In the mid-1970s, my high school acquired its
first computer. The father of one of my
classmates, who worked in a nearby military base, in one of those jobs he
couldn’t talk about, negotiated the purchase.
For $6000, my alma mater got a used machine, about half the size of a
classroom—and with about half of the capacity of devices kids carry in their
backpacks nowadays.
When I graduated the following year, one of my
relatives gave me a new Texas Instruments Model 101 digital wristwatch. With its red LED display and sleek goldtone
band, it seemed like the epitome of elegance and slick high-tech, all rolled up
into one. No one else I knew had such a
timepiece: For the one and only time in
my high-school years, I was the coolest kid in the class. At least, that’s how I felt.
Neither the computer nor my watch made it past my
sophomore year of college. The big box
(“It’s just an oversized, overpriced file cabinet!” one parent exclaimed upon
learning what it cost) assigned classes like “Sports Heroes” to honors students
who signed up for the Shakespeare seminar.
(I know. I was one of those
students.) And that was the least of the computer’s malfunctions. Worst of all,
nobody seemed to know how to fix them.
And nobody seemed to know how to fix my
watch. One shop claimed that displays of
numbers that had nothing to do with the time of day were a result of “water
damage” –only moments after I took that watch out of its box. (I have since learned that technicians and
reps say “water damage” when your electronic device is acting up or not working and they can’t figure out why.)
Less than a decade after I graduated high school,
the Yankees were giving away digital watches (with the team’s logo, of course)
as promotional items on Fan Appreciation Day. My graduation gift, in contrast,
sold for more (in non-inflation adjusted dollars) than most smartphones or
laptops cost today. And the watches the
Yankees gave away were more reliable (water resistant to 100 meters, and shock
resistant) than the one I got on Graduation Day.
I was thinking about the computer and watch as I read an article in the most
recent Bicycle Quarterly.
In “Are Disc Brakes Mature Technology? “, Jan
Heine recounts his and other BQ editors’
experiences with both mechanical and hydraulic disc brakes on road, mountain and city bikes. While the brakes on one
bike offered the power and modulation of good caliper brakes, their performance
was hampered by their incompatibility with the levers that came on the bike. The brakes on the other bike were not as good
as road calipers and, worse, there were a couple of potentially serious
failures.
Heine seems to think that disc brakes have
potential, but there are issues that need to be worked out. Braking power is still determined mainly by
the size of the disc. A larger disc is
heavier and could necessitate larger forks—both of which are anathema to racers
and other performance-oriented cyclists.
More important, though, is that while larger discs offer more power,
they seem to offer less modulation. From
what Heine and others say, it seems that larger rotors give the brakes the “all
or nothing” feel that V-brakes (at least the ones I’ve used) always seem to
have.
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Avid BB7 disc brake on Look X85 cyclo-cross bike |
The flip-side is, of course, that smaller rotors
offer less power. And, if there isn’t
enough power, whatever modulation the brakes offer is all but irrelevant.
Another problem, as Heine points out, is that on
disc brakes, the pad grabs the disc on the rear. On a front fork, that means the wheel is
pulled away from the dropout (or fork end).
When you’re barreling down a hill—or sluicing through traffic—few things
are more dangerous than a front wheel popping out of a fork.
Most modern quick release levers, Heine says,
aren’t secure enough for bikes with powerful disc brakes. Through-axles, like the ones found on
downhill bikes, might be a solution. But
even with them, the fork blades on most non-suspension (telescoping) forks
wouldn’t be stiff enough to counter the forces the brakes would put on
them. So, Heine says, a dedicated
suspension fork might be the best kind to use with disc brakes.
(In
contrast, rim brakes pull the wheel slightly upward, into the dropout. And their forces are concentrated in or near
the stiffest and strongest part of the fork:
the crown. That is the reason why
properly-installed wheels don’t fall out of forks equipped with rim brakes or
no brakes.)
I myself don’t plan to start using disc brakes any
time soon: I have never had trouble
getting the braking power and modulation I need from rim brakes, as long as I
use good cables and pads and keep everything properly adjusted. Plus, there is something to be said for the
simplicity, not to mention the lighter weight, of such brakes. So, I hope that disc brakes don’t become the
only option on new bikes or that component manufacturers stop making rim brakes
and parts.
On the other hand, I am not against some bikes coming with disc brakes, or
for such brakes to be offered on bikes where they might make sense. Most of all, I hope they don’t become a de facto standard—or the only
option—before they are a “mature” technology.
At least, when my digital watch failed, I still had the mechanical watch
another relative gave me for a birthday—my 12th or 13th,
if I remember correctly. And plenty of
others were available.