Will I need a longer chain?

[taximan]

Just a very basic question here, I need to replace my chain and I suspect that I will need to replace my cassette at the same time. The bike is currently fitted with a 9 spd 11-32 cassette and I am thinking about replacing it with a 12-34 to give me a slightly lower gear while climbing. will I need a longer chain to accomodate the larger ring? I think the present chain is 116 links but I need to check.

 

[T4tomo]

Possibly re the length depending on how much slack in the original....

but definitely.... as always put a new chain with a new cassette as a worn chain will wear a new cassette quicker

 

[roubaixtuesday]

Very unlikely re length, that's a tiny change. Just check it in big/big before cycling.

@T4tomo may be a little pessimistic re wear, but if well worn, definitely worth replacing.

 

[Ming the Merciless]

Your chain requirement will be shorter than the length they come in. Just do the usual to work out length required and remove links as required.

 

[taximan]

Thanks for your advice guys. The chain that I am replacing is definitly worn having had a hard life in hilly terrain and a winter of muddy & salty roads. As for the cassette it seems to be running sweetly enough for now with the old chain which is the second that has been used with this cassette. I think perhaps I will replace it (cassette) anyway

 

[Ajax Bay]

Thanks for your advice guys. The chain that I am replacing is definitely worn having had a hard life in hilly terrain and a winter of muddy & salty roads. As for the cassette it seems to be running sweetly enough for now with the old chain which is the second that has been used with this cassette. I think perhaps I will replace it (cassette) anyway

Don't replace the chain until you have procured your new cassette. Your drivetrain is "running sweetly": seriously no hurry; and the winter weather's not over yet.
Do what the merciless one says: size your chain in the normal way with the new cassette fitted.
If the current one is tight on large/large(32t) then a 34t sprocket will need a chain one (inch) link longer.

 

[slowmotion]

This will give you the answer........

http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

 

[sleuthey]

If the chain is worn it needs replacing full stop. Incase your larger cassette requires a couple more links it's worth buying a new one of the longer size just incase you need it (assuming you have a chain splitting tool). Are you able to post a photo of your current set up in big-big?