I think its braking force to weight ratio.
if they dont have a weight chart, or if the bike is modified, they weigh the bike....
am suprised they didnt have a modern bike chart for your bike
my Lawson was weighed back in Aug for its MOT, but is 80's bike - and heavily modded
HTIOH
AK
[Edited on 22-10-2005 by CK and AK]