BBS02 replacement crank arms

[Lardo]

First chink in the armour of my bb02s kit. Riding to work yesterday and the left pedal fell off!

Looking at the crank arm and the thread has crumbled to nothing. The pedal wasn't cross threaded and it was tightened properly.

I'm in conversation with the seller but the pitfall of buying in Asia has obviously reared its ugly head.

I'm sure I'll get a replacement from him but I don't want to wait weeks.

Can anyone suggest a replacement crank with the correct offset, or can link me to a supplier of bafang parts?

 

[Deleted member 4366]

Almost certainly, you didn't tighten it properly. When not tightened, the thread rocks up and down, gradually wearing it away until there's not enough to hold the pedal.

If the thread had been damaged beforehand, you probably wouldn't have been able to screw in the pedal, or, if the thread was compromised in some way, it would have stripped when you tightened it.

 

[RobF]

I think the pedals are about the only fixing on a bike which does need to be done up very tight.

The Park Tools pedal spanner used in my local bike shop is long.

When they put pedals on, they give it a fair bit of grunt.

As d8 says, a not very tight pedal can 'worry' in the thread, ultimately stripping it.

Not sure how to fix it.

Given the question, presumably it's not a standard crank arm.

Retapping the thread is a possibility, although if the material has worn away, there won't be anything to tap into.

It could be tapped a size larger, but I've never heard of pedals with over-sized threads.

I believe a plain collar could be driven in, restoring the internal diameter, which could then be tapped to the correct size.

 

[trex]

if you are stuck, email andy @ woosh.
They keep stock of Neco replacement cranks for CD kits.

 

[Lardo]

I can understand why the probability of a loose or cross threaded pedal is high, but I'm certain this wasn't the case. Both pedals hand tightened well before I had to use a long spanner to tighten them with significant force. Obviously I now wish I'd used thread lock as added security, but I can say that they were both installed adequately.

I've emailed whoosh but have a feeling I might need to look for alternative arms to avoid a long wait whilst I'm unable to ride the bike.

Suggestions are welcome!

 

[Ken Dando]

Helicoil??

 

[Lardo]

I'm not sure the material would take it, nor that it would be aligned straight enough on rotation.

 

[Lardo]

Crisis averted! I'd assumed my old crank arms wouldn't work having read many pages of incompatibility experiences, but my old Mongoose arm was the same length and offset and has gone on perfectly!

 

[RobF]

Have you greased the thread?

Worth doing, not to prevent seizing although it will, but because the grease enables the fixing to be done up tighter.

 

[One_Box]

First chink in the armour of my bb02s kit. Riding to work yesterday and the left pedal fell off!

Looking at the crank arm and the thread has crumbled to nothing. The pedal wasn't cross threaded and it was tightened properly.

I'm in conversation with the seller but the pitfall of buying in Asia has obviously reared its ugly head.

I'm sure I'll get a replacement from him but I don't want to wait weeks.

Can anyone suggest a replacement crank with the correct offset, or can link me to a supplier of bafang parts?

Glad you've been able to fix your problem, how come you didn't realise something was wrong before the pedal fell off ?

 

[Lardo]

It literally went from a slightly notchy feeling to coming off in about 5 revolutions. Bit of a surprise!

 

[Deleted member 4366]

Normally, the first thing you know is that your leg goes down. The next thing, you're looking up ftom the road with a sore hip. It's happened to me twice. Both times, I had forgotten to tighten the pedals after assembling by hand. I get easily distracted.

 

[Alan Quay]

Normally, the first thing you know is that your leg goes down. The next thing, you're looking up ftom the road with a sore hip. It's happened to me twice. Both times, I had forgotten to tighten the pedals after assembling by hand. I get easily distracted.

When I was a teenager I was finishing off assembling a bike when my mum shouted that dinner was ready. Afterwards I went straight out for a test drive of my latest creation.

It occurred to me that I hadn't tightened the front wheel nuts just as I pulled an enthusiastic wheelie in front of a mates house.

To this day the scratches and bruises remind me to either complete the assembly of anything critical or dismantle before doing anything else.

 

[mfj197]

I bought replacement crank arms new from a seller on ebay earlier this year but the advert is no longer live. There are some around though, it would seem.

Michael