To put a derailleur on a mountain bike, first, take off the old one if necessary. Then, attach the new derailleur to the frame, and thread the cable through it. Adjust the limit screws to ensure that the derailleur doesn’t go too far in either direction. Finally, use the barrel adjuster to set the shifting precisely.

The tire pressure on a mountain bike depends on various factors such as rider weight, tire width, and the type of terrain. As a general rule, the tire pressure should be between 25-35 psi (pounds per square inch) for most mountain bikes, but it can vary. Lower pressures provide better traction and shock absorption but can result in pinch flats, while higher pressures make the bike faster on hard surfaces but may reduce grip on loose terrain. It is best to experiment with different pressures to find the one that works best for your riding style and conditions.

To adjust rear brakes on a mountain bike, start by squeezing the brake lever and observing how the brake pads contact the rim. If they don’t hit the rim squarely, adjust the cable tension until they do. You can adjust the cable tension by turning the barrel adjuster at the brake lever or the one near the brake caliper. If the brake pads are worn down, replace them. Additionally, check that the brake rotor is true and not warped, and adjust the brake caliper position if necessary.

To measure mountain bike forks, start by measuring the distance between the center of the fork’s dropout and the top of the steerer tube. This will give you the length of the fork. Then, measure the diameter of the steerer tube at the top, where the stem mounts, and at the bottom, where it attaches to the fork crown. Finally, measure the distance between the forks’ stanchions, which are the tubes that run from the crown of the fork to the dropouts. This will give you the fork’s offset or rake measurement.