Chain jamming between the chain rings

[Barbelier]

My son has the following Dawes road bike:
http://www.bikes2udirect.com/B3196.html

The chain keeps jamming between the two chain rings when shifting.

I have spent ages over many months checking, cleaning, lubbing everything and adjusting the gears without solving the problem. Tuned a few gears over recent years so have a reasonable idea what I'm doing. I can get it to shift okay (but not that smoothly) on the work stand, but usually on the road it will drop between the rings again. I've watched/coached my son to make sure he's not shifting under load. Even resorted to various online maintence videos for help. Thinking it was something stupid I was doing I finally gave up and took it to the LBS. They tuned the gears, was a little better for a while, but after a week was back doing the same thing again. Guy at the LBS did say the chain rings appeared to be spaced quite widely apart, but didn't offer a solution - not very helpful!

Far as I can tell from looking at the components and the spec of the bike it has the following fitted:

Shifters (couldn't find the model no. on these) Shimano STI probably ST-2300 double 8 speed
Chain set (couldn't find a model no. on this either) probably Shimano FC-2303 with 165mm cranks
Front mech Shimano FD- 2300
Chain Shimano HG50 8 speed

I wondering if some bad shifting by my son and jamming the chain earlier on has widen the gap between the chain rings making it hard/impossible to fix.

I've run out of ideas and would really appreciate some help with this.
I'm also happy to replace the chain set if necessary and would welcome suggestions on any better alternatives, if it can't be fixed.

 

[numbnuts]

Are you sure it is a 8 speed chain and not a 9 speed

 

[Barbelier]

Are you sure it is a 8 speed chain and not a 9 speed

Yes definately an 8 speed. In fact it previousy had a KMC chain which did exactly the same thing.

 

[mickle]

Whatever the original cause, once a chain has gone down between the rings it'll always be prone to occuring again. The rings, particularly the inner, are now bent at the arm(s), leaving a gap into which the chain will want to drop. They're steel rings I presume, much more prone to bending than alooniman rings.If you take the chain off and spin the cranks you'll undoubtedly see a wave where the bend is most severe.

There are only two solutions.

1) Straighten them. Take the rings off and batter them straight with a soft hammer on a hard flat surface. Or, if confident in one's own hammer wielding abilities, tap it straight whilst still on the bike.
2) Replace it/them.

 

[mickle]

Are you sure it is a 8 speed chain and not a 9 speed

It shouldn't matter.

 

[Barbelier]

Whatever the original cause, once a chain has gone down between the rings it'll always be prone to occuring again. The rings, particularly the inner, are now bent at the arm(s), leaving a gap into which the chain will want to drop. They're steel rings I presume, much more prone to bending than alooniman rings.If you take the chain off and spin the cranks you'll undoubtedly see a wave where the bend is most severe.

There are only two solutions.

1) Straighten them. Take the rings off and batter them straight with a soft hammer on a hard flat surface. Or, if confident in one's own hammer wielding abilities, tap it straight whilst still on the bike.
2) Replace it/them.

Thanks Mickle
Not good news but was what I half suspected.
Any suggestions as to a decent replacement chainset that would withstand some abuse from an over enthusiatic 11 year old, without breaking the bank?

 

[PpPete]

Assuming it's square taper this is as cheap as they come.. http://www.spacycles.co.uk/products.php?plid=m2b0s109p2000
Just take the granny ring off before fitting it.

 

[Barbelier]

Assuming it's square taper this is as cheap as they come.. http://www.spacycles.co.uk/products.php?plid=m2b0s109p2000
Just take the granny ring off before fitting it.

Pete
Thanks for this. Yes square taper so this chain set looks a good value option.
Didn't think about buying a triple set and that you can just remove the inner ring. Although logically it makes sense if you can adjust the upper and lower limits on the front mech to match.
Don't suppose there is a clever way I could fit it as a triple without having to change the shifters?

 

[PpPete]

Don't suppose there is a clever way I could fit it as a triple without having to change the shifters?

I don't think there are any clever dodges.... but you could certainly "suck it and see" ... it might just work.

OTH - a triple and an 11 year old is officially "not a good combination".... trust me on this !
Mine seemed able to unship his chain almost at will .... just to prove how tired and bad-tempered he could be.

 

[Barbelier]

I don't think there are any clever dodges.... but you could certainly "suck it and see" ... it might just work.

OTH - a triple and an 11 year old is officially "not a good combination".... trust me on this !
Mine seemed able to unship his chain almost at will .... just to prove how tired and bad-tempered he could be.

LOL - good point & I know exactly what you mean!
The reason his current chainset is buggered is most probably because he carries on trying to trying to force it after the chain has dropped between the chain rings, even though he knows something is wrong.
Mind you, don't suppose we were any different at that age.

 

[mickle]

I'm not convinced that most people - especially young 'uns - should be using multi chainring set-ups.

 

[PpPete]

Come to think of it, I wasn't allowed any derailleur geared bike until I could buy it for myself. It was SA 3 speeds for me until I was 18 !

 

[Barbelier]

Assuming it's square taper this is as cheap as they come.. http://www.spacycles.co.uk/products.php?plid=m2b0s109p2000
Just take the granny ring off before fitting it.

One more thought on this - is the current 8 speed HG50 chain going to work okay with this chainset once the inner is removed?
I can't fit a 9 speed chain with the current 8 speed rear mech and cassette.

 

[PpPete]

One more thought on this - is the current 8 speed HG50 chain going to work okay with this chainset once the inner is removed?

Yes
[/quote]I can't fit a 9 speed chain with the current 8 speed rear mech and cassette.[/quote] Why not? I can see why you wouldnt be able to use an 8 speed chain on a 9 speed cassette but the other way round should be ok ?

 

[montage]

another possibility is that one of the chainrings in on back to front - unlikely but possible