He sent me this link of images from the Rosenbach Library, which was posted for Bike to Work Day on May 15, which I completely missed.
I love the dandy-horse look, and the terrified grimace on the face of the rider; it would appear that disdain for cyclists is not a new phenomenon (no, of course it's not, and maybe I need to do a post about that, too).
There are other images at the link, mostly with similar early-19th-century irreverence, but also one of a staff member actually parking a bike after riding to work! (An anomaly, I know...)
I could imagine Professor Jack on a bike, but it would be one of those English three-speeds with the Sturmey-Archer hub, the graceful-but-not-gaudy lugs, and probably the odd pinstripe. A Brooks saddle, of course; one of the ornate ones with the springs...
... and he would need somewhere to actually GO on it, which is lacking in our drive-to-everywhere suburban sprawl.
Thanks for the forward, Professor.