A couple mods I've done on my BBSHD


New Member
I've come up with a couple "new" mods for my BBSHD.. They're both existing tech. but new for this application.
The chain retention mod I'm going to list first because it's needed to do the 2nd one. I did them in the reverse order, and discovered I needed the 1st one to get the 2nd one working.
For chain retention I looked to the recumbent resources since they have very long runs of chain hanging in the air. I tried several things and found that the Terra Cycles 15t drive side idler is what worked in my very sensitive application.
I used this bracket to attach it to my 34.9mm seat post.
It sits behind my flat 50t chain ring and pushes the chain down slightly. Since it turns with the chain it adds no friction to the system. Its' also smooth and quiet.
This is working w/o an offset ring,Wide/Narrow, or short stacked cassette. Wheels up launches in the 3 cross chained lowest gears.
I'm also running a vintage Rapid Rise mid cage derailer and gripshift dumping multiple gears up or down.
Mod#2 Front top chain guide is mandatory for this.
Front Freewheel mod. ( This is what made my bike very sensitive to chain management.)
Mid drive Ebikes almost all have a front freewheel. The rear one is actually no longer needed.
It can be locked out by using 2 very small zip ties to tie the cassette to the hub, or spokes.
Shimano offered this about 50 years ago as the Front Freewheel System. With friction clutches in the cassette.
Magic Cranks still offers it zip ties and all.
1- This will keep the chain moving with the rear wheel, so shifting w/o pedaling becomes possible.
2- This can push slack into the top chain run, so better chain management is required (see mod.#1).
ANY friction in the chain retention will make this worse.
3- If the chain gets stopped for any reason the small zip ties will easily break returning the bike to normal operation.
4- Things that might help especially for offroad use.
A modern clutch type derailer with a heavy spring.
A long cage derailer with enough capacity for the gear range, AND some occasional slack in the chain.
My bike is working just fine w/o these. On the street.
Here is a thread on this at electricbike.com
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A mod that created much drama on endless_sphere. But hey! glad you're enjoying your ride. A great motor!
The ES thread has calmed down. It will have 2700 views soon. It's strange still. No replies or feedback, but 20 views per day?
I don't link to that one because of all the nonsense there. But it seems to generate the most interest, and least response!
Just an update. These recumbent chain management parts are working great. Very solid, no attention needed, they stay in adjustment.
The breakaway zip ties are not breaking any more. No big deal if they do, but nicer if they don't.
This chain management solution seems to be working just as well as an offset Wide Narrow chain ring.
Especially with bigger chain rings where inset is not possible. With my 50t Surly SS flat ring I can hoist the front wheel in all 3 cross chained lower gears.
So the recumbent parts are a decent mod on their own. Zip ties or not.
The Wide Narrow stuff takes care of side to side chainline issues. The toothed idler can handle chain slap situations also.
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I just came across a Dork Ring variation of this mod.
I like the zip tie for testing because the force goes to zero when they break, and you know if you have chain control issues.
But once everything is settled down this might be an option. But I haven't broken a zip tie in a while.
Then there is the DORK aspect of it.