Cant shift into bottom gear.

[raleighnut]

Cassette will flop around on the hub I assume?

Wait.... what If I move the spacer to the front, infront of the smallest cog, rather than at the back behind the biggest cog. Can I do that? That would fix it I'm sure.

No, but have a look how many threads are on the lockring,you may get away with a thinner spacer to move the cassette inboard a mil or 2.

 

[beany_bot]

Just double checking that you have actually released the cable completely and that you are backing off the correct limit screw? Does the mech feel smooth when you move it by hand over the whole range?

yes and yes

 

[Milkfloat]

Have you still got the old wheel to try? I would double check that the last few cogs are sitting on the freehub correctly and also check the lockring is tight. Lastly - what size spacer do you have on?

 

[figbat]

Wait.... what If I move the spacer to the front, infront of the smallest cog, rather than at the back behind the biggest cog. Can I do that? That would fix it I'm sure.

It might, but be careful if you try this that the derailleur doesn't snag in the spokes.

 

[Cycleops]

Just double checking that you have actually released the cable completely and that you are backing off the correct limit screw? Does the mech feel smooth when you move it by hand over the whole range?

Says he has to force it when moving by hand.

 

[beany_bot]

Says he has to force it when moving by hand.

I have to "bend" it beyond its natural "stop"

 

[screenman]

I assume it was working fine before, if so that rules out everything apart from the wheel, hub, spacers.

 

[figbat]

Is the hanger straight? Looks it, but it's another factor.

 

[Ajax Bay]

The free hub measured exactly the same as my last one and I just transferred over the same spacer that was on it. So it should be identical. 9 speed spacer I guess.

what If I move the spacer to the front, in front of the smallest cog, rather than at the back behind the biggest cog. Can I do that? That would fix it I'm sure.

Link to the spec of the new wheel please.
You've got a 9sp cassette on the freehub. Why do you need a spacer? Is it an 11sp freehub (wheel)? Was the last one the same?