ON DRUM BRAKES

ON DRUM BRAKES

QUESTION: Drum brakes?  ANSWER: No, thanks.  QUESTION:  A front drum brake?  ANSWER:  What are you? A comedian?  This fictitious exchange captures the essence of the spirited and enjoyable debate sprinkled with just about the right amount of sarcasm and humor that ensued when Motorcycle Daily featured BLACKSQUARE a few days ago.  Most spoke with authority and conviction:

No real motorcycle here. I’d never ride a drum front brake…

Others expressed a disappointment at a missed opportunity and felt that the use of a front drum brake was a step back in both time and technology:

I don’t understand the attraction of drum brakes, especially on a bike that originally had a front disc.

Some, of course, reminded us that drum brakes were all we had some time ago:

they ran drums on the Isle of Mann up until the late 50’s running at bodacious speeds.

and we are still here to tell the tale.

I must say at the outset that I’m not going to argue in favor of drum brakes. The widespread use of disc brakes and the associated improvements due to rising demand as well as consumers’ preferences are, in themselves, overwhelming evidence.  On top of that, disc brakes lend themselves so easily to the concept of ABS.  Allowing any driver, who “jumps on the brakes” in panic, to bring their vehicle securely to a stop.  What’s not to like?  Especially if you are a biker.  In traffic.

How did we get there?  As a culture, we have been fascinated by vehicles more than any other nation.  And we have also been fascinated by safety to a much greater extent than any other people.  VEHICLE SAFETY.  A hot topic.

They say the most important of “vehicle safeties” is braking.  Consequently, so much has been written about braking that it would take more than a lifetime to study the subject.  Something I can’t afford.  A brief look at the available opinions reveals that a consensus has emerged around these three points.

  1. Disc brakes are preferred because they are less prone to “brake fade” due to their greater efficiency in heat dissipation.
  2. Disc brakes are self-adjusting, easy to inspect, and can respond more reliably in wet conditions.
  3. The heavier the vehicle the better suited it is for disc brakes.

That is what the experts say.  No.  Let me correct myself.  That is what I think the experts are saying.  What they are actually saying is far more complex than that. But, expert opinion is often obscured in complexity wrapped in incomprehensible terminology. It is difficult to decipher. We, the general public, don’t have much time for that.  We want to keep things simple.  Clear cut.  Don’t muddy the waters!  We have children to teach. So, here is the lesson.

Disc brakes are vastly superior to drum brakes under all circumstances.

And that’s that.  End of story.  Simple.  Concise.  And on the money.

Fair enough.

It may be true.  But, maybe not always.  Simplicity, such as the one above, is, by definition, extreme.

What we have failed to to appreciate fully, I think, is that a vehicle’s ability to stop does not depend on the type of braking system alone. Braking may begin with the type of braking system used, but it does not end there. Braking is not about “drums or discs”.  It is about friction. Or to be more precise: about two frictions.  Friction between the brake pads (or shoes) and the surface they rub against.  And the friction between tires and road surface. Only when both are optimal, can we have the best breaking performance. “Both” is the key word.

As many people are eager to point out, an antiquated disc brake system from the 1970’s is inferior to a drum braking system of today due to the facts that 1) the lining used for brake shoes provides for much better friction and 2) the resins used for shoes have a much higher melting point and thus better resistance to “brake fade”.  I think they have a point.

We also have to appreciate the fact that designers and engineers have a difficult job.  They have to choose and employ a braking system that will be performing in all climates and on all road surfaces for drivers who may only have rudimentary driving skills and, because they drive an “automatic”, cannot use the engine itself as a braking tool.  So, the choice of disc brakes is obvious and, hence, perhaps, the popularity.

But, in individual and specific examples such as custom builds, the choice is dictated by the intended use.  Unlike designers and engineers who must accommodate the needs of all drivers under all conditions, the custom bike builder has to accommodate a single rider.  Himself or herself.

“Will the braking system I am using be sufficient for the intended use of the bike?” That’s the question.

It’s logical enough.  It answers the “safety question”. But there is another, far more important and not necessarily “logical”, consideration the custom bike builder will hopefully ponder when deciding on brakes and other components.  Dustin Kott of Kott Motorcycles puts it so eloquently:

What’s great about vintage bikes is that they remind you you are on a vintage machine.  They give a feedback, a mechanical feedback, that makes you feel much more connected to the road and the machine itself.

Check out Dustin Kott’s video.  The guy is just great. His work is superb. And his passion for vintage motorcycles is contagious.

From both perspectives above (the logical and the not-so-logical), here are some thoughts about my choice of braking system:

The original HONDA CB550 weighed 425 lbs. and was intended to be used all over the world under all conditions carrying as much as 750 lbs. of combined  weight (accounting for rider, passenger and some luggage).   I would like to assume that the designers and engineers thought about all of that when they decided to use a front disc brake.

BLACKSQUARE weighs 375 lbs. and it is unlikely that it will ever carry more than a combined 550 lbs. of weight.  Is a drum brake going to be less efficient in stopping 550 lbs. of weight than a disc brake stopping 750 lbs. of weight?  I don’t know.  And I have not performed the experiment.  But what I do know is that it does not feel that the bike’s braking power is any less than that of other “modern” bikes that I ride. Primitive? Cruder? Not as “smooth”?  Yes to all 3.  But, it makes you work.  It helps you be “one with the machine”.

I told a friend of mine not too long ago that riding BLACKSQUARE is like flying in a propeller driven aircraft.

You feel it.

QUESTIONS?

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