I have a bike with an 8-speed cassette and would like to switch to 9-speed cassette.
Can I keep my rear derailleur? which is a Shimano Alivio one? I understand the indexing might mess up this, but I figure the indexing is handled by the shifters, the the derailleur itself!
Also, Saint Sheldon seems to confirm it is possible (http://sheldonbrown.com/speeds.html), is that really reliably so?
Apart from that, I know I will need a new chain to handle the 9 speeds, is there a consequence on the crankset? or do cranksets support all chains width?