I was competing in NETRA enduros in the late '70s. At the time they had an active sidehack enduro community - all of may 15-18 hacks! :D I got 'basic parameters' for building one for a Hacke guy. My buddy and I built it over the course of a month, as our project, for our welding class, continuing ed, @ BOCES. Ww were fortunate to be near a horse/snowmobile trail system, w/ wide trails to practice.We could ride there, during the week, in the summer, because there were no equestrians around. So. Much. Fun. Our best placing: a 2nd @ 60 mile sidehack enduro in CT.