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As a retired Dispensing Optician and a, very retired, Trials rider, this is an interesting question. As I have never riden a bike seriously with varifocals on I can't speak from experience, but I do know from many years of fitting and advising people about varifocals that it is extremley important that the measurement and fitting of the varifocals is spot on. The modern individual design lenses are much less likely to induce these feelings of spatial displacment, although they are expensive, but how much did you pay for that latest trials motorcycle? mcman56 makes the very true statement that the brain learns to interpret what you see, after all every thing the eye sees is presented up side down to the brain. Overall I would suggest separate distance specs for riding and a cheap pair of ready readers in the pocket for adjusitng that carb.