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Puncture repair in a tubeless tyre

Having successfully (and actually unintentionally) converted a friend into becoming a biker, and sympathising over the time he got a puncture, it was finally my turn.

Riding home on a Friday evening (it was dark), I felt the steering go a bit strange, almost as though the handlebars were loose. I slowed down and gently pulled the handlebars left and right, and up and down. Nope. It wasn't the handlebars.

Hmm, could it be a puncture? Can't be the front tyre. I weaved gently left and right. The Pan seemed a bit sluggish. Must be the rear tyre then? But the last time I had a rear puncture I had to keep changing down and giving loads of power in order to keep moving. Oh wait, that was on the Yamaha. I'd better stop and check. At that particular point the motorway did not have a hard shoulder, forcing me to continue for another mile.

When the hard shoulder finally reappeared, I pulled over and stopped, as close to the grass verge as possible. Where are the hazard lights when you need them?!

I put the bike on its side stand and climbed off. The front tyre was fine. The rear? Completely flat.

In order to see if there's a nail in the tyre, I put the bike onto the centre stand, remove my gloves, and get my torch from the pannier. The rear tyre is very hot. I carefully feel the tyre surface all over, looking for the nail. No nail. Maybe it's the valve?

I open the pannier again and retrieve my foot pump. After several minutes of legwork I stop and check the pressure. It's reached 30 psi, so I conclude it must have been the valve. I fully inflate the tyre to its customary 42 psi.

One final check. I shine the torch on the tyre whilst rotating the wheel, and notice something shiny. Ah. Not a nail, a triangular shard of glass from someone's headlight. Opening the other pannier I remove the pliers from my toolkit and remove the shard.

Pssssssssssss. The tyre got that sinking feeling. As did I.

Out comes the tyre repair kit and I plug the hole. Once again I jump up and down on the footpump. At 40 psi I've had enough; it will have to do. With aching legs I pack away the tools and head homewards once more. (It was soon after this episode that I decided to purchase an electric tyre pump!)

About a mile from home, as I take the motorway off-ramp, the bike feels "squirmy" again. At the top of the exit ramp is a set of traffic lights which happen to be red, so I stop, lean over and have a look. Yes, the tyre's flat again. There's very little traffic so I decide to chance it; the light turns green and I pull away gently. At around 10 mph I carefully traversed some of the back roads, stopping once in a while just to make sure the rear tyre was not bursting into flames.

When I finally pulled in to my driveway, I discovered that manoeuvring a 290-odd kg bike with a flat tyre is not that easy, so I had to get my wife to help me turn it around and push it into the garage.

After dinner I had a look at the tyre again. The plug seemed to have disappeared completely.

I removed the rear wheel, and the following day took it to the local bike tyre place for a new tyre.

Plugging the hole

Tyre manufacturers recommend that if a motorcycle tyre is punctured, it should be replaced. Well, I suppose they would say that. But the concensus of opinion is that as long as the puncture is not too close to the sidewall, it can be plugged. If the sidewall is cut, holed or otherwise damage, then replace the tyre. It's not worth the risk of a blowout.

There are several methods of repairing a puncture in a tubeless tyre. Firstly (and the least effective method) there is the tin of aerosol tyre sealant. This is simply sprayed into the tyre through the valve. As a get-you-home-slowly fix it has its place; however tyre dealers hate the stuff with a passion. When they remove a tyre which has had sealant applied, there is a messy residue all over the place.

The second method is to plug the tyre with a vulcanising compound. Available as a kit, these plugs look like bits of thick liquorice. Also included in the kit is a tube of rubber cement, a reamer, and the plug insertion tool. This was what I used when I experienced the puncture described above. Simply locate the puncture-causing-article, and remove it. Then the small reamer is used to roughen the sides of the hole. Some rubber cement is then squeezed into the hole.

The "liquorice" plug is then inserted half-way through the eye of the plug insertion tool, and then plunged into the puncture site. The idea is to insert the tool until about an inch of each end of the plug can be seen, at which point the tool is rotated 90 degrees and withdrawn quickly. Hopefully you're left with the plug in a "W" shape when seen in cross-section. The ends are then trimmed off flush with the aid of a sharp knife, and the tyre reinflated.

The third way of repairing the puncture is very similar to how a professional tyre repair is done; except the tyre does not have to be removed from the rim first. The "Stop 'n Go" Tyre plugger kit consists of a probe, a reamer, and the plug gun (and of course some plugs!).

The nail (or screw) is first removed from the tyre, and the hole is reamed out. The plug is then inserted into the hole by means of the plug gun. Finally a pair of pliers is used to stretch the plug stem, effectively seating the mushroom head of the plug on the inner tyre wall.

Remember though that whilst these plugs will be useful for the normal punctures acquired when running over a nail or screw, they can not be used for larger tears.

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