Effing Campag chainrings!

Smokin Joe

Can anybody give me a good reason why Campag have decided that one of the holes on their Ultra Torque compact chainrings should be offset by about 2mm over the 110mm of the other four?

I have just spent an hour working precariously near the sharp bits trying to fit a 36t inner to my square taper compact to discover that the TA ring my LBS got for me won't fit. The teeth are all the same size and shape so I can't see how orientation matters, and if it does they could have just put a marker on the ring.

Bleedin' frustrating.

acorn_user

Total system Integration....

Why did Shimano change the inner ring bcd for Dura Ace triples?

grr

aracer

I presume this is a carbon crank? Supposedly due to the structure of the crank, as having the bolt further in would interfere with something due to the way it bolts on there. I have a suspicion it's at least partly marketing though! You have two options - either get a specific ring (TA do them - called Nerius). Alternatively I've heard reports of people having success with filing the bolt hole a little to make it fit.

Smokin Joe

The crank on my chainset is a bog standard square taper alloy job. I cannot see the need to move the hole by only 1 - 2mm for engineering reasons whatever the design of the Ultra Torque cranks which the new ring is obviously designed for, and can only think that Campag have gone down the road of built in obsolesence.

gundersen

Or maybe it is to insure that the ring is always attached correctly in conjunction with the new chain shifting guidelines.

Smokin Joe

gundersen wrote:

Or maybe it is to insure that the ring is always attached correctly in conjunction with the new chain shifting guidelines.

The ring is completely plain, all the teeth are straight cut and there is nothing on it to warrant a particulr fitting position.

magliaceleste

The ring is completely plain, all the teeth are straight cut and there is nothing on it to warrant a particulr fitting position.

Eh? I think gundersen is saying that the Campag rings are designed that way so that the ramping is always set-up right.

aracer

Smokin Joe wrote:

gundersen wrote:

Or maybe it is to insure that the ring is always attached correctly in conjunction with the new chain shifting guidelines.

The ring is completely plain, all the teeth are straight cut and there is nothing on it to warrant a particulr fitting position.

However it also doesn't fit. I'd put money on any chainring which does fit having ramps and pins which require a specific orientation.

Having said that I am surprised, as I thought the alloy cranks were immune from this odd bolt hole position. Are you completely sure that one hole being offset is the problem and not something else?

custom-freak

the orientation is for the big ring, which will have the pins and ramps to aid shifting, the smaller ring doesn't need the ramps and pins so much but they both bolt on to the same piont on the spider so the bolt placings are the same, campag used to put a blob (hard to describe) on the rings which was supposed to be aligned with the crank arm to give crisp shifting but i guess they went for the different design for the new compact to ensure that the rings would always be set up properly for crisp shifting ( i have seen rings put on wrongly and it ruins the shift). guess it's just something that us campag nuts will have to live with, like the 135 rather than 130mm pcd of the non compact chainsets.

Cf

Smokin Joe

Problem sorted now, took the ring back today and the correct one has been promised for tomorrow. Even the owner of my LBS (a decent one) was surprised at the design.