[mudmax]

I've just replaced my chainrings, cassette and chain (xt) on my Cannondale. All the gears shift fine and the rear deralleur lines up with the cassette in the respective gears but when I'm in the front 36&44T and rear 11T& 13T (the two lowest on the rear) the chain skips when I start pedalling hard and over rough ground its worse. So you can imagine the frustration of not being able to fully crank it on the downhills

The chain lines up; and I checked to see if the chain had a tight link where I joined it but it does't come off the cogs or guides either. I'm bamboozled as to what is causing this problem. The chains the same length as the old chain and the new parts are the same.
Any ideas greatly appreciated;

 

[hestee]

I'mm sure you tried micro adjusting the derailleur cable tension. When I have periodic skipping problems usually a small cable tension adjustment helps. Have you tried a full re-adjustment of your rear derailleur? Start over, loose the cable, reset the stops and re tension the cable. I'd start there.

 

[+push IT to the LIMIT+]

I had a bike like that too, but i sold it. Anyway, come to find out the chain was too big for my bike. So i ended up shorting the chain with a grinder and making it fit! lol. Maybe its just a tad too big.

 

[mudmax]

thanks, it was the rear deralleur after all it was a bit sticky ; a good clean and lube and i'm back in business.