Fixing a Flat Tire

How to Fix a Flat Tire lats occur when the air on the inside of your tube escapes to the outside of your tube — the audacity! Fortunately, flats are easily dealt with. The causes are numerous, ranging from a leaky valve to the obvious, massive blowout. But no matter the reason, after reading through our clinic, you'll be prepared. You'll learn how to: Remove your wheel. Check the tire for damage. Make the repair. Reinstall the wheel.

Step 1: Remove Your Wheel

It's usually easier to fix the flat if you first remove the wheel from the bike. (Some racers do it without removing the wheel, but they're in a hurry.) To remove the wheel, do these 2 things: First, Release Your Brake System Most brake assemblies sit very close to your wheel rims and rely on a release system to disconnect and reconnect them quickly and easily. The exact location and design of these quick-release systems will depend on the style of brakes you have. Most will have a knob at the end of the pull-cable that catches on a notch in the caliper arm. Or, they will have a quick-release lever, just like on your axle, which can be opened to release the brakes. Then, Release Your Wheel Once you've disengaged your brake assembly, your wheel is still held to the frame or fork (depending on if it is the rear wheel or front wheel) by the wheel axle. To release the axle, check to see if you have a quick-release (lever) axle or a bolt-on (nut) axle and then follow the steps below. Quick-Release Axles: Front Wheel To remove a front wheel, simply open the quick-release lever to release the tension holding the wheel in place. Assuming your brakes are disengaged, your front wheel should drop straight out. NOTE: Many bicycles have retention devices designed to hold a wheel in place even when its quick-release is open. If your wheel doesn't pop out after you open the quick-release lever, simply loosen the adjustment nut on the opposite end of the axle a few turns and try again. Rear Wheel Removing the rear wheel with a quick-release system is almost as easy as removing the front wheel. Almost. The chain can present a small problem. Before removing your rear wheel, shift your chain onto the smallest rear cog and the smallest front chainring. Then turn the rear axle quick-release lever until it's fully open. Pull back slightly on your rear derailleur (to give yourself a little slack), then push down on your wheel with your other hand. The wheel should pop free without getting tangled in your chain. If your wheel stays put, it's likely there's a retention device holding it in place. (See "Note" above.) Bolt-On Axles: Dealing with bolt-on axles is also easy but takes a bit longer. They work just like quick-release axles except that they must be loosened with a wrench instead of a lever. To loosen a bolt-on axle, simply grab both ends of the axle with 2 good-fitting wrenches and turn both wrenches a couple of full turns. If you only have 1 wrench, alternate between ends of the axle bolt, loosening each a half turn or so at a time. If you're removing a bolted rear wheel, follow the procedure described above to avoid getting it hung up in your chain.

Step 2: Check Your Tire for Damage

It's important to find the origin of your flat tire. It may be a nail that is now long gone, leaving you with a hole in your tube and tire. However, it may be a thorn or piece of glass that is still stuck in the tire and could damage your newly repaired or replaced tube. When searching for the cause of a flat, begin on the outside and work your way in. First, check the outer surface of the tire for any signs of damage or wear — things like foreign objects lodged in the tread, cuts or tears in the tread or tire sidewall, or worn/cracked tread patterns. Next, get inside the tire (see below) and check both the inner tube and the inside surface of the tire for similar damage. Getting Inside Your Tire Most bike tires are held inside the rims with a combination of physical grip and air pressure. The grip comes from the edge — or "bead" — of the tire interlocking with the edge of the rim. The pressure comes from the inflated tube pressing the tire against the rim. First, release all of the remaining air from your flat tire by depressing the small plunger in the center of your tire valve (Presta valves must be opened first). Next, unseat your tire bead using the following procedure: Attempt to unseat your tire by hand by pushing one bead edge in toward the center of the rim. If this doesn't work, you'll need to use tire levers to get some additional leverage. When using tire levers, start on the section of your tire opposite the valve (to avoid damage to the valve stem). Use the longer end of one tire lever to pry the bead of the tire up and over the edge of the rim. If you can't unseat the tire with just one lever, place a second one in a similar manner, 2 or 3 spokes to either side of the first. (Tires levers come with a handy notch that can be secured against a spoke, keeping the lever in place.) Some tire manufacturers suggest sliding the second lever along the rim away from the first to unseat more of the tire. Others suggest using a third tire lever instead to avoid tire and/or rim damage. Once a section of the tire bead is free, you should be able to unseat the rest of the bead with your fingers and remove the inflatable tube from beneath the tire. The tube itself should slide out easily when pulled. But be careful when you pull the tube valve out through the rim. Its sharp edge could damage the valve. Finding the Cause of Your Flat Tube damage can be difficult to spot. If you can't see any obvious punctures or blowouts, try inflating the tube so you can check for escaping air. TIP: To find very small leaks, pass the tube close to your eye or submerge it in water and look for bubbles. If you can't find any tube damage, check your tube valve. If the valve stem or base is cut, cracked or severely worn, it may be leaking. If so, the entire tube will have to be replaced. If the valve is in good condition, check the thin strip along the inside of your rim. Look for protruding spoke ends or areas where the strip may have come free and pinched the tube against the rim surface. Once the tube damage has been identified, check your tire for damage as well. Look for any embedded objects in the tread, then run a cloth (not your hand) along the inside of the tire to locate any sharp objects that might still be embedded inside. Remove any foreign debris you find.

