noisebeam

There are two components: equipment and rider(skill)

There are two questions:
1. Is front hand brakeless vs. not more or less safe?
2. Can one stop faster with brakeless vs. with front hand brakes?

The answer to both questions involve both the equipment and skill components.

The answer to question #1 depends mostly on the rider skill, not just braking skill, but overall traffic/street riding skill. Arguing about which is safer then becomes an arguement/boasting of who is more skilled.

For question #2, for discussion lets assume that the rider of each is highly skilled in each braking technique for the given setup. Given this, my understanding due to the physics is that the bike with a front hand brake will stop faster. (of course assuming all other variable like rider weight, bike, tires, street surface are the same


What stops faster (assuming highly skilled rider) in straight line on good clean pavement?
A. Freewheel with front and back hand brake
B. Freewheel with only front brake
C. Freewheel with only rear hand brake
D. Fixed with no hand brakes
E. Fixed with front hand brake

I suggest (from fastest to slowest): E=A, B, D=C. With '=' meaning approxiately the same, with edge given to first.

Al

spud

you know what stops faster than skidding and e-brakes?

DownRodeo

No, THAT is what some folks just don't get. One will stop you faster, one won't. Go have a test with your friends.

I won't be entering my front-brake-only SS with steel rims into the competition, because I'd certainly lose. Well, assuming zen isn't allowed in the competition. Otherwise I'd smoke you since I'd just take a quick look into the future and know exactly when the person was going to clap.

jfmckenna

And so for some, the real meaning of this discussion is machismo and ego boosting?

aeser

hitting a brick wall

junioroverlord

Of course.

For me not so much. I don't care one way or another, I'm quite sick of this discussion.

treechunk

Has anyone here read the book Bicycling Science ? It's by David Gordon Wilson, Professor of Mechanical Engineering Emeritus at MIT.


He goes REALLY deep into physics (WAY over my head) and explains exactly the laws of physics governing bicycles, why things work the way they work, etc, etc. We're talking, aerodynamics, rolling resistance of bearings and tires, BRAKING, steering and balancing, etc. He actually has a lot to say about rear-wheel-only braking, but I don't have the mental capacity right now to transcribe, and there is NO way I'm going to try to paraphrase.



As for me, I'm aware that the faster one can decellerate/accellerate, the faster one actually travels in the real world. When you have a brake, your decelleration time is faster, and you don't have to hold back as much speed to ride safely. What this means is that one is able to go faster because one does not have to allow as much time/room to decellerate. It's fairly plain in terms of simple physics that SKIDDING IS NOT STOPPING. When you are skidding, it means you have passed the tire's ability to adhere to the road, so you're NOT slowing down as fast as you would if you weren't skidding. That goes for ALL types of skidding. If the tire is not adhereing to the road, you just plain AREN'T slowing down as fast as you would be if you had consistent braking applied to a point short of skidding. By the very nature of how braking works, skipping and skidding are not capable of decellerating safely at the same speed as a bike with proper brakes that is braking properly. It seems to me that it's rather unintelligent to limit the speed at which one can safely travel if the point is to get somewhere in a hurry.


_____________________________________________________________________________________


The reason that races exist that are specifically brakeless is that brakeless people don't have the same chance of winning a race that isn't specifically made to their advantage, given equal speed and strength in riders. Furthermore, if the people who don't normally ride brakeless decide to race in such a race they remove their brakes and ride in a fashion they aren't accustomed to and are more likely to lose.

_______________________________________________________________________________________

My above statement is not intended to point fingers at people, or say that they are bad, or say that any of the people involved are intentionally trying to skew the races in their favor. It's a statement of how things actually work. Whether conciously or unconciously, that's the reasoning behind races of that sort. I personally think it's dangerous and stupid to encourage or push people to ride brakeless, and people who do so should be held accountable for their advice.

