Behold one of the world’s most difficult puzzles to solve:
I love tinkering with my bikes, but the perfectly tuned derailleur is the state of nirvana I have not been able to reach. Last it saw the bike shop, it shifted nicely. Unfortunately, I let it sit in the basement for the winter, and some of the spring it sat on the balcony.
After getting around to replacing the chain, degreasing everything, and brake adjustments, everything seemed okay. The only problem is the bottom sprocket on the cassette: the chain will occasionally jump, especially when I’m on a sprint and putting pressure on the cranks. One of these days I will lose my balance and wind up on the side of the road with my bike on top of me.
I don’t want to touch the high gear/low gear limit stops: Every time I do that, I make the problem 100x worse. After talking to an REI technician, he convinced me I should try the adjusting barrel. Turning the adjusting barrel counterclockwise tightens the shift cable. Shifting it too much will tighten the cable so that the chain can’t reach the bottom sprocket at all. Shifting clockwise gives the cable more slack; shifting it too much and the chain will jump. Which was my problem. So I shifted counterclockwise. A half-turn. A full turn plus one-half. Two full turns the plus one half. Up to four 360 degree turns. I returned it to the original position, and tried clockwise (even though my observation of the chain indicates there is too much slack). No dice.
So here’s where I need the help of any readers. Of which I don’t have many of. Taking this into the bike shop is the last option, so please don’t suggest that until we’ve tried everything else.
- CHAIN – could it be this? When I replaced the chain, I threw the old one away weeks previous. So I had to eyeball the new chain tension. One potential problem with the derailleur could be that it’s too loose? Is this the case?
- CABLE – Should I loosen the anchor bolt and tighten the cable? Should I replace the cable? And if I replace the cable, should I replace the housing as well?
- SOMETHING ELSE – Am I missing anything? I could easily replace my cassette, but really don’t want to have to replace the derailleur
Help me out here….
January 3, 2009 at 12:00 am
Hi,
The jumping problem you have is related to the new chain on the old sprocket. chains and sprockets wear in together and when a new chain is fitted it will jump on the higher ratios as they have less teeth. If you can put up with it for a few miles the new chain will eventually bed in and stop jumping. Simplest fix is to just replace the rear sprockets/freewheel with a new set and it should be fine.
If you replace both at the same time its worth buying a chain wear tool too. Its a simple device that allows you to see how worn your chain is. If you keep an eye on the chain and replace it when ever its showing wear you wont have to replace the rear sprockets each time.
http://www.rohloff.de/en/products/caliber_2/index.html