breadbin

I had a single speed on my mtb but found it to be too hard on my knees so i redid the wheel on a Deore hub with an XTR 9spd cassette, XT 9 speed rear mech and SRAM 9 spd chain.when i was setting it up they worked perfectly and changed gear perfectly smooth but when i put pressure on the pedals the chain slips really badly. i did play around with the barrel adjusters but the problem is still there. are them components ok together? the cassette looks perfect and the chain is brand new so don't know why it is happening

CCrew

The derailer hanger could be bent. The B Limit could be set wrong. The indexing could be out. The low limit could be set wrong. Cables could be bad or incorrectly tensioned. That's just a few

Does it slip in all the gears or just a couple?

DaveSSS 

If the chain skips on just a few cogs, then those are probably your most-used cogs and they are worn out. Chain skip is when the chain stays on the intended cog, but won't transmit power. If the chains move to a larger or smaller cog, that's entirely different and could be either the RD alignament or simply the need to adjust the shift cable tension.

The best way to test for a worn out cassette is to put a new chain on it. If you had a chain with even a few hundred miles of use on it, that chain would probably work just fine on the cassette.

operator

No

The most likely cause is a worn cassette having a new chain thrown on it. If that cassette is not new, or extremely close to being new it will skip.

CCrew

Unlike Operator who looks to have had one too many hits off the grounch bong today, I'll give the OP credit that he may actually know what he's looking at. I'd advise taking a good look at the Park Tools site and Sheldons, and stepping through from the beginning on the adjustments keeping a fresh mind that maybe just maybe something is just not quite adjusted right. I've seen something as simple as a not quite tight rear skewer cause similar issues without always arbitrarily condemning a part "just because"

DaveSSS 

CCrew...

The real issue is that the OP did not adequately describe his problem, but a chain slipping badly under a heavy load sure sounds like chain skip to me. Chain skip and poor RD adjustment do not exhibit the same symptoms. True chain skip never occurs due to an adjustment problem.

exRunner

My chain will skip if it am on the 53/25 combo standing hard. Setting it does not do it. I have always assumed it is the chain line being so far off that causes it.

Save the the "cross-chaining" remarks. Already been through that argument.

DaveSSS 

I guess there is no argument. Now you've acknowledged another reason it's not wise.

blamp28

Those components are fine together. Since you say the cassette "looks fine" and the chain is brand new, I assume you are using a used cassette. This is , I believe what operator was getting at. Look for photos on Part or Sheldons site that picture new chain with worn cassettes and you may recognize your bike. It sounds like you need to try a new cassette. If that is not it, you will have a replacement ready for the next worn cassette anyway.

engo

I had this problem once, and it turned out that one cog on the cassette was cracked radially, and when put under load, skipped. I didn't see the crack until I actually dismantled the cassette and examined the cogs closely. The skipping also haunted my GF for a while, and although the cassette on her bike looked good, it actually had just enough wear on one or two cogs to cause the problem.

I also had issues once when the removable link in my campy chain (Whipperman Connex link) was installed upside down, though that was less a "skip" than a "slip".

Hope you resolve the issue. The chain skip is probably one of the most annoying things I've ever had to deal with (in a cycling context).

exRunner

Just couldn't resist, could you?

Cross chain and try to make your chain skip. My guess is most people can't, so for the majority it still isn't an issue.

fiataccompli

could a tight link on the chain cause the skip/slip?

StanSeven

Yes.

operator

Rofl.

Nobody, on any of the bikes we sell that are 9/10/11 speed have people skipping on cross chain combos. Every gear combo that can be shifted into, can be used. You have a chainline problem that needs to be fixed - good for you. That has no relevance to this situation.

FlatMaster

broken free-hub pawls. Just replaced mine. The bike is about 20 yrs old though.

DaveSSS 

You should really try an 11 speed drivetrain running in the 53/25 (largest cog) on a bike with chainstays of 406mm or shorter. Poor idea, IMO. I never do it and wouldn't recommend it to anyone who doesn't want premature chain failure. If that's what you recommend to your customers, they'd be wise to avoid your shop.

Chainline problems are really rare these days. Frames are made more accurately and the outboard bearing crank usually put the rings spot on the proper location.

CrimsonKarter21

I had that happen to a 1.5 year old Fulcrum Racing Evo 5.