Except, nobody learned anything. How can I put this delicately? If you ride a brakeless fixed gear and you believe that you can stop as quickly as a rider with a front brake, you are a fool. A damned fool if you squawk about it to a reporter, because that shit's on the Internet and you can't take it back.
Before the young fixerati rise up and protest, I'm going to break this down so many ways that you will need to travel to another universe with alternate laws of gravity to disprove it. But first, I need to take issue with the legal definition that the Judge was trying to enforce. (I couldn't totally side with the Man.)
According to the statute in question: A bicycle must be equipped with a brake that enables the operator to make the braked wheels skid on dry, level, clean pavement. strong enough to skid tire.
I would just like to make two points:
- A front brake is twice as effective as a rear brake (to be discussed below)
- It's damn near impossible to make a front wheel (alone) skid on dry, level, clean, pavement. (This is part of what makes it so effective.)
So, in otherwords, to comply with this law, you'd have to put a back brake on a fixie, which, in the hands of a competent rider, is probably only safer by a negligible amount. If you were to put a front brake on a fixie, technically, you would be able to stop twice as fast, in half the time and distance (again, to be covered below), though you would be in violation of the law, since you'd be unable to prove the skid factor. Sure you could skid the front wheel if you stop the back one simultaneously, but that's splitting hairs, so let's get to the nut of the argument.
I had planned to get out the book and the calculator and have some supporting illustrations, but there are fixie kids out there that need to be schooled and I can't waste another moment.
I discovered the effectiveness of a front brake by accident...a couple times in traffic, a car in front of me stopped unexpectedly, and I locked up the back wheel, skidded up the bumper of the car, jammed the front brake in a panic, and immediately ended up in a nose wheelie. Out of control, almost over the bars, but STOPPED. I soon witnessed a couple badass messengers hurtling into impassable intersections at top speed, standing up off the saddle, doing a nose wheelie, and going from 25 mph to zero in about 5 feet. I now do it all the time...I find that if you make a spectacle of yourself riding (but you're not a total ass) you tend to get a little more space.
If you want to get technical, there's a book called Bicycling Science that does a decent job of discussing the math and physics. Basically (and again, forgive me for generalizing here) friction between the tire and the road stops the bike. If you put say, 100 pounds of force on a rear tire, and lock it up, you're just waiting around through a skid for friction to do its job. However, if you put say, 200 pounds of force on the front tire, the additional force keeps the tire from skidding, but it has the benefit of stopping you more quickly.
How is it that you can put 100 (theoretical) pounds of force on the back tire, but 200 on the front? It's because the downforce your tire exerts on the road is a component (cosine, sine, tan?) of your center of gravity (technically, center of momentum, since your weight has a rotational velocity). To totally water it down mathematically: some portion of your weight times the rotational force is transferred to your tire's contact patch, where the coefficient of friction does its job.
I'll take a step back from the math (since I'm doing a piss-poor job of it anyway) and illustrate. You're flying along and you want to skid your back wheel. Your center of gravity is somewhere between your cranks and saddle. You're generating a force that equals (a component of) weight times distance. Your center of momentum is ahead of the rear wheel, so the "component" factor is fairly low. That's why messenger comps have 500 foot track skids...they move the center of momentum waaaaay out ahead of the bike, so that component (which I really need to look up) is minimized. Still with me?
It's the equivalent of riding down the road and dropping a sandbag tied to a rope off the back off your bike. It will stop you, eventually. Imagine taking a stick, tying that sandbag onto it, and jamming it into the ground out in front of your bike. That rotational force is behind the point of force, making this goddamned nameless component much higher. It will make you want to flip over the bars, BUT lifting your bike off the ground will drive even more force down into the ground, slowing you down more quickly. Something to the tune of twice as fast, in half the time and distance.
Sorry I butchered it so, but Bicycling Science does a better job of explaining the numbers...so if you have a problem with it, take it up with the author (who's incidentally an MIT professor). I would also add that by throwing your center of gravity up and back BEFORE the move increases the effect, so I think you could get even better results with some skills. The book deals with the mathematics of keeping the back wheel from coming off the ground, but my gut tells me that if you can really ride your rotational center of momentum like a rodeo cowboy, you can magnify the effects. I have also noticed that by kicking the wheel out to the side, you get even MORE force and control, though I'm not sure why, perhaps because you can keep your center of gravity/momentum further back/down without feeling like you're going to endo. There's a whole other "dimension of components" there.
If you still don't believe me...go to youtube and look up 'nose wheelie' - you'll see motorcycles going from 80 mph to zero in a fraction of what you'd expect. Or watch indoor motocross and see how these guys keep from flying into the barriers after their tricks...skidding the back tire on loose dirt for 50 feet, or standing it up in a nose wheelie for 10?
Or go figure it out for yourself. Find a moderately skilled ten-year-old bmx kid and ask him to go as fast as he can, and stop asap in a nose wheelie. Ride alongside him wit yo badass fixie self and see if you can jam up the back wheel and stop as quickly. Now imagine someone's opening a door in front of you both, and see which skill you'd rather have.
Note: before trying to master this skill, remember that you should have your ass waaaay off the saddle before trying it the first time, and your legs should be reeeeally loose - I can't stress this enough. Your legs should be the shock absorbers that let your bike rotate up off the ground, and not eject you over the bars. Do it at your own risk, and start small, with quick little jabs on the brake, almost throwing the back wheel up, so you won't be surprised when it happens. It's possible to do it around corners (it can actually help you drive the front wheel into the ground forcefully and not skid out, bmx-style) but it's an extremely sketchy feel, to say the least. Not recommended for the inexperienced, though it can save your life, which is nice. It does give you nice feel on the back wheel when used with a fixed gear, you can easily unweight the back wheel and track skid with far less effort.
Insert scary anecdote here: I once knew a guy with unsurpassed skills, like riding a one-handed wheelie, fully crossing up the front wheel, for 50+ yards...often passing roadies and cops on bikes. Anyway, he was learning the nose wheelie thing, and was trying to master it on several levels: stopping as quickly as possible, riding it, in control, downhill for 40+ feet, etc. He was extremely inebriated one night and goofing off in front the messenger bar...he ended up going over and getting stitched up right on the sidewalk by the EMTs. If it could happen to him...
As an aside, there are serious legal implications of riding a brakeless FG, such as the legal definitions of negligence. There are several components of legal negligence that I won't get into, but one of them is "did the participant do all that could be reasonably expected" to prevent something from happening. How would you like to be paralyzed as a result of a bike accident, and instead of getting $10 million, the opposing lawyers said "According to the MIT professor who wrote this book, you could have stopped twice as fast...so technically you were partly negligent when that drunk driver flattened you running a red light. Here's $10 grand." I doubt insurance company lawyers are that savvy yet, but with the rise in FG riders, it's just a matter of time before someone tries it as a defense. I got hit, and I certainly didn't volunteer that I was on a FG, for just that reason (I didn't hide it either, but they were obviously sniffing around for signs that I "contributed" to the accident).
Besides, what if someone ran you over, and even though their car was "legal" it only had half as many brakes (and weaker ones) as it could have. Wouldn't you go after them for negligence?
ok, kids, school's out. There may be a pop quiz.
1 comment:
I'm glad someone wrote this. I'm tired of getting flak from hipsters because I have a front brake. Maybe it doesn't look as "cool", but I think my head in one piece is cool enough.
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