Originally Posted by
fdog
I am just getting started in fixing bikes, and seem to have the most difficulty in figuring out what is compatible with what.
For example, I have an older (not exactly sure how old) Scattante 670 with a newer, but still old, 9-speed Ultegra groupset. I was looking to replace the RD, but I have no idea what I could replace it with. I assume I don't need to find the exact same derailleur, but would most 9-speed RDs work, or do I need to stick with Shimano parts to match other parts for some reason? Also, I was looking to get shorter cranks, but wasn't sure how to match the crankset with the bottom bracket. Do I need to disassemble it all and use calipers to measure everything since there are very few markings of size and measurement on most parts?
Any tips on finding compatible parts rather than buying parts and realizign they're wrong would be great.
The BikeGremlin site attached above does a reasonable job of explaining RD compatibility. That should provide the basics of what to look for.
So, any Shimano road RD up through 10 speed (except old Dura ace 740? series or Tiagra 470? series) should work. If looking for brand new, Shimano still offers the RD-5701 in short & mid length cage.
As for your crankset question, if you have the 9 speed Ultegra crank, your options are limited if you want to keep the bottom bracket. The BB for these use a hollow splined spindle called Octalink, (commonly called Octalink V1). Only 9 speed Dura ace (770? series), Ultegra (650?) & 105 (550?) cranks fit this BB for road use.
Other cranks would need the proper BB.
Here is Shimano's published compatibility chart from 2005. Not included are earlier 550? series cranks. Also doesn't include newer model RDs that may be compatible.
