Rear cassette "slips" while powering hard up hill

[AC/BC]

Ok, first ive just replaced my cassette with XTR and my chain with a Scram PC99. I took it into a shop to get the shifting adjusted. It shifts wonderfully now. Although when I pedal really hard up hill the cassette breaks loose, it feels like it slips for a pedal stroke then engages like normal. I don't think the chain is jumping to another gear because it stays in the same gear and everything shifts fine. Do I need to torque my cassette down harder? I only tightened it to where it felt good... but im second guessing whether i should have used a torque wrench. Or, is it something in the wheel like the sealed bearings going bad? It didnt do this before I replaced all this stuff.

[berrywise]

How old is your wheel? Sounds like your freehub body could be going.

[TML]

How old/worn are your front rings? Are you sure it's your rear that is slipping? If you replaced your cassette and your chain but still have a very worn set of chainrings, it's likely you're skipping your chain up front.

Just another possibility . . .

[AC/BC]

How old is your wheel? Sounds like your freehub body could be going.



The wheels are almost 3 years old. I've done some hard riding in those three years though. I've got Bontrager Race wheels. How hard is it to replace the freehub? Sorry im kind of new to bike mechanics... but what is the freehub body?

[AC/BC]

How old/worn are your front rings? Are you sure it's your rear that is slipping? If you replaced your cassette and your chain but still have a very worn set of chainrings, it's likely you're skipping your chain up front.

Just another possibility . . .


My chainrings up front are almost 3 years old, but ive taking good care to clean them and have replaced my chain more then once in that time. Im pretty sure its coming from the back but i will take note of that and it might be time to replace the rings anyways.

[phaberman1]

How old/worn are your front rings? Are you sure it's your rear that is slipping? If you replaced your cassette and your chain but still have a very worn set of chainrings, it's likely you're skipping your chain up front.

Just another possibility . . .

I'm with TML. Sounds A LOT like worn front chainrings and a new chain that do not mesh.

[berrywise]

My chainrings up front are almost 3 years old, but ive taking good care to clean them and have replaced my chain more then once in that time. Im pretty sure its coming from the back but i will take note of that and it might be time to replace the rings anyways.

It's the piece of the rear wheel that your cassette slides onto. It is also the part that allows your wheel to freewheel while coasting and engages when you start to pedal.

I don't know if Bontrager uses anything unusual but most come off by taking a 10mm allen wrench and slipping it into the shell and then untightening (first having removed the cassette).

Does it make a lot of crunching noise when it skips? Usually a freehub body that is going just slips and doesn't really make much noise, where as slipping on gears (like your chainrings) is gonna be louder.

[jkalla]

Is it slipping in the higher gears or the lower gears? I had this problem when my cassette started to loosen up on the freehub. I still can't keep it on tight - eventually it loosens up. I always notice it first in the higher gears ( smaller cogs) because they are individually mounted on the cassette and can get a little bit sloppy when the cassette is loose.

[AC/BC]

Does it make a lot of crunching noise when it skips? Usually a freehub body that is going just slips and doesn't really make much noise, where as slipping on gears (like your chainrings) is gonna be louder.



Hmmm now you've got me thinking its my chainrings up front. Because it makes a really loud metal-beaking-type sound.

[AC/BC]

Is it slipping in the higher gears or the lower gears? I had this problem when my cassette started to loosen up on the freehub. I still can't keep it on tight - eventually it loosens up. I always notice it first in the higher gears ( smaller cogs) because they are individually mounted on the cassette and can get a little bit sloppy when the cassette is loose.

It is very possible that I didnt torque the cassette hard enough. I didnt use a torque wrench. But when I get home, im going to borrow my friends torque wrench and retighten everything.

[berrywise]

It slips in low gears. It is very possible that I didnt torque the cassette hard anough. I didnt use a torque wrench. But when I get home, im going to borrow my friends torque wrench and retighten everything.

By the way if you have a bench vice, I find it easiest to put your cassette lockring tool in the vice. Slide on your cassette, tighten the lockring by hand and then put the cassette into the tool in the vice. Then just use the wheel itself as leverage and tighten the cassette down. It'll make a fair amount of crunching noise and it tightens into place. Can't say I've ever used a torque wrench for doing it just tighten er down till it feels pretty tight.