Step 3: Make the Repair

If your tire has sustained little or no permanent damage (as is often the case), your decision will be whether to repair your tube or replace it. Repair — Repairing a bike tube can be easy, once you get the hang of it, and inexpensive as well. Most commercial patching kits contain everything you need to create a durable, effective patch in the field, including step-by-step instructions. Replacement — In some situations, replacing your tube is the only alternative. Replace your tube any time the damage is too extensive or severe to patch, or when a patch job fails to hold. NOTE: Replacing tubes is almost always more expensive than patching them. However, the resulting tire/tube combination is usually stronger and longer lasting than a patch job. To repair a bike tube, follow the instructions included in the tube repair kit that you use. Kits use different methods and materials, so read the entire instruction page before beginning. Typical Patching Steps Find the damaged area. Clean and dry the damaged area. Rough up the surface of the damaged area with sandpaper (to help the glue set). Spread the glue (vulcanizing fluid) and allow it to set until tacky. Apply the tube patch and hold it in place with pressure. Apply talc to repaired area once the glue has bonded to make the tube easier to reinstall. Talc should also be applied to the inside of your tire. Replacing a tube is simply a matter of using the right size. Size information is available on the tube itself, on the sidewall of your tire, or in your bicycle owner's manual. Putting Your Tube Back In Make sure the rim strip is seated properly. Fully inflate your repaired tube (or your new one) to make sure it's in good shape. Deflate the tube until it's limp (about one-eighth of maximum pressure). Carefully reinsert the tube valve into the hole in your rim. Reseat the tube in its proper position in the rim. Putting Your Tire Back On Reseat one edge (or "bead") of the tire completely. Beginning close to the tube valve, push the valve back up into the rim slightly and reseat the other tire bead inside the rim, using your hands only (using tire levers or other tools during reinstallation can cause damage to both the tire and the tube). Proceed around the wheel (in both directions at the same time), reseating more of the tire bead. This will get harder as you go. Pinch both sides of the tire in towards the center of the rim to make things easier if you have trouble. Once the tire is in place, check along its edges to make sure that the tube is not caught between the rim and the tire bead. This could cause another flat. Once everything is in the proper position, pump up your tire slowly, checking both sides of the rim to make sure that the tire bead stays firmly seated. Check your tube valve as you go to make sure that it remains straight (an angled valve may mean a poorly positioned tube). To make sure your tube doesn't get caught between your tire and the rim, go around the whole tire once and pinch both sides of the tire inward. With your tube partially inflated, push the tube valve up into the rim once, and then pull it back out. This helps you avoid pinching your tube around the valve. If the valve looks ok, inflate the tire to its recommended pressure (printed on the tire itself or in your bicycle owner's manual).

Step 4: Reinstall the Repaired Wheel

To reinstall your repaired bicycle wheel, simply reverse the procedure you used to remove it. Open up your brake system again (unless it's still open from the removal process). Then reattach the wheel to your frame dropouts. Be sure to reattach your brakes before riding! If a bolt-on axle holds the wheel in place, be sure to tighten it securely. If a quick-release mechanism is involved: Make sure the quick-release lever is open before reinstalling the tire in the frame dropouts. Make sure that the wheel is installed evenly, centered in the dropouts. Turn the quick-release lever to the fully open position, then turn the adjusting nut on the opposite side of the axle clockwise until it resists turning (don't use a tool to tighten this nut). Close the quick-release lever. Resistance should begin when the lever is sticking out perpendicular to the bicycle frame, then build until it is fully closed and parallel to the chainstay, seatstay or fork blade (depending on which tire you're working on). Final Checks Wheel Position — Make sure your wheel is level, lined up with the bicycle frame and fully seated in the frame/fork dropouts. Your brakes will not line up properly if your wheel is installed incorrectly. Brake Position — Make sure your brake assemblies are properly positioned and functioning. Simply squeeze them. Your brakes should hold solidly against your leaning weight. Chain Installation — Make sure your bike chain engages the same smallest rear cog and smallest front chainring that it was connected to when the wheel was removed. Check your reinstallation by shifting through the gears while spinning your pedals with your hands.