How to fix gears on a Kilimanjaro bike

Question

I've just bought a Kilimanjaro bicycle for cheap. One reason it was cheap, I expect, was the gears system. It's only partly functional, and I don't understand why. I would go to the bike shop with it, but they'd charge me five times as much as I've paid for this bike, and I still wouldn't have an idea what to do if this happens again.

Rear gear minimum position (second-to-smallest ring):

I somehow forgot to take a picture of the maximum position, but it's like two rings up. I'd like it to be able to go to all rings.

Front gear:

It only goes to the lowest and middle ring. I'd like it to go to the highest one too.

Front gear control:

Rear gear control:

Is there anything I can do to fix it?

EDIT:

I've made a video showing the shifters. Does this help identify what's wrong? Do I really need to replace them?

Video

Answer 1

You need to read about derailleur adjustments. The first thing to do is check that the rear derailleur is not bent. If it is, you need to unbend it.

Once that has been determined, you can read up on rear derailleur adjustments and front derailleur adjustments. I'm including cable tension as a derailleur adjustment.

Other problems may be cable friction (replace the cables) or the shifter pawls not catching (replace the shifters). But start with the derailleurs.

Answer 2

The thing I tend to start with with derailleurs is (same applies for front and back):

1. Make sure gear changers are set so that you'd be in the smallest gear (e.g. smallest ring on freewheel / smallest ring on front mech - i.e. least tension on gear cable. It looks like that's the case from your photos - front mech is on 1 and rear mech is on 7.

2. Undo screw that holds gear cable against derailleur. Your derailleurs are now in their resting positions without any tension on the gear cable.

3. Lift up back wheel and pedal a bit to see where the chain comes to rest when there is no tension on gear cable. You'll be able to see now if the chain drops down into the smallest ring, or if it is resting on e.g. the 2nd smallest.

4. If the chain is on the 2nd smallest ring, try using the little adjusting screws on the rear mech - trial and error will tell you which one to use. One of them limits how far towards the smallest ring the mech moves, the other limits how far towards the biggest ring on the freewheel the rear mech moves. Use the one that controls movement towards the smallest freewheel ring, and make sure that the wheels on the rear mech line up with the smallest ring - should be possible assuming nothing is bent.

5. Pedal again to make sure the chain slips into the smallest ring.

6. Now move to the front mech and do the same thing - make sure that the chain is running in the smallest chainset ring - you can use the adjusting screws in the same way you did on the rear mech.

7. Once you've got all that lined up, get some pliers and go to the rear mech. Pull with the pliers so that the cable is nice and tight. Tighten the screw / allen bolt to clamp the cable in place. Once done, try using your gear changer to change up through the gears. Hopefully you can get all the way to the biggest ring on the freewheel. Use the other adjusting screw to make sure the rear mech does not pull the chain into the spokes.

8. Do the same now on the front mech - hopefully the same logic will apply and you'll be able to get into the biggest chainring.

It can take some trial and error, but this approach usually works for me. Undoing the cable to start with lets you use the adjusting screws to line things up before there is any cable tension, and is usually a good place to start.

Good luck!