Bicycle Mechanics - rear Shimano brifter not shifting

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amvapor
09-07-11, 07:03 AM
I have a 5 month old Bike, Redline Conquest Classic, quite happy with it. This morning, the right (rear) brifter started acting up, it will pull the chain up to larger cassette cogs, but doesn't want to reliably drop the chain back to the smaller cogs.

It's a Tiagra 9spd brifter, so the "inside" paddle nearest the bars is the one that's not working.
Anyone have any ideas what's wrong? I'm guessing it's a busted spring or ratchet or something, but I've never taken one of these apart, and from what I hear, it's not a good idea to do that anyway.

Thanks.

mikezs
09-07-11, 07:10 AM
As going to the smaller cogs is the loosening of the cable, I'd check if the cables have "worn out" (gone rusty or are kinked or the outers have sharp bends) or similar.

The spring you mentioned about being busted will be in the RD, rather than the brifter itself. As it's only 5 months old I'd say the ratchet mechanism would be ok too.
amvapor
09-07-11, 07:18 AM
worn cables in 5 months though? that seems a little fast to me. I rode my last bike very similiarly, shifting just as often and the cables on that are 4 years old. That bike had flat bars, so no brifters, so maybe you're right. I'll look at the cable wear.


EDIT:
Looks like you are right, I have a snapped 'fibre' in the derailer cable that's probably bunching up somewhere. Guess I know what I'm doing on lunch

mikezs
09-07-11, 07:52 AM
worn cables in 5 months though? that seems a little fast to me. I rode my last bike very similiarly, shifting just as often and the cables on that are 4 years old. That bike had flat bars, so no brifters, so maybe you're right. I'll look at the cable wear.


EDIT:
Looks like you are right, I have a snapped 'fibre' in the derailer cable that's probably bunching up somewhere. Guess I know what I'm doing on lunch

Any problems within 5 months seem soon unless it's been left outside over winter or huge mileage done without maintenance.

You can get away with just taking that single "fibre" out if you're stuck at work and have minimal tools/no spares. Might need to cut the end of the cable to get it back in the outers if you go down this route.