Bicycle Mechanics - My Shifting Problem

Greetings everyone...hopefully I can find some help here.

I have a Nishiki mountain bike (I'm not a hardcore mountain biker by any means). Since my last tuneup, my bike has developed this nagging problem with the gears. The bike has Shimano grip-shifters, and the right-hand shifter broke on me last summer, so it was replaced during the tuneup.

The problem is that the chain will sometime hop around on the gears on the rear tire (it wont stay 'in gear'). There are 7 gears on the rear gear assembly (I dont know the technical term). At first, the chain would only hop around when the the shifter was in the 6 position, but now it will hop around anywhere from the 4 position on up to 7. Yesterday I was in the middle of a 25-mile ride, and the gears started hopping around pretty badly; thankfully I wasn't on any hills because the problem is really bad when I'm on hills. Sometimes the chain will hop right back into the gear it was in, but most times it will hop onto another gear entirely.

The other problem the bike is having is that sometimes when I'm really hauling ass, the right-side grip shifter will start rattling really bad. This is the same shifter that controls the rear gears (where all of my problems are) so I'm wondering if the two problems are related?

I had this same problem going on a few years ago, but it was nowhere near this severe. I took the bike into a shop to get looked at back then, but they told me they could find nothing wrong with it, but obviously the problem is still there and it's getting worse.

If anyone has any idea what's going on, please feel free to toss me your ideas. If you need some more info on the problem, I'd be glad to go into more detail.

Thanks,

- Jason

I used to have chain hop around too, but that because the spring in the read derailer was soft. The problem went away after I switched to a new RD.

Anyway, when was the last time you replace your chain, cassette, and RD?

Measure your chain. 12 links should equal 12 inches. Make sure the chain is clean and lubed. Use WD-40 or Simple Green to clean the chain, wipe dry and lube liberally with bike lube.

Check you cassette for any wear. If the gear has hooks (chain wear the metal in) you should look to replace it. Again, clean the cassette.

Check the read derailer. Put it to the highest gear (highest number) and make sure it spin smoothly. Adjust the H screw until the pulley align with the highest (smallest) gear in the cassette. Now shift to gear 1 and spin. Make sure it is smooth. If not, adjust the L screw until the pulley align with the largest gear.

Otherwise, you may have to replace worn out parts. Chain is cheap to replace, if it longer than 12 inch (for 12 links) replace it. While you are at it, replace the RD cable and housing (if they are old).

Have you replaced the noodle (cable housing section between frame and rear deraileur)? This sounds indicative of a worn out, kniked or to tightly bent noodle.

-and-

Are you maintianing a clean and properly lubed chain / cogset"

Hope this helps since these are the only two causes I've come across for what you are describing.

During the last tuneup (which was about a month ago) a brand new chain was put on the bike. Since it was a tuneup, I was under the impression that they would be looking things over to see if the bike had any problems (like worn out gears in the back). I'll have to check those out tonight. The bike is about, oh, six or seven years old.

Like you said, it could have something to do with not cleaning and lubing up the chain and gears. Right after I got the bike back, everything appeared to be working fine, but then we had a couple of days of rain, and the muddy biking trails down here were calling my name. My bike and I came out of that covered completely in mud and debris, and right around then is when the problem started.

I know it's bad, but I've never properly maintained my chain and gears. What kind of lubricant do I use on them, and how often should I lube them up? I'll give that a shot first to see if that's the problem. The chain and gears appear really dry right now as if there's little or no lubricant on them at all.

Thanks for the input,

- Jason

My MTB gets lubed after every ride in wet conditions, once every three to five rides when conditions are dry.

My prefered lube is "Finishline Dry" in the aerosol, but I would use "Tri-Flo" without hesitation.

Good luck

Given that the bike is that old and providing this was the first time the chain wa replaced, the cassette should have been replaced as well. This should cure the problem.

Probably a worn cassette, and possibly a sticking or over loose rear cable.