cassettes and chains

biker0910

So my chain keeps slipping on my cassette so I thought I would buy a new cassette but apparently I have to buy a new chain too even though my one is fine. Is that right?
Anyway I was looking at this cassette
http://www.amazon.co.uk/gp/product/B003 ... d_i=468294
but it has different options such as 12-23 and 12-25. what does this mean? I have a trek 1.5 so do only certain cassettes work on only certain bikes or can I buy whichever cassette I want. Also if I do have to get a new chain how do I know which chain works with which cassette?
Please help!

thistle_

12-23 just means the smallest cog has 12 teeth and the biggest cog has 25 teeth.

foggymike

That's biggest has 25 teeth of course If you are happy with you're current gearing just get the same again.

What groupset do you have on your bike at the moment? If we know that we can tell you what you need.

biker0910

these are what is on my bike atm DRIVETRAIN
Shifters Shimano Tiagra STI, 9 speed
Front Derailleur Shimano Tiagra
Rear Derailleur Shimano Tiagra
Crank FSA Vero, 50/34 (compact) or 50/39/30 (triple)
Cassette SRAM PG-950 11-26, 9 speed
Pedals Nylon body w/alloy cage

ademort

If you have a 10 or 11 speed cassette and it,s Shimano or Sram then you can only replace it with a Shimano or Sram compatible cassette. You will then need to buy a Shimano or Sram compatible chain. There are many different companies who make Shimano or Sram compatible chains. If you can look at what you have on your bike at the moment it will be much easier to say exactly what you need. If you remove the rear wheel you should be able to see exactly what cassette you have on your bike at the moment. The information is written on the side of the cassette, Type/Model. Your chain will also have some information on it if you can locate that and write it down for members to read i,m sure you will get some good recomendations from forum members as to replacement parts.
Ademort

southdownswolf

The HG-50 is fine to use with your derailleur, however have a look at CRC as you may find it cheaper.
http://www.chainreactioncycles.com/Cate ... rtBy=Price
The cassette that you have at the moment (PG950) is £22 for the 11-26. However, you could get the HG50 for £14 - 11-25, 12-25 or 12-27 will be fine. CRC are also doing the PC951 chain for £9.99 at the moment which is a decent price.

Next thing is, do you have the correct tools or know somenone that does? You will need a lockring remover and a chain whip to get the old cassette off the wheel.

biker0910

so SRAM chains can work with shimano cassettes? because the PC951 is SRAM and the HG 50 cassette is shimano? Also it is a fairly easy job to do if you have a lockring tool and a chain whip isn't it?

sungod

sram chain is fine on shimano cassette

yes, chainwhip and lockring tool, you'll also need a chaintool so that you can shorten the chain to the correct length

if the old chain is very worn, it will cause the cassette to wear fast, eventually slipping (and a worn chain will do the same to a new cassette)

it's worth learning to check your chain for wear every month or two, a 12" ruler is all that's needed, then you can spot chain wear and replace the chain before the cassette is damaged