mm outboard.

Luckily this simple spacer gave me a best-case solution without having to reinvent any wheels. Which I have had to do in the past.

If your luck isn’t so great when your turn comes, Here’s a link to the likely path to your solution.

Attach the Crankarms

The crankarms are the next logical step after fastening the chainring. Here again we don’t really need them on the bike other than to make some forward progress.

Jump into the time machine again: Drivetrain fully assembled. Note the stainless M5 socket caps bolting the chainring down, courtesy of the local Ace Hardware store.

Crankarms – especially the square-taper variety commonly found on aftermarket ebike motors – must be tightened down by a torque wrench. Torque specs for crankarms specify to a range, typically, of 25-35 ft lbs. Even at the low end, thats tighter than you can guess at.

Especially because you are tightening down onto a tapered spindle (axle), for two reasons. First, the crankarm will slowly tighten down onto the spindle, going deeper and deeper, and you won’t realize it has bottomed out at the right place unless you are monitoring the actual torque being applied. You will be turning and turning on that wrench and watching the crankarm descending down, further and further and think ‘gadzooks thats got to be enough’… It won’t be. If you don’t go too little and tighten too much, you will smoosh your crankarm onto the spindle. The softer aluminum crankarm will spread as its jammed too far down onto the steel, and it will be forever loose (wobbly) once you make that mistake.

Seen from the right and left edges, this square-taper spindle end (from a Cyclone) looks square. The taper isn’t noticeable until you look at the bevel at the corner, head-on.

And of course, if you don’t tighten it enough, its going to come loose sooner rather than later. In fact, square taper crankarms will ALWAYS come loose, and do so faster the more you ride. They have to be maintained. If you are pedaling hard 30 miles a day on a commute, for example, you should check crankarm torque roughly once every two months. If you are riding around the block on a leisurely cruise every week or so, once a year should be fine. But make no mistake: It has to be done or sooner or later your luck is going to run out.

So… thats why you need that torque wrench. This is the first and maybe only time we will use the larger 3/8″ version, because the torque needed is too much for the little 1/4″ unit to handle. Worth mentioning: Its possible to use the larger 1/2″ torque wrench for this job, although its overkill. Still, if you are not down with buying three wrenches, two (the 1/4″ and 1/2″) will suffice.

For square taper spindles and both high end and low end alloy crankarms, I have found a setting of 25 ft lbs (30 tops!) to suffice. I know that Lekkie says 50-60 Nm (37-44 ft lbs) right on the crank extractor plate of the crankarm… I don’t go that hard and I have not suffered any ill effects from being a bit kinder and gentler to my bolts and (expensive!) crankarms. But I also keep on top of my torque settings by checking the bolts regularly.

How do I perform a routine torque Check?

I said this was crucial, and it is. So we’d better go over how to do it, since if done wrong, you will snap off the head of your crank bolt. Don’t ask me how I know this.

Failure is always an option. Could not get the sheared bolt out of this axle, so I had to buy another axle, disassemble the motor and replace it. Use a torque wrench.

If you just set your torque wrench to the desired setting, then stick it in the socket and give it a tug until you hear a click, just the act of doing that imparts added torque to your bolt. So lets say you check it once a day (you won’t) and in so doing you give it that click once a day. A torque wrench either clicks when you reach the required torque or it clicks if you are already past that torque limit when doing a checkup. Yikes. That means once a day if the bolt has not loosened in between checks you are overtightening it a little at a time every time until … snap. Now you are screwed and you will literally have to take an angle grinder and cut your crank arm off to move forward.

The good news is alloy cuts pretty easily with a power tool. Thankfully these were cheap Bafang crankarms and not something a lot more expensive like Lekkie Buzz Bars. Use a torque wrench.

Here’s how you do it right: Back off the bolt a hair. 1/8 of a turn is enough. Now you’ve loosened the bolt just a little, when you tighten it again the click you hear will be the torque wrench for-reals reaching the desired value. If this technique sounds familiar it may be because its used at any decent automotive tire shop, after a pneumatic impact wrench has been used to install your new set of tires.

