Wednesday, May 29, 2013

Brakes


Ask 100 people what bicycle brakes are for, and likely 99 of them will respond with a blank look and then say,  “For stopping.”

Well…  yes.  But there’s a bit more to it than that.

A brake is a device that converts kinetic energy to heat.  Roughly (and very loosely) a cyclist in motion has a kinetic energy.  This energy can be measured and is equivalent to E = ½ mv2.  In that equation, E is the kinetic energy, m is the combined and total mass of the vehicle (cyclist + bicycle), and v is the velocity at which the vehicle is traveling.  (Please take a deep breath and relax!  We’re not going to turn this into a Physics lesson.)  The important thing to remember here is that two things affect the kinetic energy.  They are the mass of the vehicle and its speed or velocity.  Of these velocity has a much greater effect.

There are a great number of situations where a cyclist would want to decrease velocity without stopping.
Examples abound.  Here are a few:
  • I’m going to fast to make that turn!
  • That truck won’t be out of the intersection before I get there!
  • I’m going as fast as I can, and that idiot Honda is moving into my lane!
  • I can’t hear what my riding companion is saying, and she is the one who knows how to get home.
  • I’m going too fast to read the street signs, and there is an important turn coming up.
  • If I go down this mountain much faster I risk becoming “street pizza”!
  • Yipe!  They stopped pedaling!


Personally, I’m not fond of braking.  I prefer to make my ride fluid, using deceleration  only as needed to adjust the line in a curve, or to make necessary full stops at intersections.  Sometimes, when riding with others, I find it necessary to brake, just to stay in contact.  It’s a mild annoyance.

There are those times…  The ones when we are following someone up a hill, and they, for no apparent reason, abruptly slow down so much that we must apply brakes, while climbing.  Lordy!

Most folks don’t pay a lot of attention to their bike brakes…  until they stop working.  Fortunately these devices are fairly reliable.  That wasn’t always the case.

When the Tour de France race started, in the very early days of the 20th century, all the bikes were fixed gear, and rim brakes were still a thing of the future.  Oh there were bicycles with brakes, but these were deemed too heavy and too clunky for serious racing.

The early Tours did include significant climbing sections, but mountain descending was not a feature.  The advent of the first rim brakes made two things possible.  A cyclist could mount a lower gear on the bike for climbing purposes, and freewheels became practical.  Still, those early brakes weren’t much.  Remember, the rims of racing bicycles were made form bent wood.  The first rim brakes were crude, “single-pull,” and the pads were a sticky laminate of leather and tarry rubber.

I have ridden authentic reproductions of those early bikes.  I can state that the brakes were only slightly more effective than dragging one’s feet along the ground.  By the late ‘40s metallic rims and rubber had improved things considerably.  Road bike brakes were then up to the level of miserable performance.  That’s where things stayed for a while.

When I first got into road riding, the best that we could obtain worked only fairly well.  A good set of roadbike brakes, with the best pads available, was good for three hard applications,  they heated too much and faded to near useless.  And rain?  Fuggedaboutit!

Today’s brakes, road or mountain, are marvels.  And, like it or not, disc brakes are coming for the lightweight road bikes.

A bit of wordplay:
To Brake = to slow down.
To Break = to damage beyond function
I braked = I slowed down or stopped.
I broke = I damaged beyond easy repair.
I braked hard, and the brakes broke, and then I got all broke up.

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