zvez

First off, this is a new bike so will definately take it back to the LBS to sort, but I'd kind of like to learn about this a bit.

I've read Sheldon Brown's info on front and rear derailleurs, etc, as well as a search here.

This is a new bike fitted with dura ace 9000. Has a 52/36 rings. Couple issues I seem to have. The front 52 chainring is most definately warped. I can't really tell how much, perhaps 1/16" of an inch. When chain is on the 52 ring, the chain rubs the right front of the outside edge of the front derailleur cage. I notice when it's on the three smallest cogs in back and big ring in front, their is an audible dragging or clicking sound (almost but not quite like cross chaining). If I move to the fourth smallest cog, it goes away.

The other thing I notice, when on the small ring in front (36), the chain rubs against the inner side of the front derailleur cage. I notice a plastic type bumper on that section, so is it normal for the chain to rub there?

Bike has 150 miles on it.

rhenning

Has the derailleur been changed from factory. I can't imagine any Dura Ace handling the spread of a 36/52 front. Roger

zvez

HI Roger, no totally stock out of the box cervelo r5. crankset is rotor 3d+

Retro Grouch 

Try the Park Tool website. Go to the section about installing a front derailleur.

Disconnect the shift cable and start with the very first step about the position of the derailleur on the seat tube - that's important. Do all of the steps in order because each adjustment affects subsequent adjustments.

zvez

this was excellent info! Thanks

dsbrantjr

"First off, this is a new bike so will definately take it back to the LBS to sort"

Excellent plan, I'd leave it alone and let them sort it out. You don't need them blaming your fiddling around for damaging something, with warranty hassles. You can learn to work on it after the warranty runs out.

Looigi

Personally, I like the OPs original plan better: Let the shop sort it out but use this as an opportunity to learn as much as possible about it. I think it good to prepare with a little study and prep before taking it to the shop, have the shop do the work, then have them explain what they did and why they did it.

Kimmo 

A warped 9000 big ring? Hoo boy, warranty time... the retail price on those puppies will make your eyes sting. A 54t is $380...

Seems a bit odd though; it's like the laterally stiffest chainring ever. Maybe someone goofed big time on assembly...

jimc101

If you read post #3 the OP says the crank is a Rotor 3d+, think we need clarification from them about the ring that the OP is running, as it could be Shimano, but is most likely a Rotor ring. If it is rotor, if it's a Q ring, is it the design that they look warped?

zvez

The 52 chainring is a Rotor and marked noQ.

As mentioned I'm new to this, but with the bike on the stand, I can turn the crank and in relation to the cage you can see where the rotor seems to be warped. I looked at it again, and it seems probably between 1/32 and 1/16th in., in other words most of the way around it's perfectly in line with the cage and then bulges out and rubs against the front edge of cage.

Thanks for all the great input guys!

Kimmo 

Tried pulling the ring off to see if there's a spurious washer?