Front cranks (35/49) won't allow chain to jump to larger ring unless going DOWNHILL!?
I have a 89 Merlin Ti which I got last summer. From day one, I found the bike reluctant to move from the small ring to large in front crank. Initially, I had trouble with the bike going up hills, so I went to a 'compact' 35/49 crank, still w.in the mfr. specs for the Shimano 8 spd. set up (Dura Ace 8000). I replaced shifters (N.O.S), the rear derallieur (now a Shimano Deore) and nothing improved, but I started getting a lot of cat calls from various shops implying the changes are to blame, even though the slippage was the same.
I am ABSOLUTELY certain the bike likes moving to the large crankwheel when the bike is going down a hill. That, of course, also shows up when they put it on a bike stand at the shop w. the front wheel pointed down. Soon as I get on even a level road or one with even a slight rise, the left shifter doesn't do squat, or occasionally clicks with the chain looking like a snapping summer garden hose, never reaching the wider ring. Very frustrating.
Apart from only using the bike in zero gravity, and assume I pedal as lightly as Spongebob chasing butterflies when trying to shift, what in anyone's guess is a reason why the bike shifts reasonably well in front when I'm going down hill, in any rear gear, but acts like it has no earthly connection when flatlands arise?
Last edited by jjohart; 11-30-11 at 01:06 PM.