Upgrading SRAM PG850 8 Speed Cassette on Defy 4, must Be Compatible with Claris Shifters I need to replace my SRAM PG850 8 Speed 11-32 Cassette &amp; Chain on my Giant Defy 4 2015, due to general wear and tear, however I would like to upgrade to something a bit better though within budget (about £50).

*It needs to be Compatible with my Shimano Claris Shifters and Derailers.

Any suggestions or advice on what I should be looking for would be great. This is the first time I have replaced anything on my bike, so I have a limited knowledge of what parts go with what.
Almost any 8 speed cassette will be compatible with your bike.* As far as the chain goes, that more or less depends on the cassette.

As long as you stick to 8-speed, there are basically only two things you need to worry about.


Your cassette should fit within the range of your rear derailleur. Every derailleur has a minimum and maximum cog size that it can accommodate. Just check the specs for your derailleur and stay within that range.
Your chain needs to be the right length for the largest ring on your new cassette. If you get a cassette that has a cog that's bigger than 32 teeth, you will almost certainly need a longer chain. If your big cog is smaller than 32 teeth, you may need a shorter chain. The venerable Sheldon Brown has a great guide on how to choose the correct length for your set up. If you're unsure, just buy a chain that has as many links as possible (at least as many as your current chain) and remove links as needed.


In short, any Shimano or Sram 8-speed 11-32 cassette and chain will work without any issues. If you're changing the range, just check your rear derailleur compatibility before you buy.

*The one major exception to this rule is Campagnolo. As a general rule, their stuff isn't compatible with anything else. That's not entirely true, and I'm not sure about 8 speed cassettes in particular, but I find it's easier to just steer clear unless you're willing to switch everything over to Campagnolo.