T
Tim Graichen
Guest
Hi all,
I am riding an early 90s steel Serotta frame with a 8 spd Campy group with a
28 tooth big cog and downtube Campy friction shifters. I am having a
repeating issue that if I am in the big cog and small chain ring (ie.
climbing steep grade), the moment I choose / need to stand up in the pedals,
the chain and downtube friction shifter jump to the second cog position.
This only happens at the moment I choose to stand. If I remain seated, the
chain will remain in the big cog. Somehow, I think this is related to the
increase in torque (frame or wheel flex) when standing. I know there is
some additional flex happening when I stand because I can hear a faint
ticking of the derailer cage on the spokes when I'm standing that I don't
hear if I am sitting.
I don't know if it matters, but I can recreate the same while the bike is in
the repair stand. If the chain is on the big cog and I put a little bit of
additional tension on the shift cable coming from the friction lever with my
finger, the shift lever will and chain will move to the second cog position.
FWIW, I do have the center screw of the friction lever tightened down
securely.
Any help would be appreciated.
Thank you
Tim
I am riding an early 90s steel Serotta frame with a 8 spd Campy group with a
28 tooth big cog and downtube Campy friction shifters. I am having a
repeating issue that if I am in the big cog and small chain ring (ie.
climbing steep grade), the moment I choose / need to stand up in the pedals,
the chain and downtube friction shifter jump to the second cog position.
This only happens at the moment I choose to stand. If I remain seated, the
chain will remain in the big cog. Somehow, I think this is related to the
increase in torque (frame or wheel flex) when standing. I know there is
some additional flex happening when I stand because I can hear a faint
ticking of the derailer cage on the spokes when I'm standing that I don't
hear if I am sitting.
I don't know if it matters, but I can recreate the same while the bike is in
the repair stand. If the chain is on the big cog and I put a little bit of
additional tension on the shift cable coming from the friction lever with my
finger, the shift lever will and chain will move to the second cog position.
FWIW, I do have the center screw of the friction lever tightened down
securely.
Any help would be appreciated.
Thank you
Tim