This page outlines the class structure for the series and rules for machine eligibility. In order to compete in the series machines must comply with this criteria. If a machine that does not comply is ridden in a round of the series, championship points will not be awarded and to compete in future rounds you will need to ride a machine that complies.
It's a classic series. The series was created primarily for classic twinshock and air cooled monoshock bikes, not highly modernised hybrids. Modifications are allowed in keeping with those made in their respective eras with a small leeway for fitment of a few modern items, but heavily modernising bikes to extremes is not allowed as this contradicts not only the principles of the series but also the reasons of wanting to own and ride a classic twinshock / air cooled mono. The organisers don’t want the twinshock equivalent of what has happened with Pre65 machines, it's not what this series is about.
Sections are traditonal format, not stop/hop, the rules are no-stop riding and the bikes in standard spec are capable of competing on them. This is the format, you know what you are signing up to when you enter an event so don't complain if your bike is found to not meet the criteria
CHANGES FOR THE 2024 SERIES
Due to the drop off in Pre75 British Expert entries, the running of a championship for this class can no longer be justified. In 2023 only three riders contested half or more rounds, in 2022 it was one and in 2021 it was two.
Therefore Pre75 British Expert riders will now contest the same championship class as Twinshock Expert riders. They will still enter the trial as British Pre75 Expert class but will be amalgamated with Twinshock Expert riders in class 2 results
This does not affect clubman riders who will continue to contest individual Pre75 British and Twinshock championships
CLASS 1 - Air Cooled Monoshock
This class is open to all air cooled monoshock bikes that were in production before 1996. Although air cooled bike production had effectively finished by 1990 making way for the water cooled bikes, a couple of exceptions are the Beta Supertrial and Fantic Coach/Clubman which were produced alongside their watercooled bikes as budget alternatives up to 1996.
Machines should maintain the original silhouette as of the date of manufacture.
Permissable alterations :–
Frames must be of original design
Billet yoke conversion
Footrest position can be altered
Steering angle can be altered
Swingarm length altered
Tubeless rims may be fitted
Disc brakes may be fitted front and rear - discs were production items in this era on virtually all machines and aftermarket disc conversions were also available
Any carburettor may be fitted
The following alterations are not allowed :-
Fork stanchions must not exceed 36 mm*
No hydraulic clutches
No water cooled era engines fitted with air cooled cylinders and heads
* Late model Fantic Coach and Clubman were produced with 40mm forks, therefore these are acceptable on these bikes. They cannot be retro fitted to earlier models or models from different manufacturers.
CLASS 2 - Twinshock
This class is open to twinshock machines manufactured up to 1986.
Machines should maintain the original silhouette as of the date of manufacture.
Permissable alterations :-
Frames must be of original design. Copies must follow original design
Billet yoke conversion
Footrest position can be altered
Steering angle can be altered
Swingarm length altered
Tubeless rims may be fitted
Any carburettor can be fitted
Electronic ignition
Cycle parts can be inter-changed as long as they are Pre 1986 (ie: Ossa forks in a Bultaco etc)
The following alterations are not allowed :-
Modified monoshock bikes converted to twinshocks
Air cooled monoshock engines
Disc brake conversions
Hydraulic clutches
Fork stanchions must not exceed 36 mm**
** Original SWM Jumbo 38mm Betor forks are acceptable
Anyone entering on a monoshock converted to twinshock will be placed into Class 1
CLASS 3 - Pre-75 British Bikes
This class is open to Pre-75 British bikes
There is little point in creating a specific rule set for this class as hundreds of bikes have already been built to existing criteria set by most classic clubs countrywide. Eligibility for this class follows existing criteria although some have been relaxed slightly
Permissable alterations :-
Replica frames or modified originals
Billet yokes
Billet forks
Billet hubs
Forks, yokes, wheels from twinshock bikes
Forks with modern internals, modern REH forks
Tubeless rims
Any carburettor
Electronic ignition
The following alterations are not allowed :-
Disc brakes
Hydraulic clutches
Fork stanchions must not exceed 35mm