Giant Defy 3 possible upgrade

[Cyc_al]

I have been offered a used 105 groupset which I am keen to put on my 2011 Giant Defy 3. Only concern is whether I can swap the 9 speed cassette to 10 speed. Any thoughts

 

[Joffey]

Can't see why not, wheels are usually 9/10 speed compatible. Phone a Giant dealer and ask them to make sure.

Also that groups is worth about £200, if the cassette won't go on it might be worth selling your old group set on eBay (or here) and funding some new wheels (or second hand ones). Then you are really upgrading your bike!

 

[bonsaibilly]

Should be OK as a freehub made for 9 speed Shimano cassettes is wider than one made for 10 speed, so the 10 speed cassette will fit if you include a spacer - bike shop will provide.