Boyd has chosen to make the plans-specified angle iron runners, which perform quite well. The bicycle was a donation to the project, and he has separated the steering head in preparation for mounting.
You may also note Boyd was thinking of making the steering runner longer (on the left in the pic), but he may end up shortening it to plans.
A longer runner will distrubute the weight more, and so for a given weight will not sink as deep. So lengthening the runner could actually make it "grab" less, rather than more. But how much length before an asset becomes a problem? Weight of boat, speed, and ice conditions all affect performance.