Sharpening knobs on your Dirt Bike

The more you ride your dirt bike, the faster you’re going to wear out the knobs on your tires. If you race competitively in motocross, replacing worn tires can quickly become a significant expense. Obviously, the best solution to a worn out dirt bike tire is a brand new tire, but I have a few thoughts and suggestions that may allow you to put off that purchase.

I’m mostly a weekend rider and enjoy some low-key riding with my younger sons – so a good tire can actually last quite a few seasons for me. That being said, I also like to go hard occasionally, on the track or on the trail; and every bit of traction counts. As well, I sometimes find a great deal on a used bike, often because the tires are worn. (it makes the whole bike look more worn, so the seller usually has a lower price).

Replace, Reverse, or Razor

So what are your options when the knobs start rounding off? A lot of riders will roll their entire dirt bike or just the wheels into the local bike shop and have new rubber mounted. Really expensive and more than I’m willing to spend. The not-quite-as-expensive option is to buy new rubber and change the tire yourself. This might take you a whole Saturday afternoon the first time, but it’s certainly doable if you have some upper arm strength.
Does Your Dirt Bike Have a Reverse Gear?

I almost never ride my dirt bike in the direction my helmet’s not pointing… and when I do, it’s not on purpose. That means the tires are always spinning in the same direction and, more often than not, only one side of the knobbies are wearing down and rounding off. The solution here is to take the rubber tire off — the same way you would to change it — flip it, and re-install it facing the other direction.

Rubber Rejuvenation

Chances are real good that you still a have lot of rubber left on the tire… it’s just that the corners are rounded off. The traditional solution is to clip a razor blade into a pair of locking pliers (Vise-Grips) and slice off enough of the knobby so that you end up with a sharp corner instead of the rounded one. The best way is to have your bike on a kickstand so that the back wheel is against the ground. That way you’re not pinching the wheel between your legs while working with the razor. If you don’t have a kickstand, support the bike any convenient way you can, as long as the wheel isn’t spinning. Depending on how worn your tire is, you can probably sharpen your tire one to three times before you have to replace it.

Some guys speed up the process by using an angle grinder, but I recommend against that. It’s way too easy to take way too much off the knobs and ruin the tire. The grinder also has a habit of grabbing and shooting off to the side.

New Technology!

While looking for tire sharpening options, I stumbled on a tool called the KnobbyKnife.

The KnobbyKnife was invented by a guy named Mark out in Soddy Daisy, Tennessee. Like a lot of us, he realized that regular riding was wearing down his tires faster than he could afford to replace them… and, like a lot of us, he hated changing tires.

The difference between him and most of us is that while he sat there cutting his tires with a razor blade, he was thinking of a better way to do it. After a lot of trial and error, he came up with what he calls the KnobbyKnife. It’s basically a sharp edge hooked up to a heat source and it lets you shave a controlled slice off the face of each knob.

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