Open Source Climbing Wrist Roller - Heavy Roller

This is a wrist training device that allows you to develop grip strength using an offset loading mechanism. By squeezing the device and working your wrist against the direction of spin, you can target your forearm flexors or extensors. 

ISOLATE THE FOREARM: Build grip strength while reducing strain on your fingers. A great option for climbers seeking an alternative to hangboarding.

SUPER SLOPER STRENGTH: The OS Heavy Roller trains the same forearm and wrist muscles used for slopers, so you can save your skin while preparing for those tough holds off the wall.

COMFORTABLE DIAMETER: Forget awkward barbells and wrist strain. The 60mm (2.4in) diameter offers a comfortable grip for wrist curls.

What you'll need

• A 3d printer
• Some paracord ≤ 6mm in diameter

How it works

To use the OS Heavy Roller, wrap the cord partway around the device and attach weight (we recommend using our Lifting Pin). This creates an offset load that causes rotation as you lift. Gripping tightly to resist that rotation works your forearm and wrist. Depending on the direction you resist, you’ll engage either your wrist flexors (by curling your wrist inward) or extensors (by extending your wrist outward), effectively targeting these muscles for strength development.

Targeted training

Forearms Without Finger Strain: The OS Heavy Roller lets you train your forearm flexors and improve grip strength while reducing finger strain. Force is spread across your palm. Unlike traditional hangboarding, this device directly targets the forearms, making it perfect for building strength without overloading sensitive finger tendons.

Wrist Stabilization: Free weights like the OS Heavy Roller require your body to control the load across multiple planes of motion. They force your muscles to balance, coordinate, and stabilize throughout the entire range of motion, engaging smaller muscles that support the forearm flexors and extensors.

Prevent and Rehab Injuries: Regular use helps ‘bulletproof’ your wrists, lowering injury risk. The device can also be used effectively for rehabbing existing injuries, such as wrist issues and tendonitis (including golfer’s or tennis elbow), through controlled, progressive loading of the affected area.

Train slopers and save your skin

Climbers know slopers demand a unique type of strength, especially in the forearm and wrist muscles. The OS Heavy Roller mimics the demands of sloper grips by working the same muscle groups used in open-hand positions. By training off the wall with the OS Heavy Roller, you can build the strength needed for slopers without wearing out your skin on friction-heavy holds. The high-friction powder-coated finish provides a secure grip, even during sweaty workouts, making your training both effective and comfortable.

Comfortable training is consistent training

The OS Heavy Roller is built for comfort and durability, helping you stay consistent with your wrist and forearm training. Our product research found that the large 60mm (2.4in) diameter is the most comfortable size for gripping. The high-friction, powder-coated finish offers a secure hold—even during sweaty sessions—while protecting your skin from excess wear. Durable construction means the OS Heavy Roller is made to last. Adjusting the load is as easy as adding a weight plate, making it more convenient than juggling multiple dumbbells. Paired with our Lifting Pin and Fractional Weight Plates, you get precise load control, allowing small, incremental adjustments to fine-tune your training intensity.

Example usage

For an example of how to use a similar training device, check out this video from Lattice on their Heavy Roller: