SF2G How to Fix a Flat Tutorial
How to fix a flat the right way
Fixing a flat can be divided into two areas of study:
- Replace the faulty tube
- Patch the faulty tube
Replace the faulty tube
This is the most common scenario, as patching can be time-consuming and success is far from certain. The two most important things to know:
- Do not use a tire lever to get the tire back on
- Do not fail to carefully inspect the inside of the tire for the agent of the flat (metal shard, piece of glass, etc.)
- Shift into the highest gear (smallest cog) with your rear derailer (right shifter) -- this makes it easier to reinstall the wheel later, trust me on this one.
- Open the rear brake caliper -- most common brakes have a lever to do this which is easy to find.
- Open the rear wheel quick-release and pop the wheel thru the brake; you do NOT need to touch the chain or derailer in most cases. Remove the wheel and set down the bike somewhere soft (iceplant is best); some people set the bike on its brake hoods upside-down, but I don't becuase you can scuff the hoods.
- Deflate the tire, if it has any air left.
- Insert the tire lever under the tire bead and push away from you (or pull toward you, personal preference) until you have one bead entirely off the rim.
- Find the valve stem. Pull the tire away from the tube enough to pull the stem out of the rim.
- Remove the tube from the tire; leave the tire in place.
- Hand the tube to a buddy and ask them to pump it up a bit and locate the leak; this will help identify the culprit.
- Remove any gloves and carefully run 2-3 fingers along the inside of the tire. Do this until you have identified and removed the flat-causing agent (shard of metal, piece of glass, drywall screw, etc.), or satisfied yourself that there's nothing there.
- IF YOU DON'T FIND THE CULPRIT, it is important to find out if you suffered a pinch-flat (there will be a telltale "snakebike" 2-hole pattern in the tube), if the object fell out on its own, or if you just haven't found it yet. If the 3rd thing, keep looking.
- Inspect the new tube, and be sure the valve stem is long enough for the rim.
- Inflate the new tube enough that it holds its shape, and make sure, if it's used, that it holds air.
- Insert the valve stem into the hole in the rim, and work the tire over the tube around the entire wheel.
- Starting at the valve stem area, work the tire bead back onto the rim in both directions.
- When/if you reach a point where most of the tire is back on the rim, but a pesky small area is resisting you, rotate that area toward you and crack your knuckles for battle.
- Deploy your 2 strongest fingers from each hand and gradually work a very small section of bead back onto the rim. It will get harder until *pop*, it's back on the rim.
- If you can't get it back on with finger strength, you have a few options.
- Power Towel: take a small-ish hand towel and wrap it around the section in question, wrapping toward you. Use this larger-diameter/increased leverage to force the tire on. You may have some tube under the bead to work back in. Knead it like dough, DON'T use a lever.
- Double Power Fish: like abover, but with two fists instead of a towel. Hurts your skin.
- NUCLEAR OPTION: use a tire lever only if you absolutely must. You will likely puncture the tube and be back to square one, so be VERY CAREFUL.
Patch the faulty tube
This is best done in the comfort of your beer-equipped garage, but sometimes you gotta do it roadside.