Attach the Pedals

Again, we are just ticking a box and thankfully this is a pretty simple item. Or… is it?

As an admin and moderator on a couple of online ebike support groups, I literally cannot count the number of times I have seen noobs have a disastrous experience with pedal installation, or catastrophic failure after the fact from a botched installation, where the tragic flaw wasn’t recognized right away. So lets make something simple as complex as possible by looking very closely at it.

One Pedal is Reverse-Threaded

This one item is the cause of almost all pedal installation problems. You would not believe how many people don’t know this, and then cross-thread the pedal in whether it likes it or not. This results in the pedal threading in nice and tight. Until the now-shredded threads give out a month or two later, at which time they see the trashed threads and blame the manufacturer for making crummy parts. Yeah. No. The problem is the loose nut holding the wrench.

Having suffered through so many of these sagas, I was thrilled when in 2019 I bought my Mongoose Envoy and saw it came like this (see pictures below) from the factory. Obviously they’ve seen enough of the same mistake to try and do something about it.

So if you are trying to thread a pedal on and it doesn’t go easily right in… STOP, gather your wits for a moment, think about what you are doing and why the pedal may not be going in like it should, and remember the reverse threading on the non drive side. Then proceed.

You Can Always Tell Which Pedal is Right Or Left

Just by looking at it! You won’t need any stickers. Look at the left picture above and check out the threaded pedal bolts. You can just barely see the left pedal’s threaded portion, but you can see enough. Just above the threads, its ridged. Now look at the right pedal sitting underneath it: No ridges. This is a theme across all pedal manufacturers. Usually what you see is a single circumferential line around the left (non drive side) pedal. Here are the pedals I am using on the Apostate right now. Left on the left picture and right on the right picture.

See that? There is a line scribing the pedal axle on the left, no line on the right. Easy peasy.

Grease The Pedal Threads (Anti-Seize)

I believe I have mentioned what a good idea the use of anti-seize is, and why its especially useful when bonding dissimilar metals like the steel of the pedal and the alloy of the crankarm. Its also particularly helpful if you are going to be connecting and disconnecting a threaded part, as the anti-seize will protect those threads from galling while they are being screwed and unscrewed repeatedly over time.

Why would you be taking the pedals off? Well, on a bicycle that is going to be stuffed into the back of a car, the pedals stick straight out on both sides. Also thanks to the rippy, stabby little studs festooned across most mtb pedals, they are going to hang up on and tear into all sorts of things. Just taking the damn pedals off makes the bike amazingly easy to manipulate and move around inside of a car.

Good luck leaving the pedals on and packing a bike in with all that soft cloth and canvas to rip into.

Can it be done with the pedals on? Sure. Can it be done as easily after taking 30 seconds to remove the pedals? You know the answer 🙂 .

Use Very Light Torque When Tightening Pedals

This goes hand in hand with ease of removal, but the benefits of doing this are not limited to a bike that has its pedals frequently removed. To the contrary, this is how you should install any pedal on any bike.

And no, this is not the advice you are going to get from most everyone else, everywhere else. I’ll make my case:

Its common to see torque specifications for a bicycle pedal in the ballpark of 40 Nm. Thats pretty tight. I never do this. Instead I use a pedal wrench and just give a quick, light tug to snug the pedal on when it bottoms out in the crankarm.

Unless someone helps them come undone, pedals will not work their way loose through normal use. That is why the left pedal is reverse threaded. In fact, the threading on each pedal, coupled to forward pedaling action, means pedals self-tighten as the rider rides (assuming the pedal bearings are functioning, but that is a rabbit hole we don’t need to go down; especially given the modern use of sealed bearings).

