Chain pulling off

[Alan O]

No, this was happening when in the largest chain ring 50t and in the tallest rear gear 11t.

Just out of interest, why are you using 50/11 at slow speeds?

 

[Andywinds]

Just out of interest, why are you using 50/11 at slow speeds?

I was going through high gear starts. Probably not a good idea, but it seems to help with mountain biking.

 

[Alan O]

I was going through high gear starts. Probably not a good idea, but it seems to help with mountain biking.

Ah, interesting, thanks.

 

[Andywinds]

Just one more pic of the chain ring. It does have signs of wear.

 

[Andywinds]

I'm probably talking rubbish!

Ah, interesting, thanks.

 

[Alan O]

I'm probably talking rubbish!

Hehe

It sounds plausible that it would help build leg strength.

(And yes, that 50 ring does look very worn indeed.)

 

[Andywinds]

Ok, thanks, I'm going to order new 50t. Cheers.

Hehe

It sounds plausible that it would help build leg strength.

(And yes, that 50 ring does look very worn indeed.)

 

[Alan O]

Ok, thanks, I'm going to order new 50t. Cheers.

Looking a bit closer, the most badly worn teeth appear to be around 3-4 o'clock in that photo, and they'd be the ones around the top and pulling the chain when you're putting the most pressure on the RH crank downstroke.

 

[Andywinds]

Looking a bit closer, the most badly worn teeth appear to be around 3-4 o'clock in that photo, and they'd be the ones around the top and pulling the chain when you're putting the most pressure on the RH crank downstroke.

Ok thanks, would you still agree that this is worth replacing?

 

[Alan O]

Ok thanks, would you still agree that this is worth replacing?

I might be tempted to try remounting the 50t at a different rotation to get different teeth to engage at the maximum power part of the stroke, but only really to check if that makes a difference and try to confirm it's just wear. But I really do think it needs replacing - especially comparing the wear to the 34t. (But don't just go on my suggestion - there are far more experienced folk here than me, so maybe wait and see what other opinions you get?)

 

[Andywinds]

I might be tempted to try remounting the 50t at a different rotation to get different teeth to engage at the maximum power part of the stroke, but only really to check if that makes a difference and try to confirm it's just wear. But I really do think it needs replacing - especially comparing the wear to the 34t. (But don't just go on my suggestion - there are far more experienced folk here than me, so maybe wait and see what other opinions you get?)

Thanks Alan, this post has beem around and this is still an issue. I've just order the chainring, it was fairly cheap. It will be here in a few days so I will you know how it goes. I had someone from the bike club look at the position of the BB and crank, and he said it looked ok.

 

[Alan O]

Thanks Alan, this post has beem around and this is still an issue. I've just order the chainring, it was fairly cheap. It will be here in a few days so I will you know how it goes. I had someone from the bike club look at the position of the BB and crank, and he said it looked ok.

Do let us know how it goes.

 

[Andywinds]

Ok, so last night I found I was having the same problem again. The chain is being derailed of the front chainring. All I can put it down to is that the front chainring is sitting slightly into the BB more since I replaced the BB. Is there a spacer that I can use to move the this to the right, even for 1-2mm?

 

[Milkfloat]

When the chain is pulled off, is there any sound of rubbing beforehand, as in the derailleur pulling it off? Also, you still have not posted photos that might show if your bottom bracket is fitted correctly.

 

[Andywinds]

Nope, no rubbing. There is space between the derailleur and chain. This only started when the BB was replaced (by me). When I fitted the bearings, I pressed it in up to the internal C clip within the BB frame, before I noticed that the old bearings was never fitted this close, this is an obvious difference. But I thought that the point of the internal C clips was that you pressed the bearing to that?