Deck-lowering rationales and strategies

rulerOn a performance scooter, a lower deck means more efficiency, although this is traded off against less exercise and ground clearance that’s too low. Gary Schmitt has suggested some math to compare the effort required to kick a marathon distance (26.2 miles or 42.2 kilometers) for two riders with a half-inch, or 1.25 cm, difference in deck height:

If 100 minutes x 3 kicks per second, then = 2000 kicks
0.5″ footboard deck height difference x 2000 kicks = 1000 inches difference
1000 inches = 83.33 feet

If a stairstep has a riser of 7 inches, then 83.33 / 7 = 142.857 steps

If there are 20 steps per floor (story) of a building, then 142.857 / 20 = 7.142 stories

So, if your footboard is 0.5″ higher than the other guy, then you’re not only going the same distance as them in the marathon but in addition it’s as if you are climbing the stairs a 7-story building.

Still, in the recent World Championships, some riders’ extremely low decks were hitting the pavement on the sharpest corners, causing them to lose grip and spin out.

So the best thing for a racer might be two footbikes: a higher one for rough courses and training (like a baseball batter swinging three bats before his turn at bat, or a bicycle racer training on heavy clincher tires), and a lower one for smooth races.

But many kickers still fixate on lower decks, like bicyclists who fixate on weight. In the past, cyclists have gone to extremes like drilling out every non-stress-bearing metallic part on their bikes (sometimes inadvertently increasing wind-resistance) in order to lighten them. Many kickers have gotten the deck clearance on their machines to less than an inch, likewise to the detriment of the paint on the bottom of their frames.

There are some easy ways to lower kickbikes an inch or so, though, which shouldn’t have them scraping every sidewalk joint, but which will increase efficiency for those l-o-n-g rides.

  1. Get some flat shoes, with the heel no higher than the sole. Probably the simplest thing you can do to effectively lower deck height. (You kick with the ball of your foot, but stand on your heel.)
  2. Use lower-profile tires. Kickbikes and AW Footbikes, especially, come with fat tires on their street models. You can see a conservative chart of what size tires will fit on which rims here.
  3. Buy a shorter fork. They are available in every material from cromoly steel to carbon fiber. A carbon fiber fork will also lighten your ride, but a Tange steel fork will still be shorter than a stock Kickbike or AW Footbike street model fork.

    At press time (Aug. 2009) a Tange fork for a 700c wheel was $52 at BikeUSA.com, who had threaded forks for those pre-G4 Kickbikes. They’re just cromoly, but shorter than FB forks, as the specs say they need a short-reach road brake.

    You can check how much shorter by measuring from the hole in your current fork crown to the center of your brake pad – that’s the brake reach. Short-reach brakes measure 40-50mm there. The difference between your current reach and say 45mm (median for a short-reach brake) will be how much shorter the new fork will be. The brake reach on my G3 Kickbike City Cruiser, from the factory, and my stock AW Footbike street model were both 70mm.

    And with a new short-reach caliper brake you would need a front brake lever meant for caliper brakes. They need different levers than V-brakes, as the cable take-up is different. Some levers can be set either way, so you could use them for either kind.

  4. But before you buy those brakes you might want to consider my last option for lowering your deck – a 650b front wheel. This archaic size, once popular on French touring bikes, is making a comeback for those bicyclists who want to fit comfortable fat tires and fenders on old racing bikes. The radius of the rim is 19mm smaller than a 700c wheel, so that must be taken into account when buying brakes – 19mm must be added to the brake reach (so it may be possible to use the stock front sidepull on a pre-G4 Kickbike with a new fork and a 650b front wheel).

    The Maxy Fasty 650×33 is the lowest-profile tire I’ve found for 650b wheels. 650B’s usually use fat touring tires, which on a kickbike may negate the lowering results from using the smaller wheel in the first place. (Bicyclists are more interested in maintaining their bottom bracket height, so pedals don’t scrape the pavement.)

    A 650b wheel with a stock fork is barely possible on a pre-G4 Kickbike; adding 19mm to the already long reach would make it necessary to use a homemade drop bolt or a BMX front brake with an extra-long reach. But with the V-brakes on all modern footbikes, the brazed-on brake anchors might interfere with the new caliper brake, if they weren’t sawed off, and that’s a bridge I wouldn’t burn on a footbike fork.

    Update: I finally got around to holding a BMX brake up to my Footbike front fork, and it doesn’t interfere with the existing brake anchors. Also, there seems to be about 15mm of brake-pad movement available on the existing brakes, so it’s possible that the stock brakes might be usable with a 650B front wheel. The thing to do would be to mount the new wheel and try it, having a BMX brake ready just in case.

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