Construction Specifications

All soapbox carties and gravity sidecars taking part in Cairngorm Soapbox Extreme must comply with the construction specifications. 

There will be a thorough inspection of all entries before the event, and any that do not pass will not be allowed to take part. (This inspection does not constitute a warranty of safety, and all teams are solely responsible for the safe construction and operation of their vehicle).

Just Gonnae NoThis soapbox race is going to be very demanding, and machines that have taken part at other soapbox races might not necessarily be considered safe to run at Cairngorm without modification. You will be racing head to head down the course at speeds in excess of 60 mph, and will need to brake from maximum speed in some places, so for the safety of drivers and spectators we need to be comfortable that every cart is entirely "fit for purpose". We intend to work with the teams to make sure that nobody is disappointed, but the organisers decision on this matter is final.

If you are at in doubt about whether or not your cartie or sidecar is up to the required standard, please contact us to discuss it. We are happy to provide advice and, where convenient, arrange to inspect your pride and joy well in advance of the event in order to avoid disappointment on the day.

We advise teams to pay particular attention to brakes, steering and stability.


You must ensure your vehicle has been thoroughly tested prior to taking part at Cairngorm, and your team members must have experience of driving it or, in the case of sidecars, being a passenger.

The course is very demanding, and it would be extremely foolhardy to attempt it in an untested crtie with an inexperienced driver. 


Good brakes are an absolute must have. Brakes which act directly on the tyres or the road surface will not be acceptable. Good rim brakes, disk brakes or hub brakes will be required. They can be mechanically or hydraulically operated by either hand levers or foot pedals.

The primary brakes should be designed to operate the brakes effectively while keeping both hands on the steering control.


PassSteering must not be overly sensitive. Simple "kart style" steering or rack & pinion is prefered. There must be no free play in the steering. There must be some form of mechanical linkage or gearing in the steering that reduces steering inputs so that large inputs produce relatively small steering outputs. Steering ratios that are less than 2 will not be acceptable.

"Rope and plank" steering will not be acceptable, and neither will "feet on the front axle".


Make sure your centre of gravity is as low as possible and your wheels are strong enough to withstand the side loadings they will experience.

Protective Clothing

Drivers protective clothing will also be examined. Drivers and passengers of gravity sidecars will be required to wear full leathers (including boots and gloves) and a full face helmet. Drivers of carts will be allowed an open face helmet and do not need to wear leathers, although reasonably sturdy clothing will still be required. Jeans, t-shirt, trainers and a cycle helmet are just not going to cut it.