[soupboy]

I can't imagine how the cassette would slip. The smaller rear cogs still sit on the same splines as the main cog body. Unless the spacing is off you're talking about either having rounded off the inside of the small cog, the outer bit of freehub spline, or both. I've never seen that.

You might just have a dead/dying FW that can't handle the torque, or as TML suggested, you might have bad front rings. The middle is the most common to go - are they badly rounded off? Three years is a long time to keep rings if you're riding fairly often. Since you have a new chain and cassette this steers me more towards the chainrings as being the culprit.

[ppgc]

You might just have a dead/dying FW that can't handle the torque,

I have had this happen 2x now. The first time was up a climb and it blew up and I started going backwards down hill. Not fun. The second time it was very similar to this...

[AC/BC]

I can't imagine how the cassette would slip. The smaller rear cogs still sit on the same splines as the main cog body. Unless the spacing is off you're talking about either having rounded off the inside of the small cog, the outer bit of freehub spline, or both. I've never seen that.

You might just have a dead/dying FW that can't handle the torque, or as TML suggested, you might have bad front rings. The middle is the most common to go - are they badly rounded off? Three years is a long time to keep rings if you're riding fairly often. Since you have a new chain and cassette this steers me more towards the chainrings as being the culprit.

Good point about the small cassette rings and the splines. Splines looked good once the cassette was off. Oh and I ride 2-4 times a week during the warmer months and get out occationally in the winter.

[AC/BC]

So I guess my next question is should i just buy a set of new chain rings or should I buy the FSA Carbon Pro Team Issue ATB crankset? The difference is 100 grams. pricewise I can get into the a new crank for $275. Is it worth it to save the weight on the drivetrain? Or should I go with a lighter set of chain rings?

[nord0306]

So I guess my next question is should i just buy a set of new chain rings or should I buy the FSA Carbon Pro Team Issue ATB crankset? The difference is 100 grams. pricewise I can get into the a new crank for $275. Is it worth it to save the weight on the drivetrain? Or should I go with a lighter set of chain rings?

What crankset do you have now? basically, how much of an improvement is replacing the crank? What's the Bottom Bracket situation? Could you use new bearings as well or are they fine? I wouldn't go for lighter chainrings if you want them to last another 3 years. If you are okay with replacing your chain, cassette and chainrings every season, then the light ones would be good.

Also, from a trouble shooting standpoint, is there a certain gear in front that skips, granny or middle? Because you can just replace the one that is skipping, normally the large ring is pretty tough to wear out unless you ride in it 90% of the time.

[jkalla]

If you replace your chain frequently you won't need to replace your cassette and chainrings.

Does anyone really replace their chainrings that often due to wear? I replace my chain when it measures more than 1% (1/8 of an inch over 12 inches) and I have never had to replace my chainrings on any of my bikes.

[Aaroneous]

Does anyone really replace their chainrings that often due to wear?

I just ride until something craps out. Then I replace all three parts of my drivetrain at once.

That's a benefit of a singlespeed, I guess... ;)

[dejorn]

Last year I had to replace what appeared to be a perfectly good middle chainring on my Truvative Stylo crankset because of the same problem you have described. The problem is most prominent when you replace the chain and the new chain doesn't match the "slightly" worn teeth on the middle ring. As you press hard on the crank the chain climbes up to the top of the teeth skips when there is enough force. I am 99.9% sure this is what is happening. It took me a couple of long days to determin exactly what was happening and it wasn't until I purchased a new middle ring that I was sure I found the problem.

There are a couple of things you can do to further troubleshoot the problem. One, can you get the chain to skip in the small and big chain ring. Two, if you have another wheel or can borrow one from a friend does the problem still exist.

I hope this helps.

[soupboy]

Don't buy new cranks unless you have to for other reasons (worn splines, etc.). New rings are cheap. I might even have some laying around.

I'll bet an ice cold Grain Belt (or Coke if you're under age) that it's is the middle ring.