Here's your chance to play Jim Boswell, minus the trick knee and
weight problem: I'll give you two seemingly unrelated events and
you spot the idea for a column. Ready? Watch the lights:
Event #1) Ford Racing executives tell "Automobile" magazine
they are extremely pleased with the performance of their new Ford
Taurus NASCAR racer.
Event #2) A mountain bike company publicizes a downhill bike with
an internal (no derailleur) seven-speed gearbox, noting that they
hope to have the technology on their team bikes in the near future.
If, after reading the above items, you shook your head and muttered,
"Big trouble ahead for BMX," you're as crazy as I am.
And I mean that in a good way. For my sane readers, here's
the explanation.:
We'll start by looking at Event #2-the "internal" gearbox.
"Internal" hub gearing is nothing new to cycling, as
anyone who's ever owned an old "3-speed" knows, but
nobody's been able to make it work for BMX--yet. "So what
if they did?" you might ask-and with good reason. Multi-speed
setups for BMX have been around for nearly 20 years, the Browning
Automatic Transmission being perhaps the most famous of the various
efforts to bring gear-shifting to BMX. More recently, Brian Lopes
has made some waves using a Dura-Ace road derailleur on a three-speed
cassette, but so far BMX bikes have remained mostly single-speed
devices.
A multi-speed BMX bike would be a lot faster, but so
far nobody's made a reliable system despite the obvious benefits.
How obvious? Let's bring Riders A and B back from obscurity to
answer that question. Longtime "BMX Basics" readers
will remember that Rider A and Rider B are identical twins. You
know how competitive twins can be, so it's no surprise that when
Rider A turned Pro, Rider B followed him. (Sure they're young,
but Greg Hill turned Pro at the age of 14, and cleaned house.
How many 14 Experts could do that today, I wonder?) As Pros, A
and B have no trouble maintaining 180 rpm on the straights. Rider
B, however, has a two-speed bike, and he shifts to his top gear,
which is 3 teeth above Rider A's, in the first turn. Every second
the two of them are at "full spin", Rider B moves about
three feet ahead. That's a heck of an advantage, even if you don't
consider that Rider B's "low gear" probably lets him
beat A out of the gate.
In a race in which the riders spend just fifteen seconds at full
spin, that is forty-five feet--more than the difference between
worst and first in many a Pro main. For that reason, the first
company to come up with a reliable BMX multi-speed will win, and
win big.
It hasn't been done yet. The hub gearing setups used with success
on other types of bikes aren't reliable under BMX conditions.
Derailleur-based systems are still too fussy for anyone without
a team mechanic and enough patience to tolerate blowing a chain
off the gears now and then. Nor are they particularly tolerant
of full-power shifting. To work in BMX, a shift system has to
be dust-proof, impact-resistant, and strong enough to shift under
pro-level power. Impossible, huh? It's no wonder it took me all
of thirty minutes yesterday to design one.
My system is heartbreakingly expensive, but fairly simple. It
uses a pair of planetary gears in the same arrangement as a GM
Turbo-Hydramatic transmission. The cranks drive an input shaft
which in turn drive the gears. (For an excellent introduction
to planetary gears, I recommend Frank Thiessei's "Automotive
Drive Trains".) Two planetary gears give us three "speeds"
to choose from. I don't have the space to explain the planetary
system, so trust me when I say that all gears are always connected
and that shifting is done by applying a set of small clutches.
The Boswell tranny uses compressed air to drive the clutches.
A "fly-ball" governor senses wheel speed and shifts
up and down automatically, just like your dad's Buick Roadmaster
does. It's always in the right gear. There's no chance of missing
a shift. The whole assembly is about the size of a coffee can,
excepting the air cylinder, which you just "pump up"
before every race.
To keep it light, I specified dimensionally stable polymers for
the gears and clutches, similar to the stuff used in various Austrian
sporting goods and military hardware. A total system weight of
2 pounds is very possible. Since I only "built" this
transmission on paper, I don't know exactly what it would cost,
but it probably would not be less than a new Turbo-Hydra-Matic
tranny--that is, a couple thousand bucks.
Are you willing to spend that kind of money to win? I'm not, but
some folks are-specifically, the company that developed its own
seven -speed internal transmission, and probably most
of the companies it competes with on the very high-profile and
big-bucks world of NORBA downhilling. Once it proves its worth
there, it will be available for BMX faster than you can say "SPD".
Pretty soon, you'll need a gearbox to win Pro. Shortly after that,
everybody in Super will run one, followed by 17x, 16x, 15x, et
cetera. What will this do to BMX?
That's where Event #1 (look at the beginning of the column) comes
in. The Ford Taurus used in NASCAR has nothing in common with
the one you can buy, because NASCAR racers are all pretty much
the same. There are some small differences permitted, but in general
everybody uses the same technology and has to conform to the same
rules. On the street, Tauri have front-wheel-drive and four doors;
in NASCAR they're rear-wheel-drive and have no doors, because
those are the rules. NASCAR made those rules to prevent a "technology
explosion" and keep racing (relatively) affordable for everyone.
I'm not a NASCAR fan, but you can't argue with success. Millions
of people are huge fans despite, or maybe because of, the fact
that the cars haven't changed much in twenty years. Since the
cars are very similar, the attention focuses on the drivers, and
that's why so many people have a number 3 in the corner of their
car windows. (It took me years to figure out who "#3"
is. It's Dale Earnhardt, I think.)
BMX sanctioning bodies have always been fairly "tech-friendly."
We have a history in the sport of nearly thirty years of technical
innovation. It has been pretty much all good news up to this point-in
fact, a top-notch race bike doesn't cost any more today (in adjusted
dollars) than it did in 1975. BMX isn't cheap, but it doesn't
cost nearly as much as road cycling or downhill racing. At some
point in the future, however, that will change. It might be the
internal gearbox that does it; it might be plastic frames, or
carbon fiber cranks---or magic beans, for all I know.
When the change comes, the NBL and its riders will have to make
a decision. Will we limit technology, NASCAR-style, or will we
open the door to every useful innovation, no matter how expensive?
The answer is up to all of you, so choose wisely, okay?