Cotic BFe. 9 speed SRAM set up (X7). New rear derailleur, new cassette, new chain.

Derailleur set up as per instructions, all 3 limit screws set properly (but see below).

8 out of the 9 gears indexing perfectly, but I can’t get the chain onto the smallest cog at all. I can just about get it to shift if I manually pull the derailleur out, but it won’t move far enough on its own.

Hanger looks straight.

Any ideas as to [a] what might be causing this and how I can fix it? Would spacing the derailleur out with a couple of washers work?

Cable too tight?
Un bolt the cable from the derailleur and see if you have full range.

Undo the cable, and the mech should drop the chain onto the smallest sprocket.

If it doesn’t, back off the end stop screw until it does.

If backing off the end stop screw does not work, then look at the drop out.

Did you put a new cable in too? This could be sticking if not, I’ve had this and a new cable or take the old one out and clean and grease and it’ll work.

are the cables new? could be sticking if they’re old and dirty

what he said ^

I know this 🙂

SRAM have changed their specs on the rear mech to cope with “thicker” rear dropout styles, resulting in shifting issues to the smallest sprockets on some steel frames. Dropout thickness should be 7mm or more. Not sure about Cotic’s but steel dropouts on frame’s I’ve made have been 6mm. They don’t need to be any thicker mechanically.

How to fix it so your mech will be far enough over to allow it to drop into the smallest cog? Easy – remove your rear mech and add one or two “pedal washers” that come with Shimano pedals. This will space your rear mech out, and the mech will drop the chain into the smallest cog.

Other issue to check is hanger aligment, as you can imagine that might make it hard for the top jockey wheel to be “far enough across” too.

HTH

Cheers all (and especially Brant).

Even with cable off it wouldn’t go far enough. As I said hanger looks straight, so will be measuring dropout thickness tonight (from memory certainly doesn’t look 7mm) and finding some washers I reckon.