The small wheel bias comes from near death experiences riding in traffic outside the USA. Wheel size doesn't have much influence on speed, but it has HUGE impact on pavement ability.
Please take a look at the following images:
Do you believe a person riding a 700c road bike would have some advantage going from A to B under these conditions over someone, let's say, riding a skateboard?
I am in the market for something that is a conventional bike replacement with Brompton folding capabilities. I just can't find it.
Believe it or not those have a striking resemblance to the roads by my old apartment on which I road my Carryme all the time. It sucked, but I can't say it was much better on 20" wheels...and certainly no worse than 700x23c wheels. Skateboards and most other small wheeled devices are different because:
1. They don't have pneumatic tires.
2. Ultra short wheelbases and bolt upright body positions mean you can't lean forwards or backwards as hard as you can on a bike. By alternating weight between front and rear tire a bike can almost "walk" over things...especially if the wheels are light and the frame is rigid (which the Brompton isn't). Most importantly a bike also allows you to maintain forward propulsion while implementing such hard leaning which is essential when going over things like cobble stones because no matter what your wheel size you need momentum to get over the bumps.
Think about it, even MTB 29er wheels have tiny contact patches which only bridge the smallest gaps. Everything else requires lifting the mass of the rider up over the obstruction which primarily comes from momentum and leaning. I don't doubt that large wheels help slide up a bit better, but IME the effect is rather small and unimportant at normal cycling speeds/momentums. Alex Moulton had it right when he noted that there's a reason most vehicles evolve towards smaller wheels...their disadvantages are far less significant than most people think.
But we're getting off topic. One of the advantages of the Brompton is it's nice long wheelbase, which I agree is very good for riding longer distances and over rougher terrain, but for shorter distances I think a much lighter bike with a shorter wheelbase is better (not to mention more convenient to fold).
Originally Posted by
Human_Amplifier
Small wheels do work OK. But check out cycling in any big city, worldwide: 90+% people prefer full sized bikes.
Vestiges of the Ordinary bicycle. I'm sure you also know that 9/10 people also think that smaller wheels require "more pedaling" (as most of them put it). Most people just aren't capable of the cognitive leap which led to the safety bicycle. Therefore, they will choose the largest wheel which doesn't have any other
obvious disadvantages (not too high off the ground, weight distribution which lends easy balance/steering, etc).
Of course, as a designer/businessman, that's what you have to live with, but as an individual the misunderstanding of 90% of the world has absolutely no bearing on my personal opinion that 20" wheels are the best size for general riding with wheels far smaller than that striking the best compromises in compactness etc.
Originally Posted by
Human_Amplifier
BUT still low down, needing to be lifted and carried - So add a handle and roll it ............
While I personally agree, I think 14Rs primary requirement is easily packing the bike into a suitcase. So for him a bike designed around a handle which only makes it more difficult to get into a suitcase isn't going to work.