Given that pedals in good working order, used properly, cannot loosen: there’s no mechanical reason I have ever come across to use high torque on a pedal. On the other hand, I have repeatedly been thankful my pedals come off easily when I want them to – and only when I want them to – as a part of the routine maintenance, transport and wear/tear of a stable full of bicycles over many years.

So thread them on, put the right pedal on the right side, just give a quick tug on them after they are threaded on and fuggedaboudit.

Install Shifter, Chain and Adjust Derailleur

I have used the Box Two derailleur and single-shifter in the past. Since I am using a Box Two derailleur here, I decided to upgrade to the Box One single-shifter, with a matching Box One shifter cable kit. The Box Two shifter worked great, but the upgrade is not much more money and has a marginally better handlebar clamp. So I splurged.

Installing a shifter involves some standard jobs. I’ll cover those in brief and then note how this bike, because of how old it is, needed some special handling.

Unbox The Shifter

I find that I don’t have a picture of the actual Box 1 shifter I put on this bike, so I swiped a couple from the store page at Box Components where you can buy one for yourself (I got mine at Jenson USA).

Looking at this shifter above, the most noteworthy thing to be aware of as a new bike builder is the fact this shifter has a hinged attachment ring. That means you don’t have to pull off (or cut off as is often the case) the grips on your handlebars, should at some point in the future you need to remove the shifter, reposition it… whatever. That silly little feature – that seemingly has nothing to do with the intended functionality of a shifter – is a big deal over the life of the bike.

Box Components does not deliver the shifter as shown in the picture above. What you get is like what you see in this different shifter, below:

Put simply: you are given a shifter with the shifter cable already installed. this is a nice little timesaver I have come to expect from every shifter I have ever bought. They all seem to come with the cable. Thats great, but you need more than that. Here is a complete parts list for a plain vanilla shifter cable; completely installed from the shifter on the handlebars to the end of the cable sticking out of the derailleur:

  1. A cable ferrule stuck onto the end of
  2. The shifter cable housing, which goes over the shifter cable and all the way back to the derailleur and terminates in
  3. Another cable ferrule. The ferrule snicks into a slot made just for it on the derailleur, where the cable continues on into its clamp, and is terminated by
  4. A cable end crimp

While I have all of these parts in quantity in little cubbys in my workshop, I decided to buy the Box One Shift Cable and Housing Kit. Box’s marketing people put up some snazzy graphs showing how muck slickerier their cable housing is versus The Other Leading Brand. So… fine. In for a penny, in for a pound. I spent the $25 on a dedicated parts kit that gives me everything I need for how I intend to build this bike. You’ll see why I put that in italics further down the page.

Now that we’ve established the parts in order of assembly above, your first job to install your shifter assembly is to bolt that shifter loosely onto your handlebars. It goes on the right hand side unless you fancy yourself some kind of rebel and want to put it on the left. Upside down and backwards. Either side, at this point the shifter and its bare cable should be just barely be able to hold its position on the bars. Not so tight it will leave a mark if you move it around.

Whats a Ferrule?

Its a metal or plastic finishing sleeve that covers the end of your bare, cut shifter cable housing.

Above: The little whatsit sitting next to the bare cable is a ferrule, which I then stuff onto the end of the shifter cable housing. The fit will be snug but easy to make just by hand. No tools necessary. We are not going to attach the ferrule on the other side just yet.

Once we have fit the ferrule onto the end of the cable housing, we want to run the wire coming out of the shifter thru the housing. All the way through. The shifter cable will be longer than the shifter housing and we want it that way. Snug up the cable to the just-snug-on-the-handlebars shifter.

Now that we have the cable-and-housing hanging loose and on the ground, we want to run it back to the derailleur along the bike in the path its going to take when its finally installed. There are a variety of ways you can do this, but perhaps the easiest is to use cheap, reusable velcro OneWrap cable ties. I love these things, and they are perfect for this job as they are reusable, easy on/easy off and not permanent – unless you want them to be at which point they seem to last forever on a bike.

