Anybody who's tried to take a standard manual wheelchair (e.g., by coasting downhill) much beyond a fast walking speed (i.e., 6 or 7mph), knows about (and hates with a passion) the annoying gyroscopic instability that creates caster shimmy. I know I do - and do
Scholarly papers have been written about wheelchair caster shimmy.
But I've never been able to find a practical commercial product that addresses the problem. So here's a DIY one.
This simple gadget (actually a pair of them) totally and absolutely eliminates it. It consists of a nylon worm-drive hose clamp (McMasterCarr # 5471K1) threaded through a length of vinyl tubing (McMasterCarr # 5103K35), wrapped between the caster downtube and fork - one for each side of the chair.
Details on request. Wear a helmet.