Gear Adjustment (part 2) - Ballyhoura Mountain Bike Trails

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Gear Adjustment (part 2)

Friday, 30 October 2009

We have looked at some of the more fundamental things that can cause gearshifting problems. Now we’ll assume that all the components are clean and in good condition - then we’ll try to get our heads around all those fiddly little screws!

FRONT DERAILLEUR

PROBLEM: CHAIN JUMPS OFF GRANNY GEAR ONTO FRAME

This usually happens at the worst possible moment, when you begin a steep climb.
The chain jumps past the granny ring and onto the frame. You end up spinning thin air and falling over sideways
FIX: Shift to the granny gear and largest sprocket on the rear, tighten the ‘L’ screw until the derailleur just clears the chain.

PROBLEM: CAN’T SHIFT INTO MIDDLE CHAINRING

This can happen either shifting up from the granny or down from the big ring. The derailleur doesn’t move far enough to push the chain across onto the middle chainring.
FIX: The position of the derailleur over the middle chainring is controlled by the cable tension. Use the cable adjuster at the handlebars to set the position of the derailleur cage directly over the middle ring. Anti-clockwise to move the derailleur out towards the big ring, clockwise to move in towards the granny ring.

PROBLEM: CAN’T SHIFT INTO GRANNY GEAR

The chain won’t drop down onto the smallest chain ring [granny gear].
FIX: The ‘L’ adjustment screw sets the limit for how far the derailleur can move towards the smallest chainring. Loosen the ‘L’ screw a quarter turn at a time, until you can shift smoothly to smallest chain ring, but without going too far and dropping onto the frame. If this doesn’t work, it’s possible that the cable is too tight, to check this, shift to the smallest front chainring and check that there is no tension on the cable, there should be a very small amount of slack.

PROBLEM: CAN’T SHIFT INTO BIGGEST CHAINRING

You can’t push the thumb lever far enough to get the chain onto the big chainring.
FIX: First, check that the ‘H’ screw allows the derailleur to move out far enough, loosen it a couple of turns and see if this fixes the problem. If this works, tighten the ‘H’ screw just enough to prevent the chain going too far and jumping off completely. This can also be caused by incorrect cable tension, increase cable tension by turning the adjuster anti-clockwise until the chain shifts smoothly.

PROBLEM: CHAIN JUMPS OF BIG CHAINRING TOWARDS PEDAL

As mentioned above, if the ‘H’ screw is too loose, the derailleur can move out too far and the chain may jump off the big chainring towards the pedal.
FIX: Shift to the big ring, tighten the ‘H’ screw a quarter turn at a time until the outside derailleur cage just clears the chain without rubbing.

REAR DERAILLEUR

PROBLEM: CHAIN SLIPS OFF LARGEST SPROCKET INTO SPOKES

Fix: The ‘L’ screw limits how far the derailleur can move towards the wheel. Tighten the screw a quarter turn at a time, until you can shift to the largest sprocket without the chain jumping off.

PROBLEM: CHAIN SLIPS OFF SMALLEST SPROCKET

Sometimes, the chain jumps off and ends up between the smallest sprocket and the frame dropout.
Fix: The ‘H’ screw limits how far the derailleur can move away from the wheel. Tighten the screw a quarter turn at a time, until you can shift to the smallest sprocket without the chain jumping off.

PROBLEM: SHIFTING IS SLOW AND UNRELIABLE

You have to ‘overshift’ to change to a larger sprocket [push the lever further than should be necessary], or the chain just moves half-way when you click the finger trigger to shift to a smaller sprocket. [Vise-versa for Shimano Rapid-Rise]. The chain may also skip or ‘tick’ when pedaling an intermediate gear.
FIX: The cable length adjuster fine tunes the position of the derailleur at each ‘click’ position. Shift to 4th or 5th gear and look in from the rear of the bike. Turn the cable adjuster until the derailleur jockey-wheel is perfectly lined up with the selected sprocket, anti-clockwise to move the derailleur towards the wheel, clockwise to move it away. Ride the bike and fine tune the adjustment, using the adjuster at the handlebar end of the cable.

Phew! There are lots of different things to check, but take your time, be methodical and it will all work out

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