How to know and which to use? I have these shifters and derailleurs:
front shifter Shimano ST-EF41, 3spd
front derailleur Shimano FD-TZ500, 3spd
rear shifter Shimano ST-EF41, 7spd
rear derailleur Shimano RD-TZ31, 7spd
I want to change my rear system with SRAM X5 rear derailleur (Long 9 -Speed) and SRAM PG-950 9 speed cassette(12-23 t).
The present Shimano has a freewheel whereas SRAM has cassette. What else will be needed?
If your goal is to convert your 3 gears in the front and 7 gears in the back to a 3 in the front and 9 in the rear this will be quite expensive. A new rear wheel will be required Your current rear wheel uses a screw on freewheel to mount the rear gearset. Nine speed rear wheels use a freehub mounting system with a cassette. You will need a 9 speed rear shifter and derailleur of the same brand, Shimano shifter with a Shimano derailleur or Sram derailleur with Sram shifter. You may need a new front derailleur, some 7 speed front derailleurs can be adjusted to work with narrower 9speed chains but it is trial and error and shifting may not be optimal. If you front shifter is a non indexed type this may actually improve shifting in this mismatch scenario. You will need a 9 speed chain. If you are doing these improvements yourself you will need to add the cost of a chain-tool, freewheel removal tool, cassette install/remove tool and a chaiin whip.