Hi there,

Search isn't giving me any love do I'm posting here even though I have a feeling this has been done to death before or hopefully nicely explained on a website somewhere.

So basically I have been offered a bike from a friend to get me into road cycling. It's an older frame with a two year old ultegra groupset that is well used and have been told parts may need replacing soon, particularly the right shifter. It's currently a 9 speed, regular double set up.

I plan on using this set up until it starts to fail but in the meantime I'd like to keep an eye out for some good deals on replacement parts as it's still cheaper than a new bike. But if I wanted to change something how do it know if it is compatible with the rest of the gear?

For example, the main points I am considering are switching the rear cassette to 10 speed and possibly the front cassette to a compact double or perhaps triple. I know changing the front chainrings will require more changes, but exactly what I am not sure or if it has to be replaced with the same range (eg. ultegra).

Is there any guide or rule of thumb as to what parts or what style parts fit with what?