Shifting from Shimano 2300 to Tiagra I have a road bike that I use mostly for touring (2-3 day trips) and my daily commute (~25km). It's loaded with the Shimano 2300 (2013) 3 X 10 groupset. I know it's not the most efficient or lightweight, but for my purposes it has served me well.

I just broke the rear derailleur. My policy is to always replace parts with ones of the same or better quality.

My problem is that 8-speed parts are becoming less and less common for road bikes, so buying better or equivalent parts for the 2300 is becoming difficult (I live in Singapore).

Is it worth it to upgrade to a complete higher tier groupset like the current Tiagra? My hope is that with this change I can access the market of 10 X 3 speed components and have room to upgrade part by part later if I want to.

Would I need to change more parts than the ones included (derailleurs, shifters, cassette, crankset, BB) other than the chain if my bicycle already handles 2300?
As usual Sheldon has the answer. However you can also find a great range of second hand parts such as derailleurs from your local bicycle shed.

There's little point replacing the entire groupset, however if you want to move up to 9-speed then there's no problem replacing the rear derailleur, cassette and shifters. If you're replacing your cassette, replace your chain.

Sheldon writes:


  In general, all Shimano Cassette Freehubs will work with all Shimano
  cassettes, any number of speeds.


Your crankset, front derailleur and bottom bracket can remain as they are (matched groupsets are a lie sold to everyone by Shimano). If you do decide for a lighter crankset, you can still leave the front derailleur alone so long as it suits your chainring choice. Similarly you can reuse the bottom bracket if it has the right interface and spindle length.