Gear adjustment with new rear cassette

Legolam

I changed my rear cassette on my MTB last night and now I'm having issues with the rear derailleur. Basically, I swapped an SLX 11-36 cassette for an XT 11-36. The old cassette didn't have any spacers either behind the cassette or between the cogs, but the new cassette has a small black plastic spacer between the third and fourth smallest cogs. I installed the new cassette with this spacer in that position as the cogs seemed wobbly and didn't sit properly without it. I also installed a new chain.

With the bike still in the stand, I cycled through the gears, and noticed that the jockey wheel on the rear derailleur is now fouling the big cog. Some of the gears are skipping too. Before I start messing around with the B limit screw and adjusting the rear mech, is there any way that I might have installed the new cassette incorrectly? Specifically, should I have installed this plastic spacer on the new cassette?

Chunkers1980

Pics of what you've done. On a 9spd XT cassette there isn't anything black, just a silver spacer to space the flat sprockets.

Legolam

It's a 10sp XT cassette (both cassettes were 10 speed). I'm at work at the moment so can't post a pic, but everything looked like it was flush when I put it back together (although I can take it all off this evening and check again), and the wheel is in the dropouts correctly.

The Rookie

Did you change the chain? Otherwise the fact it's hitting the largest gear susggests the SLX was 11-34.

The gears may be slightly offset from the SLX and need indexing, all the gaps should be consistent so if the gap is different where the spacer is you have it wrong.

http://techdocs.shimano.com/media/techd ... 704675.pdf
The spacer does indeed go between 7th and 8th gears

Chunkers1980

That's not a spacer as such, it is built into the sprocket cluster to space it out.

The Rookie

Chunkers1980 wrote:

That's not a spacer as such, it is built into the sprocket cluster to space it out.

6 Y1Z805000 Sprocket Spacer (t=2.35 mm)

Hmm yes, whatever, I prefer the Shimano description, and from the pic it is loose and not built into anything, although I've not had one myself.

Chunkers1980

I was looking at the diagram numbers. Yes 6 is a loose spacer, and like I said on the 9spd XT is silver and not black. OP specifically says black and (the black bit) 'That's not a spacer as such, it is built into the sprocket cluster to space it out.', so from the diagram 7-8 and 8-9 on the sprocket cluster.

The Rookie

Chunkers1980 wrote:

. OP specifically says black and (the black bit) 'That's not a spacer as such, it is built into the sprocket cluster to space it out.', so from the diagram 7-8 and 8-9 on the sprocket cluster.

I've tried and can't find a translator that makes sense of that at all.....

Anyone it's clearly number 6 (the spacer) he refers to as it's in the right place in the cassette.
I too have a 9sp XT and it has no spacer, clearly the 10 does.

Sounds like it just needs indexing properly.

Legolam

Great, thanks for all the replies!

Just to answer a couple of them:
It's a brand new chain and a brand new cassette, but I haven't changed any of the chainrings. They don't look too bad, but I'm willing to accept that they might be a bit worn.
The old SLX cassette is DEFINITELY 11-36 (I checked the markings AND counted the teeth!)

I HATE indexing gears, but it looks like that's what I'll be doing when I get home from work this evening! I have an XC race tomorrow evening, so hopefully I don't balls it up too badly. Anyway, it can't be as bad as the shifting on the old cassette - I literally had about 3 working gears (and not any useful ratios) at the last race... not very conducive to being competitive!

Chunkers1980

The Rookie wrote:

I too have a 9sp XT and it has no spacer

It does. It is silver, not black, and says 9s on it

Chunkers1980

Leglam, I'd take it to a bike shop!

The Rookie

Legolam wrote:

Just to answer a couple of them:
It's a brand new chain and a brand new cassette, but I haven't changed any of the chainrings. They don't look too bad, but I'm willing to accept that they might be a bit worn.
The old SLX cassette is DEFINITELY 11-36 (I checked the markings AND counted the teeth!)

I HATE indexing gears, but it looks like that's what I'll be doing when I get home from work this evening! I have an XC race tomorrow evening, so hopefully I don't balls it up too badly. Anyway, it can't be as bad as the shifting on the old cassette - I literally had about 3 working gears (and not any useful ratios) at the last race... not very conducive to being competitive!

It sounds like the chain may be too short then, as that will pull the upper jockey into the cassette.

Indexing is one of the easiest jobs going, good indexing takes a lot of stress out of a ride with good clean and fast shifts when you want them.

The Rookie

Chunkers1980 wrote:

The Rookie wrote:

I too have a 9sp XT and it has no spacer

It does. It is silver, not black, and says 9s on it

http://techdocs.shimano.com/media/techd ... 625614.pdf
11-34 no spacer along the lines that he has, only the 11-32 does.

Chunkers1980

My bad, thanks Simon. Only ever had 11-32s myself to pay any attention to.

The Rookie

I've only ever used 11-34, so I have at least learnt the 11-32 has one!