Chain break blues...drivetrain upgrade options?

[ColinC]

'Got out on my first ride today with my BBSHD conversion on my 26" fatbike. What a blast...I can see why these mid-drive kits and ebiking in general is so popular!

The fun ended quickly though when my chain broke. I knew this was a possibility with my 11spd setup, but decided to keep my drivetrain "as is" for the conversion just to see if it might work. My setup: 36T Luna Eclipse front chainring, Shimano XT 11-46 11spd cassette, SRAM GX derailleur and SRAM XX1 11 spd chain.

I wasn't pushing the torque too much prior to the breaks. I programmed my BBSHD to a "relaxed" profile from Luna, and I wasn't using anything above PAS 2 on a slight incline.

I'd really appreciate any advice/recommendations on a durable cassette, derailleur + chain combo that could take the abuse of the BBSHD. Most of my riding is off-road-/trail, so the low-end gearing is much more important to me than the high-end. I'll probably be changing the front chainring to a 42T Lekkie or Luna to gain some more offset/improve my chainline, so I'd want my choices to work well with that 42T front ring. It would be nice to keep the Shimano XT cassette if at all possible, but it may not be durable enough to work for the BBSDH long-term (https://bike.shimano.com/en-US/product/component/grx-11-speed/CS-M8000.html

Thanks!

 

[Buckow]

I’ve had the best experience so far with a 12 speed GX Eagle chain, cassette and derailleur. I broke a bunch of chains on the SRAM EX drivetrain as well as the XX1 drivetrain.

 

[ColinC]

Interesting that you've had good luck with the 12spd. I've read in a few other threads that others were opting for 10spd and below drivetrains to avoid the thinner/weaker 11spd chains. But there seems to be a lot of inconsistent experiences folks have with their chains breaking, which I suppose is to be expected when you have so many variables in the mix (riding style, terrain, amount of lube/maintenance, etc.)

 

[dogman dan]

well, the only times I ever actually broke a chain on hub motor bikes, was when I put a chain back together not quite right. So you might just try repairing the chain you have carefully. It could be just that simple. Sounds like a strangely quick failure, that points to a bad connection on that chain that was going to break just pedaling.

But If I was changing stuff, it might be a good idea to go with 7 speed chain and derailleur. But if you really think about it, the weak point is the same on both kinds. Its that pin. I'm not sure if the links themselves are any thicker on 7 speed chain.

 

[kcuf]

avoid wimpy light duty bicycle components

8 speed steel stuff wins round

frequently use wear gauge

replace cheap steel chain showing any signs stretch wear

 

[Grantmac]

Lots of the serious EMTB guys are running 1x11 setups with more power than that. How you run it is the important part. Get your downshifts done before the hill, don't shift under load. Keep the derailleur adjusted perfectly.

 

[markz]

hubs dont need no chain

 

[martin]

Get a Rohloff, bin your derailleur and cassette.

 

[john61ct]

Costs more than the rest of the bike.

A 4-5 speed version, able to go to higher torque is what I'd reallyvlike.

 

[ColinC]

Well Dogman I think you were correct. I threw on a spare 10spd chain I had and I've had two solid rides since with no breakage, so clearly an issue of some sort with the first chain.

Long-term, however, it seems like having a beefier overall drivetrain makes sense, starting with an all steel-cog cassette that can handle the additional stress.

 

[dogman dan]

I smelled a rat when it broke that quick.

Yep. get a wheel with screw on freewheel, and go to 7 or 8 speeds, shifters are cheaper too. Derailleur quality won't matter so much as you might think. Then search out a good chain to put on it, with thicker links less prone to stretch than thin chain.

Definitely, get off the throttle, pedal to switch gears, get back on.

 

[john61ct]

how about moving from roller chains to cam chains?

I've seen them recommended for quiet running

but also apparently handle higher power too?

thinking torque ranges 150-200 N.M

 

[Grantmac]

You can't shift a cam chain and 7-8spd free wheels aren't going to have the range offroad.
High end EMTBs have this stuff figured out and they are putting out more torque than a BBSHD.

 

[john61ct]

You can't shift a cam chain and 7-8spd free wheels aren't going to have the range offroad.

But with a IGH, say a Rohloff?

I think they only take 130 N.M not sure what's more robust out there.

> they are putting out more torque than a BBSHD
This is for heavy cargo bike in mountain country, I think would need multiple motors if a BBSHD were involved.

 

[Grantmac]

A series mid drive isn't what I'd run on a bike like that, I'd go parallel.