larger cassette and new chain

hodge68

Now I could be being dumb, I would like to increase the size of my cassette on my cx bike, from 26 to 30/32 . So I reckon the chain would need to be longer. However when fitting a new chain I was under the impression that you measured it on the large from chain ring and small cassette ring with the jockey wheels inline with the cassette. But how would this take into account the larger cassette ring. The bike is fitted with sora long cage.

maddog 2

Two things:

1. a 32 sprocket cassette probably won't work with a road rear mech, unless you run a Sram Apex. Shimano are rated to 28t currently and your can sometimes squeeze 30t out of them but 32t is pushing it.

2. That method is crap, as you've spotted. Fit chain on big-big and adjust accordingly. No good having a chain length that busts your mech if you go big-big.

hodge68

Cheers for the reply, I will give the 30 a go. Now to choose a chain.

maddog 2

KMC

arlowood

With a long cage rear mech you should be OK if you opt to go for 32 as your largest ring on the cassette.

Shimano now make 12-30 cassettes in both the Tiagra and Ultegra range. I have a Tiagra 12-30 fitted and my rear mech is just the standard not the long cage version. I have no problems at all. To get a 32 tooth that though you will have to source an SRAM cassette as Shimano road cassettes don't offer the 32 option. The SRAM cassette will be compatible with your Shimano set-up.

BTW a more reliable chain length calculator is available at the following link. Does mean you have to measure the chainstay length but still better than faffing about winding a new chain round the cassette and chainrings

http://www.epicidiot.com/sports/chain_l ... tm#results

hodge68

Great link, cheers.

hodge68

changed cassette from 26 to sram 32 and the sora 3400 long cage rear mech handles it fine had to screw in the B screw about half way. The cx comp is brand new and I think the chain may have been long as after changing I had about one and a half links over when on big big rings, sram recommend 2 links. May risk it, ive got a new chain at the same time I got the cassette, time will tell.