Fastest monowheel motorcycle
Mark Foster
129.891 km/h kilometre(s) per hour
United Kingdom (Elvington Airfield)

The fastest monowheel motorcycle is 129.89 km/h (80.711 mph) and was achieved by Mark Foster (UK) in Elvington Airfield, North Yorkshire, UK, on 25 September 2022.

The UK Monowheel Team comprises of 4 engineers: Kevin Scott, Peter Orton, Peter

Kay and Tim Mann, plus the rider: Mark Foster. The team have been building

monowheels since 2010 and Mark Foster achieved the current GWR in 2019 at

72.915mph on the same machine, Trojan, which was featured on the cartoon cover

of the 2021 GWR Annual.

Monowheels have a rotating hoop supported by rollers around a frame with the

engine & rider. Drive comes from balancing engine torque or braking with CoG of the

combined machine & rider about a single contact point on the ground. Lateral

stability comes from gyroscopic effect of the rotating hoop about that single contact

point. The challenge is to design a system where by control of power & brakes you

can accelerate & decelerate without ‘Gerbilling’ (the term used if the rider were to

loop round with the outer wheel). A more difficult challenge is the control of lean

(which is how they are steered). A few people have experienced ‘gerbil loops’ at

around 20mph (which is quite dramatic). At 75 mph the force at rim of our wheel is

>100G - so a rider would be unlikely to ‘walk away’ from such an incident at high


Trojan has a Carbon Fibre outer frame on which the rider sits, Stainless Steel SubFrame, and 300cc rotary wankel engine that drives a 1,5m x 50mm rotating hoop.

That hoop has a rubber tread and runs on 3 custom made rollers. The lower roller is

large flanged wheel under the seat with rubber drive surface. It’s mounted in subframe with the water cooled engine, transmission, freewheel, hydraulic brake &

exhaust system. The carbon frame, twin radiators handlebars & rider are separated

from the sub-frame with an adjustable air spring. The Aixro XR50 rotary engine

produces around 45hp at up to 11,000rpm & involves a custom inlet manifold and

centrifugal clutch. Mass distribution is arranged to minimise risk of a ‘gerbil’ if there

were an engine failure.

Having completed Trojan in 2018 the team held Rider Trials to find somebody

prepared to help them find out how much faster this model could be taken. As an

experienced motorcycle racer who runs a motorsport consultancy, I was fascinated

by both the technology and the opportunity to set new speed records with such an

established and world leading monowheel team. Having broken their existing speed

record in 2019 I was keen to take it higher, particularly as Trojan was designed for a

top speed of 80mph.