Technical Expert Help Needed!

[mseanschmidt]

I've had an ongoing vibration/resonance problem for almost a year now on my Seven ID8 with full Campy Record components. The vibration occurs ONLY in the big front ring, on a flat road and at a steady consistent cadence. There needs to be some torque on the chain but not an all out hammer. I get a vibrating/resonance coming up through the cranks. Outside of that unique situation, the bike is smooth as butter, which makes it frustrating. The LBS has changed out every component- pedals, tires, wheels, crank, chain, derailleurs and cassette. The bike went back to Seven for 3 weeks and they sent it back saying it was the most aligned bike ever to come out of the factory. I found a thread on Campy Only describing my exact problem... they fixed it by changing from dry lube to wet lube and torquing the rear cassette to Campy specs. I did both and it did not solve the problem. The only "variable" at this point I can use for diagnostic is that Campy sent us a rear record derailleur that was set at the factory at the tightest setting. This actually changed when I feel the resonance. With the old record rear derailleur I would feel it at a higher steady cadence like 90 rpm. With the newly set derailleur there is NO resonance (butter smooth) at a higher 90 rpm cadence but when I slow down to a steady 55-60 rpm cadence the resonance starts.

I'm at wits end on this!!! Could any experts out there offer any suggestions at all???

 

[Peter@vecchios]

I've had an ongoing vibration/resonance problem for almost a year now on my Seven ID8 with full Campy Record components. The vibration occurs ONLY in the big front ring, on a flat road and at a steady consistent cadence. There needs to be some torque on the chain but not an all out hammer. I get a vibrating/resonance coming up through the cranks. Outside of that unique situation, the bike is smooth as butter, which makes it frustrating. The LBS has changed out every component- pedals, tires, wheels, crank, chain, derailleurs and cassette. The bike went back to Seven for 3 weeks and they sent it back saying it was the most aligned bike ever to come out of the factory. I found a thread on Campy Only describing my exact problem... they fixed it by changing from dry lube to wet lube and torquing the rear cassette to Campy specs. I did both and it did not solve the problem. The only "variable" at this point I can use for diagnostic is that Campy sent us a rear record derailleur that was set at the factory at the tightest setting. This actually changed when I feel the resonance. With the old record rear derailleur I would feel it at a higher steady cadence like 90 rpm. With the newly set derailleur there is NO resonance (butter smooth) at a higher 90 rpm cadence but when I slow down to a steady 55-60 rpm cadence the resonance starts.

I'm at wits end on this!!! Could any experts out there offer any suggestions at all???

Not uncommon to see/feel this on many drivetrains. It is the chain 'vibrating' back and forth as it leaves the cogset on the way to the chainring. I would suggest perhaps stiffer chain, which is probably Campag, compared to shimano and Sram. If you have a Campagnolo chain, well..it is not uncommon tho.

 

[benkoostra]

I think Peter is on to something, only I would look at the vertical motion of the chain as it leaves the cogs and head for the chainring.

It has to be the chain IMO.

Can you get it to happen on a stand or a trainer? If you can, get it going and have someone touch the chain with a stick (or whatever) above or below the chainstay and see if that stops it.

 

[alfeng]

It might not be a factor, but you did not mention the size of the frame -- 60+ cm?

While I presume it is a Ti frame, is it?