Strange gear issue!

Coxy_UK

2010 Canyon Nerve XC 9.0, SRAM X0 with SRAM chain and Shimano XT cassette. The cassette, chain and cables are brand spanking new. I have set plenty of gears up before and never had an issue, particularly one such as this.

On indexing the rear gears I can get gears working perfectly for the first half of the cassette, but towards the top end the chain rubs and isn't smooth. Supposedly having got the first 4 perfect the rest should follow suit but this isn't happening.

I have had no big spills which could of bent the frame and the hanger appears straight as an arrow. Limit screws set perfectly along with the B screw as best as I can tell.

Any ideas or suggestions please?

supersonic

Cable routed into the rear derailer correctly?

Coxy_UK

Yeah all correct

supersonic

Top end being the lower gears (larger cogs?). Hanger straight?

snoopsmydogg

Cable tension?

cooldad

Undo everything and start again.

Coxy_UK

Yeah top end the low gears, big cogs.

It's not cable tension.

It may be the hanger but I took it off and it seems straight to me, dunno what else it could be.

supersonic

Let's have a pic of the mech, and cable stop on the mech.

cj11

Had this exact problem last week with a friends bike. mech hanger appered straight to the eye but when offered up toa straight edge was very slightly out of true i straightend the hanger and then started again from scratch removing all parts and fitting as if from new. Worked fine after that i could not believe such a small bend could make such a differance hope this helps.

Coxy_UK

Replaced hanger and is indeed a lot better, but not perfect. With all other gears running perfectly, the smallest cog doesn't want to go up to the next with one click. I have fine tuned the cable tension and all, there's clearly something else wrong perhaps the mech is bent slightly?!

cj11

If the mech hanger was bent its possible that the mech was damaged aswell sounds like a great excuse for an upgrade got to be honest i have used far worse excuses to bye that new must have item :twisted:

supersonic

Is the H stop set correctly?

long_guts

New hangers aren't always straight so it might be worth getting an alignment tool on there to check?

Coxy_UK

Yeah H stop fine, I have setup gears plenty of times including on this bike, so hopefully I'm not making some noob error... though you can never rule it out!

The previous SRAM cassette had a small cog of 12 teeth, whereas my new Shimano XT has 11, but this shouldn't make any odds at all right? I do believe chain length remains the same? Plus I was having issues which caused me to buy new parts in the first place.

supersonic

So if you add a little more tension, the chain then will not drop cleanly back onto the previous smaller cog?

Ouija

Had the same problem on one of my Carbon fibre bikes with SRAM X0 shifters, XO long cage derailleur and Shimano 11-28T cassette. Solved it by replacing the Shimano 11-28T cassette with a SRAM 11-34T cassette (after replacing the derailleur and mech hanger, only to discover those weren't the cause of the problem).

Some time later i put that Shimano cassette on a aluminium bike knocked together from spare parts.... same problem. Fine on the first half of the cassette but just wouldn't index properly on the second half. Took it off and replaced it with a Shimano 11-32T cassette... problem disappeared again.

So the only conclusion i can think of was that either there was something wrong with mixing Shimano cassettes with SRAM derailleurs or that long cage derailleurs really shouldn't be used with smaller 11-28T cassettes (maybe the chain isn't pulling the derailleur open as much as it should have by the time it's moved that far inwards.. who knows).

Something to think about.

cooldad

Or the spacer(s) between the cogs are back to front.

Ouija

cooldad wrote:

Or the spacer(s) between the cogs are back to front.

A reasonable assumption. But if the OP's problem was anything like mine, it was the fixed section of the cassette that has no spacers that didn't want to index properly. No amount of altering cable tension could get the largest five rings to work smoothly. The smaller four, with the spacers, were the only ones that shifted smoothly (suggesting the space between rings was correct).

Coxy_UK

I've now read on a few forums that people are saying Shimano 10 spd and SRAM 10 spd stuff do not mix. Apparently the Shimano chain is directional and their cassettes are designed specifically for them and shouldn't be used with anything else.

Can anyone confim this?

Thanks

supersonic

That is what they say. But many mix them up, even manufacturers.

Try winding the H stop out a quarter of a turn, and add a quarter turn to the cable tension.

Coxy_UK

Well I think I've tried everything. Took the cassette apart to double check it was assembled correctly, it was. Maybe the mech itself is ever so slightly bent, I don't know.

I guess I will have to bite the bullet and put it into a shop to sort out

Coxy_UK

Right well I've taken the plunge and ordered a new X0 mech for £70 which was a good price. Fingers cross all will be fine when it's fitted.

the_moodster

Coxy_UK wrote:

.Apparently the Shimano chain is directional and their cassettes are designed specifically for them and shouldn't be used with anything else.

Can anyone confim this?

Thanks

No that's crap, I've got a SRAM chain on an otherwise Shimano drive train on the Mojo and it works perfectly.

Coxy_UK

Yeah I have since indeed learnt it was crazy, canyon sell bikes with mixed stuff even.

Hopefully mech will arrive tomorrow and I can get back to riding rather than tinkering!

Plyphon

This might sound silly - but how clean & clear are your cable outers?

It's always surprising how grime buildup inside a cable can effect performance.

Coxy_UK

Plyphon wrote:

This might sound silly - but how clean & clear are your cable outers?

It's always surprising how grime buildup inside a cable can effect performance.

Brand spanking new along with the chain and cassette... and soon the mech!

Coxy_UK

SORTED!!!!

On comparison of the new and the old mechs, it was obvious that something was slightly bent. Once fitted indexing was easy as an easy thing which studied easiness at Oxford.

Now this bloody weather just needs to piss off :evil:

Dirty-Boy

the_moodster wrote:

Coxy_UK wrote:

.Apparently the Shimano chain is directional and their cassettes are designed specifically for them and shouldn't be used with anything else.

Can anyone confim this?

Thanks

No that's crap, I've got a SRAM chain on an otherwise Shimano drive train on the Mojo and it works perfectly.

+1 I think manufacturer's are too quick to say their parts are only compatible with their branded components, more of an attempt to market their gear than acknowledge compatible options

The Rookie

Coxy_UK wrote:

On comparison of the new and the old mechs, it was obvious that something was slightly bent. Once fitted indexing was easy as an easy thing which studied easiness at Oxford.

Fellow Blackadder fan then!

Good news, well done!