Back to basics: how to change a bike tube

Punctures are enough to leave anybody feeling flat, but as Iain Treloar demonstrates, it’s easy to get rolling again. 

There are three certainties in any bike rider’s life: death, taxes and punctures. Regrettably, Ride On can’t help much with the first two. Happily, we can help with the last one. From changing tubes to preventative measures to reduce the risk of punctures happening in the first place, here’s our survival guide for one of life’s deflating scenarios.

Diagnosis

There are two primary causes for punctures—one that you can to some extent control and one you can’t.

The first is what’s known as a pinchflat and is caused by tyre pressure being too low, causing the tyre to compress when hitting a bump and pinching the tube against the rim. What this looks like is two thin slits in the tube. This gives a pinch flat its other name: a ‘snakebite’.

One way of avoiding such punctures is by ensuring you maintain correct tyre pressure. This is usually marked on the sidewall of your tyre (given in PSI). Your optimal pressure may depend on a range of different factors, including surface conditions, weather, tyre volume, your personal preferences for a harder or softer ride and your weight. Let’s just focus on the last one for now. Simple solution: if you’re at the heavier end of the spectrum, inflate the tyre closer to the upper limit, as more weight presses the rim closer to the ground, increasing the risk of a pinch-flat. If you’re a lighter rider, it’s safe to run the pressure toward the lower end of that range; if the tyre is too firm, you may find the ride is uncomfortably jarring, and lose grip as the tyre won’t conform to the ground.

As materials used in bicycle inner tubes are slightly porous, it’s normal for them to lose pressure over time. As such, it’s a good idea to get in the habit of checking your tyre pressure weekly.

The other major cause of punctures is something working its way through the tyre, pricking the tube and causing it to deflate. This can either be instantaneous, or a delayed process presenting itself some way down the track—always, it seems, at a time of great inconvenience. Keep an eye on the condition of your tyres and every so often, deflate the tyre, and go around it picking out any fragments of glass with a sharp point. To prolong the life of your tyres, a dab of superglue on larger slits will help seal the hole.

Never leave home without…

• Spare tube
• Patch kit
• Tyre levers
• Pump or CO2 canisters

My tyre is flat. What do I do?

• Remove the wheel from your bike, and let out any remaining air in the tube by depressing the valve.
• Insert one tyre lever under the bead of the tyre, and lever it over the rim. Repeat this process until one side of the tyre is sitting outside the rim [Figures 1 through 4].
• Remove the flat tube and store it away for repair.
• Run your fingers around the inside of the tyre to feel whether there’s anything sticking through the tyre casing. If you find anything, remove it. [Figure 5].
• Check the sidewalls of the tyre for any cuts or slashes.
• If you still haven’t found any obvious cause for the flat, run your finger around the inside of the rim—check that the rim strip/tape is in good condition and hasn’t exposed any spoke holes.
• Inflate the replacement tube just enough for it to hold its shape inside the tyre—this limits the risk of it sitting under the bead of the tyre and pinching on full inflation.
• Insert the valve of the tube through the valve hole and then work your way around, inserting the tube into the inside of the tyre [Figures 6 through 8].
• Slowly work the tyre around onto the rim. You should be able to do this with your thumbs most, if not all, of the way around. As soon as you use tyre levers, there’s a far greater risk of pinching the tube and taking yourself right back to square one [Figures 9 and 10].
• Once you’ve seated the tyre correctly on the rim, inflate the tube about halfway, check that there are no unsightly bulges or asymmetries, and then inflate fully. Job done!

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

 

I’m out of spare tubes: how do I patch one?

• Inflate the tyre until you can hear the air hissing out. Locate the source, then mark it with a dab of saliva.
• Let any remaining air out of the tube.
• Rough up the area around the hole to help the patch stick [Figure 1]. All patch kits come with a square of sandpaper or a course metal tab for this purpose.
• If your patches are self-adhesive, remove the backing and firmly press down. Hold for a couple of minutes to be on the safe side.
• If your patches are glue-on, apply a generous film of rubber cement around the hole. The glued area should be larger than the size of the patch so that it doesn’t peel off [Figure 2]
• Leave the glue to sit until it’s tacky, rather than wet. Then peel off the foil back of the patch and place over the hole. Press and hold for several minutes [Figures 3 and 4].
• The plastic sheet covering the patch is technically supposed to be removed. In reality, don’t bother. peeling it off risks lifting the edge of the patch and compromising the deal.
• Install tube and inflate.

Figure 1

Figure 2

Figure 3

Figure 4

Handy hints

• Realign any logo or branding on the tyre with the valve hole. Not only does it look neater, but will also help you locate what caused the puncture, as when you locate the hole in the tube you have an instant reference point tracing back from the valve for where the tyre was pierced.
• Use plastic, not metal tyre levers (and definitely not spoons). Most rims are made from comparatively soft aluminium these days, and metal levers can damage these. Tyre levers cost between $5 and $10 a set.
• If you don’t wish to repair your tube, at the very least put it in a bin rather than dumping it on the side of the road.
• If you have a handpump that clamps onto the valve, brace the valve and pump head with one hand when inflating. If you’re pumping away without doing so, there’s a high likelihood that you’ll break the valve or tear it from the rubber at its base. Neither of these two outcomes is repairable. If you’re in the market for a new mini-pump, Ride On recommends models that have a hose that threads onto the valve, meaning you won’t have to brace the valve and freeing up a hand for on the pump instead. Happily, this style is becoming increasingly popular, with Lezyne, BBB, Giant and Airace all making variants.

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