I've been wondering about this since riding an old bike of mine a few years back now that was sold to a friend and recognizing how much better the front end felt with the 'old' 51mm offset. Other data point, I had a KTM with a an adjustable offset, 20 or 18. Standard was 20 and was, not great (back when KTMs didn't handle great), I tried 18 and it was horrific, totally unrideable. Then I managed to get a factory clamp that was 22mm, nirvana handling. All settings made really large differences. Anyways...