Replacing my cassette and chain

jeannot18

Hi guys, been a long time since my last post. I think it is time to replace my cassette and chain on my trusty Specialized. It is a Shimano 105. I have a few questions.
For the cassette, i saw that you have to select the "ratio", I don't know what I have got on mine, but i guess I will have to remove the cassette first and check it, is it engraved on the cassette? or do you have to count the teeth?
For the chain, I found on Wiggle a 105 10 speed, do you have to measure your current chain and match it with the new one. Sorry if these question sound stupid, but I have never done it. Any tips, links to videos would be much appreciated

JC

simonj

Just count the teeth on the small cog (it's sometimes stamped) and big cog to work out what you have. If you don't want to change then just buy the same ratios, if you have a 12-25 and fancy something with lower or higher ratio you may be able to go all the way down/up to 11-28 or 12-30. If you like what you have for the roads you ride on (presume they're hilly) then stay as you are as a wider ratio will give bigger gaps/jumps between gears. New chain will almost certainly be longer, you'll need a chain breaker to shorten it and it may be worth while there also getting a KMC link whist ordering.

jeannot18

simonj wrote:

Just count the teeth on the small cog (it's sometimes stamped) and big cog to work out what you have. If you don't want to change then just buy the same ratios, if you have a 12-25 and fancy something with lower or higher ratio you may be able to go all the way down/up to 11-28 or 12-30. If you like what you have for the roads you ride on (presume they're hilly) then stay as you are as a wider ratio will give bigger gaps/jumps between gears. New chain will almost certainly be longer, you'll need a chain breaker to shorten it and it may be worth while there also getting a KMC link whist ordering.

Thanks! I think you answered all my questions
J

littledove44

If you clean the cassette you will see the numbers are engraved on each cog.

I had Shimano 105 on my Spesh and anything up to 11-34 works fine. So, have better climbing gears if you want, but be award the bigger the range the bigger the gaps and that can mean you can find yourself struggling to keep your preferred cadence because you want to be between the options you have.

Fit a really easy job to do yourself if you have the right tools, but it's even easier for your LBS. Mine changes a cassette for nothing as they feel guilty charging me for sixty seconds work.

Get a chain tool to remove the old one (you carry one with you anyway don't you) and a quick link to match the length to your existing chain, as long as you are not changing cassette size. If you are you might as well get the LBS to show yo how to remeasure when they change your cassette.

wishitwasallflat

If your old chain does need replaced it will have stretched so make sure you make the new one have the same number of links NOT be the same length. Also I've never seen a cassette where the cogs weren't stamped with teeth numbers so don't expect you would need to count at all (can't say Ive seen every brand of cassette in existence by any means though).

kajjal

If you buy the cassette from you local bike shop they will normally fit it for you in a few minutes while you wait. Which saves buying tools etc. but will cost a little more for the cassette. Chains are easy to match in length to the original chain but just make sure you check how the original chain feeds through everything and put the new one on the same way. I rushed putting the new one on my MTB and when I pedalled it made a grinding noise. Checked and I hadn't fed it through the rear properly.