Mountain Bike Tube Replacement and Repair

The first step in changing the tube on a mountain bike is to open the wheel quick release and drop the wheel out of the frame. It can be awkward to get a fully inflated tire through a brake, but since I am talking about a flat tire here, it's not a problem. If it is, open the brake quick release by squeezing the blocks together and pulling the straddle or link wire out of the brake arm it hooks into. If it's a rear wheel, put the gear on to the smallest sprocket, open the quick release, pull the mechanism back out of the way and drop the wheel out.

Front wheels simply drop out of the fork, unless you've got safety dropouts. In that case, you'll have to unscrew the quick release level a few turns to get the wheel to drop out, making it into a slow release. Racers tend to choose forks without safety dropouts or grind them off; when you're in a hurry, they can get to be a real pain. If there's any air left in the tire, let it out. To do this, first remove the dust cap and depress the center of the valve and push it down to release the air. Then push the valve into the tire to allow the bead to move on the rim without the valve holding it in place.

To get as lack tire off the rim, push the bead away from the edge of the rim, into the well, right round the circumference of the rim. This liberates all the slack that's available. Grab the sidewall with both sets of fingers and thumbs, with your hands about three inches apart. Pull the bead up out of the well and pop it out over the edge of the rim. Gradually work your hands apart, pulling out more and more of the bead until you can just slip your finger under and pull it off the rim. Most tires are a slightly tighter fit than this, and need one tire level to get them off. Very tight tire / rim combinations need two tire levels. I will discuss the single level technique in this article.

When performing a one level tire removal, insert the level, pull up the bead, push the lever round the rim, and pull off the tire. With practice, you will be able to perform this process in one smooth motion. This is also a critical technique when racing. Now to discuss pumps and canisters. Some puncture kits come with fairly tiny gas canisters, but there are also huge 25g cartridges available. These cartridges will pump a two-inch tire up to full pressure in seconds, although they're quite an expensive way of fixing a flat. For racers, it's worth it, but for your average rider it's probably not going to be the wisest investment in the long run. It is advised to put the punctured tube in your tool bag and take it home for later repair. To get the tube into the most efficient size for storing, roll it up while holding the valve open. This is a good way to store any kind of tube; the less space is being taken up in your bag, the more room you will have for tools. If you happen to carry more than one tool, it is advised to wrap a zip tie around the punctured one so you know which one it is.