How Do Small Wheels Ride? (Part 1)

This is a very important question for many people considering a folding bicycle, or the many other small wheeled options on the market, and it does raise a legitimate challenge for small wheels. Before addressing this though, I should thank Tony Hadland as much of my knowledge of this issue is drawn from his excellent articles and books. Anyway, for a given tire, pressure, load, and road surface, bigger wheels roll more easily. This is due to the fact that a larger wheel will roll over many of the small crack and crevasses in the road that a small wheel will sink into. Due to its' larger rotating mass it also rises and falls more slowly than a smaller wheel. Finally, a small wheel will contact the edge of any hole or bump at a steeper angle than a larger wheel. Envision a monster truck as compared to a regular car:
Or, if you like, check out this graphic I had Pixar whip up to demonstrate my point: Pretty convincing huh? Seriously though, it is an issue. This is actually one of the key reasons that small wheeled mountain bikes don't work particularly well.

Another issue impacting ride comfort is the fact that small wheels are inherently stiffer than larger wheels. This is great sprinting or hill climbing since you don't have to worry about your wheels flexing laterally, but not as great for general riding comfort as it means that the wheel is less compliant vertically, and thus produces a slightly harsher ride quality. (Does this bit remind you of anything you have heard in a bike magazine or shop . . . i.e. "this carbon bike is completely laterally stiff, yet wonderfully vertically compliant -- it produces the perfect ride!!!" Yeah, yeah, yeah, tube shaping and layup techniques have worked some magic in this department, but does it strike anyone else as a bit of an oxymoron to claim that a bike is stiff and compliant? Having worked in the bike industry, I can assure you that most of these claims are just marketing, so don't buy into the hype too much!) Well, enough of that digression . . .

All of the aforementioned issues combined with wood or steel rims and the most primitive of tires led to the modern approximately 28" nominal wheel size. It was the largest wheel size that could be easily accommodated in the diamond frame of the early "Safety" bicycles. However, much as the medieval carts of old have evolved into the Mini Cooper of today . . .


. . . modern technology can adapt to these issues and produce excellent ride quality in a folding/small wheeled bicycle. How? Find out next time, as for now, get up and go ride.