8 Characteristics of the Best Soapbox Racers

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C12 - The UK's Fastest Soapbox RacerThere are no big secrets in soapbox racing. The very fastest racers all pay attention to the same basic principles; make it safe, make it sleek, make it steer and make it stop.

Although at first glance there are a bewildering array of different designs at any race, when you look more closely at the ones taking home the silverware you will spot several common features...

1. Safe
Centa BavariaYou can't go fast in something if you are not confident you will be protected in an accident. All the fast racers have a strong chassis with a solid and properly braced roll bar. The chassis is made from good quality steel and is traingulated for strength.

Drivers must wear a full racing harness and protective clothing, including a proper motorsport helmet, even when they are testing. Every single time. No exceptions.

2. Low Drag

Above about 20mph, aerodynamic drag is the biggest factor limiting your top speed. All the fast racers are very streamlined and have a small frontal area.
3. Low Rolling Resistance

Guy Martin's World Record Soapbox Racer Your wheels are the second biggest limit on your top speed. The fastest carties use slick tyres run at high pressures. Bearings are very free running. In the UK, the commonest wheel is a 20" BMX wheel. Do not be tempted to try larger bike wheels as;

a) They are not strong enough and will flex or buckle when cornering
b) They are larger and hence create more aerodynamic drag, thus more than negating any reduction in rolling resistance
[read more about soapbox wheels]

4. Stiff Chassis and Suspension

Your chassis needs to be stiff and strong to keep you safe and so it doesn't flex when cornering, which can have disasterous effects on steering. Some suspension is needed to keep the wheels in contact with the road.
5. Good Brakes

Soapbox BrakesGood brakes are an absolute must have. This usually means having disk brakes on all wheels.

[Read more about soapbox brakes here]

6. Good Steering

Steering using either using either a bell crank or a small steering rack. Correct steering ratio, ackermann, camber and caster angles are vital.

[read more about soapbox steering]

7. Well Balanced

Centre of gravity as close to the middle of the cartie and as low as possible.

8. Close to Maximum Allowed Weight

The heavier a cartie is, the faster it accelerates and the higher its top speed, because physics. If you are adding ballast, make sure it is solid and securely attached. Do not ever use water.


scottishcarties's picture

Same things apply to novelty soapboxes

The same basic things apply eveni if you are building a fun soapbox, although low drag is probably not so much of a priority if you are building a replica of the Empire State building or the Millenium Falcon. But good brakes, chassis, steering and driver protection are going to make your ride much better regardless of whether you are going for speed or style.
scottishcarties | July 6, 2016 - 09:01

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