Important: When running the cable back to the derailleur for this fitment exercise, leave slack up front coming out of the shifter so the cable is never tugged upon no matter what position the handlebars are turned to.

You should be able to figure out the path the shifter cable is supposed to take as there will be braze-on cable guides along the frame dictating the appropriate path. Most modern frames will have what looks like a little altar that you lay the cable across. Under the altar there is a slot made to run a little clip or a zip tie through to … strap the cable down… er… onto the altar (I should have sounded this out in my head first before coming up with that name).

Most modern frames have these simple cable mounts where you just lay the cable over it and use one zip tie (or two very small ones) to clamp it down.

I am bringing up this ‘altar’ and ‘modern frame’ business because my frame, designed in the previous century, is a product of an era when such things didn’t exist. So I had to improvise. But, I digress. We’ll get to the improvisation part last. For now I want you to see what it is that most likely you will be looking at on your own frame.

So you have followed the path laid out by your frame’s braze-ons to route your cable, and strapped it down temporarily with wire ties or similar. What you have now is a cable and guide assembly that is hanging out past your derailleur and is way too long for it. Its time to cut the cable to size.

Top Tip:
Don’t screw this up. Its better to cut a little too long than it is to cut too short. You can cut again if its too long. Too short… not so much.

Hold the cable with your hand such that it loops up and goes directly into the socket on the derailleur that is meant to accept it. You want the cable to go in straight, but not have so much extra in the loop it will catch on something – when you are whizzing down a hill a branch could tear that cable clean off, or worse.

I am measuring the cable to go right into the little hole where that arrow is pointing.

Find a way to mark the spot you’ve chosen. Do not cut!

Why? Because the cable is still inside the housing. After marking the cable, you need to get some slack up front at the shifter and pull that cable entirely out of the housing. I know you only really need to pull it back several inches, but lets not guess wrong and screw up. Another 10 seconds of effort and the cable is safely, completely removed.

NOW you can take your cable cutters and, with one quick authoritative snip, cut the cable housing to size. Run the cable back thru the now-snipped housing. And here we are:

Snipped housing and still a full-length cable.

Now that the cable has been threaded back thru the housing and pulled gently taut, we fit the second finishing ferrule over the bare wire, and snug it down onto the end of our cable housing.

Next, pull the wire through the receiving socket on the derailleur and gently pull the cable housing assembly into that socket so the cable is snug inside of it. You aren’t trying to clamp anything down at this point so I am using words like ‘gentle’ on purpose.

Turn all of your ‘provisional’ and ‘temporary’ cable mounting into permanent mounts. If you do it right, ‘permanent’ is a misnomer as all you will have to do is cut the zip ties to free your cabling up again. But for our next step, we want everything in place as it is going to be as a final assembly. Try and get your positioned shifter about right on the handlebars. This will be one place where having a little extra slack in the fitment will help you later on down the road.

At this point I’m going to jump from written description to video. We’ve covered the installation of a new cable and a new cable housing. From here I can let the Box Components installation video do all the heavy lifting for final cable attachment, chain sizing, chain installation and finally derailleur adjustment. These instructions work great for the entire rest of the process, and not just for a Box Components drivetrain. Remember if something confuses you, you can always hit pause, drag back the cursor and play a step over again until you understand it.

Some quick notes on the video above:

When I first saw the instructions on derailleur adjustment in this video, I was skeptical. I was very familiar with the method shown in the excellent – and gold standard – Park Tool video below. However, what Box is describing above is a lot simpler than the method Park lays out… and it is after all the manufacturer’s official installation instructions. So I followed the instructions and was entirely surprised they worked perfectly.

The chain sizing method shown is different than many other instructions on chain length. Nonetheless it is absolutely correct for a 1x (single front chainring) drivetrain. Many builders get this wrong in part because there is so much misinformation on how to size a chain; particularly on a 1x system.

