Balance

I took the MSF safety class last weekend. Almost completely by whim. I was looking at the course schedule, saw it had a free seat, and whipped out the plastic talisman, and there I was in the classroom friday night. Plastic magic. The classroom was filled almost exclusively with young men. They showed us videos, lectured a bit, and answered a few awkward questions. It reminded me of sex ed. Except we got to practice the next day. Viva la difference.


A portion of the course was unremarkable, really. The mechanics of a motor vehicle are remarkably similar across the board. Engine. Clutch. Brakes. Gears. I had not really thought hugely about the physics, which the other portion was about. They never mentioned physics or talked about it much, but that's what it was.

 I had not really paused to consider how a motorcycles center of mass, traction, and weight transfer characteristics are different from cars, bicycles, and motorscooters. They all have more stopping power with the front wheels, but the spectrum is surprisingly wide, with motorcycles being on the rear-brake-is-useless end and bicycles and some scooters on the -completely-possible-to-forgo-back-brake end. (I'd be fair to unicycles and put them in the middle). The  major implications of this had been lost on me until the class:
1) it's very hard to stop a motorcycle in a curve
2) front brake is massively destabilizing at low speed and in curves, and
3) motorcycle back brake has different lockup rules than other vehicles (If you lock up, keep it that way until you stop...)




There had been quite a few practice rides in parking lots (directed by the girly) with the Motorpickle (a Genuine Buddy 125). I practiced low speed turns, swerves, leans, and hard stops quite a bit. That all proved mostly useful, except for the braking, which may have been detrimental to the MSF course, where I was on a actual motorcycle. The Buddy has a low center of mass with the engine below and behind the rider over the rear wheel, with the seat on the gas tank. A motorcycle has it in front of the rider, between the knees, with a gallon of gas perched on top. Between the motorpickle and the endless hours of bicycle commuting, I organically expected a certain braking dynamic. I expected the rear brake to feel sluggish but effective and forgiving in draining speed, and to tend to pull the front end into the direction of lean, and the threshold before a lockup is large. I expect the front brake to be a better stopping force, and it's use does not substantially impact the bikes stability. In contrast, the rear brake on the motorcycle seemed to lock up far too soon, it bleeds speed very gently, but has no capacity and little range. The front brake felt almost grabby. Using it in a hurry, particularly at low speeds, initiated some frightening dives that were highly destabilizing if in a turn. After the first day on the range, I spent the rest of the day trying to mentally retrain my mindset for the new vehicle. Easy on the front brake. To slow just a bit, use the rear. Use both calmly to stop when upright. The emphasis on gentle is a contrast to my bicycle style, where I use lots of hard braking to keep my precious, hard earned velocity until the last moment, and my center of balance is very very fluid, even with 50 lbs of groceries.

I'm a science wonk, I'm used to thinking about things in terms of force, friction, acceleration, velocity, inertia, and center of mass. The class wasn't in those terms. (Heck, why not just print this out for people?  I guess the math isn't as fun as doing it.)

To me, taking a curve is leaning to balance the force of gravity against the centrifugal force on my center of mass. To make that happen, it helps to steer the bikes wheels out from underneath to setup the lean. Accelerating in the turn helps with the stability. The course said: slow, look into the turn, push the handlebars that way, then roll on the gas. We got a lot of instructions that, but not a lot of discussion of what was happening. Derivation left as an exercise to the r(ea/i)der.

Regardless of the form the instruction (really, it needs to be usable to a large group of people), it was the best way to get the license. Riding a motorcycle is not something that can be just made up as one goes along in dense urban areas. There's a right way to do things, and a lot of wrong ways. It was totally worth the time and money.