I'm with Charon on this... I'd like to see a blind test...
It ain't gonna' happen, but it would be neat...
I've ridden with and without a fork brace (friends bike), and never noticed a difference...
I noticed more difference in surface tracking, by going to a different front tire...
On a bobber, without a front fender it might make a difference that I could perceive...
I think the results most people are looking for, would come more from a steering stabilizer, than a fork brace...
JMHO...
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