Shimano 105 Compatibility.

torvil Posts: 5
edited February 2013 in Road general
Hi I've searched for this but I'm struggling to find a definitive answer. Will the 10 Speed Shimano front and rear derailleur be compatible with the Shimano 9 speed running gear that's already on my bike?
When I say compatible I mean will it give me the same service as the 9 speed, I.e. 9 speed cassette, chainset, shifters etc.