Mountain Bike Gear Wont Shift

I am often asked how to fix a bike that won t shift gears or will only shift to some gears.

Mountain bike gear wont shift. With the bike in the highest gear the upper jockey wheel should run just clear of the cassette. I walk through the steps to isolate and locate. The problem will be the shifters derailleurs or cables. Turning clockwise will increase the gap anti clockwise will close it.

To put the bike into the top gear run the chain through and check it s not touching the side of the derailleur. Most of the time a bike will shift properly with the upper pulley wheel 5 6mm away from the lowest cog. On modern mountain bike shifters barrel adjusters are mounted on the shifter right where the cable housing exits the shifter body. The front shifter is a shimano integrated brake and shift assembly.

This applies to both mountain bike trigger shifters as well as road bike sti type shifters. I take apart a trigger shifter and show the most common reason why old shifters won t shift. The bike is still ride able and the chain moves okay but the bike is stuck on the number 5 gear. Adjust until there is about.

When you shift gears on a mountain bike it s important to continue pedaling through the gear change until the drive chain is completely shifted to its final position. It has a single right hand six speed twist grip type shifter that is too hard to shift. As you do that make sure you hear the chain catching on the lower end. The lower limit screw is needed to adjust the lower cogs.

The chain will not move sprockets of the pedals are turning and the chain is moving. Turn the b screw clockwise to make the gap larger and counterclockwise to close the gap. It requires substantial force to move from 6 to 1 especially from 3 to 1. Then click through your gear selection to the top gear.

The bike is a diamondback cobra jr. I m experiencing a serious lack of sur la plaque i can still move the shift and the cage does move over the top of the two chainrings but the chain itself won t move. The front derailleur groupo is shimano sis. However the right handle will only move from 7 to 5 and won t even rotate to gears.

The left handle moves fine although i ve never used it much anyway i usually just leave it on 2. I can pull the cable to make the derailleur shift into third but the shifter doesn t have enough throw to do it via the shifter.