Originally Posted by
Andrew R Stewart
I haven't done the math but I wonder how it relates to Jan Heine's wheel flop factor.
Well wheel flop is directly proportional to trail. More trail = more flop. I use this
online trail calculator to figure trail and it gives you flop too. I view flop mostly as an annoyance since, as a practical matter, we only see it's exaggerated effects at ultra low speed. (BTW I think the wheel size he uses in that calculator are wrong. I use the figures from
this chart to get the wheel diameter and then just play with the tire width figure in the trail calculator till it agrees with the desired diameter)
Originally Posted by
Andrew R Stewart
One aspect not reflected by mere math on paper is the rotation inertia and how it changes due to wheel diameter (and maybe tire width).
Yeah, wheel inertia is definitely a big part of the stability problem with small wheeled bikes since I=mr2 meaning that the inertia varies as the
square of wheel radius. And weight weenies like me make it worse by using the lightest tire that we can get and therefore reduce the rotating mass on the
rim of the bike where it has the maximum effect. Fortunately
Jan Heine has rescued me from the mythology that skinny tires are faster and so my new folder will have the lightest 451 x 41 tires I can get.
Tom