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Old 01-12-2005, 08:29 PM   #8
Lone Rider
Registered User
Joined: Jan 2002
Location: out and about
Oddometer: 25,130
Originally Posted by Poolside

String Plug Tire Repair

I end up doing this more than a few times a year and I hope you find this photo essay informative. It may allow some riders to view a string plug as an excellent and permanent repair choice.

- Jim


A couple of weeks ago I found this screw in the rear tire. I don't know how long it was in there.

Unless the tire is flat when I find it, I leave things like this in the tire for a while. And instead monitor the tire pressure.

While I monitored the tire pressure, this screw remained in the tire for two additional tanks of gas. The tire lost 3 pounds of air pressure over ten days. Based on that leak rate, the screw had been in the tire for no more than a week before it was discovered.

These pieces of road debris made holes in this tire and the last tire. Two each. All four holes were string plugged. Every string plug-repaired tire has remained in service until worn smooth. I have never worn out a rear tire without first getting at least one hole in it, and repairing it with some type of plug or patch.

This will be the second string plug repair for this tire. Here are two views of the first string plug repair, after 5000 miles.

Typical string plug repair supplies. These are from Camel. I have used Monkey Grip brand with equal results.

Different brands of string plugs have different instructions. (The Monkey Grip brand says not to use rubber cement on their string plugs.)

Unscrew with pliers.

Once the 'temporary plug' is removed the hole starts leaking.

Placing the burr in the hole will stop the air leak. Or, let the tire depressurize. Neither makes any difference to the repair. But if your bike does not have a center stand, maybe you do not want to let the tire go fully flat.

Two strokes with the burr. Without cement.

Add some cement to 'flush' the rubber particles.

Coating the plug with rubber cement makes installation easier. Rubber cement can be used with Camel string plugs. The Monkey Grip brand instructs not to use rubber cement with their string plugs. With Camel string plugs, use rubber cement or not.

The rubber cement is neither sealing the hole, nor holding the string plug in place. The string plug is made of viscous 'goop', and this 'goop' is doing both those jobs. The string serves to get the viscous 'goop' into the hole. Using rubber cement is fully optional.

Insert the string plug to the depth in the instructions. If you make a mistake and push the plug all the way into the tire, just put in another plug.

Trim to fit.

And refill tire.

As you like it.

The plug may bulge small bit after airing the tire up. And it can be trimmed flush with a razor. If the hole is on a tread block as this one was, trimming the plug flush is important.

If the string plug is placed in the tread siping, trimming the string flush is not as important. The other string plug in this tire is in the siping. And it was trimmed to the tread depth at the time. (see images 3 and 4 above)

It's fixed. Let's go for a ride.

After about 20 miles, the plug looks like this. Riding pushes the excess 'goop' to the side.

I rubbed the excess off so you can see.

That's it. Good as new.

I've always enjoyed your posts!
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