I'm intrested in changing my Tripple crank to a compact or even a regular double. My bike is five years old so I don't want to spend big $ on it. If I change to a double will I need a new shifter or a new FD(mine are both Tiagra). I think that the switch is doable if I just need a new BB and Crank. Also would this be a good time to change the chain and cassette.
You would need a BB and crank (you can def. get the FD&RD to work, but I have no experience with Tiagra shifters), but I would not bother. It is a waste of money on any bike IMO, but particularly for one that is five years old. Just buy a double next time.
There are a million threads on this subject if you do a search.
Sorry, I should have searched. The last time I tried it was down, but I see it is working now. You are right it is a waste of money. I just like to tinker with things and thought this could buy me some time before I "need" a new bike. The main reason I would want to switch is better shifting and that I seldom use the 30 ring, but I think a 39 or 36 would give me all the low end needed with better and less shifting. I often resist going to the little ring by pushing the 42 because I know it would just be for 100 meters and right back up into the 42 ring.