Lost BBSHD Crank arm bolt-Alternatives

Peddling up hill I felt the crank arm a bit wobbly, next I see the bolt fall out and roll back down into a drain

managed to get home nursing the battery with only one crank arm attached must have looked a strange sight! 8)

As I live in the UK only Banfang bolts are available in the USA,

Is there any one standard crank bolt I can use to replace the Banfang or is it specific to bafang.

Just read that once the arms become loose they are pretty much ruined being soft aluminium. do I need to get replacement arms too then?

Thanks

Any regular crank bolt fits. Search Ebay, its .99cents free shipping. With some plumbing tapes on the thread when you put it in will not come off.

zippy500 said:

Just read that once the arms become loose they are pretty much ruined being soft aluminium. do I need to get replacement arms too then?

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Shimano make a nice set of cranks for their STEPS mid-drive that are an excellent replacement for the BAFANG cranks. You can also use cranks from the Schlumpf drive if you can find them. Maybe others too. The bolt is a bog standard one that comes in a couple of different forms (hex head or Allen keyed).

When you first install square-taper cranks make sure that the mating surfaces are clean and free of grease - wash them with detergent or metho if you like and rub them dry. Then carry a suitable ring spanner with you and tighten them every few km as they settle in. Especially the LHS one which - for various arcane reasons only obvious to Sheldon Brown - will tend to work its way loose if it can!

Sam.

The left one comes loose more as its torque is transmitted thru the bottom bracket... the right one doesn't twist on the spindle the way the left one does....

Never maiden and/or ride any new Bafang mid drive install without carrying 8mm Allen wrench. They do become loose in the 1st few miles of use but with simple re-tightening they'll eventually remain snug. But if you allow them to get loose and run loose, they'll never be the same and nearly impossible to keep tight on the BBSXX spindles.

samsavvas said:

When you first install square-taper cranks make sure that the mating surfaces are clean and free of grease - wash them with detergent or metho if you like and rub them dry. Then carry a suitable ring spanner with you and tighten them every few km as they settle in. Especially the LHS one which - for various arcane reasons only obvious to Sheldon Brown - will tend to work its way loose if it can!

Sam.

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haha here's this endless debate about grease again. speaking of sheldon brown he was a greaser 8)

periodic re-tightening is what causes split cranks. i grease then torque properly. blue loctite if the pre-applied one has rubbed out already. if done properly you don't need to touch it again

The left one comes loose more as its torque is transmitted thru the bottom bracket... the right one doesn't twist on the spindle the way the left one does....

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on a normal crank no, but the bbs right crank does transmit through the BB spindle because the chainring isn't directly connected to it

Yes... They are one of the increasingly common exceptions to the wiggly left thing...

I used my 90 degree air grinder (~$15 at HF) with a 2" Scotchbrite pad to remove the paint on the BBSHD shaft.

Loctitie would not stick to the paint. The paint was wearing off bit by bit and letting the crank arm get loose. I THINK I finally have it fixed. Am running Schlumpf crank arms. While I think the arm is now tight, the left pedal got loose - am waiting for a replacement battery charger to see if will remain tight. I think it partially stripped the pedal threads when it got loose. I loosened it and used Loctite before tightening it back up.

This whole BBSHD project has been one little problem after another that as taught me SO much. A good thing.

The kit was good but my 2007 mtb bike was due for a lot of maintenance that I did not recognize until I ran all that BBSHD power through it.

Brakes, cable adjustments, new rear derailleur, bent derailleur hanger, trued up rear wheel, new chain with stuck link causing a skipping chain, loose crank arms, etc.

I'm close, really, really close to reliable bicycle transport. I've ridden it to work twice and the second return trip was battery power only b/c the left crank arm got so loose.

When my left crank arm fell off, I re-tightened and applied loc-tight, and it came loose again. It never really felt like it went on as far as it should.

After closer inspection, I noticed it wasn't tapered correctly. I purchased a new (easy to find) left crank arm at the LBS with a proper taper and it has t came loose since.

If you look at them side by side, you can tell the Bafang crank arm was not machined correctly.