Zen and the art of bicycle maintenance

nexuscrawler

Ok so to get some ex cerise and get around a bit better I bought myself a used mountain bike. It's probably like 8 year old but it works pretty well and seems sturdy enough. It does however need some tune-up. The biggest problem right now is the gear shifting seems to be off. Like it skips some gears and other it shifts to pretty jumpy. I looked at the shifter and on both the front and back there are two screws that look to be for adjusting the shifter. They're labeled H and L. I tried to monkey with them a little but couldn't get ti to work perfectly. Can anyone offer any advice on how to approach this and other ways to get this thing running smoothly?

Aldo

To me it sounds like your chain is a bit loose. Probably because it's 8 years old. Does it shift better in higher gears?

*edit: Or listen to japan, that's probably better.

japan

On the rear shifter, the one labelled H is the High adjustment screw, the one labelled L is the low adjustment screw.

Shift the chain onto the smallest sprocket, then use the high adjustment screw to align the centre-line of the top derailleur jockey wheel with the smallest sprocket.

That done, shift the chain onto the largest sprocket, then use the low adjustment screw to align the centre-line of the top derailleur jockey wheel with the largest sprocket.

Next, there should be a B-tension screw somewhere that adjusts the vertical distance between the top jockey wheel and the sprockets. Once you've found it, shift the chain onto the smallest chainring and the largest sprocket, then adjust the B-tension screw until the top jockey wheel is as close as possible to the sprockets, without them touching. Once you've done that, shift up and down over all the gears and make sure they never come into contact.

Lastly, there should be a barrel adjuster where the shifter cable reaches the derailleur. Shift the chain onto the middle chainring, and smallest sprocket. Try shifting up to the next sprocket. If it doesn't quite make it, turn the barrel adjuster counter-clockwise to increase the cable tension. If it tries to skip to the third sprocket, turn the barrel adjuster clockwise to decrease the cable tension. Keep fiddling until it shifts smoothly from the smallest sprocket to the next. Once you're done, check it shifts smoothly across the entire cassette. adjusting as above for over- and under-shifting.

EDIT: Oh, and buy a new chain. They should be replaced every so often and they only cost a couple of bucks. I only just caught the "eight years old" part.