THE 406mm WHEEL -- The compact wheel standard
Dave Mirra getting air on a bike with 406mm wheels...the wheels are bulletproof.
The Xootr Swift leverages developments in 406mm tires and rims over the past decade.
History
The 406mm ("20inch") has come a long way in the last decade, largely due to the developments in the BMX racing world. These wheels are now incredibly robust and tires are widely available. As a result, they make the perfect standard for compact bicycles. If anything, the 406mm wheel is stronger and lighter than the 700C standard sold on most recreational bikes. There are tons of advantages.
Advantages
- Front foot clearance. Unless you wear clown shoes, your toes will never hit the front wheel on a hard turn.
- Overall length of bike. For the same wheelbase (and ride quality), a Swift is about 12 inches (300mm) shorter in overall length than a conventional cycle.
- Elevators and hallways. This bike fits the short way in most elevators.
- Weight. A 406mm wheel weighs 200-400g less than a 700C wheel with the same tire and rim.
- Tire availability. Compared to other small-wheelers, the 406 wheel has a huge array of affordable, high-performance tires.
- Sizing flexibility. The bike has a very low "stand over" height, and so fits riders from 5'0" to 6'7" (1.5m to 2.01m)
Disadvantages
- 1 % higher rolling resistance. There's really just one disadvantage. Rolling resistance of a tire decreases with increasing diameter. However, rolling resistance is a tiny fraction of the energy loss on a bicycle. Unless you race, you won't notice this.
Red Herrings
- Ride quality. Some people have the perception that wheel diameter has a large effect on ride quality. There is a small effect. However, the much larger effect is tire selection and tire pressure. If you run our Kenda's at 65psi, the ride will be like a stiff road bike. If you run them at 45psi, the ride will be quite plush. It's as easy as adjusting the tire pressure to meet your preferences.
- Ruggedness. Some people believe little things are not as rugged as large things. The opposite is actually true of wheels. These things are pretty much impossible to taco in normal urban use.
When aren't 406 wheels the right choice? (Short answer: rarely)
- Downhill mountain bike racing. Let's be clear. If you want to go near-vertically down the side of a mountain, you don't want to do that on a bike with 406mm rims. You want to be able to roll over huge boulders and clear giant felled trees. This isn't the bike for that job. USCF road racing. The Swift (nor any 406mm-wheeled bike) doesn't meet the precise technical standards of the Luddites in charge of most bicycle racing standards. Besides, if you are a road racer, you are going to obsess over grams of weight, tiny fractions of a percent of rolling resistance, etc. The Swift is not your racing bike.
- Super tiny bikes. Some folding bikes out there fold in a complex sequence of steps resulting in an intertwining of their complicated little bits. We are generally impressed that these bikes work at all, given the hinges, clamps, knobs, etc. Almost all of the super tiny folders rely on an itsy bitsy wheel (e.g., 16inch) to achieve their impressive tiny state. The 406mm wheel is a tad too big for this game.
