To be honest i am not one for upgrading parts until they wear out, however! I have done a fair few kms on my giro since buying it and found a few issues.
Issue One. When pulling off from traffic lights or in tight maneuvers in built up areas (like nipping to the shop to buy beer and cat food) I found myself changing gear unintentional due to the twist grips. Very uncool to lose the chain when you are between three lanes of traffic. I think this is due to the twist grip making up half the available Handel bar grip plus pressure exerted on the bars when pulling off or doing slow maneuvers. Solution x-9 trigger shifters (ebay $68)
Issue Two. Brakes not powerful enough. I am use to disks or V brakes. Solution Avid BB7 disks ($100)
Issue Three (and this is shallow and vain) The RD is just ugly. Solution, Sram X-O (used $70 Ebay)
These upgrades have improved the bike immensely. Better, more reliable shifting and better stopping. I really cannot foresee any need to upgrade anything else until they wear out (honest)
RR


