Rear Cassette Ratio

[grellboy]

Looking to get new wheels so was going to get a new cassette at same time. Have 8 speed Shimano on my road bike currently. Anyway, just been on Chain Reaction and they have five different ratio cassettes available!!! These range from 12 - 21 to 13 - 26. I have a vague idea these numbers refer to teeth but what is the actual difference out on the road?

 

[blackgoff]

I'd recommend the 13-26 as this will give you a biggish rear gear (the 26), for hills. The 12-21 is pretty small unless you've big legs and like to go fast?

 

[mwktar]

Small on front + big on back = easier hills!

Check this out

http://gears.mtbcrosscountry.com/#26I1I1

You can compare different setups and see the differences in the ratios in the different gears (lower is easier!)

Very useful

 

[Smokin Joe]

The more teeth on a rear sprocket, the lower the gear ratio. 12 - 21 would be the sort of range you'd use if you were racing on flat circuits, you'd find it very hard going if you lived somewhere hilly or were not a very fit rider.

What have you now and how does it suit? Count the teeth on the smallest and largest sprockets to find out.

 

[helston90]

What have you now and how does it suit? Count the teeth on the smallest and largest sprockets to find out.

This.
Buy the same as what you have if you're happy with it- you can easily buy a slightly different sized one if you're not (e.g. my new steed only has 12-30 which is a waste at both ends- I'll get 11-28 when time comes to replace.)