Bafang crank arms are crap

[Dewey]

700 miles on my BBS01 and I need to replace one, it's been educational reading other people's experiences with Bafang crank arms: https://electricbike.com/forum/forum/main-forum/general-discussions/16233-left-crank-always-loosens - sure enough it's the left arm that has gone, I'm going to see how long the replacement lasts tightening down the bolts to the Bafang torque spec before springing for a higher quality replacement pair.

 

[JRA]

It is not just the initial tightening down of the bolts (both sides) to spec that is the problem. It is riding the bike for a bit and the not re-tightening down the bolts as the aluminum crank arms need to seat themselves on the steel bb spindle taper. They will loosen enough to take more tightening with just a test ride around the block. I even recommend a third effort after a few good rides as you will get even more. Once the crank is seated it will stay there but still a good idea to check it once in awhile. Because once they come loose the taper interface is basically ruined and the crank will need to be replaced.

This isn't just a Bafang problem but ALL square taper systems require this treatment. Also I would suggest that you keep an eye on the actual motor mount nut, for lack of a better term, that secures the system to the bb. It will also come loose and as it isn't on a taper will continue to do so over time and keeping an eye on it is a good thing to put in your normal maintenance program.

 

[rich c]

A little grease on the taper, and on the pedals when you thread them in helps. But the cheap alloys are soft enough that as JRA says, you have to constantly check the bolt and pedals to make sure they are tight. An eBike is heavier than a standard bike, and that also adds to the load on the crank arms.

 

[Dewey]

Nursing the bike home tonight was an education, the retaining screw kept coming undone every 100 yards so I had to ride pushing only the right pedal. I stopped into a Trek shop to be told they had a square taper left crank arm but incredibly the Bafang crank arm has the hole at a 45 degree angle in a diamond shape rather than square on, why the change? Thankfully I got home by stopping and tightening the screw every now and then, ordered two crank arms and new retaining screws from California ebike.

 

[Sage Oz]

I'm having a difficult time sourcing some higher end ISIS crank arms to fit my Ultra unit, especially as I'm trying to find 160mm or at most 165mm arms. Best I've found online are the RaceFace aeffect arms which should fit but everywhere is out of stock. Miranda is another possibility but hard to source here in the USA. Seems like there is a small need for bafang upgrades, especially in the Americas as the European market is a couple years ahead in the ebike popularity and sales availability. Strange why Bafang would choose to make the main drive and display so nice but yet crank arms are an obvious cheap quality cast and other parts like the thumb throttle are such chintzy plastic. Anyone have a source for such crank arms or nice thumb throttles?

 

[Pegasus]

A friend I cycle with has a Bafang system and has had a crank arm come loose on two occasions. I think the answer is to tighten them on a regular basis as it does seem the aluminum arm allows for expansion on the square taper - hence looseness. I now check mine weekly.

 

[tomjasz]

7 BBSxx bikes, and 14 crank arms. Never a problem. Thaks just my personal bikes. I've sold scores of kits and typically it's user failure. This is an issue with kits. N00bs to building make simple mistakes and the manufacturer gets the blame.
Use a bit of Loctite blue and recheck the torque. This is what a professional LBS would do, or should. Admittedly they are soft aluminum, but proper torque will avoid any failure.

 

[Sage Oz]

I'm just surprised that in the world of something as mass produced as bicycles are, that completely obsolete tech standards are still being used. I get that square arms are cheaper to manufacture than the much better and yet still outdated ISIS standard(so unluckily named now) or any other newer spec, but both customer and manufacturers have to start striving for higher quality and longer lasting products even at base levels. Square taper should have been phased out completely for all new bikes way back in Y2K. Cheap things including bikes that prematurely end in landfills and cost twice that environmental impact just in the process of manufacturing are saccharine sweet.

 

[Redrock]

I got these Shimano crank arms for my Bafang BBSHD on the recommendation of others and they have worked well.
(Link Removed - No Longer Exists)

 

[tomjasz]

Lekkie BuzzBars! Designed for the BBSxx with offset arms available.

 

[Redrock]

Good to know!

 

[BBassett]

I put 9000 miles on my BaFang cranks and never had an issue. I just upgraded to a set of Lekkie off-set cranks... mostly for the looks and for the off-set.

https://imgur.com/a/3w6izz7 - Bike and Trailer
https://imgur.com/a/DKpcF0a
https://imgur.com/a/zXXlyuv
Check out 70 miles w/front panniers & trailer on Relive! https://www.relive.cc/view/g37290970278

 

[tomjasz]

I put 9000 miles on my BaFang cranks and never had an issue. I just upgraded to a set of Lekkie off-set cranks... mostly for the looks and for the off-set.

https://imgur.com/a/3w6izz7 - Bike and Trailer
https://imgur.com/a/DKpcF0a
https://imgur.com/a/zXXlyuv
Check out 70 miles w/front panniers & trailer on Relive! https://www.relive.cc/view/g37290970278

they’re the typical $500-$700 dollar bike quality. Most problems come as a result of inexperience installing bike parts. Not torqued down correctly they loosen and the hardened steel crank eats the aluminum up. I have two 5 year old builds with original cranks. I support Lekkie products but am to cheap the fix what I’ve never broken

 

[BBassett]

they’re the typical $500-$700 dollar bike quality. Most problems come as a result of inexperience installing bike parts. Not torqued down correctly they loosen and the hardened steel crank eats the aluminum up. I have two 5 year old builds with original cranks. I support Lekkie products but am to cheap the fix what I’ve never broken

Sometimes I want more than just the minimum.

 

[Dewey]

It happened again! Twice replaced with stock Bafang aluminum crank arms, had enough, am going to try out a unicycle steel crankset

 

[tomjasz]

Wow! I have never had an issue but I do check every few rides. I have arms from 2014.

 

[Redrock]

On recommendation of others, I replaced mine with the Shimano STEPS EC-6000 when I installed my motor. I haven’t had any issues with them.

 

[Dewey]

On recommendation of others, I replaced mine with the Shimano STEPS EC-6000 when I installed my motor. I haven’t had any issues with them.

I thought about them but will see how I get on with a shorter steel crankset. I’ve read Schlumpf crank arms are also good.

 

[JBANKY]

I'm having a difficult time sourcing some higher end ISIS crank arms to fit my Ultra unit, especially as I'm trying to find 160mm or at most 165mm arms. Best I've found online are the RaceFace aeffect arms which should fit but everywhere is out of stock. Miranda is another possibility but hard to source here in the USA. Seems like there is a small need for bafang upgrades, especially in the Americas as the European market is a couple years ahead in the ebike popularity and sales availability. Strange why Bafang would choose to make the main drive and display so nice but yet crank arms are an obvious cheap quality cast and other parts like the thumb throttle are such chintzy plastic. Anyone have a source for such crank arms or nice thumb throttles?

can you send me a link to the race face arms that work....the lekkie one will work...they are 160mm and have an offset of 15.6 for the bafang ultra...I am looking for other options too...The lekkie one just look kinda plain.......thanks Jeff [email protected] I can't post the link...here is a picture...maybe you already know about these...


https://lekkie.bike/product/buzz-bars-isis-160mm-v2-1/

 

[tomjasz]

can you send me a link to the race face arms that work.

Just a Google search away! Raceface 160MM offset crank arms .

Lekkie are the best selling crankarms but I suggest they still be taken off the axel with a crank puller tool.