46x17

Yeah well, but how come riders riding without handbrakes in mixed races still very regularly place on the podium if there is such a disadvantage? Could it be that the riding without handbrakes somewhat forces you to make your riding style more fluid? I use to think handbrakeless was slower but I no longer do so. I think it all averages out.

treechunk

The point is VERY SIMPLE. If you put those same riders back on a bike with brakes, THEY'D BE GOING EVEN FASTER! Come ON!!! I would say that there are skills that can be learned riding brakeless that would make one a better rider (they can be learned without going brakeless, but it's harder to make yourself learn them) but the simple practical point is that given equal skill and strength, brakeless LOSES.

treechunk

In direct response to your first question, I think lots of the people in the messenger scene gravitate towards a brakeless fixed gear because it's a cultural thing as well as simply having less parts to break. There are always fast people on all sorts of bikes. Some people are so fast they'd school you on a mountainbike with knobbies. Serious roadies, given equal skills, would stomp the **** out of the field in most alleycats. Fixed gears, by nature, are slower than an equivalent road bike. Shifting was invented because it helps you go faster.


Philosophy and feelings don't change the laws of physics.

46x17

Yes gears will make you go faster for sure. That is why the TDF involves gears these days.

However, your post was talking about brakes vs. no brakes (your drive train still is one though) and that was the point I was talking too. I believe the same fixed wheel bicycle (no gears on those remember) can be ridden as fast with a handbrake as it can without a handbrake by the same skilled rider.

noisebeam

Of course it can, no one debates this.
The question is can one or the other stop faster?

(to keep this from being confounded, remember that stopping faster does not always mean safer, safer or not may depend nore on the riders overall urban cycling skills)

ps- a fixed gear bike has one gear, not none.

Al

spud

well i was looking for the more generic impact situation, but yes a brick wall will do.

spud

i think hes referring to the big wheel, penny farthings.

treechunk

The rear brake of a bicycle, applying forces that are LESS than those required to cause the tire to lose adhesion, will cause a bike to decellerate at a rate that is SIGNIFICANTLY slower than that caused by a front brake that is applied to the same degree (tire maintaining adhesion, bike not flipping). Car brakes work the same way.


Obviously, the drivetrain is capable of producing the same speeds no matter how many brakes you have, but it is PHYSICALLY IMPOSSIBLE to stop ANY VEHICLE as fast with just rear brakes as one can with both front and rear. IT JUST DOESN'T WORK!


If you don't believe me, ask an expert! Jobst Brandt, Sheldon Brown, David Gordon Wilson, your physics professor, whoever!

treechunk

I was addressing the part of your response where you talked about the podium in a regular alleycat. Gears have DEFINITE bearing on that.

Ira in Chi

Sam, the crucial point here is your assumption that the ability to stop quickly makes you a faster urban rider. As you know, stopping is often not the best thing to do in a dangerous situation. Therefore, the ability to stop quickly will not necessarily give one of a pair of identical riders the advantage of speed, especially in the city. Your physics are rock solid, I'm questioning the philosophy

treechunk

What I'm saying, in terms of actual street performance, is that the ability to SLOW DOWN faster and SPEED UP faster, adds up to more time spent at higher speeds, which will add up to getting places faster. Those two abilities really work best if you have both of them (brakes and lower gearing).

onetwentyeight 

I find that the ability to pace and keep myself hitting green lights, as well as how to carefully navigate through traffic is more important than actually hauling ass. i get passed by mtn bikes and roadies all the time, but i always catch up 3 blocks later when they get stuck at an intersection and i just leasurely paced myself to hit 7 greens in a row.

Ira in Chi

The only thing a brake helps you do is slow down faster. If you're constantly tempted to dump speed, your average goes down. A good brakeless rider rarely stops, hence less fluctuation and better average. I'm playing devil's advocate a little, but the fact is there are two different techniques and between two skilled riders, one isn't necessarily superior.

treechunk

This is true, provided you keep hittin' the greens (no pun inteded). This would be negated if you were riding anywhere with stop signs (given the fixed/brakeless assumption). Personally I find it impossible to hit ALL the green lights at speeds that are sufficient to get my late ass to work on time. I rode a tallbike exclusively for a pretty long time, and that involves even more pacing ability than riding fixed does. It's MUCH harder to trackstand a tallbike (I've seen it done) and getting up and down is such a pain that it's better to ride very slowly up to the light and time the green than it is to do anything else.

46x17

Thanks that is what I was trying to say.

treechunk

while a good brakeless rider might stop less (true, in my experience) they do have to slow down a good deal sooner and more often to gauge traffic situations ahead to allow adequate time for safe stopping.

46x17

I said gears. The "s" at the end of the word is for plural.

46x17

And I agree - gears in general are faster.

But you said that brakes are faster which I don't agree with.