CHAPTER 17 TRIALS Appendix 7- Charts and Diagrams
Under 850cc
Chart 1
National Trials Car Formula dimensions( in mm) for Under and Over 850cc Classes.
Over 850cc
A Minimum wheelbase 1905 1981 B
C
Minimum front track measured on C / L of tyre’ s contact patch Minimum rear track measured on C / L of tyre’ s contact patch
Class
1117 1117
1117 1117
D Minimum cockpit width 813 813 E Minimum to Passenger handle 635 635 F
Maximum front axle to no. 1 plug( tolerance 10mm)
1 / 5 of wheelbase 1 / 5 of wheelbase
G Maximum rear overhang 1 / 3 of wheelbase 1 / 3 of wheelbase H Minimum height side to seat 152 152 J Minimum seat back height 305 305 K Minimum front mudguard arc 90 ° 90 ° L Maximum rear mudguard from tyre edge 51 51
Note: CD Radiator in front of engine, if water-cooled.
NATIONAL TRIALS CAR FORMULA DIMENSIONS
F
Front Spark Plug
G
K
H
J
Front Axle A
Rear Axle
B
1 D
E
Motorsport UK National Competition Rules 2026 Edition 1
Chapter 17 Appendix 7- Charts and Diagrams 636