What a rim lock does and why you need one

A rim lock is a metal band that clamps around the inner edge of your wheel rim, holding the tire bead in place so it cannot slip during hard acceleration or braking. Without one, the tire can rotate independently of the rim, breaking the seal and causing a sudden flat. On a dirt bike, where you're constantly accelerating hard through loose terrain, a rim lock prevents this from happening.

Most dirt bikes come with at least one rim lock on the rear wheel, where the forces are strongest. Some riders add a second one to the front wheel for extra security, though this is less common. The rim lock is a small, inexpensive part—usually $15 to $40—but it's one of the most important safety items on your bike.

Key Takeaways

  • A rim lock bolts to the inside of your wheel rim and prevents the tire from slipping during hard acceleration.
  • You will need a rim lock designed for your specific wheel size, a socket wrench, and a torque wrench to install it correctly.
  • The rim lock bolt must be tightened to the manufacturer's specification—usually between 7 and 12 foot-pounds—or it will either loosen or crack the rim.
  • After installation, you must rebalance the wheel because the rim lock adds weight to one spot on the rim.

Gather the right rim lock and tools

Before you start, confirm the rim lock size matches your wheel. Rim locks are sized by wheel diameter: a 19-inch front wheel needs a 19-inch rim lock, and a 18-inch rear wheel needs an 18-inch rim lock. Check your bike's manual or the sidewall of your current tire to find your wheel size. Buying the wrong size will not fit, and forcing it can bend the rim.

You will need a socket wrench set (usually 8mm or 10mm, depending on the rim lock bolt), a torque wrench that reads in foot-pounds, and the rim lock bolt itself. Most rim locks come with the bolt included, but if you are replacing an old one, keep the original bolt—it is often the correct length and hardness for your rim. You will also need a tire machine or a shop to rebalance the wheel after installation, since the rim lock adds weight to one side.

Remove the wheel and tire from the bike

Lift the bike on a stand so the wheel is completely off the ground. Loosen the axle nut or quick-release lever, then remove the wheel. If the tire is already mounted, you can leave it on the rim during rim lock installation. If the tire is off, you will need to remount it after the rim lock is bolted down.

Set the wheel on a clean, flat work surface where you can see the inside of the rim clearly. The rim lock will bolt to the inside edge of the rim, so you need good access to that area.

Locate the bolt hole on the rim

Look at the inside edge of the rim. You will see a small hole drilled through the rim wall—this is where the rim lock bolt goes. On most rims, there is only one hole, positioned so the rim lock sits at the bottom of the wheel when it is mounted on the bike. This placement keeps the rim lock out of the way during normal riding.

If you do not see a hole, your rim may not be drilled for a rim lock. Some aftermarket rims and some older rims do not have this hole pre-drilled. If this is the case, you will need to have a machine shop drill the hole for you, or you will need a different rim. Do not attempt to drill the hole yourself—the rim wall is thin, and a mistake can crack it.

Install the rim lock bolt and tighten to spec

Insert the rim lock bolt through the hole in the rim from the inside. The bolt head will sit on the inside surface of the rim. Slide the rim lock band over the bolt so it sits flat against the inside edge of the rim. Thread the nut onto the bolt by hand first, so you do not cross-thread it.

Once the nut is hand-tight, use your socket wrench to tighten it further. Stop when you feel resistance—do not force it. Now attach your torque wrench to the bolt and tighten it to the specification in your bike's manual. Most rim locks torque to between 7 and 12 foot-pounds. If you do not have your manual, start at 8 foot-pounds and check the rim lock after your first ride to make sure it has not moved.

Tightening too much will crack the rim. Tightening too little will let the rim lock slip during hard riding. The torque wrench ensures you hit the middle ground.

Reinstall the wheel and rebalance it

Mount the wheel back on the bike and tighten the axle nut or quick-release to the correct torque. Lower the bike off the stand and check that the wheel spins freely without rubbing.

The rim lock adds weight to one spot on the rim, which throws off the wheel balance. Take the wheel to a tire shop and have them rebalance it on a balancing machine. They will add small weights to the opposite side of the rim to compensate. A properly balanced wheel will spin smoothly and will not cause vibration at highway speeds or on long straightaways.

Check the rim lock after your first ride

After riding for 30 minutes to an hour, stop and check the rim lock bolt. Use your socket wrench to see if it has loosened. If it has, tighten it back to spec with the torque wrench. Rim locks sometimes settle slightly after the first ride as the bolt and rim adjust to each other. After this first check, the bolt should stay tight.

If the bolt keeps loosening after multiple rides, the hole in the rim may be stripped or the rim may be cracked. Stop using the wheel and have it inspected by a shop. Continuing to ride on a damaged rim is unsafe.

Frequently Asked Questions

Can I install a rim lock without a torque wrench?

You can tighten the bolt by feel, but you risk either cracking the rim or having the rim lock slip. A torque wrench costs $20 to $50 and will last for years. It is worth buying one before you install the rim lock, or take the wheel to a shop and have them do it for you.

What happens if I tighten the rim lock too much?

Over-tightening can crack the rim wall where the bolt passes through. A cracked rim cannot be repaired and must be replaced. This is why the torque specification exists—it is the maximum safe tightness for your rim.

Do I need a rim lock on the front wheel?

Most dirt bikes come with a rim lock only on the rear wheel, where acceleration forces are highest. Adding one to the front is optional and is more common on bikes used for racing or extreme terrain. Check your bike's manual to see what the manufacturer recommends.

Can I reuse the old rim lock bolt if I am replacing the rim lock?

Yes, if the bolt is not bent or stripped. The bolt is often the correct length and hardness for your specific rim. If the old bolt looks damaged, buy a new one with the rim lock to be safe.

Why does the wheel need to be rebalanced after installing a rim lock?

The rim lock adds weight to one side of the rim, making that side heavier. An unbalanced wheel causes vibration and uneven tire wear. Rebalancing redistributes the weight so the wheel spins smoothly.