Carbon Blue

I have a 27 speed hardrock pro disc that has deore rear and front deraileurs. Whenever im trail riding and really get on it my gears seem to slip. Upshifting and downshifting are fine throughout the gears but when im in any gear (i do not cross them) and start pedaling down hard it feels as if it slips and grabs again. It really throws off my balance and momentum when this happens and is quite annoying when im on the trails trying to get uphill. Ive tried messing around with the barrel adjusters but it just wont fix it and with the barrel adjusters counter clockwise tightens the cable and clockwise loosens it correct (adds slack)?

ExMachina

Sounds like you might be getting close needing least a new chain and possibly new cogs (and even a new chainring(s)).

Ricardo

...or maybe cable stretch...

Ricardo

Carbon Blue

probably cable stretch. The bike has about 200 miles on it and is about a month old.

ExMachina

Cable stretch would not account for chain slippage in the same gear, especially as you describe it happening only under load.

Do you mean that your gears are slipping into different gears?

bruiser2

When you say that it feels as if it slips is it like a smooth slipping like the way a clutch in a car would work or is it like a clunky slipping.

Carbon Blue

For instance, if im on 9th gear and im accelerating hard to catch up to someone and all of a sudden i have ZERO resistance for about a second then it grabs again. Sometimes when i shift into 9th gear, right after the switch into 9th it feels like its shifting again but its not, it still stays on 9th gear but there are two big jerks as compared to one simple shifting jerk.

iamthetas

it actually sounds a little too tight not loose to me. I had that problem on my SRAM stuff once and I loosened it just a smidge and never had that problem again

jst0076

I had a similar problem recently, but it was only doing it when the chain was on the middle sprocket. After checking the cassette and chain on the trail I figured that I was due a new cassette. Once I got the bike home (without using that gear) I checked it out properly and found a very small piece of twig lodged firmly in the rear cassette just out of sight of a quick on-trail inspection. Got this pulled out and didn't have to open my wallet.

I'm not implying in any way that you haven't checked properly, I'm just saying check absolutely everything before you buy new kit. I once nearly bought a new rear wheel, as no matter what I did I could pull it back into dish. Then I noticed my quick release wasn't fastened properly. Problem solved. Check every detail, then check again, and again. Then buy new kit.

LowCel 

When I used to have the same problem I found out that my derailleur hanger was slightly bent. If you try everything else and still have a problem take the bike by a shop and ask them to check the hanger and make sure it is straight. You probably won't be able to do this yourself unless you have a Park DAG-1 hanger tool.

outdoorboy

Sounds like cable stretch to me. New bike, 200 miles? Yeah, check cables first and adjust. That costs nothing. Then if that's not it start with the chain, cogs and derailier. My money is on the cable stretch. One thing not mentioned is a rear hub issue but usually it happens with quite a bit more age.

nodnerb

Could be a loose cassette. My outer three cogs (the free cogs) on the cassette I'm replacing can rotate about 10 degrees back and forth from being loose or worn. If I hold the larger cogs steady I can actually move the three smallest cogs by hand. I can't see cable stretch doing that though.

gingerbread

same kind of thing was happening to me - i found out i had bent my rear deraileur

Raiyn

Time to take it in for a free tune up. (Something that nearly every shop gives at least one of when you buy a new bike) Beyond that it's nothing more than cable stretch

outdoorboy

Wow, Raiyn and I agree on a fix without seeing the bike! How cool is that?

Raiyn

Nothing unusual in this case. I see it constantly. The whole 200 miles + a month old thing clinched it for me

nodnerb

I still don't see how cable stretch can cause what he is explaining. The derailleur is already in th correct position, not moving, and fully in gear, but yet he is still getting a 10 degree slip before catching. I just don't see how the cable has anything to do with it at that point. I still say it HAS to be a loose cassette from what he is saying. I'll also be it only happens in the highest 3 or 4 gears that are not mounted permanently to the large cogs.

Raiyn

Did you see how new the bike is? I guarantee it's cable stretch. A loose cassette would give much more inconsistant shifting than what is being experienced.

dundrummer

This thread is a few months old, but I thought I might add my comments for future reference. Like Carbon Blue, I also own a Hardrock, and I have also experienced nasty problems with gears "slipping" when you put a bit of pressure on the pedals. The bike was new when I bought it and I had the problem from the word go. It is espicially bad going up hills - so much so that the bike was almost unusable and you would have to get off and walk. Unusually for an irish summer - 2005 has been a lot drier then normal so the problem had appeared to correct itself. Then along comes one of the wettist Octobers in years and the problem returned with a vengence. So it seems to me that water must be a factor, and after liberally dosing the chain and gear mechs with WD-40 I have not had a problem in a week. I'm not a bike mechanic and no next to nothing about the mysterious goings on under my saddle. No doubt WD-40 is doing terrible things down there but what the hey - I can now accelerate from a stationary position and go up hills without any bother. Grand stuff!

Raiyn

Were you actually using a chain lube in the first place? There are COUNTLESS numbers of inexpensive proper chainlubes on the market why in the heck would you want to use the one thing guarenteeed to send your drivetrain to an early demise? Do a search here on WD40 and I guarentee you'll never use the **** again on a bike.
I hadn't guessed
Then why not ask someone who does? You found your way here.
Better believe it. WD40 isn't a true lubricant. It's water displacement formula 40.
Grand stuff my eye.
Go to your local bike or motorcycle shop and get a can of Boesheild T-9 lubricant
I apologize for being a touch harsh, but you stepped on a major pet peeve of mine. Rusty drivelines are one of my least favorite things, (although replacing them is worth a good deal of money) The one thing the folks who bring me these bikes have in common? You guessed it they lubed thier stuff with WD40

xshim_myx

it happened to me too...it might be your gears...check if the teeth on it aren't worn down.

Prozakk

Frame flex can sometimes cause this problem too.

biggsmoothe

sorry to bring back this old thread, but i'm having the same problem. i just got an '05 Rockhopper Comp - probably 2 weeks old, and when i apply hard pressure on the pedals, the chain slips. same ring, same gear, but its like it slips off of one link and catches the next. could it be cable stretch this soon?

iamthetas

who are you and what did you do with Raiyn?

xshim_myx

i'm actually getting it fixed right now by ordering a new cassette and i assumed it cause of the worn down teeth. if it's a pretty old bike, that's probably it.