Front Derailleur Installation
This guide will cover installing the front derailleur on a bicycle.
- Repair stand
- 5mm Allen wrench
- Small Phillips screwdriver
- Needle nose pliers
- Cable cutters
1. Place your bike in a repair stand if you have one, it will make the adjustment much easier. (You can always build a repair stand yourself.)
2. Start out by taking out the clamp bolt (most likely 5mm Allen) and spreading the clamp around the seat tube of your bike. Position the derailleur at a reasonable height around the chainrings, and tighten it down just enough that it doesn't slip.
(If it is a braze-on model, fasten it to the braze-on mount.)
3. Now you'll want to set the correct height. Pull the derailleur's cage outward so that it is over the large chainring. The cage should clear the chainring teeth by about 2 mm, or the width of a penny. (Check this by slipping a penny between the derailleur cage plate and the chainring teeth.)
4. Check the derailleurs horizontal adjustment, too. The outer cage plate should be parallel to the chainring. When it's straight, you can tighten the derailleur's clamp bolt to secure it to the seat tube.
5. Place your chain through the derailleur cage and wrap it around the small chainring and large cog; then connect it.
(With the chain passing through the derailleur cage, it will be easy to tell if you got the cage parallel to the rings. If the chain hits the sides of the cage, you probably want to adjust the derailleur horizontally!)
6. Now run your derailleur cable through the anchor bolt on the derailleur and pull it taut. Use the needle nose pliers to keep a good hold on the cable while you tighten the anchor bolt. (Depending on your frame, the cable may be coming from above or below the derailleur. This is why front derailleurs are classified as "top pull" or "bottom pull." Be sure you have the right one for your bike.)
7. Since new cables will stretch, push the shift lever back and forth a few times to try to "prestretch" the cable. Loosen the anchor bolt, pull the cable taut, and retighten.
8. Use the cable cutters to cut off any excess cable. You only want an inch or two sticking out after the anchor bolt. To stop the cable from fraying, put an end cap on it or coat the end with nail polish.
9. Adjust the front derailleur properly and ride!