A derailleur that skips a gear or refuses to shift to the big chainring – it happens to everyone. Before bringing your bike to the workshop, here's how to diagnose and fix the most common issues – without special tools.
Step 1: Identify the cause. In 80% of cases, the problem comes from a derailleur cable that has stretched over time. Not from a poorly adjusted derailleur, not from a serious mechanical problem – just slack in the cable.
Step 2: Use the barrel adjusters. On your shifter or on the derailleur itself, there's a black knob called a "cable tension adjuster." Turn it a quarter turn to the left (counter-clockwise) to add tension. Test by pedaling. Repeat until shifts are crisp.
Step 3: Check the high and low limits. These are the two small screws marked "H" and "L" on the derailleur. They prevent the chain from falling off. If your chain falls off the large or small sprocket, adjust the corresponding screw a quarter turn.
When to go to the workshop? If after these adjustments the gears still shift poorly, the cable may be frayed at the end of the housing, or the derailleur cage may be bent. At this stage, it's best to entrust the bike to a mechanic.
📍 Routes and Roads — 14 place de Rungis, Paris 13e.
Workshop open Monday to Saturday. We diagnose your bike the same day.
