HOW TO FIX A FLAT

Required Tools

You should carry these items with you on your bike at all times.

  1. A good lightweight air pump.
  2. A set of tire levers, also sometimes called tire "irons" (usually made of plastic).
  3. A patch kit, most preferably one designed for bicycle tires. Periodically check your patch kit (especially if have not used in a few months), they will deteriorate with age.
  4. A spare tube, on longer rides 2 spare tubes are suggested.
  5. If your bike does not have quick releases on the wheels a wrench that fits the axle nuts may be necessary. There are many small, quick tool sets available and most have among other things a tool to fix broken chains which might come in handy.
  6. The tube of glue in your patch kit is sealed with foil inside the plastic cap, so it's a good idea to add a toothpick to your patch kit for this purpose. The toothpick can also serve to mark the location of the hole.

Why are the patch kit and the spare tube both necessary? It's usually quicker to patch a tube than replace it; however, sometimes a tube can not be patched due to a torn seam, multiple holes, or a damaged valve. Occasionally, you will not be able to find the leak, the glue will have dried up, or rain will prevent the application of a new patch (which must go on dry).

Types of Flats

There are basically four types of flats: punctures, blowouts, pinch and deterioration.

  • Punctures are caused when a foreign material (a piece of glass, a nail, or a piece of wire, etc.) penetrates the tube. This type of flat will go psssssss and just go flat. If this happens you should look for something that caused the flat and remove it from the tire or it will obviously cause another flat after you fix the first one.
  • If your tire goes POW!, you've had a blowout. When this happens, you should find a big hole in the tire someplace-usually in the sidewall-that will need to be booted to allow you to get home. After you get home you should replace the tire as soon as possible. Boots are a layer of material laid inside your tire where the hole is and should be considered a temporary fix until you get home. A folded dollar bill makes a good boot ... a folded nutrition bar wrapper makes an excellent tire boot. Just fold it into about 4-6 layers and it stop debris from working its way into your tire and creating another puncture in your tube.
  • A pinch flat or "snake bite" will always be on the underside of the tube and will generally be two, side by side punctures...like snake fang holes. This is caused by hitting a pothole or possibly a rock. This pinches the tube against the rim, and even though there is foreign material involved, you won't find it stuck in the tire...you just hit it. You'll usually know when you have done something to cause this type of flat...by the THUNK!
  • Deterioration flats can go psssss or POW! Age plays havoc with rubber. It will simply wear out and won't hold air over time. If you haven't ridden in a couple of years and you dust off the old bike and pump up the tires, you may be in for a surprise. You should check your tires regularly at home for wear, weather rot, or foreign material. It's much easier to find the problem at home where you can fix it in the comfort of the indoors than to fix a problem when the heat index is over 100 on the road. Replace any badly worn or rotted tires or tubes to prevent these problems.

Preventative Care Daily Tire Check

  • Check Tread & Sidewalls, worn-out, cuts, cracks, embedded glass, seating on rim
  • Air Pressure, under inflated, over inflated
  • Valve, aligned in rim, bent, leaky

Procedures for Fixing Your Flat

  1. When you experience a flat, stop riding as soon as it's safe. If you're riding with friends, let them know you've flatted so they don't run into you as you slow down; and so they don't just keep riding. If it's a rear flat, shift to the smallest cassette cog this will make the chain wrangling easier when you remove the wheel and a reminder of where to place the chain when re-installing. Get off, move off the road, then open your brake quick-release (road bikes) or unhook the cable on V-brakes and cantilevers brakes.
  2. Open the wheel quick-release (QR) and remove the wheel (or unscrew axle nuts if that's what's on yours). For front flats, lift the bike by the handlebar with one hand while removing the wheel with the other. For rear flats, grip the seat with one hand and lift. Remove the wheel with your free hand by pushing down (or forward for horizontal frame dropouts). To keep your hands clean, try to shake the chain off the cog as you remove the wheel. If it resists, lift it off with one finger (it's easy to clean just one finger). Then rest the bike on its left side. On most modern forks, you'll need to hold the round end of the QR mechanism and rotate the other end (where the lever is; or vice-versa) to create enough space to clear little safety nubs on the tips of the fork put there to keep the wheel in the fork should the QR mistakenly open.
  3. Release any air still in the tire. If there's a cap on the valve, remove it so you can release all the air from the tube. With presta valves, unscrew the top and press it with one finger. With Schraders, press the hook on your tire lever or whatever you have into the valve. While doing this, go around the tire with one hand squeezing to get all remaining air out. Also go around the rim and squeeze and work the tire toward the center of the rim because that's the deepest portion. If you can get the tire to sit in the rim's trough, it'll create slack between the tire and rim making it much easier to remove the tire (you'll use the same technique during installation). If you have a threaded presta valve, you may need to remove a nut at its base before you can free the tube. Schrader valves (sometimes spelled "Schraeder") are deflated by pressing on the tip inside.
  4. To remove the tire, insert one tire lever under the tire's edge (called the tire bead) opposite the valve stem. Wiggle it beneath the bead and pull down on the top of the lever to pry a small section of the bead over the rim. Hold the lever in place against the spokes (or attach its hooked end to one spoke if possible). Put another lever under the same tire bead about 4 inches from the first, and pry another section over the rim. Move 4 more inches, pry, and continue until the entire bead is removed. Then reach inside the tire, grasp the tube, and pull it out. To allow the valve stem to be removed, uncover it by pushing the tire away with the heel of your hand. To ease inspection of the tire and rim, remove the other bead (it should come off easily). If you decide to replace the popped tube with your spare, you should stuff the bad tube in your jersey pocket or seat bag to patch later.
  5. Before installing the patched or new tube, it's crucial to check the tire and find and remove whatever it was that gave you the flat. You can check with your hand, but if there's a piece of glass in there, you might cut yourself. So, a safer way to check is to run your glove around the inside of the tire. If there's something sharp in there it'll snag the glove. Be sure to go in both directions, though, in case it's a piece of wire or something lodged at an angle. Also check the tire tread visually. Remove any sharp objects in the tire or tread. If nothing snags the glove and you don't find anything, it's likely that whatever popped the tube has already fallen out of the tire. Also check the wheel to see if the rim strip (it covers the rim holes and/or nipples so they can't cut the tube) has shifted allowing sharp edges to cut the tube. Make sure the strip covers every hole/nipple.
  6. If your choice is to not patch your tube but to use your spare, don't toss your popped tubes! Patch them. They'll keep working even after they've been patched a dozen times or more. But, use regular patches, not the new glueless patches. These are best for mountain bike tubes, which don't hold high pressure. And they're only temporary patches. They can work for getting home. But, if you intend to rely on the patched tube in the future, do a proper patch job.

