1. If your bike is making clicking noises near the hub, is not shifting properly, or the chain is coming off of the gears, you most likely need to adjust your rear derailleur. This set of instructions will guide you step by step. All you need is a 5mm allen key, and a Phillips head screwdriver.
2. Take a look at the back of the bike and see if the derailleur is lined up straight below the gear the bike should be on. If it’s straight, it should look something like the picture below. If your derailleur is bent, and does not hang straight below a specific gear, then you will need to take your bike to a bike shop to have the derailleur hanger professionally bent back, or contact technical support.
3. You’ll need to be able to pedal your bike, so put the kickstand down, and lean it over so the rear wheel is lifted off the ground.
4. If you want the chain to jump to a bigger cog, screw the barrel adjuster counterclockwise until the chain jumps. If you want the chain to jump to a smaller cog, screw the barrel adjuster clockwise until the chain jumps. It helps if you pedal the bike while turning the barrel adjuster so you can stop as soon as the chain switches gears. If you look at the back of the bike while you move the barrel adjuster, you can see the derailleur shifting slightly left or right. You can use this to adjust the derailleur to be directly underneath the gear you want.
5. Shift up and down all the gears again and check to see if it’s smooth transitioning. If it is, you’re done! If the chain won't go into first gear even with adjusting the barrel adjuster all the way out, then you’re going to have to adjust the cable tension.
6. To adjust cable tension, while pedaling, shift the bike to 7th gear, or the smallest cog and turn the barrel adjuster clockwise until it stops.
7. With the 5mm allen key, loosen the bolt that holds the cable so that the cable becomes slack. The derailleur might move, and that’s ok.
8. Now, take all the extra slack out of the cable so that it’s about as firm as a guitar string, and retighten the 5mm bolt, making sure that the cable is pinched behind the bolt.
9. Go ahead and shift through all the gears, and then back again to see if that did the trick. If all the gears shift smoothly, you’re done! If not, go back to step 4 and follow these next steps below if the barrel adjuster doesn't fix the issue.
10. If the chain is falling off the largest cog, screw in the upper limit screw. Keep experimenting with how much you have to screw it in by pedaling the bike and seeing if it stops coming off.
11. Similarly, if the chain is falling off the smallest cog, screw in the lower limit screw until the chain no longer drops off the smallest cog.
12. After that, your derailleur should be all adjusted! The limit screws, barrel adjuster, and cable tension can all be readjusted a second time if need be. If you’re still having trouble, contact technical support, or take it to your local bike shop.