How to Install a Derailleur on Your Mountain Bike: Tips and Tricks
To install a derailleur on a mountain bike, first, remove the old derailleur and attach the new one to the derailleur hanger on the bike frame. Then, thread the chain through the derailleur and adjust the limit screws so it shifts smoothly between gears. Make sure the chain and derailleur are aligned properly and test it out before heading out on the trail.