The Phillips Historical Society has an SR&RL velocipede, which it's interesting to note has not one but two wheels on the outrigger. This would appear to be consistent with Marcel's observation about the problem of weight and balance on narrow gauge. The 4-wheel design makes the car look like an "Irish mail" track car with one powered wheelset, but it really is a velocipede with powered wheels on one side only. ("Irish mail" cars appear to have been much more common on the Two-Footers, almost certainly for the reasons above, and were used by the WW&F as well as the B&SR. One of the photos of the Whitefield section house has a guy on one.)