Bullitt with BBSHD (3x9 gearing prior) - Post build advise

[MoneyPit]

A reminder that I need to read your 2wd notes, as I've wondered how the motors are synced and the like.

You bet! If you don't know already, at that site I have a specific series on 2wd start to finish, and it includes some mythbusting. Your comment on synching the motors/wheel rotation I used to hear all the time. In short: It doesn't happen. The different sized wheels on the Bullitt demonstrate that there cannot be any form of synchronization.

The back motor has a freewheeling rear hub, and the front geared hub motor has a freewheeling clutch. So lets say the rear motor starts to overpower the front - and this happens as speed increases past the hub motor's rpm limit - the hub motor just freewheels forward (in practice output melts away to around 50w so its always providing at least some goosing of the wheel). Likewise if I hit only the front throttle coming up from a stop, the rear wheel freewheels forward if I just let the back wheel motor sit idle.

Here's another example: Say I have a front hub motor only: I have 2wd thanks to the muscles in my legs powering the rear. Front-motor bikes work fine, right? (ignoring the issues with sheared dropouts and traction :D ). Same principle.


Pic of my gen1 Lizzard King Bullitt, nestled between my Big Fat Dummy and Envoy builds, for attention.

[ncmired]

Thanks much for the write-ups & photos, MoneyPit

A reminder that I need to read your 2wd notes, as I've wondered how the motors are synced and the like.

[MoneyPit]

This is quite an old thread but since I have built two Bullitts frame-up, both of which are BBSHD-powered from initial assembly, I thought I would add a bit to what the OP put up.

My first Bullitt was built in 2021 (late 2020 frame manufacture date), and the second in early 2023 (late 2022 frame manufacture date). Technically both are the same, identical and current design. Howeer there are slight differences in the two. The one that matters is the underside of the bottom bracket is just a bit different, particularly with a changed-placement cable guide. That change will require you to file down the cable guide so you can fit the BBSHD axle thru the bottom bracket, along with filing down the forward-most mounting bolt socket so its barely functional.

The alternative to this is, in hindsight, a better idea: Leave the frame entirely alone and sacrifice that forward mounting bolt socket entirely (filing it down past where it is usable) and leave the frame alone. This is the better way to go and if you do, you need to use the interlocking hose clamp trick to stabilize the motor. Doing this will make for a highly stable motor that cannot move.

This is a pic of the motor, a few months post build (hence the grimy hose clamp cover, which is white heat-shrink). The hose clamp is linked to another one that is running around the circumference of the motor housing.



Note also there is a PAS ring on the spindle. That is because this bike is 2wd and has a front hub motor. This bike lives in super-steep hills and distributed traction makes for vastly better performance under load, which can be 100 lbs or more of added stuff dumped into the cargo box, plus my own body weight making for a bike with the potential for a 500 lb total system weight.

The OP talks about using the Luna wrench to affix the motor. I use the Luna sockets and a 1/2" torque wrench. Unfortunately Luna no longer sells the sockets but that knuckle-busting tiny BBSHD wrench and all of them sold like it everywhere are a poor substitute for a proper socket and torque wrench set to 90 ft lbs. Also I use two inner lock rings stacked on top of one another to form a jam nut, which also keeps you from having to buy two different sockets to tighten down the motor.

The OP talks about routing the wiring, and we both ended up with routing them behind, up and over. However I brought them up behind the secondary housing and kept them out of the rear wheel's triangle. then I used a bit of PVC to run the wires cleanly along the bottom frame rail. You can see the rear-most part of that PVC above.

I don't know why the OP needed a spacer on the drive side. That shouldn't be necessary. I have no issues on two Bullitts using Lekkie 52T, Lekkie Pro 40T and Luna Eclipse chainrings, and the Eclipse gives enormous offset. It fits fine without contact.



I have extremely steep hills in my local area. The Luna Eclipse chainring is the absolute best choice for extreme hills thanks to the wicked tooth profile, which lets the chain stay on in the big cogs even while putting 1000w thru the chain with 100 lbs of landscape gravel in the cargo box. The original Lekkie Pro 40T had teeth so small they skipped under that kind of load. The 42T Luna ring with its long teeth, and its extreme inboard offset, is far better than a smaller ring with less offset and a kinder/gentler tooth profile. I learned this the hard way after several hundred miles of trial and error, and two completely different drivetrains (Box2, followed by Microshift Advent X).

My 35ah battery on my hill-climber is in a hidden battery box, along with an onboard weatherproof charger, and the front motor controller.



I did a detailed writeup on all this, including everything needed to build the white Bullitt frame-up, and a bunch of detail on how to do the 2wd intelligently.

https://talesontwowheels.com/2023/04/30/larry-vs-harry-bullitt-hill-hauler-back-to-front-part-1/

[Retrorockit]

You might look into a Sturmey Archer 3x9 rear hub.The overdrive portion probably won't be much use to you, but the lower range will get the gearing back down where you like it.

https://www.universalcycles.com/shopping/product_details.php?id=51579

You can play around with it at Sheldon Browns Gear Calculator to see what it has to offer.

https://sheldonbrown.com/gear-calc.html

Speed at 90rpm is a useful setting for the Gear Units menu.
The SA 3 speed is considered strong enough for a BBSHD.

