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
Last edited by sch; 07-29-03 at 06:33 PM.