Bafang BBS02 - non-bafang aftermarket crank arms available?

[toxie]

Hi all,

I had my left crank arm work itself loose after around 700km. I got a replacement bafang crank and installed it, making sure to tighten it extra hard this time.

It seems to me that these crank arms are of very low quality, they're heavy but still made of very soft metal. It's very easy to strip the threads, and I guess both cranks having the same screw threading does not help either (usually one is reverse threaded).

Is it possible to use any other kind of crank arm with the bafang kit or is it a completely custom job?

 

[--freeride--]

You can use any crank you want but they normally have more Offset...

I grease all the threads, the plane where the screw hits the crank arm and the axle. I then thighten it very hard with my hole weight.

Nothing did come loose for now. But I have two spare Sets of cranks liing here (12$ a set). So we will see what happens.

 

[Triketech]

Different lengths are available from Hostel Shoppe.

I've got a BBS02 on the way to play with and will be fitting the 155mm arms.

 

[rscamp]

Also there are very inexpensive unicycle arms that fit - which can be great if you want shorter arms...

 

[tahustvedt]

Hi all,

I had my left crank arm work itself loose after around 700km. I got a replacement bafang crank and installed it, making sure to tighten it extra hard this time.

It seems to me that these crank arms are of very low quality, they're heavy but still made of very soft metal. It's very easy to strip the threads, and I guess both cranks having the same screw threading does not help either (usually one is reverse threaded).

Is it possible to use any other kind of crank arm with the bafang kit or is it a completely custom job?

The kit is no supposed to come with two right hand arms, of course, so something went wrong there. They don't come loose either if they are just tightened to the right torque, 40 Nm. What tool do you use to tighten the crank arm bolts? A little allen wrench isn't going to cut it on its own.

 

[alfantastic]

+1

I've had mine torqued to 35Nm since I fitted the kit 700 miles ago, and no problems whatsoever :wink:

 

[tommie]

+1

Allen keys just won`t cut it unless you stand on them, also use Loctite or similar on the threads.

 

[toxie]

Hi all,

Thanks for the info.

I originally used a torx screwdriver to tighten the screws as far as I could. The second time around, after the crank worked itself loose, I tightened them much more with a ratchet wrench. Unfortunately my ratchet wrench does not have a tension meter, and they seem very expensive so hopefully I won't need one.

It does seem solid still after some hard test riding yesterday.

I didn't mean the kit came with two right arms, they were marked left and right. I thought that when I removed the original cranks one of the fixing bolts had a counter-threaded screw (tighten counterclockwise), but I guess I must have misremembered - it looks like it's only the pedals that are set up that way.

EDIT: Also going to look into getting some loctite and seeing if that makes a difference.

 

[--freeride--]

The schlumps crankarms have more Offset that the original Bafang, which are nearly straight. I would not want those.

 

[rscamp]

The schlumps crankarms have more Offset that the original Bafang, which are nearly straight. I would not want those.

I'm using the Schlumpf arms and they have so little offset my heels are prone to striking them at the hub.

 

[byebyepetrol]

I've found scribing grooves (with a Dremel disc) across the four tapered faces prevented my BBS01 cranks from loosening:

http://endless-sphere.com/forums/viewtopic.php?f=4&t=64837

 

[tahustvedt]

If all you have to tighten with is an allen wrench then it's nearly impossible to achieve enough torque. Here's a trick to increase the leverage, in a pinch. If you're going to work on bikes a lot, just get a cheap torque wrench. It will be accurate enough to make a difference.

 

[amigafan2003]

Unfortunately, after a crank arm has worked loose once, it'll keep happening regardless of how tight the bolt is, as the hole will have enlarged itself in the processes of loosening.

If you're working on bike - a torque wrench is a good investment - you don't need a mega expensive on (just don't leave it wound up or "set" - reset it to zero after every use for storage) and you only need one that goes up to 50nm or so.

http://www.ebay.co.uk/itm/Draper-34570-3-8-Torque-Wrench-Adjustable-10-80-Nm-Calibration-Certificate-Case-/400156849877?pt=LH_DefaultDomain_3&hash=item5d2b34f6d5

 

[kammo]

I've have had luck using Shimano step cranks. Also there 175mm Also available in 170mm. Bafang cranks are 170
https://www.bike24.com/p2138455.html
Also can't wait to check lekkie buzz bar cranks
http://www.emax-ebikes.com.au/products/lekkie-buzz-bar-cranks

 

[sannder]

It looks like the buzz bar are available - anybody has any experience with them ?
These cranks should be stronger than the stock Bafang - and lightweight.
Offset is 0mm which is a bit unexpected to be honest.

 

[WoodlandHills]

Unicycle crankarms: cheap, strong, and all sizes from 75mm to 175mm.......

 

[Nanoha]

It looks like the buzz bar are available - anybody has any experience with them ?
These cranks should be stronger than the stock Bafang - and lightweight.
Offset is 0mm which is a bit unexpected to be honest.

The Lekkie buzz bars are amazing, self extracting and available in offset and no offset.
I chose the no offset version as I it cleared my bbs02 with plenty of room to spare.