I have a Giant Defy 9-speed road bike, and a thief stole the front wheel. I found a good deal on a set of used
Bontrager (Edit: Mavic Aksium) wheels, so I bought them as a set. I want to swap both wheels so that they match, and also because the new wheel is 72g lighter. Probably a higher quality wheel overall. The trouble is, it's a 7-speed.
I know how to change a cassette, but I've never changed a hub. I can see that the 7-speed hub is smaller, so 9 gears won't fit. Can I move the 9-speed cassette over? I'm guessing there might be some kind of compatibility issues, but I don't know what to look for.
Edit: I just realized the Mavic hub has a spacer behind the cassette, which can be removed, leaving enough room for 9 sprockets. But now the locknut doesn't quite tighten all the way, it looks like I need to add a spacer of less than 1mm.