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Mouse Trap Cars: Increasing Traction

January 18, 2012

Without proper traction your mousetrap racer will loose grip and spin out at the start line wasting energy. Learn how to increase traction and improve acceleration.

The maximum acceleration of a mousetrap vehicle depends on the amount of grip or traction the vehicle's drive wheels have on the road surface. Traction is a form of friction that shows us that not all friction is a bad thing. In order to walk your foot needs to be able to push against the floor and the floor needs to push back. It is the friction between the bottom of your feet and the floor that provides the grip you need to move. It is also the friction that exists between the road and a wheel that keeps the wheel from spinning out causing the car to along the road.

When Traction is Important

Traction is only an issue for those mousetrap vehicle contest that require a lot of acceleration such as all top-speed racers and/or those contest that require a lot of torque such as all King of the Hill climb contest. If you are competing in a stopping type challenge were the objective is to stop closest to a target then you will also need to make sure your vehicle's wheels have good traction so your mousetrap vehicle does not skid past the finish line or the target. For most long-distance mousetrap vehicle challenges traction is not a big issue and adding rubber bands and/or balloons to a wheel will only increase the rotational inertia and thereby decrease the maximum travel distance. Long-distance mousetrap vehicles should be slow moving in order to maximize the energy and decrease the forces of friction acting against the mousetrap vehicle's motion.

Selecting Your Tire

What type of wheel will provide the most traction: fat tires, thin tires, knobby tires, or smooth tires? Knobby tires have good traction if the road surface is rough, but the trade off is that they are inefficient and use more energy than smooth tires. When pressure is placed directly on a tire's knob, the tire compresses causing the rubber and the air inside of the tire to heat up. This heat energy is a wasted form of energy that decreases the efficiency of the vehicle. Knobby tires become hotter and hotter with continued use and are designed to be used on rough surfaces only.

bonus tip: test fit different sink washers at a hardware store in order to find the best fit that will also tapper the center hold down to a smaller axle.


Most racer cars use smooth tires called slicks. These smooth slick tires are more energy efficient and will allow a vehicle to travel faster on a smooth surface. For mousetrap cars, smooth tires will allow your vehicle to travel a longer distance with less energy loss. But the amount of grip a tires has on the floor does not only depends on whether-or-not the tire has knobs but also depends on the compound or material that the tire is made from. Different compounds of materials will have different amounts of grip or traction on the same surface. For instance, rubber bands wrapped around a wooden wheel will provide better grip during acceleration than the wood of the floor alone. The type of drive wheel(s) you select should always depend on the type of contest you are performing. For any contest that requires a lot of traction you need to select or design tires that provide the maximum grip possible on the floor. Tires with poor grip on the floor will have a tendency to slip when under a load thereby decreasing a mousetrap car's maximum acceleration or limiting the force that can be applied to the floor. In some situations you can increase the traction of a wheel by adding a non-slipping gel such as Traction Action to the tire's surface. Traction Action is a sticky gel that is used by many slot car racers to keep their cars from sliding off the track. Many dragsters commonly use a sticky liquid that is applied to a tire right before the start of a run in order to give the dragster more traction at the start line so the dragster can explode off the start line. Experiment with different materials in order to find the best traction.

bonus tip: CD/DVD spacer can be used to tapper the large hole of a CD/DVD down to a smaller axle size.

Soft vs. Hard Wheels

With small light-weight mousetrap powered vehicles hard wheels tend to be less forgiving and waste more energy than softer wheels. The soft wheels can act like a shock absorber and prevent the small imperfections of a road from being a stopping force against a vehicle's motion. On a real car this is a bit different, the wheel and the shock absorber work together to handle the imperfections in the road but with mousetrap cars the wheel can do double duty. Try to pick wheels that provide some cushion. Hard wooden or plastic wheels will be less forgiving and will not travel as well as foam wheels. For slow moving long-distance traveling mousetrap racers this is not a big issue.

bonus tip: CD/DVD spacer can be used to tapper the large hole of a CD/DVD down to a smaller axle size.

Ultra Stick Foam Wheels

Doc Fizzix's Ultra Sticky Foam Wheels are made from a lightweight urethane that is specially designed to grab the road and provide maximum traction for maximum acceleration. While the rest of the field is spinning their wheels at the start line, your racer will be flying across the finish in world record time. These wheels are manufactured specifically for Doc Fizzix Products and are the same wheels that were used on Doc Fizzix's world record setting mousetrap racer that traveled 5 meters in under 1.2 seconds. By far, the biggest secret to Doc Fizzix world record setting speed-trap racer was the use of the ultra sticky foam wheels that were essential in keeping his Speed-Trap Racer from spinning out at the start line and providing maximum traction to the road. Ultra sticky foam wheels are 2-inches in diameter and machined to fit a 5/32-inch axle.

bonus tip: CD/DVD spacer can be used to tapper the large hole of a CD/DVD down to a smaller axle size.

Adding Traction to Wheel

Adding traction to a wheel will give the wheel more grip and greater acceleration potential and will also give a wheel a bit of cushion to act like a shock absorber. One way to increase the traction of a wheel on smooth surface is to add a rubber traction tread that has more grip than the original wheel alone. Various brands of rubber may have more grip than other brands of rubber so it is always best to experiment. Rubber bands can be stretches and placed directly over a wheel or the middle section of a balloon can be cut and then also stretch around a wheel to help increase the traction. The balloon trick should not be used on Doc Fizzix DVD-layers.

step #1: cut the center section of a rubber balloon as pictured.

step #2: stretch the cut section of the rubber balloon around the CD/DVD.

alternate option: rubber bands can also be stretched around a wheel to increase the traction.

The Rocket Start

The Rocket Start is a way to increase the traction of a mousetrap racer at the start line by providing your own road surface that has more grip than the normal road by itself. In the Rocket Start a piece of 60 grit sand paper is placed under the mousetrap racer at the start line so that the wheels can get more bite from the sand paper than can be provided by the floor. The sand paper will need to be held in place in order to insure that the paper itself does not slip during the start. With this secret tip, your mousetrap racer will rocket off the start with an almost unfair advantage but be warned, this may not be legal so check all contest rules prior.

bonus tip: a piece of sand paper is placed under the mousetrap racer at the start to help provide more traction off the start line.

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