Bicycle Mechanics - unwanted shifting

So I finally got my 85 Pinarello put together... all 1st gen C Record. Took it out for the first ride yesterday, and every time I stood up and hammered my rear dérailleur would begin to shift into smaller cogs... ever 2nd or 3rd pedal stroke. Just cable stretch?? or something else?

If Friction Shifters, are they too loose?

If they are downtube, there should be a screw or wing nut on the side, tighten this, and it should be OK

Yah.. downtube shifters.. I wondered if this could be it.. I just didnt understand why it would shift the way it was... I will check.

Oh yeah, just remembered this article from Shledon's site:

http://www.sheldonbrown.com/autoshift.html (http://www.sheldonbrown.com/autoshift.html)

Yah.. downtube shifters.. I wondered if this could be it.. I just didnt understand why it would shift the way it was... I will check.

You've got it.

You need to tighten down the bolt that threads into the braze-on and attaches the shifter to the frame. Should take all of 30 seconds.

You've got it.

You need to tighten down the bolt that threads into the braze-on and attaches the shifter to the frame. Should take all of 30 seconds.
Since they are Campy shifters, plan on tightening this bolt fairly often. These thing have a long-term reputation for losing their adjustment and allowing the "ghost shifting" you are experiencing.

I had a set of Record friction shifters on one bike years ago and had to retighten them about every three weeks to prevent unwanted shifts. I replaced them with Sun Tour Cyclone shifters and the problem never came back.

I guess I have read that before... and that the Sun Tours had a better reputation for staying put. Thanks for the help.. I am glad no one said, bent frame,,,frame flex,,, etc.

Well crap.. now Sheldon (RIP) has said the dreaded "flex" word... it is an SLX frame and I do weigh 185lbs... wonder if I am flexing it.

Well crap.. now Sheldon (RIP) has said the dreaded "flex" word... it is an SLX frame and I do weigh 185lbs... wonder if I am flexing it.

SLX? I doubt you're not flexing it so much that that's causing the ghost shifts.

Try Loctite 222 on the threads of the fixing bolt.

Yeah.. Columbus SLX.. right?? I guess I just heard that some of the 80's light tubing could be a bit flexy for "heavier" riders.

Per Sheldon, clean, and try a little dry lube on the cable where it goes through the guide on the underside of the bottom bracket. Frame flexing alone shouldn't cause a shift, but the friction at this point can result in the flexing "walking" the cable against the friction of the shifter.

would old cables contribute? I have no idea how long these cables have been in use.