Registered Forum User
BSB Star
Posts: 5,018
Join Date: Jun 2003
Location: Chelmsford, Essex
Mood: the rain in spain falls mainly on me!
about 8% out.
if you want to check yours fairly accurately use your lap timer to 'calibrate' it. the lap timer is meant to be a true reading.
so you can go along do a top speed on your speedo of say 100 then look at you lap timer back at home and see what your real speed was.