05-26-2010, 07:54 PM
I am waiting for a call from a guy that is selling some used 105 (9 speed) STI shifters at a good price. I currently have an 8 speed cassette. I have looked around this site and others and cannot seem to find a good answer. The bike (Trek 2120) originally came with 105s, but that was back in '97 when 8 speed was still fairly standard. The previous owners replaced them with Soras and while they are functional, I really hate the thumb shifter on them as I have to take my hand off the drops whenever I want to go faster. For a reference, here is the bike here and it's the same other than the shifters: http://www.bikepedia.com/QuickBike/BikeSpecs.aspx?Year=1997&Brand=Trek&Model=2120&Type=bike
The basic questions are these: Can I run a 9 speed shifter on the 8 speed cassette? Or do I need to upgrade to a 9 speed cassette? I do know that upgrading to a 9 speed cassette will require a new chain and I may as well get a new one with a new cassette.
Will I have any problems with the front derailleur? I have a triple and the shifter is a triple.
Will freehub with an 8 speed take a 9 speed?
Thanks for any help. I will probably buy the shifters regardless as I think I can easily sell for the same price I buy them.
The basic questions are these: Can I run a 9 speed shifter on the 8 speed cassette? Or do I need to upgrade to a 9 speed cassette? I do know that upgrading to a 9 speed cassette will require a new chain and I may as well get a new one with a new cassette.
Will I have any problems with the front derailleur? I have a triple and the shifter is a triple.
Will freehub with an 8 speed take a 9 speed?
Thanks for any help. I will probably buy the shifters regardless as I think I can easily sell for the same price I buy them.