Originally Posted by
wkndwarrior
Lately, something hasn't been right with my rear shifter. When I shift up (to smaller cogs), there is sometimes a 3-5 second delay between me pushing the lever and the actual gear shift.
This problem does not occur when shifting down to lower gears (to larger cogs). Only when I shift up.
What's the problem and what should I do? I'm thinking of taking it in to the bike shop today.
The problem is caused by the friction that slows down the cable tension release. I would trace the RD cable from the shifter all the way to the RD and see if there is anything that may cause the increase in friction. One time I had the RD cable zip tied accidentally at the down tube and it had the same effect as you described.
Also, take a look at the bottom bracket cable guide underneath the bottom bracket shell, the plastic piece where your gear cables go through. It gets dirty easily.