Newbie question - changing cassettes

simDP

Hi all,

apologies if this is a stupid question/asked before but my searches have been inconclusive.

My issue is that my current cassette is a 12-25 shimano tiagra 9 speed which came as standard on the bike. As I spend lot of time trying to get up some pretty steep hills i'm looking to swap the cassette. My preferred options are all 10 speed.

Question is will my existing 9 speed shifters and rear mech work with a 10 speed cassette?

I am loathe to change the whole lot as i'm going to be upgrading the whole groupset in due course. For now though I wondered if there was an easy (cheap) option i.e. just swapping out the cassette?

Any suggestions welcomed.

Thanks

danowat

Why not just put a different 9sp cassette on it?

Fursty Ferret

Just swap the cassette to a 12-27 or 12-28 and 9 speed or not hills will be no problem

snoopsmydogg

short answer is no.

the cable pull is different for 9 speed to 10 speed. You would be better off getting a larger rear cassette or compact chainring if you dont already have one.

If you wanted to fit 10 speed then you would need shifters, cassette and chain and probably wouldn't notice the extra shift tbh.

simDP

blimey, thats was quick. thanks for the responses.

to be a little more specific i was looking at the 12-30 cassette to give me 2 more lower gears. May sound wussy but I am trying to tackle 20% (and more) gradients in the Pennines and my feeling was 1 extra gear might be a waste of time. Course I could just man up....

simDP

snoopsmydogg wrote:

short answer is no.

the cable pull is different for 9 speed to 10 speed. You would be better off getting a larger rear cassette or compact chainring if you dont already have one.

If you wanted to fit 10 speed then you would need shifters, cassette and chain and probably wouldn't notice the extra shift tbh.

Thanks - I think that answers the question perfectly.

Pross

simDP wrote:

blimey, thats was quick. thanks for the responses.

to be a little more specific i was looking at the 12-30 cassette to give me 2 more lower gears. May sound wussy but I am trying to tackle 20% (and more) gradients in the Pennines and my feeling was 1 extra gear might be a waste of time. Course I could just man up....

Something else to be aware of there is the maximum tooth capacity of your rear mech. This is calculated by deducting the smaller chainring from the larger chainring and the smallest cassette sprocket from the largest cassette sprocket and adding the results. For example if you are running a compact 50/34 chainset and a 12-25 cassette you would need a tooth capacity of (50-34)+(25-12)=29 which I believe is the capacity of the current Shimano 105 set up and I think that Tiagra is the same. If you switched to a 30-12 cassette the capacity required would increase to (50-34)+(30-12)=34 so you would need to replace with a longer cage rear mech (unless you already have the long cage version).