Need new cassette. Ratios?

junii

Im getting a tiagra 8spd cassette. Heres the link to the one I want to get.
http://www.chainreactioncycles.com/Models.aspx?ModelID=1864

I haven't a clue what ratio I need to match the one that came with the SCR3.

Can anyone help?

Morgan

If you want it to match an existing cassette just check the ratio of that one - you can either count the teeth or, if you look closely, the size is stamped on each cog. You just need to check the smallest and largest.

beans

I got a new large chainring installed on the front and a 12-25 hg-50 on the back to give me a higher top-speed when it came to changing my casette. Just to say, you may want to consider getting a slightly different ratio if you want different performance? For me, the new casette and chain made it feel like i was cycling a whole new bike

otherwise, if you still have the old casette, just count the teeth

ruprect

I would go with lower numbers i.e. higher gears, I do not understand why they put such low granny gears on all bikes. I had an 11 on the back of my old MTB and do on my new hybrid, picks up decent speed but I still would like faster, I never ever go past my mid range gear.

If you have a lot of miles on your chain you should probably change it too.

junii

ruprect wrote:

If you have a lot of miles on your chain you should probably change it too.

Is there a site that says you should check & change chain after this many miles, derailleiur after this et cetera?

I actually ordered a cassette with a slightly different ratio because they didn't have the same one as is on my bike. I wanted to have them similiar because one of them is just going onto a wheel specifically for the turbo trainer with a indoor tyre. I want to mimic the road setup.

Morgan

You can't really base it on miles cycled - 100 miles in the rain will have a more detrimental effect than 100 in the dry.

You can read about chain/sprocket wear here:
http://sheldonbrown.com/chains.html

junii

Ok. Thanks.

Will you get any benefits in say using and utegra cassette with a tiagra derailleur? (apart from weight decrease obviously).

Or mixing and matching other components?

aodhu

Good Question,
I'm looking to build up a bike in the near future and would love to hear people's thoughts on mixing and matching components.

Morgan

You won't really notice a cassette upgrade at all (unless you take to weighing your bike ). Higher-end shifters and derailleurs will usually be smoother and feel nicer though.

Mixing components isn't a problem (as long as they're compatible e.g. don't mix 9 and 10 speed, or Shimano and Campagnolo). Many bikes these days are specced with a variety of components rather than a complete groupset.

junii

I got the cassette and and will be putting it onto the wheel tomorrow. Theres no cassette on the wheel at the moment. Is it just a case of sliding it on?

blorg

I have never done it myself but this link may help. Someone with experience on the board may have more practical advice.

Morgan

Yeah, just slide it onto the hub and tighten the lockring (you'll need a lockring tool for this).

junii

Will I definitely need a lockring tool???

Any need to put lube on the sprockets or anything?

Morgan

Definitely.

You should put a bit of grease on the threads of the lockring. You don't need to grease the freehub body or cassette.

junii

Which tool do I need then?

http://www.chainreactioncycles.com/SearchResults.aspx?Search=lockring&x=0&y=0

Morgan

Any of these:
http://www.chainreactioncycles.com/Models.aspx?ModelID=7975
http://www.chainreactioncycles.com/Models.aspx?ModelID=7213
http://www.chainreactioncycles.com/Models.aspx?ModelID=13799
http://www.chainreactioncycles.com/Models.aspx?ModelID=13800
http://www.chainreactioncycles.com/Models.aspx?ModelID=1056
http://www.chainreactioncycles.com/Models.aspx?ModelID=10183

You'll also need a big wrench to hold the lockring tool (mine uses a 22mm).