    Patching

    To find the hole in the tube, try inflating the tube and listening (if the hole is at the valve's base, or if there's a giant tear in the tube, the tube probably can't be repaired). If you can't find the hole, place the tube in water and look for bubbles. When you've found the leak, mark it, or better, tear it slightly larger. That way, you'll be able to find it (glue can make pen marks disappear). Scuff the spot with the sandpaper in the patch kit and brush off the dust with your hand. Apply a thin layer of glue about the diameter of the patch you'll use. Let the glue dry for at least five minutes. Then, peel the foil off the patch and apply the patch being careful to cover the hole. Leave the cellophane in place on the patch. Knead the repair into the tube by rolling the end of your pump over it a few times. Now the tube is better than new; just reinforced in one spot and a tad heavier!

  7. Inflate new tube. Until it just takes shape.
  8. Install new tube. Poke the valve in the valve hole. Then work the rest of the tube into the tire, making sure there are no folds or bunches.
  9. Rest the wheel on your knee and push down to roll the last difficult section onto the rim

  10. Reseat bead. Start opposite the valve. Work the bead onto the rim using the heel of your hands (more durable than thumbs). When you can't go any farther, deflate the tube completely and squeeze the beads into the rim center to create the slack you need for the final stretch. DO NOT USE TIRE LEVERS. If you do, you could pinch the new tube and probably puncture it. Levers should be used for removal only.
  11. Inflate tire. Some portable pumps have gauges. If yours doesn't, just pump as much air as you possibly can into a road tire. Inflate a mountain bike tire until it feels about as full as the one you didn't puncture.
  12. Inflate and Release. As you're pumping, stop at about the halfway point then let most of the air out again. This will help work out any kinks where the tube might have been pinched. (A pinched tube will pop as soon as you air it up all the way and sit down on the bike.) There's some debate over whether this really helps, but it certainly can't hurt.

    You can tell if the tube is seated correctly by spinning the wheel in your hands. Watch right above the rim, where you'll see a fine line (the "bead line") molded into the sidewall. If this line bulges up, the tube is under the bead. Let the air out, massage the tire at the bad spot to work the tube into place, then pump again. If the bead line dips below the rim, keep pumping. It should pop into place as you reach higher inflation.
  13. Reinstall wheel. Make sure the chain goes on the smallest cog. Pull back the rear derailleur body to help the rear wheel slip into place. With the weight of the bike on the hub axle and a rearward tug, the wheel should center in the frame. Close the QR levers on the hub and brake. The lever on the hub should be on the left side of the bike and pointed up or back.

    don't even think about riding until you're sure the hub QR is tight. It must take firm hand force to close it.
  14. Get ready to roll. Put the valve cap back on. This will help keep the air in if the valve has a slow leak.
  15. Reconnect the brake cable. Don't forget this part

    Repack your punctured tube, tire levers, patch kit and tools. Hand pedal and shift into an easy gear before restarting your ride. After all has been completed, but before you get back on the road, check your brakes to make sure that their quick releases or cables have not been loosened, even if you didn't loosen them. A simple trick is to push the bike forward and apply each brake in turn. In fact, it's not a bad idea to have the habit of checking the brakes after every occasion when the bike has been worked on, stored for a period of time, or carried in a vehicle.

    After riding away, watch your repaired tire carefully for a while. Two problems are likely: 1) the just-mentioned rubbing of the tire, and 2) the tire becoming flat. In the case of the second, do not immediately assume that the leak was not patched correctly. Sometimes air is trapped between the tire and tube, and this air leaks out after you begin riding, giving you a flat tire again. Instead, stop and pump up the tire one more time, and then proceed. It would be nice to be able to say that a successful patch is possible 100% of the time, but alas! This is not true. However, with a little care, a success rate above 90% is readily obtainable.

Cleaning your Hands

A little water from the water bottle and some vigorous hand rubbing will get most -- but not all -- of the dirt off of your hands. A little dishwashing liquid in a tiny bottle makes an excellent hand cleaner. Or carry some individual wrapped hand-i-wipes.

--Thank you to AIDS/LifeCycle for the above information.

 


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