autodidact

I apologize if this has been beat to death but theres a lot of information on this site and I'm new.

I picked up a bike earlier this week off Craigslist and love it aside for some issues with the shifting. First off, it has Shimano Sora components which I understand aren't the greatest but it's what I could afford.

While riding today I noticed that my bike was hesitant to shift down to the smallest ring up front, I did a little tweaking and have it moving through all 3 front rings relatively smoothly. However I've noticed in the upper gears on the 2nd and 3rd ring the chain seems to not be able to settle in smoothly on the cassette. It sounds like its popping back and forth, perhaps between 2 gears? It's only doing it when I'm pedaling heavy [up a hill for example], when I flip the bike and cycle through the gears it does everything very smoothly.

The guy I bought it from said it had been sitting inside a garage all winter so I was thinking maybe the shifters themselves needed to be cleaned and lubed after sitting in the cold for so long? If that's the case, I've read Formula 409 or Simple Green cleaner can be used to degrease them and then a spray on lube [not WD-40] can be used to lube it.

My only other thought is that the deraillieurs need adjusted because the chain rubs a bit in some of the gears as well.

Any other suggestions as to what it might be?


Thanks!

pdlamb

The first two places to start with this kind of problem are with the cables and housings themselves, and the derailer adjustment. Don't touch the shifters! (yet)

It's likely the cables need to be lubricated, and perhaps, depending on the age of the bike, the housing should be replaced. One of those is likely the cause of the pause before it shifts.

Look up derailer adjustment on the web, or get your LBS mechanic to look at the adjustment. That should take care of the "which gear am I in?" problem.

Only after you've looked at those might you think about flushing the shifter. I might go with WD-40 if things were really gunky looking, but your LBS should have or recommend a good lithium spray lube.

FBinNY 

Could be a simple trim adjustment and derailleur fine tune job, or cable friction. It doesn't sound like it's in the levers, but if they don't feel right, you can flush them out with WD-40 or a similar product to soften and/or remove old, dried grease.

demoncyclist

Start by a thorough visual inspection of the derailleurs and all cabling and housing. That is where a bike that has been sitting around usually has issues. If your investigation still points to the shifters, spray the heck out of them with WD-40 (a great solvent for the job, and inexpensive), and follow it up with a good dry formula spray lube. I agree with the above posters that it is more than likely a combo of adjustment and cables/housing being gummy.

gsa103

What front gear are you in when the back slips? Most triples are sensitive to cross-chaining, and require perfect trim to run with the chain at an angle.

The other possibility is it sounds like the chain is slipping. Check the chain for wear. Typically smaller gears wear faster, so 2nd and 3rd smallest rear gears would be good candidates for chain slip. If the chain is worn, replace it. If it still slips you need a new cassette.

autodidact

Its the top 2 gears, so the two smallest rings in the rear but its a pretty new bike, a later model Scott Speedster S50. I may have to check into the cross chain thing, that could be possible. At least I know its likely the deraillieurs instead of the shifters whcih are something I can work on at home. I'm hoping not to have to replace the whole cassette, that sounds pricey.

autodidact

Turns out the rear shifter cable just needed some tension...D'OH!

Thanks for the ideas guys! Now I'll know what to look for in the future.