tdub4

Have had an entry level Trek mountain bike for a while but have not used it in a long time. Recently picked up riding again and determined to learn how to do my own maintenance. I recently picked up a Gary Fisher Mako for my son to ride with me. Got it off Craigslist and was a good deal so was aware there may be some issues, although to my not-so-trained eye, all looked well. That being said, I have come across my first issue that I would like to diagnose and fix, if possible.

The net is that on the Gary Fisher bike when the rear gears are in gears 1-6, there is a noticeable clicking noise coming from the chain when pedaling the bike. I put this up on a rack and looked closely and noticed that, when it is in those gears, at the idler pulley the chain seems to "kick" nearly every rotation of the pedal...(hopefully, that makes sense). Again, this is not every link but approx. every rotation or two...so at about every 20+ links, the 20th jumps through the the pulley faster than the others...not smooth at all.

Here is a video, although it is not as easy to see it as I was moving the pedal faster than when I noticed it.... https://www.youtube.com/watch?v=k4udr_oKEDw

I see a number of suggestions related to tightening the tension, aligning the derailleur, etc. but thought I would start with this to see if I could get some initial guidance. I am mechanically inclined but new to working on bikes. Thanks in advance for your help!

bikeman715

this should help Park Tool Co. » ParkTool Blog » Rear Derailler Adjustments (derailleur) .

FBinNY 

Make a note of the crank position when these clicks occur. If it's always at the same place, that would indicate the chainring as the source of the problem. It may be a bent or damaged tooth, or if riding the inner ring/outer cassette combinations, the pickup pin touching the chain, or might simply be the normal result of the chain running past the shift gates (cut down teeth).

If the crank doesn't match the frequency, look for something that does (if there's a repeat frequency). Also, since it's happening on all sprockets except the outermost, it could be the soi=und of the chain passing over the shift gates in the cassette (on all but the outermost).

Lastly, if it's totally random, it might be a very slight trim issue (cable adjustment). Cable trim doesn't affect the outermost RD position which is set by the outer limit screw. I wouldn't fret about the slight click, but would check if the RD shifts up and down with equal crispness. If so, leave it alone, but if not, adjust the trim toward the direction of sluggish shifting (slightly).

BTW- is some ways bicycles are like sausage, it doesn't pay to look at the inner workings too closely. Ride and enjoy, and deal only with actual problems.

Phil_gretz

Two things come to mind. First would be to watch the chain pass through the pulleys from directly behind while someone turns the cranks slowly for you. It may very well be a cable tension issue, so you'll see that the guide pulley isn't aligned to the rear cog above it. Adjust accordingly.

Or, the other thing might be a stiff link in the chain. So, while watching from the drive side, see if you can mark the chain link where the jump/noise occurs. A dot of white-out on the outer plate. Same link jumping? Then manipulate the link and see if it pivots freely. If not, you free it up by bending inward and outward (out of plane) using your hands. There are videos on this on YouTube.

Good luck. Phil

Andrew R Stewart 

The slow and hesitant shifting from a larger cog to the smaller one suggests that the cable tension is too high. Of course there could be other issues involved too. Andy

ramzilla

Place bike on rack. Put a shop light over drivetrain. Get behind freewheel. Check line of sight along chain between RD & chainring. Top & bottom. Verify that everything lines up properly & nothing is bent out of shape. If you're good to go, then make small adjustments to cable tension to eliminate the mis-matched RD alignment on gears. Hope you don't have a bent part somewhere. Good luck.