Here’s another source that describes the same method. This time in writing:
Installing A New Chain For Your 1X Drivetrain (How to do it Right!)

The key is to only slightly tension the rear derailleur cage. That ensures you have a taut chain, but also that there is much chain on your bike as your derailleur cage can possibly wrap. Make it any longer and it will sag and skip. Any shorter and you have shortchanged yourself when moving up to your biggest, lowest gear.

If you have followed through step by step on the video above, you have now installed and adjusted your your drivetrain. However, if shifting isn’t perfect, here are a couple of alternatives.

A Different Example

I recently installed a low cost Microshift Advent system on my Mongoose Envoy. The Microshift install video shows an entirely different derailleur adjustment procedure. And since the Box video worked so well when I first used it (on 2Fat), I decided to follow the Microshift directions to see what happened. It worked. This video has a slower pace and gives a much better look at some of the components and operations common to all 1x drivetrains (like the limit screws). However, I would not follow their directions on cutting/sizing the chain, as the method shown in the Box video addresses the real issue that has to be addressed (chain cannot be too long, so you make it as long as possible).

The Park Tool ‘Gold Standard’ Tutorial

This is the method I have used for years. It takes the most time, but it always works, and if you do nothing else, just watch it and learn all about how your derailleur’s adjustors interact. The methods above worked great, but they may not translate to your derailleur. If so, do it the long way with these detailed adjustment instructions. Since this is not an installation video it concerns itself solely with adjusting a derailleur in a completely installed drivetrain. This video is also the best in terms of helpful visual instruction of common component parts.

Unique Weirdness Worth Mentioning

My chosen frame comes from a bygone era. In that era, cable routing was done differently. First of all, those handy little zip-tie altars hadn’t been conceived yet. Instead on this frame we have circular braze-ons that require the cable to be routed inside of them. Want to re-route the rear brake cable? You have to disassemble the brakes to make that happen. Which was a pain back then, but more so now that we have hydraulic brakes that you don’t just take apart unless you feel like bleeding the system all over again.

It gets worse with the shift cables. Here again on this vintage frame we have the fixed cups meant to accept a cable end… but back in the day, cable housings were nowhere near as well-engineered (and slick) as they are today. So you see a frame designed to only use a minimal amount of cable housing wherever there is a bend, and then run all straight lengths of shifter or brake cable bare and out in the open air.

Well its not 1999 any more. In 2022 we have some pretty slick cable housings, and in fact my Box 1 shifter kit’s main purpose in life is to provide super slick performance with resistance so light the Box Components marketing department went crazy making sure you know all about it. On top of that, the brake cable runs meant for wired cable aren’t going to get any since we are using hydraulic hose instead.

Luckily there are inexpensive little doodads made that let you convert – more or less – these old school fittings to accept hose. Here they are installed, prior to cable and hose installation.

And below, here is how they are used. Not ideal, but a necessary evil unless I wanted to compromise performance for a vintage look on the shifter cable (which I didn’t) You can find these little parts (listed as ‘cable guides’) on the parts list in the Planning post.

And you will not need to use them at all if you are building your bike with a frame manufactured in the modern era.

Yes we’ll trim that zip tie. And I think this is the only picture of the battery mount on the bike, before I permanently attached the battery.

Figure Out Placement and Install The Speed Sensor

I’ll make no bones about it: This item was very time consuming And there’s no reason it should have been. In the end I used almost exactly the same approach as I have taken with all of my other bikes, and the final solution looks like something I could have knocked out in a half hour. Sometimes when you are building a bike these things just happen. I only bring this up because I want to emphasize that if something similar occurs in your build… don’t get frustrated or upset about it. Just stick to it – or maybe walk away for the afternoon and come back tomorrow, fresh-faced. It’ll work out.

Like this one did. Here it is fully installed and wired up:

At left, you can see an overview of the entire sensor assembly including the magnet on the wheel, attached to the spoke. Please note this is not the Bafang magnet that came with the sensor kit. The Cateye sensor magnets you can buy from Amazon are lighter weight, and at least as strong if not more so.

