Rear mech confusion

Cheshley

Hello

I need a new rear mech for my 8 speed hardtail. Everything I look at says that it's 9 speed compatible but 9 speed mechs have 11 teeth on the jockey wheels whereas the jockey wheels on the mech currently hanging off my bike have 10 teeth.

Why does it seem to be so hard to get hold of 8 speed equipment?

Does anyone know where I can get hold of an 8 speed rear mech? I usually buy Shimano but as the chain and cassette I have just ordered are SRAM, I may be tempted to change if the price is right and they will work with my XT levers.

Help, I need to get my bike back together.

Thanks

nicklouse

any shimano mech will work with the XT triggers.

Cheshley

nicklouse wrote:

any shimano mech will work with the XT triggers.

sweet, but does the 9 speed and 11 tooth jockey wheels versus 8 speed and 10 tooth jockey wheels make any difference?

supersonic

Nope, it will work fine.

Alivio, Acera and Altus are the designated 8 speed groupsets.

Guy Brooke

the number of teeth on the wheel will only affect how the wheel wears - odd numbered teeth wear better than even numbers. Half the links on the chain are narrower than the other half, which puts more wear on the teeth of the chainring/casette/mech than the wider link. with odd numbered teeth, every tooth gets both the wider and narrower links as opposed to just one or the other.

as far as compatibility between the shifter/mech, as long as the mech is wide enough to take an 8speed chain it'll work with an 8speed setup because the movement of the mech is regulated by the shifter.

Cheshley

Sweet, thanks guys. Shiny new XT mech ordered and I'll be out annoying ramblers by mid-week.

dave_hill

Guy Brooke wrote:

the number of teeth on the wheel will only affect how the wheel wears - odd numbered teeth wear better than even numbers. Half the links on the chain are narrower than the other half, which puts more wear on the teeth of the chainring/casette/mech than the wider link. with odd numbered teeth, every tooth gets both the wider and narrower links as opposed to just one or the other

EH? :shock:

That's quite possibly the funniest thing I've read in these forums!!!

supersonic

Bizarre it sounds, but true! The reason why we have odd numbered teeth on jockeys is for even wear reasons.

Mark_K

Guy Brooke wrote:

the number of teeth on the wheel will only affect how the wheel wears - odd numbered teeth wear better than even numbers. Half the links on the chain are narrower than the other half, which puts more wear on the teeth of the chainring/casette/mech than the wider link. with odd numbered teeth, every tooth gets both the wider and narrower links as opposed to just one or the other.

as far as compatibility between the shifter/mech, as long as the mech is wide enough to take an 8speed chain it'll work with an 8speed setup because the movement of the mech is regulated by the shifter.

Well there you go i never knew that :idea:

dave_hill

Half the links on the chain are narrower than the other half, which puts more wear on the teeth of the chainring/casette/mech than the wider link

OK, that I understand

With odd numbered teeth, every tooth gets both the wider and narrower links as opposed to just one or the other.

That I don't understand - it just doesn't make sense!! Can you explain?

supersonic

Regardless of how long the chain is, it always alternates inner link/outer links. So with odd toothed jockey wheels, every revolution of the wheel it encounters the inner link 'hole' then the outer link 'hole' on the next revolution.

dave_hill

supersonic wrote:

Regardless of how long the chain is, it always alternates inner link/outer links. So with odd toothed jockey wheels, every revolution of the wheel it encounters the inner link 'hole' then the outer link 'hole' on the next revolution.

Gotcha! I think...

But even so, I can't really see that it would make that much difference to how quickly the jockeys wear.