3x10 cog slip

S

swmtbr

Likes Dirt
Hi all
I'm having an issue with my chain slipping/jumping on my smallest rear cassette cog under hard load. The cassette is a SLX HG-81. The cog doesn't look worn and I just replaced the chain thinking that a bent link was causing the problem. Check my derailler and everything thing looks good and properly aligned. There is no problems on any other cog even when under very hard load. I can take the wheel off and post a pic of the cog if anyone an help.

Cheers
 
S

swmtbr

Likes Dirt
image.jpgimage.jpg

If that cog is causing the problem then will I need a new cassette? Seems like a waste to replace the whole thing for one cog, which is actually seperate from the rest of the cluster. Does anyone know if you can buy just that one 11t cog? I can't find one online at all.
 
hifiandmtb

hifiandmtb

Sphincter beanie
It's worn, buy a new cassette from Chain Reaction Cycles...they are cheap, and you now have a new chain anyway.
 
Minlak

Minlak

custom titis
The drive train is like a complete package. you can normally get away with changing a chain but generally if you are changing sprockets (Cassette) you get a new chain and usually front Chainrings. Are you sure the issue isn't chain angle? Trying to keep the chain off the extreme angles is the goal. EG littlest front and littlest rear and biggest rear and biggest front.
 
S

swmtbr

Likes Dirt
Minlak said:
The drive train is like a complete package. you can normally get away with changing a chain but generally if you are changing sprockets (Cassette) you get a new chain and usually front Chainrings. Are you sure the issue isn't chain angle? Trying to keep the chain off the extreme angles is the goal. EG littlest front and littlest rear and biggest rear and biggest front.
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Angles are fine, I've used this setup for a long time now. It's only slipping on that cog no matter what ring it's on at the front.
 
T-Rex

T-Rex

Template denier
It does look worn, but also check you haven't shredded the ends of the splines on the free hub body, which would allow that cog to spin under load.
 
redbruce

redbruce

Eats Squid
swmtbr said:
Cheers, yep happy to replace if that's what's needed. Free shipping this weekend with CRC too!
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The lower (smallest) sprockets are significantly worn (look at line of teeth at roughly 20 past the oclock). Larger ones out of focus so hard to say.

Cassette needs replacing.
 
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S

swmtbr

Likes Dirt
T-Rex said:
It does look worn, but also check you haven't shredded the ends of the splines on the free hub body, which would allow that cog to spin under load.
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Just pulled the cassette off, and no wear on free hub. New XT wheelset is only a month old.
 
fatboyonabike

fatboyonabike

Captain oblivious
the two teeth next to the shimano part no. look totally mashed, and would cause slippage for sure..is a shadow mech involved?
 
redbruce

redbruce

Eats Squid
swmtbr said:
Just pulled the cassette off, and no wear on free hub. New XT wheelset is only a month old.
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Freehub is last place to look for wear, and subsequent issues.

Looks to me if the wear rate is that high on those last (smaller) four cogs (caveat: I cant see larger clearly), you need to review gearing/riding style (mate tends to ride big/big in the false assumption is has less friction = major wear in fewer teeth end of cassette).
 
The Duckmeister

The Duckmeister

Has a juicy midrange
Derailleur type is irrelevant. High use of that sprocket is the cause, as evidenced by the significant burrs on the teeth, particularly those two near the model mumber on the lockring. And yes, it's stuffed.
 
Ideate

Ideate

Senior Member
Could just get a new cassette.. Or you could actually check chain wrap!?!? It's been a very common problem for me having played with single speed and 42t which requires B screw to wound in causing skipping under load. Worth a look?
 
Dicky

Dicky

Punter God
+1 for review gear choice & riding style.

32:11 (middle ring + smallest cog) is close enough to the same ratio as 44:15 (big ring + third cog, or thereabouts).
(Divide the front by the rear to calculate gain ratio, in this case about 2.9).

A triple chainring setup has a large number of duplicate ratios, and only a small amount of useful extra range over a 2x10 setup, which is why they are becoming increasingly obsolete on mountain bikes.

Using bigger rings at both ends for a given ratio spreads out the load on both chain and rings, and will help them last longer.

Given your current chainring selection, you're using the middle chainring too much at higher speeds. Shift up to the big dog before you run out of cassette, or consider a swap to a 2x10 setup.
 
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rowdyflat

rowdyflat

chez le médecin
Sorry but your gear selection is just wrong and the same problem will rearise w anew cassette.
As others have said try to use the bigger chain rings at the front so you aren't using the same small back ones w fewer teeth.
I have seen this a lot where I live big climbs requiring grannies then they ride home still in granny but use small cogs at the back to get a higher gear. Cross chain not good
 
S

swmtbr

Likes Dirt
All good advice, thanks everyone.

I just ordered a new cassette. Not sure if my riding/gearing style can be adjusted much as I'm often in those smallest cogs on the big front ring. Lots of long flat sections where I ride and I run out of gearing. In terms of chain angle the middle ring is the only time I'd nearly use all ten gears. In the big and small rings I only use maybe 4 or 5 gears at the respective side of the cassette.
SLX cassettes/chain rings and XT chains are relativilly cheap at chain reaction so I can handle replacing every 18 months or so.
The front chain rings have very little wear due the the large surface area, can I get away with just the new cassette and chain this time round?
 
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The Duckmeister

The Duckmeister

Has a juicy midrange
Try pulling back a few gears & spinning a higher cadence. It will take a little bit of time to work up to sustaining it for longer rides, because your aerobic system works harder to keep oxygen flowing to the faster-moving muscles, but in the long run you'll wear out your gear less frequently, and will be less likely to injure yourself from high strain, which can occur from big gear grinding.
 
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