medium181

Hey there,

I am new to upgrading components on bicycles; therefore, this may sounds dumb to most of you.

I have a surly crosscheck that I bought stock. Between commuting to school, to work and riding it for fun, I put quite a few miles on it.

I want to put a mtb cassette on it so I can take it out to a few trails near my house. Hills are pretty gnarly around where I live.

Is it possible to put on a 9speed 11-34 cassette on my bike? If it is, is it wise to make such swap?

So far that bike took whatever I threw at it, I wanna see what else I can do with it.

Thanks in advance

cny-bikeman

You need to determine what model of derailleur you have, then look up what it's capacity is, both largest cog and tooth difference. https://sheldonbrown.com/gloss_ca-g.html (look at the Capacity entry). You will also need a new, longer chain. Haven't seen a lot of choice but if you are going up to 34 teeth you should get the largest small cog you can - 12 or 13 instead of 11.

medium181

The stock derailleur is tiagra. I looked it up online and it says that the capacity is 27t...

Thanks for the info!

fietsbob

capacity is the cog size(27t , vs 34t) wrap is the amount of chain slack to be wrapped up

between the sum of the 2 largest and 2 smallest tooth counts ..

In short you Might need a MTB RD. [ of course new chain , left longer]

HillRider

The 27T is the largest cog that derailleur will officially handle so, yes, an MTB rear derailleur is certainly called for. "Wrap" capacity is another issue.

djb

a long cage LX or Deore LX will work well for what you want to do, easily up to 32 teeth (one of my bikes uses a deore lx and has a 32 on it, is rated max of 32t, but would easily take a 34)
do some searches for prices. A good bike store should be able to give you prices and other options of reasonably priced RD that can handle up to 32-34.

other option to get even lower gearing is to change the granny gear to a smaller one.

FastJake

- New chain (longer)
- Shimano MTB RD. Anything except the new 10-speed MTB stuff.

surreal

FWIW, that RD will take a 28. It'd be cheaper to just roll a 12-28 cassette with the existing RD (may need a chain with a few more links, depending on how well you're set up now.)

Yeah, it's "only" a 28, but you might be surprised how much difference 3t can make, especially in the smaller ring (which is prolly a 34 or a 36t, if you got a stock complete SCC).

10 Wheels

Mine works with the long cage.

surreal

Indeed. Having a hella-long RD hanger helps...