Originally Posted by
BlazingPedals
It's probably a matter of geometry, and specifically wheelbase. I bet the folder has a *really* short wheelbase. In fairness, it's not designed to go 50 kph; it's designed to stash in the trunk and ride around the campground.
I agree that the shorter wheelbase is a contributor, but combined with the 20" wheels vs 26" wheels the difference in overall stability would be dramatic. Smaller wheels spin faster and inherently steer quicker due to their smaller radius. No bike with 20" wheel is ever going to hold a line or maintain the stability of one with 26" or 700c wheel.