March 6, 2020
by TheCuriousCyclist
Filed under Advice
This advice is cobbled together from various internet sources.
Step 1: Remove the wheel and tube
Your best friend here is a pair of plastic tire levers.
Unscrew the little metal ring at the base of the valve and remove it, so you can separate the tube from the tire. Insert one lever between the tire and the rim, just next to where the valve is, and lift that part up and over the edge of the rim so it’s outside it. Usually a tire lever has a little anchor on the opposite side that you can then use to fix the lever in place by hooking that end onto the nearest spoke.
Leave that lever in place, and grab the second lever. Use it the same way you used the first, except instead of hooking it onto a spoke, drag it in a circle around the inside of the tire, levering the whole tire off one side of the rim.
With one side of the tire off, you can then grab the tire and pull the other side over the rim in the same direction, removing the tire entirely with the tube still inside it. Some people who are in a hurry will try to pull the tube out from between the tire and the rim without taking the tire all the way off, but I don’t recommend this. If you take the tire all the way off, you can check the inside for the piece of crud that caused the flat in the first place, and remove it.
Step 2: Find the puncture
Often times a puncture is very hard or even impossible to see. Especially a slow leak. Your best bet is to re-inflate the tube a little bit, then immerse it in water and watch for bubbles to rise. It probably won’t be a dramatic leak when you find it. In fact you may need to squeeze the tube a little bit to drive air through the puncture, in order to find it.
If you’re “in the field” and don’t have a spare tube, and you need to conserve water, you might want to try listening for an obvious “hiss” as you run the tube close to your ear. Another way that works even in loud traffic is to move the tube past your mouth and feel the air from the leak with your lips. It’s strange but it works! Your lips are very sensitive to air pressure and movement.
Once you’ve found the leak, mark it with something obvious. You can use a pen, or you can just place your finger near it and hold on to the tube.
Step 3: Roughen the area around the leak
To work with the tube, you need to get it pulled taut and flat with the puncture centered. You can take your tire levers and snap them together, then wrap the tube around them (it’s what I do) or you can wind the tube around a handlebar or a big stick (also good), or lay it across your knee (I don’t recommend this). The point is to get the area exposed and flat where it won’t slip around.
To roughen, you can use the little square of sandpaper that comes with a puncture kit, or a nail file on your pocket knife, or something similar. The important factor is that whatever you use, it can’t leave any residue like grease or dust.
The area you roughen should be bigger than the patch you’re applying to it, and if this is the first time you’ve done this, you’ll want to roughen it up a bit more than you think.
Step 4: Apply vulcanising solution
This is the tube of stuff that comes with most patch kits. It’s what you’ll want to use for larger punctures. If the leak is slow, and the hole is like a pinpoint, you can use a stick-on patch and skip this step.
Spread the solution over an area that’s larger than the patch, then leave it to cure for at least five minutes. Don’t proceed until this curing is done: This isn’t glue; it’s a surface preparation that only lightly seals the hole but makes the tube a much better bonding surface for the patch.
Step 5: Apply the patch
Patches usually have a foil backing. The backing is usually in two parts, so you can peel off half of it, then put the patch in position, then peel the other half.
Peel the backing off the underside, taking care not to touch the underside itself. Make sure the patch is centred over the hole, then press it into place firmly for 30 seconds or so. Then peel the top side of the backing, being careful to avoid lifting the off patch as you go. Then press down the entire patch for another minute.
Step 6: Inflate the tube (just a bit)
You’ll want to inflate the tube just a little to get it back inside the tire easily. As you do, check that the patch stretches with it. If a gap appears under one edge of the patch, remove it and start again. You’ll need to roughen the tube more thoroughly, and let the vulcanising solution dry for longer.
Once the patch looks solid, you can prevent the tube from sticking to the inside of the tire by running your (probably dirty) hands over it the patch, or even scattering a little road dust on it.
Step 7: Check the tire for the vile beast that did the deed
Before you put the tube back inside the tire, grab the tire and run your fingers carefully around the inside. You will probably find a piece of wire, or glass, or a thorn, or something else that shouldn’t be there. Keep looking until you find something. If you don’t, there’s a good chance you’ll just spring another leak a few more miles down the road.
Sometimes if you can’t find the thing on the inside, you can see it on the outside of the tire, so have a look there next.
Step 8: Get the tire back on the wheel
Once the tube is inside the tire again, without any kinks, and with the valve pointing the right way, it’s time to get the tire back on. At this point you might want to press the valve inward to drain the air entirely out, so the tube is flat along the inside of the tire, as far out of the way as possible.
Many tires have tread on them that works better when the wheel is rolling in a specific direction. Check the side of the tire for an arrow, pointing towards the direction of spin. Chances are your wheel has a disc brake or some cogs on one side, so it fits your bike in just one way. Make sure the direction of the arrow on the tire is the same as the direction the wheel will spin when it’s on the bike.
Use the tire levers to lift one side of the tire over the rim, and then the other, in a reverse of the procedure you used in step 1. Here’s some advice for getting a stubborn tire back over a rim. Once the tire is in place, re-inflate it in two or three stages, rather than taking it all the way up to the maximum in one go. It gives the patch more time to stretch without breaking.
After the first 10 or 15 PSI, I like to pause and then flex the tire back and forth around the rim a bit, to make sure the tube isn’t pinched between the rim and the tire.
Don’t forget to re-apply the metal ring you removed at the beginning!
After all that, put the wheel back on the bike and give it a spin. The tire should not have any obvious bulges or wander around too much along the rim as you spin it.
You’re good to go!
