lotek 

For the life of me I can't figure this one out.
Small ring up front (39), mid rings in the back,
upshift seems to take time to seek cog, shifts, shifts
back.
Downshift again time lag, and will jump 2 cogs.
THis is a new situation (just started this w/e).
Chain and cogset are both fairly new. Chain has
minimal stretch (less than 1/16 inch).

Does not seem as severe when bike is in worksand
but still lags and misses shifts.

Any ideas?

thanks,
Marty

Rich Clark

Clean and lube the cables. Flush the levers with WD-40. Check the cable where it goes under the BB shell (if it does) for free travel. Sounds like the cable isn't moving smoothly.

RichC

Davet

One thing that I have found with 'ghost shifting' is if you have head-on adjusters, sometimes with all the vibrations the bike encounters they will back out slightly adding too much tension to your cable. Turn the adjuster in maybe an eighth to a quarter turn and try it out. And as the previous poster said, make sure that the area under you bottom bracket is clean and the cables are moving smoothly.

roadfix

Sounds like sticky cables to me...... what do you carry in your water bottle?

lotek 

I carry Cytomax in 1 water bottle, but as far as I can
tell it doesn't leak.

Thanks for the advice, The Serotta has surprizingly crude
guides under the bottom bracket. I have an old NOS
Campy clamp on cable router which I may apply if this is
what's causing the problem. I'll let you know.


Marty

roadbuzz

Check the derailleur is operating smoothly, too.

sch

Another common reason for this is cable stretch so that the rear der is no longer centered on the cassette cog in each position but is slightly over or more commonly under and causes an auto shift under torque not apparent on the stand where there is no load. Barnetts manual pp 32-9/16 cover this in more detail than needed. This basic approach is to shift the rear der onto the smallest cog, loosen the cable clamp at the R der, then twist the cable tension collar where the cable housing enters the R der to the minimum reach (all the way in) position. Then unscrew two full turns. Check the alignment of der pulley and cassette cog, should be exact, adjust if needed with H screw on der. Pull cable to tight with plyers and tighten clamp nut. Be sure shifter is in lowest position and all housings are fully seated in their stops. Now shift to largest cassette cog and be sure no overshift into spokes is possible by adjusting the L screw on the der. If the der/shifter is not dead on then the housing adjust screw can be turned 1-3 detents either in or out (remember which way and how many!) to fine tune for snappy shift and minimal noise.
Takes just a few minutes. You have to ride it to check action under torque though. Steve

Toothpick

So how'd it turn out, Lotek? Get it figured out?

JimB

I agree, by all means, to flush and lube the shift cables. I was doing maintenance on my bike and injected grease inside the cable housings before sliding the cable in. Let me tell you that with the housing full of grease it was just like glue. Slow and sluggish shifting!!! I removed the cable and flushed the housing with electrical contact spray cleaner and lubed with silicone spray and it shifts soooooo smooth now.

lotek 

I sort of answered in the sometimes you eat the bear
thread.
I lubed all of the cables, did find some improvement
(I'm pretty sure its hanging under the BB shell). I'm gonna
put on my retro cable guides!.
I still have one cog in the rear that when I shift to it
causes the chain to jump (1 up, back down, 1 down),
so I'm thinking that cog is shot.

thanks for all the responses.

Marty