Luke Breen brought a pair of Ice Bike fork add-ons. These are installed on a bikes existing fork, replacing the front wheel. Sort of "Instant Ice Bike"
He described his 1st one, which produced a nearly unridable machine. Placing the blades horizontal pivot near a BikeE's fork tips, gave the equivalent of a few inches of anti-trail. We have found over the years that you want to put the section of the skate that is directly under the horizontal pivot, in the same position, relative to the fork, as the center of the tire's contact patch
The 2nd one, shown lower right without springs, worked much better. Giving accurate steering, but a harsh ride.
The 3rd one, with springs, works fine even though it looks a bit Rube Goldberg. The elastic cords in front were intended to be the sole suspension medium. Turns out he needed a higher spring rate, so he added the compression spring in the back.