Cant shift into bottom gear.

[beany_bot]

So, I recently got new (second hand) wheels for my bike. Been very happy with them. except one thing. I cant for the life of me get the rear derailleur to shift into the bottom (smallest) gear. No matter if the cable is completely slack and the limit screw is completely out. It just wont drop into that bottom cog. At best it makes a sound like its thinking about it... but never makes it in.

Now this isn't a deal breaker, I dont use this gear in my daily commute. But I just thought it was weird that with the mech fully slack and limit screw right out it wont go in. Am I missing something obvious? Have I installed the wheel wrong??? Everything else works just fine.Indexing on all the other gears works perfectly and it stops at the top gear as it should. Bizzare.

 

[Cycleops]

The first thing to do is release the cable and and turning the cranks push the derailleur across the block by hand, this at least will tell you if there is something wrong with the derailleur.

 

[beany_bot]

The first thing to do is release the cable and and turning the cranks push the derailleur across the block by hand, this will tell you if there is something wrong with the derailleur.

Tried that, it shifts. but only just if i force it. It's not comfortable doing it. It's as if the mech is just too close to the bottom cog. If I put a spacer beween the derailleur and the frame I know it would work. But that cant be right?

 

[Cycleops]

Shouldn’t have to force it. Remove it and give it a dose of oil and see if that improves things, if not maybe time for a new mech.

 

[beany_bot]

But it feels like that is the limit of its closed travel. I dont think its an age or wear thing. Its as if that gear is just too close. Was fine on the last set of wheels.

 

[Globalti]

When was the last time the cable outer was changed where it curves round to the derailleur? They get crudded up with muck and rust and prevent the RD from going across where the spring is at its least tensioned. Change the inner and that piece of outer and the performance will return.

 

[raleighnut]

It looks too close to the rear dropout to me, are the correct spacers in use on the freehub?

 

[beany_bot]

It looks too close to the rear dropout to me, are the correct spacers in use on the freehub?

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

 

[beany_bot]

When was the last time the cable outer was changed where it curves round to the derailleur? They get crudded up with muck and rust and prevent the RD from going across where the spring is at its least tensioned. Change the inner and that piece of outer and the performance will return.

Bike is a year old.

 

[Cycleops]

Can’t be the cable as he’s tied pushing it across by hand with cable unclamped as above.

 

[raleighnut]

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

It just looks very close, almost like the chain would be rubbing the dropout if it was on that smallest cog.

 

[beany_bot]

It just looks very close, almost like the chain would be rubbing the dropout if it was on that smallest cog.

I know right? Thats why I included the picture. FYI. The chain doesnt rub the frame when i manually put it in the smallest cog. But it does look close doesnt it

 

[vickster]

Try without the spacer?

 

[beany_bot]

Try without the spacer?

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.

 

[Milkfloat]

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?