Question for anyone who owns/rides a folding bike with small wheels like a Brompton - can you realistically average 20mph+ on these things on flats? I seem to have read in places that you will spin out in the 20-21mph range, just curious, as I always thought it would be fun to own one of these things.
I guess you could always modify the drivetrain of the Brompton with a larger cranksize, but I think there’s a limit on how big you can go up front.
It is counter intuitive by a shorter crank is effectively a higher gear !!! So 150 mm cranks are way larger gearing than 200mm cranks!!!
To your question, you want a massive pizza plate large chainring in the front but it is doable. Massive large chainring, tiny rear smallest cassette and shortest cranks and you can get to a big number of gear inches on small wheels.