[UrbFab]

Interesting the whole description, I don't have a Bullitt yet and I'm dreaming of it but soon I will have it, I'm looking for offers for the engine in the meantime, so could you tell me the width and other necessary dimensions that I have to consider for the frame in the bottom bracket of the pedal pin? Thanks.

[Defjr333]

Mine has always had that fuse as well. It is hidden under some heat shrink aprox 3-4" from the motor on the power lead. I have never needed to open up the heatshrink so I never knew the rating. Interesting that it is a 25A fuse if the BBSHD handles 30A and with the Ludi controller up to 60A(maybe higher rated fuse on Ludi controller?). But fair warning, using a "normal" automotive ATM fuse will probably see it "blow" frequently as most ceramic cylinder type fuses like those are slow blow. ATMs are generally fast blow. I would bump it up to 30A if using an ATM style. Just my $.02

[LizardK2000]

Update: Broken fuse plate?

With routing the wiring there was a bulk on the positive wire about 6" from the motor. Shortly after rerouting the wiring the motor & controller stopped working, not getting any power. After some debugging I discovered that this version of BBSHD had an inline 25A ceramic fuse (see pic). I got to spice the wires, and added a more modern 25A ATM fuse (see other picture) closer to the battery.

I'm not clear if this is a standard BBSHD feature or just a random variation. Struggled to find other people talking about a in-line fuse on the positive wire of the BBSHD motor.

[LizardK2000]

The last couple years I have loved owning a Bullitt by Larry vs Harry. I came to the bike through a random series of events, but since getting it, my kid and I have lived on it all summer. We often pack up in the morning then bike to the park, zoo, pool, museum, wherever going for day long adventures, by bike. I live in a hilly town, but the gearing was low enough, that with determination I could make it around.

Well, my big kid got bigger (4) and got a little sister. So I researched conversion kits. I'm writing this so others can learn from my errors.

I went with the BBSHD from California E-Bike with 52v 14.3 Ah battery and a EggRider Controller.

The order:

• Overall happy, frustrated that the website listed a 5V port on the battery which it doesn't have (minor)
• Doug has been helpful with the one exchange I need to make due to order an extension I didn't need.

The build:

• Getting this onto the Bullitt was a process... the shaft of the BBSHD would not fit through the bottom bracket, without minor Dremmel work. Once through the reduction gear collided with the rear chain stay, needing two 1.25mm in spacers (https://california-ebike.com/shop/sp...ttom-brackets/).
• Once in, getting it tight was another challenge. Tried a universal tool, no luck. Not sure if it was initial break in, or just couldn't truly lock down. Eventually ordered Luna's wrench (https://lunacycle.com/parts/bafang-p...allation-tool/), it worked! But the wrench also bent in the process. I would definetly start by ordering Luna's wrench.
• Another minor challenge was routing the wiring. Since I'm unable to rock the BBSHD forward much, the wiring doesn't have much clearance. I don't want the wiring going under the batter (ground clearance issues), so instead it comes behind and over, giving 5mm of clearance to the wheel. Not ideal, but maybe will make a skid plate to protect. Luckily the Bullitt has lots of wiring attachment points that worked well
• The stock crank arms were miss threaded, so ordered a basic pair of Shimano e-bike crank arms.
• I struggled to decide where to place the battery. I ended up putting it in the front of my kid carrying box, just behind the front wheel. To acomodate this had to get additional wire to splice in.
• The e-brake cutoff magnets nicely sit on a metal part of the brake, silly, but made testing and instal supper easy.

First 200 miles

• It has been game changing. Previously getting up our hill was doable, but would take all the energy out of you. Now I can kick up the assist to get up the worst parts, and turn it off/down for the flats. This has given me more confidence to take my bike when I'm feeling less then a 100%. Both my kids are also loving it. One day we had to take the car for school drop offs, and my 4 year old complained that he didn't get to ride in the speedy bike.
• Initially had wanted to keep low range gear options with 36T front ring (https://california-ebike.com/shop/le...-hd-chainring/). Learned this through my chain so far out of line I only kept my top 4 rear gears. So I had to change to a 42T front ring (https://california-ebike.com/shop/le...-hd-chainring/) which lined up my chain, allowing full rear sprocket options. This plus a larger rear cassette has helped me maintain most of my range, but I don't think I'll be able to do the steepest hills with out e-assist.
• Even with the gear shift sensor the shifting has been less than smooth. Workable, part of a conversion... but an internal gearing hub would be nice.
• I love the EggRider controller. It has been fun being able to tinker with the settings via the phone app. I find that I don't touch the app, except to change the settings on the controller. The batter doesn't have 5V port to charge my phone, so I don't want my phone on the whole ride. My only minor gripe, is the screen is hard to see with polarized sun glasses.
• With my setup and local terrain I have a range of about 22 miles. This is just enough to do kid drop offs and pick ups.

Hopefully someone finds this information helpful. When going to do my conversion I struggled to find some of this info in relation to Bullitts, obviously being a noob to conversion didn't help ether.