Cassette Question

[xybadog]

If I was to buy a new 9 speed cassette for my bike (to fit to a spare wheel) would I have to have the same tooth ratio as I have currently (11-32)?

If not, what would be a better ratio to get?

[Oggy]

You can have any tooth ratio you want, never experimented with different ratios tho, ive never taken much notice but i suppose different ratios will give a differn feel to the gears.

[sikora]

Would the B tension screw on the rear mech not need to be adjusted for different sized cogs?
More teeth = larger cog, so the jockey wheel might rub

[tc]

you can get 11-34 which gives a little extra spin ,but im not sure weather you would need to add a link to your chain though?? mind you if ya getting a new cassette ya might aswell invest in a new chain neways.???Im going for the 34 tooth when i invest in my next cassette .11-34 is better i'd say!!

[tc]

Jul 13, 2008 18:25:45 GMT sikora said:

Would the B tension screw on the rear mech not need to be adjusted for different sized cogs?
More teeth = larger cog, so the jockey wheel might rub

yeh you would have to adjust it i would of thought???makes sense dun it!

[Arnie]

i'm also replacing my existing cassette with an 11-34 next time. all the other cogs are the same ratio as an 11-32 cluster apart from the largest cog, obviously, which means that it won't affect you on downhills but you get the added benefit of extra help on the steep stuff

[sunbeamgls]

No probs changing for a different set of ratios, as long as you have a long cage rear mech. You'll probably need to add at least one more link to the chain. When you've changed the block, you'll need to reset the rear mech. Always best to start from the beginning:
- chain on middle chainring at the front
- put the rear mech into top gear (smallest rear cog)
- loosen the cable clamp
- with the cable having a very small amount of play (ie just loose enough not to sound like a guitar when you pluck it), tighten the clamp up again
- now attempt to go through the gears onto the lowest gear (largest rear cog)
- adjust the stop screw until you get the chain onto the largest cog and until (viewed from the rear) the two mech jockey wheels align perfectly with the cog
- shift to the middle of the cassette and shift between the third and fourth cogs a few times - if you don't get clean shifts, twiddle the adjuster where the cable enters the mech very small amounts until shifts are clean and the jockey wheels correctly align with the third and fourth cogs every time
- now check the shifting onto the largest and smallest cogs again, making sure the chain isn't thrown off
- with the chain on the largest cog, the 2 mech jockey wheel centres should be vertical. If they're not, you need to add or remove a link (or links) until they are vertical
- with the chain on the smallest cog, make sure the jockey wheels and cogs are not touching each other
- go have a celebratory pint, or phone the bike shop, whichever is most appropriate to the result!

[xybadog]

Sept 23, 2008 21:27:53 GMT sunbeamgls said:

No probs changing for a different set of ratios, as long as you have a long cage rear mech. You'll probably need to add at least one more link to the chain. When you've changed the block, you'll need to reset the rear mech. Always best to start from the beginning:
- chain on middle chainring at the front
- put the rear mech into top gear (smallest rear cog)
- loosen the cable clamp
- with the cable having a very small amount of play (ie just loose enough not to sound like a guitar when you pluck it), tighten the clamp up again
- now attempt to go through the gears onto the lowest gear (largest rear cog)
- adjust the stop screw until you get the chain onto the largest cog and until (viewed from the rear) the two mech jockey wheels align perfectly with the cog
- shift to the middle of the cassette and shift between the third and fourth cogs a few times - if you don't get clean shifts, twiddle the adjuster where the cable enters the mech very small amounts until shifts are clean and the jockey wheels correctly align with the third and fourth cogs every time
- now check the shifting onto the largest and smallest cogs again, making sure the chain isn't thrown off
- with the chain on the largest cog, the 2 mech jockey wheel centres should be vertical. If they're not, you need to add or remove a link (or links) until they are vertical
- with the chain on the smallest cog, make sure the jockey wheels and cogs are not touching each other
- go have a celebratory pint, or phone the bike shop, whichever is most appropriate to the result!

That's excellent instruction. But I have one query...Why does this need to be done. Isn't putting a new block on the wheel and then placing back on the bike, the same a putting the old block back on? What I mean is, how does the drivetrain now that it's a new block, or is this procedure necessary each time the wheel is taken off and replaced?

I only ask as I'm about as mechanical as a smurf when it comes to bike mechs. Give me a BMW and I'll strip the engine and put it back together, but a bike...!

[sunbeamgls]

In theory, the mech should be OK everytime you take the wheel out and put it back in, as long as the wheel sits exactly in the same place in the drop outs (you do this by being certain it goes all the way into the drop outs every time). With a new block it should theoretically work, but sometimes manufacturing tolerances can affect things, and an older chain with a newer block can make a difference. No harm in putting it on and seeing how it goes, but if you do have problems, I was just suggesting that its often easier to start from scratch rather than spending ages trying to get fine adjustments to work (or not).

I was also trying to help with your first question - do you need to get the same ratios on your spare wheel as you have on your regular wheel - hopefully from my feedback you will be able to work out that the answer is "yes" unless you want to change the chain length each time. Don't forget, chain and block wear together and a brand new block with a new chain (and vice versa) might not work together 100%

Good luck.

[xybadog]

Thanks for your help. I'll have to save some more pennies to get the new wheels etc.