How to Install a Derailleur
Installing a derailleur can feel daunting, but it’s manageable with the right approach. I’ll walk you through the process, step-by-step. Whether it’s a front or rear derailleur, follow these instructions and you’ll be set.
Tools and Materials Needed
- New derailleur
- Hex wrenches
- Screwdrivers (Phillips and flathead)
- Chain tool
- Bike stand (optional, but recommended)
- Lubricant
- Cable cutter
- Needle-nose pliers
Preparation
Before starting, ensure your workspace is clean and organized. A bike stand will keep your bike stable. Remove the old derailleur if it’s still attached. Shift the chain to the smallest cog on a rear cassette, or smallest chainring for the front. Disconnect the cable by loosening the cable pinch bolt. Use a chain tool to break the chain if re-attaching it through the derailleur is not possible.
Installing the Rear Derailleur
Begin by attaching the derailleur to the derailleur hanger. Ensure it aligns properly. Insert the bolt into the hanger hole and tighten using a hex wrench. Align the derailleur’s B-tension screw with the hanger tab. Tighten but avoid over-tightening.
Next, thread the chain through the derailleur. Make sure it goes through the jockey wheels correctly. If needed, refer to the manufacturer’s diagram. Reconnect the chain using the chain tool. Turn the pedals to check if the chain runs smoothly.
Then, adjust the limit screws. These screws stop the derailleur from shifting too far. Begin by setting the high limit screw. Shift to the smallest rear cog. Adjust the H-screw so the upper pulley aligns with the cog. Shift to the largest cog and adjust the L-screw similarly.
After that, install the shifter cable. Insert the cable into the housing, threading it through the derailleur’s barrel adjuster. Pull the cable tight and secure it with the cable pinch bolt. Turn the pedals and shift through the gears. Fine-tune using the barrel adjuster for smooth shifting.
Installing the Front Derailleur
Start by mounting the derailleur onto the frame. Ensure the derailleur cage sits parallel to the chainrings. Position the cage about 1-3mm above the largest chainring. Secure the derailleur using a hex wrench but avoid over-tightening.
Next, adjust the limit screws. Begin with the low limit screw. Shift the chain to the smallest ring. Adjust the L-screw so the cage sits just clear of the chain. Now, shift to the largest chainring. Set the H-screw so the cage clears the chain by about 1mm.
Thread the shifter cable through the cable guide and the barrel adjuster. Secure the cable with the pinch bolt. Check the shifting by pedaling and moving through the gears. Adjust the barrel adjuster for fine-tuning.
Final Adjustments
Lubricate the derailleur pivots to ensure smooth operation. Pedal the bike and shift through all gears. Listen for any unusual sounds and watch the derailleur movement. Make further adjustments to the limit screws and barrel adjuster if needed. Check the chain tension and make sure everything operates smoothly. It might take a few rides to get everything dialed in perfectly.
Regular maintenance will keep your derailleur working well. Keep it clean and lubricated. Replace worn cables and housings as needed.