built this little critter to use "large" 20-inch wheels (451 mm).
More commonly, 20-inch wheels are 406 mm. On this bike, I can run
narrow 451 mm tires, or 406 mm wheels with very fat tires such as
Schwalbe Big Apples. The bike uses disc brakes front and rear, so
tire clearance isn't an issue.
frame and fork are TIG-welded steel, and the sliding rear dropouts
are from Paragon Machine works. I use a 16-tooth White freewheel,
and plain 48-tooth chainring, for 60 gear inches. The crank is an
Ultegra double, but it's attached to a triple bottom bracket to
give the correct chainline with the Paul disc hubs.
Brakes are lightweight Hope Mono Minis, which provide more than
enough stopping power! The bike weighs 21 pounds, ready to ride.