How to Fix a Flat Mountain Bike Tire

How to Fix a Flat Mountain Bike Tire
Hearing that sudden burst of air spewing out of your tire can really make your stomach sink, especially if you don't know how to fix a flat. Fixing a flat is a skill that every mountain biker and cyclist should have; don't just hope that your tires don't go flat, learn how to fix them. It's not difficult but can be a truly important, particularly if you regularly bike far away from home.


Difficulty: Moderate

Things You’ll Need:
  • Pump for either Schrader or Presta valve Two tire levers Repair kit (patches, glue, sandpaper) Wrench for your wheel (if you don't have quick release)
  • Pump for either Schrader or Presta valve
  • Two tire levers
  • Repair kit (patches, glue, sandpaper)
  • Wrench for your wheel (if you don't have quick release)
Step 1
Release your brakes. If you have v-brakes, you'll need to release them so that you can get the wheel off the bike. Pull the cable out of the fixture and the brakes will separate.
Step 2
Remove the wheel. For quick release, pull down the lever and unscrew a couple of turns until you can pull the wheel off. If there are nuts securing the wheel, you'll need to loosen both with a wrench.
Step 3
Fully deflate the tire by pressing the release on the valve. Insert your first tire lever between the tire wall and rim. Push it down and leverage the bead up and over the rim. Leave the first lever in place so that it holds the bead over the rim.
Step 4
Take your second lever and pull the bead up just like you did in the last step. Work about two inches from the first lever and continue prying the bead over the rim in two-inch intervals until it is loose enough. Slide the tire lever around the remainder of the tire to separate the rest of the bead from the rim.
Step 5
Pull the tube out. For a Presta valve, unscrew the nut at the base and pull the valve through the rim.
Step 6
Locate the hole. Unless you can quickly see it, the easiest way to find the hole is by inflating the tire and looking and listening for the spot where the air is rushing out. Examine the tube until you've found it. If you have trouble, another method is to run the tube through water in about foot-long segments. The hole will be immediately clear because it will cause the water to bubble.
Step 7
Mark the hole with a piece of chalk or by roughing it up with the sandpaper. Clean the surface off with a rag or your shirt and rough up the area around the hole. The roughed area should be centered on the hole and should be large enough to accommodate your patch.
Step 8
Place glue on the area around the hole that you roughed up. Let the glue sit for two or three minutes. You want it to dry to the point that it is thick and tacky, rather than thin and runny.
Step 9
Once the glue has dried sufficiently, pull the film off the back of the patch. Lay the tube flat and stick the patch on. Push it firmly against the tube for a good minute or two to ensure a strong bond. Wait several minutes for it to firmly bond.
Step 10
While waiting, examine the inside of your tire to see if the cause of your flat is still there. Look for any sharp objects that may still be stuck in the tire. Also look for any damage to the tire itself. Examine the strip inside the rim that covers the spokes and ensure that no spokes are sticking through. Carefully examine the tire and rim all the way around and remove any remnants that could be responsible for the flat.
Step 11
Pump some air in the tire to give it shape. Before proceeding, check to make sure the patch is fully adhered to the tube. If it's sticking up or falling off, try reapplying it. If not, proceed with putting the tube back in.
Step 12
Place the valve through the hole in the rim and put the tube back into the tire. Be sure that it is seated evenly and isn't bunched up or pinched anywhere.
Step 13
Pry the bead of the tire back onto the rim. Many would recommend that you do this only with your hands; however, this can be quite difficult because it will get very taut. If you can't get it with your hands, use a tire lever to pry it back on, but insert only a tiny bit of the lever. Be mindful not to prod or pinch the tube with the lever.
Step 14
Pump the tire up. As you pump, be sure that the bead of the tire remains neatly in the rim. Pump to the pressure that is recommended for your tire.
Step 15
Reinstall the wheel, make sure it's straight, and fully tighten and close the quick release or nuts. Finally, put the brakes back together.

Tips & Warnings

Certain holes and multiple punctures may be irreparable. In this case, you should replace the tube rather than patching it. Always carry a spare tube or two, since they can provide a quicker, more reliable repair.
Stop immediately when you notice a flat; don't ride on the rim. Don't overinflate the tire.
Stop immediately when you notice a flat; don't ride on the rim.
Don't overinflate the tire.

Article Written By Joe Fletcher

Joe Fletcher has been a writer since 2002, starting his career in politics and legislation. He has written travel and outdoor recreation articles for a variety of print and online publications, including "Rocky Mountain Magazine" and "Bomb Snow." He received a Bachelor of Arts in political science from Rutgers College.

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