Losing your bike key or dealing with a jammed lock is frustrating. And when it’s an OnGuard lock, you’re up against one of the toughest brands in bike security. If you’re stuck outside your home or office wondering how to cut OnGuard lock rotary tool, you’re not the first—and you won’t be the last.
In this guide, you’ll learn exactly how to cut through OnGuard bike locks using the right rotary tools and other options. We’ll also cover tools like bolt cutters, angle grinders, diamond blades, and explain what works and what doesn’t when it comes to cutting bike locks in real-life situations.
Why OnGuard Locks Are Difficult to Break
OnGuard locks are built with hardened steel, thick shackle diameters, and smart locking techniques that make them hard to break. They’re not your cheap cable locks. The company designs their locks to stop common theft tools—like bolt cutters, lock picks, and even power tools.
Some models claim to be angle grinder resistant, especially those aimed at protecting expensive bikes. That means if you’re locked out or lost your key, getting through one of these requires serious equipment.
Can You Use a Dremel to Cut a Lock?
Many people ask, can you use a Dremel to cut a lock? If it’s a simple cable lock, maybe. But if you’re trying to cut an OnGuard U-lock or thick chain lock, a Dremel won’t get the job done. The discs are too thin, and the motor doesn’t deliver enough power to cut through hardened steel.
Instead, go for a rotary tool with a stronger motor, or better yet, use a portable angle grinder with a metal or diamond blade. That combination will actually work when you’re dealing with a lock that’s built to stop attacks.
How to Cut OnGuard Lock With a Rotary Tool
If you’re set on using a rotary tool, make sure you’re using one that’s built for metal cutting. Here’s a safe and effective way to handle the job:
Start by choosing the right blade. A diamond blade or carbide cutting disc is your best bet for hardened steel. Don’t even bother with generic metal discs—they’ll wear out in seconds.
Next, secure the lock. Whether you clamp it to a workbench or wedge it against concrete, you need it stable. If the lock moves while cutting, it increases the risk of the tool slipping.
Always wear safety gear. Sparks will fly, and metal shavings can cause injury. Put on gloves and eye protection.
Now, look for the weakest spot in the lock. On most U-locks, this will be either side of the shackle, away from the locking mechanism. Avoid the keyhole—it’s the most reinforced area.
Cut in short bursts to control heat. Rotary tools overheat quickly, and high heat can damage the blade or your tool. If the blade starts glowing red, pause and let it cool.
Depending on the lock’s size and material, expect to spend 10–20 minutes cutting through. If it’s a newer or thicker model, even longer.
Will Bolt Cutters Cut a U Lock?
If you’re thinking about bolt cutters for bike lock jobs, you should know that most OnGuard U-locks are made to stop them. Standard bolt cutters won’t open these locks unless the shackle is worn, rusted, or less than 12mm thick.
For better odds, use a heavy duty lock cutter—at least 30 inches long with hardened steel jaws. Even then, some locks like the Hiplok D1000 have steel that’s purposely designed to crush bolt cutter heads instead of breaking.
So, will bolt cutters cut a U lock? Sometimes, but only if the lock is old or cheaply made. Don’t expect them to slice through newer OnGuard models without a fight.
How to Cut a Bike Cable Lock
If you’re dealing with a basic cable lock, you’re in luck. Wondering how to cut bike cable lock in seconds? Use standard bolt cutters or a high-RPM rotary tool. Even a compact cutter will go through most cables with one clean slice.
Cable locks usually have a rubber coating and braided steel inside. They’re easier to cut than any other bike lock. That’s also why they’re the first choice for bike thieves—quick to break and quiet to remove.
Cut near the center of the cable for best results. That area is usually the most flexible and easiest to cut clean.
How to Cut a Bike Lock Lost Key
Losing your key doesn’t mean losing your bike. If you’re locked out, here’s how to cut bike lock lost key without wasting time:
First, figure out what kind of lock you’re dealing with. Cable? Chain? U-lock? The tool you use depends on the material and thickness.
If it’s a cable lock, use a strong pair of bolt cutters or a rotary tool with a sharp disc.
If it’s a U-lock, you’ll need either an angle grinder or a heavy duty lock cutter—preferably one over 30 inches.
Position the tool on the side of the shackle, not the locking end. That area is often slightly thinner and easier to breach.
If you’re doing this in a public space, be prepared. People might assume you’re stealing bikes, so it’s a good idea to inform property staff or call local police to confirm it’s yours. Better safe than reported.
How to Cut a Stuck Bike Lock
When your lock won’t open because it’s jammed, rusted, or frozen, it’s not much different from losing the key. Here’s how to cut a stuck bike lock quickly:
Try spraying penetrating oil like WD-40 first and give it 10–15 minutes to soak in. Sometimes, that’s all it takes.
If the lock still won’t move, grab a rotary tool, angle grinder, or bolt cutter depending on the type of lock.
Always go for the thinnest part of the metal—usually the straight side of the shackle or a flexible chain link.
Be careful not to damage your bike’s frame during cutting. Use a metal shield or even a piece of wood between the lock and your bike.
What Size Bolt Cutter to Cut Bike Lock?
Choosing the right size cutter is the difference between breaking the lock or breaking your tool. So, what size bolt cutter to cut bike lock?
For cable locks or basic chain locks, a 14 to 18-inch bolt cutter works fine.
For chain locks with thick links or U-locks, you’ll need 30-inch cutters or larger.
Keep in mind: hardened steel in many modern locks will resist even heavy-duty bolt cutters. That’s why professionals usually reach for angle grinders or saws with diamond blades.
Bike Lock Cutting Tips You Need to Know
Before you start cutting any bike lock, here are some quick tips that will save time and possibly your fingers:
- Use gloves and goggles—sparks and metal shards are dangerous.
- Never cut directly over the bike frame—you’ll damage your bike.
- Know your lock’s material. Chain locks with soft metal are easy. Mini U locks made of hardened steel? Not so much.
- If you live in a city, use multiple locks. Locks chain setups slow down thieves.
- Avoid cheap locks. Low security ratings mean fast break-ins.
- Stay alert in public. Tools like angle grinders draw attention and sound like you’re breaking the law—even if you’re not.
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