As you can see in the photos above, the sensor is not sitting directly on the stay. Its sort of strapped to something. That something is a marine cable crimp. A couple of them are pictured below, and while they are not quite the same as the one I used on this project, the picture gives you an excellent idea of what they look like. I buy them at my local hardware store, but you can find them on Amazon too.

I have used crimps like this for most of my BBSHD builds. They are square-ish enough and rounded enough that they can easily be mounted either on a round surface or as here: a square one. They have rounded edges that mimic a rounded chainstay, which the Bafang sensor mount is curved to and designed for. And of course being a hunk of hollow aluminum, they are both strong and light. Below is perhaps my first use of a cable crimp (I was still using the Bafang magnet back then. This photo was taken in 2018).

In both cases as shown above, the cable crimp was used to move the sensor inward, closer to the spokes. If I hadn’t done that on either of these bike builds, the sensor would be nowhere near close enough to that magnet to register.

Here is an up close look at the entire Bafang speed sensor kit. the wire that goes to it comes directly off the motor and is included with same.

Also above is a close look at all the parts that make up the speed sensor. The silver screw goes into the back side of the magnet to glom it onto a spoke. The black screw is a set screw. The actual sensor end is a sliding arm that you can move inward or outward to help you come up with a fitment that works on your bike. This set screw anchors the parts once you’ve decided what position they need to be in. You can also see the two slots on the sensor base that you will thread a couple of zip ties thru to do your final anchoring. On the other side of those slots is an adhesive-backed curved surface that we’ll use as described below.

Lets go step by step on how this mounting is accomplished:

  1. Figure out placement before sticking anything onto anything else. Your speed sensor will need to pass within about 1/4″ of the magnet (see the installed pic above – the middle of the three. That is how close you want to get). You can get away with a little more separation if you use the stronger Cateye magnet seen in this project. But don’t push it if you can at all help it.
  2. Lay down a bit of 3M 2229 mastic rubber tape directly onto the chainstay. Just big enough for the crimp to smoosh into, which is what you will do next. This will provide a vibration free base for the crimp, as well as protect the paint on your frame.
  3. Wrap the crimp with your paint-matched silicone tape. You can see in both pics above I used white. I actually have some gray now that I will use if I ever have to remove and replace this working mount (if it ain’t broke…). Between the tightly wound tape and the sticky, thick mastic, you have pretty much locked that crimp onto your frame.
  4. Attach the speed sensor’s curved base to the curved corner of the crimp. This is where the shape of the boat crimp really shines as it mates the sensor perfectly to what is now a solid mount. The speed sensor has an adhesive base. Peel off the protective film and carefully stick the sensor onto the crimp. It should now stay put, but that sticky base cannot be relied on for long. Which is why our next step is to…
  5. Zip tie the sensor to the mount and chainstay. For the Apostate, you can see I used grey zip ties to make as close of a color match to the bare alloy as possible. For the white bike above (that is the Stormtrooper in case you were wondering) I used translucent white zip ties. Once those zip ties are on, you have a rock solid mount whose only weakness is the plastic of the sensor. Be careful when you remove a wheel (on some bikes its smart to deflate the tire. You’ll know after the first try at taking the wheel off).

Connect Display and Speed Sensor

Coming out of your motor is a plug with a captured knurl-nut on it. That is your speed sensor cable. It has a flat side on its otherwise circular surface that matches up to the speed sensor. Plug it in and thread that knurl nut onto the threaded sensor, so the connection is locked together nice and tight.

Attach The Battery

Ordinarily I would not be placing the battery in the bike in its final position at this point. I’d usually put it on a table next to the bike stand; perhaps connected by an extension cable for convenience. This bike was different as I expected the battery to be a permanent fixture on the bike. I needed to be able to see the wiring challenges ahead of me: all of that wiring was going to have to live in plain sight. Cable management was not just something cosmetic I could tidy up later when I felt like it on this build.

