Breaking down on the trail will happen to you sometime. You may experience a mechanical problem that will have to be repaired if you want to make it home. Some problems can't be fixed without going to a bike shop. However, some can be easily repaired enough for you to make it home without having to walk.

A damaged inner tube - If your inner tube becomes damaged beyond repair, remove it and tightly pack the tire with grass.

A split inner tube - Usually a tire blowout will cause a split inner tube that is almost impossible to repair. For a quick fix, cut the tire where it split and tie the 2 ends in a tight knot. Then pump up the tire as high as possible.

Loose cranks - Never ride on loose cranks. They may fall off or you will wear them out. Instead hit them with a piece of wood or a rock to tighten them for the ride home.

Patching an inner tube -

1. Find the hole by inflating the tube and then running it past your lips to feel for air coming out.
2. Once you have felt the air, look for the hole so that you know where to put the patch. Mark the hole so that you don't lose it.
3. Rub the area around the hole with sandpaper so that the glue will have a rough surface to stick to.
4. Spread a small amount of glue evenly around the hole with your finger and allow it to dry for 5 minutes.
5. Remove the patch from the foil packing, leaving on the cellophane. Put the patch in position over the hole and remove excess glue by punching outwards from the center.
6. Let the patch sit for about 5 minutes. Then remove the cellophane and make sure the patch is well attached before putting the tube back into the tire.

Repairing a trashed rear derailleur - A completely trashed rear derailleur will not function. The best thing to do is to remove it.

1. Undo the gear cable and unscrew the rear derailleur from the frame with a 5mm Allen key. To prevent it from catching in the wheel, tuck the gear cable up around the frame and around the saddle. Then brake the chain using a chain link extractor.
2. Route the chain on the middle chainring and the middle rear sprocket. You will probably be able to ride most of the way home in this gear. The chain will have to be shortened so find the correct length and remove the necessary number of links.
3. Rejoin the chain off the bike then put it on the middle rear sprocket and on the top of the middle chainring. Make sure the chain is the right length. If it is too long it will jump.

Straightening a badly buckled wheel -

1. A buckled wheel is impossible to ride on because it will not spin. It must be removed and straightened.
2. Find a large flat stone and lay the wheel over it so that the wheel axle rests against the stone. Stand with one foot on the side of the wheel resting on the ground and your other foot on the part of the wheel that is most bent.
3. Using all of your weight press down on your top foot to straighten the wheel. If you are not able to get it fully straight and it is still a little buckled, release the tension on your brakes until the tire does not rub against the brake blocks.