citizenerased

I just received my first road bike and was test riding it and noticed that when I pedal with a lot of force the middle gears on both the large and small chain rings will skip. It's most noticeable when I stand to pedal. When the chain skips off the cassette, it will sometimes throw me into another gear as well

I put the bike up on a stand and shifted through all the gears, little -> big and big -> little on both chain rings and there doesn't seem to be any problem shifting between any of the gears or mis-shifts (by hand pedaling). I did notice as I was looking for a bad link in the chain (there weren't any) that the cassette is loose. I can move/wiggle all the cogs easily about 2mm around the hub as well as lateral play of the cassette itself along the skewer. Set up is a Centaur RD, Daytona shifters, 10-speed cassette on Campagnolo Nucleon wheels.

The chain appears to be within the 1/16th of an inch limit for stretch and the teeth on all the cogs look just as good or better than my commuting bike. Would simply tightening the cassette eliminate my chain skip? Or, is there more to worry about?

This is the only reference I could find to chain skip being caused by a loose cassette: https://www.webmountainbike.com/toptencausof.html, don't know if it applies to road bikes as well (just getting started on learning to wrench things myself)

MTBaddict

If the chain is good, the rings are bad. Same thing happened to me shortly after installing a new chain. I could not tell by looking at the chain rings, they did not look worn or distorted. After getting new rings and laying them right on top of the old rings and holding them up to the light, I could see the difference. The chain was just climbing right out of the chain ring whenever I stood and applied a lot of force/torque.

At first I though it was my freehub mechanism that was slipping. It was easy to see that the problem was up front when I simply stood next to my bike, applied the rear brake and stomped down on the pedal. The drive train slipped all right, but the chain never moved forward, only the crank turned.

citizenerased

thanks, I'll give this a try tomorrow and see. It would probably be a good idea to also make sure the cassette is tightened as well.

StanSeven

Is this a brand new or used bike? Check the cassette and see if the spacers are properly installed. Also be sure the cassette is tight. A new chain and an old cassette often don't work together. Unless the bike has extensive wear, the chainrings aren't worn.

citizenerased

Tried to pedal with the brakes clenched and no slipping on the chain ring...

Used '03 Masi Gran Criterium, cranks/wheels/shifters were purchased used (unknown mileage) by owner who built up the NOS frame, brand new fork, RD, headset, stem and brakes. He didn't mention if the cassette/chain were new or used when he built up this bike. He said he rode it less than 500 miles and from what I can tell the cassette and chain are most likely part of the new components since they have a lot less wear than the cranks/chain rings.

I just checked the spacers and they look just like described in the attachment. So, maybe it looks like I'd just need to get a lockring tool and tighten up the cassette and hope that will solve the problem since the chain and cassettes look good to me, wear-wise.

citizenerased

Well, I got myself a chain whip and BBT-5 and went to work on the cassette. After taking the cassette off, there was still lateral play between the hub and axle. I tightened the lock nut, placed the cassette back on and tightened the lockring and put the wheel back on.

Adjusted the RD and went for a test ride and tightening things up seemed to eliminate the chain skip and make the drive train noticeably more silent Working through the cassette cogs on some short sprints it seems to be okay.

Should I worry that the lock nut was loose and that it will come loose again over time? Or, once things are tight I should be good?

Mondoman

Seems like there's a very good chance the wheel hubs might not be properly adjusted (it sounds like the wheels are used with unknown mileage?). I'd overhaul (or have overhauled) the wheel hubs w/new bearings/grease just to make sure they're properly lubed and properly tightened.

citizenerased

Thanks, I'll see about tackling that this weekend then since it looks like more rain here.

cyccommute 

Probably not the chainrings but definitely the cassette. The chain and cassette aren't mating up properly. Change both and the problem will go away. Chainrings, by the way, last much longer than cassettes.