Mount Fitment

As noted earlier, I found – via a V1.0 pack I already owned – the Luna Wolf pack was a perfect fit for this frame. I had a spare V2.0 magnet mount I wasn’t using, and that is what you see in my early fitment pictures with the bare frame. Here’s a closeup of that magnet mount.

Thats a lotta magnets!

Its a really well-thought-out product, what with its variety of mount holes and lonnnnng magnet engagement. On a frame with a big triangle you won’t be moving that pack without really wanting to, which is a good thing. On the Apostate, fitting it in the space available was tough, but once that pack clomps onto that magnet it really is best to not try to move it at all (and yes, it did eat one of my fingers once when I wasn’t careful).

To be brief, I bolted the magnet mount as centered as I could in between the two bottle bosses on the frame. The idea was, the attachment is so strong I did not want to create a situation where the battery being pulled up bends a long extension of magnet mount. These two pieces really, really do not want to separate and damaging the frame or the mount is a real possibility (my bottle bosses are drilled steel inserts into the alloy frame… 1999 technology).

As with some other elements of this build, this mounting issue was unique to this specific frame. Your experience is much more likely to be simpler and less drama-filled. This magnet mount is not problematic on modern frame construction.

Battery Placement

I wanted this puppy pushed as far forward as possible. For starters, once this pack is on its on. Its not moving and I need to be able to connect and disconnect my cables to and from this otherwise wireless battery pack (a unique feature of the Luna Wolf – you make your own cables and plug them into the battery using built-in XT60 and XT90 receptacles).

Speaking of which, when building an ebike you are going to need to be making a cable or two. This is a great time to introduce you to a complete tutorial on the subject:

How To: Safe, Reliable Electrical Crimp Connections

Since I didn’t do the wires on Day Two, we’ll save that discussion for Day 3. Suffice it to say as Day 2 wound down, I just made a test connection to the motor from the battery with a short Anderson-to-XT90 adapter (BBSHDs from the factory have a long battery lead terminated with Anderson powerpole connectors).

Test Motor Functionality

Its getting late, and I’m starting to get sick of looking at this bike. I need to knock off for the day. But before I close up shop I want to just test the motor to make sure it works. Otherwise I’ll be tossing and turning in bed, wondering if I got it all right. With the speed sensor and battery connected, all I need to do to make a functioning motor is to

Connect the Display

Remember how early in the day we put the display on the bars, and left the connection wire dangling? Its got a green HIGO female plug on it and the only place for that to go is the green male HIGO plug on the wire harness that we also left dangling nearby. HIGO plugs have little arrows on each side that you line up (also there are pins on the inside you need to see to double-check you have it right). Push them together once you have them lined up. These waterproof connectors will often come together with a little, audible pop.

Connect The Throttle

When we put the display on the bars, we also put the throttle on. Now its time to reach for the female yellow plug on it, and mate it to the male yellow one on the wiring harness which is the only possible match. Same deal here: Match up the arrows, and double-check by also visually watching the inside pin on the male side line up with its matching slot on the female side.

Turn On The Display

This is it. Moment Of Truth time. At this point, if you hit the On switch the display should light up (naturally you need to have at least some juice in the battery 😀 ).

When I did it for this bike, it worked! Now what do I do? Well the bike is up in a stand, so its safe to give it a little throttle… and the wheel spins around! Yay throttle works! What about pedal assist? Click down to the minimum level of assist (“1”). Grab the wheel to stop it from spinning (since we haven’t put the brakes on yet) and now… rotate the pedals. If the motor fires up and spins the wheel again, our pedal assist sensor works! Look at the speedometer display. Is it registering some kind of speed value? If so, the speed sensor is working. Look at the back end of that sensor. There’s a little red light you probably didn’t notice before. Is it lit up? Hooray. So far so good.

And with that, its time to call it a day.

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