Matthew:

I'm hoping someone can help with this question - I've trawled the internet and this forum high and low and can't find any clues.

I have a 2007 R3 equipped with Campagnolo Chorus compact (the UltraTorque variety with an Ultra Narrow chain). The rear cassette is an 11-25 and is fitted to a rather delightful pair of Campag Neutron Ultra's. All has been great for the first few hundred miles until I was doing some routine cleaning and gear adjustments.

I realised that when on the 11 tooth cog on the back (and either of the front chain rings - obviously the small front chain ring is to be avoided to prevent poor chain crossing action) that the chain lightly rubs the rear derailleur hanger. Now, this isn't a massive problem, except if you happen to back pedal. In this case it seems to catch and ride up a bit bringing the rear derailleur with it.

On another post Redcorn mentioned straightening the rear derailleur hanger, my concern with this approach is that the R3 derailleur hanger is quite substantial and I wouldn't like to risk causing damage to the frame (I might be being overly cautious).

Has anyone else experienced this? If so, how did you fix it?

Thanks in advance...

Parktool has a rear derailleur hanger that will not harm your frame. I do not suggest you do it yourself unless you have had experience since the rear derailleur hanger is made from very soft aluminum and can crack. The frame will not be harmed with the Park Tool derailleur adjustment tool. Take your R3 to a Cervelo dealer and have them do it for you.

The issue you are having was one of the reasons why I did not like the Campy Record set up. The chain line on the 11 cog was way to close to the hanger and even when properly adjusted leaves less then 1mm clearance on certain wheels such as the Zipp wheels. Sram and Shimano leaves at least 5mm gap between the 11 cog and hanger so the chain doesnt rub. I am not sure if its a design issue with Cervelo or the combo of Campy and Cervelo and certain wheel manufacturers.

Thanks Redcorn. Will get the derailleur hanger checked at the weekend.

I'm glad that it isn't something different with my frame / setup and that this is a common issue - which led me to the following...

One thought that I have had is to add a spacing washer between the wheel axel and the frame (1mm - 1.5mm thick plate washer) which would provide a little extra clearance. I don't think this would cause any structural or performance issues with the frame as this gap is bigger than this and then compressed when the QR skewer is tightened.

Can anyone suggest if this is a terrible plan or one worth persuing?

Thanks again.

Well I am delighted to be able to say that the washer trick has done the job and I now have a 1mm gap between chain (on the 11 tooth cog) and the derailleur hanger.

The washer had an inner diameter of 10mm (to fit over the axel) and an outer diameter of 16mm - which is roughly the same diameter as the lock nut.

Having thought through my idea I did a little more research and have now found an excellent resource on the internet for all things related to chain lines and what they should be. It also gives detailed specs of the width of various cassettes and other 'useful' if quite technical information that might be of interest to someone else on this forum - so here is the link: http://www.sutherlandsbicycle.com/Chapter5.pdf - some of the info is a little out of date (e.g. 10 speed chains for Campag are now 5.9mm not 6.1mm - as anyone who has bought the wrong perma-link can attest to).

Does anyone have the full manual? If so, is it as informative and helpful as this 'freebie' chapter?

Anyway, hope that my update is useful to someone out there. And thanks again Redorn for info. Had I known of this Campag / Cervelo issue I might have bought a different groupset,  but then again I have had Campag Chorus on my bikes since 1987!