CLASS 1
This class will be open to all air cooled monoshock bikes that were in production before 2000. This also includes and any air cooled monoshock that has been converted to a twinshock, as such bikes cannot run against genuine twinshocks
Eligibility – the motorcycles should maintain the original silhouette as the date of manufacture.
Acceptable modifications are;
The option to run tubeless tyres, to make minor modifications to the frame, and a choice of carburettors
Unacceptable modifications;
Disc brake conversions unless already fitted.
Fork stanchions must not exceed 36 mm
CLASS 2
This class is open to older twinshock machines manufactured up to mid 1970s.
Click here for bikes eligible for this class
The object of this class is to enable earlier twinshocks to compete against each other in their own class as opposed to competing in the same class against the later and more advanced twinshock machines
Acceptable modifications are;
The option to run tubeless rims, to make minor modifications to the frame, a choice of carburettors, cycle parts can be changed as long as they are from the same period. Shock absorber and suspension movement should be to the original specification. Steering head angle can be moved and the swinging arm length altered. The position of the footrest can also be moved.
Unacceptable modifications;
Disc brake conversions
Fork stanchions must not exceed 35 mm
Components from later twinshock machines
Long travel suspension modifications
CLASS 3
This class is open to later twinshock machines manufactured from mid 1970s to 1986 which benefitted from improved suspension and chassis geometry and improved engine technology.
Click here for bikes elgible for this class
Acceptable modifications are;
The option to run tubeless rims, to make minor modifications to the frame, a choice of carburettors, cycle parts can be changed as long as they are from the same period. Steering head angle can be moved and the swinging arm length altered. The position of the footrest can also be moved.
Unacceptable modifications;
Modified monoshock trials bikes converted to twinshocks
Air cooled monoshock engines
Disc brake conversions.
Fork stanchions must not exceed 36 mm
Note SWM jumbos fitted with the original 38mm forks are acceptable
CLASS 4
This class is open to Pre-75 British bikes
Replica frames or modified originals are allowed, as are billet yokes and hubs and forks with modern internals. This is the format followed by most classic clubs countrywide and there seems little point in changing that for this series
Acceptable modifications;
Tubeless rims, there is no restriction on carburettors
Unacceptable modifications
Disc brakes, forks exceeding 35mm