True. I didn't think about that.

I'll hook up with you guys soon. I'm still getting my strength and lungs back. I ruptured my Achilles Tendon in Feb. Rehabing now. Right now, I'm only good for a few miles at a time.

C

ouch, i'm sorry to hear that. best of luck rehabbing, and i look forward to seeing you out there.

uhhhh where to begin pointing out the errors in this.

1. Your average normal force cannot exceed that of your wiegth.
2. The inability to apply force smoothly throughout the pedal rotation is another reason why brakes will stop you better then back force.
3. Your normal force when riding is divided between the two wheel. When you are stoping it is mainly on the front wheel therefore only a front brake will stop you almost as fast is two brakes but only a rear will stop you much slower.
4. It soundly like most people exagerate this by leaning forward while skipping or skidding since they aren't strong enough to lock up the back wheel while leaning back.


All of this combines to make skidding your rear wheel much much slower then carefully modulated braking.

uhhhh, reading the thread would be a good start. the big kids were discussing the merits of slowing by resisting the pedals versus skipping/skidding. no one ever mentioned brakes.

normal force, averaged over time, is constant. averaged over distance, it is not. normally i wouldn't dignify such belligerent contrarianism but i write this on the outside chance that you might have confused an innocent bystander. this will be my last post on the matter.

dutret, if somebody here hurt your feelings at some point, that's a shame. i hope you don't let it turn you into as bitter of a person as your posts reflect.

uhhhh where to begin pointing out the errors in this.

The previous posts were "Regarding skidding/skipping versus slowing down" NOT "Regarding skidding/skipping versus brakes".

Reading Is Fundamental

http://www.rif.org/images/hm_reader.gif

I am way too stupid for the internet today.

None of the posts on this page are. I didn't realize you where responding to something numerous posts back.

I still disagree with dirty photons however. Yes you could clearly stop faster if you could vary the normal force so much that you stopped on the first skid. That is skipping however. Yes normal force doesn;t have to always average over distance however in this case the occillations of the normal force are tied directly to distance by the pedals. Therefore in the specific case of skipping it does average over distance.(unless the occilation is of some wierd shape but that would not be "like skipping")

That whole argument is immaterial anyway. The normal force is not the limiting factor in normal cyclists skidding or skipping. If it was people wouldn't lean forward to do them. The limiting factor is leg strength so the fastest way to stop should be a skid and modulated the normal force by shifting your weight forward and backwards.

I for one prefer to use implements designed for the stresses of dynamic friction when dynamic friction is neccessary to stop however so its kinda moot point for me. I do however understand the physics here I just did not reread the entire thread as I'm sure most people who had read it before did.

jeez, I thought school was out too... we can argue high school physics all day if we want, but it all comes down to the riders preferences and abilities. The OP will likely be riding with brakes to start, and then go from there as he/she sees fit.

Here's how I rank stopping power: Brakes, slowing down, skidding, skipping. I personally do not recommend skipping because of the 4 methods it is the least effective and the most likely to taco your wheel (when the wheel bangs the ground on impact).

But, skidding is soooOOOooo cool. Here's how you do it.

The physics of skidding:

Let's define:

static friction = the measure of opposing force that keeps the tire from sliding on the road whether the bike is rolling or not. This is a function of how hard they are pressed together (how much you weigh).

dynamic friction = the measure force opposing between the tire and the road after the sliding has started. This is a function of how hard they are pressed together (how much you weigh).


You are right, when you say "the limiting factor is leg strength". This is true for a lot of riders because they cannot create an amount of force greater than the static friction force. Transferring more force than that of static friction will "break" the coefficient of friction and change the state to dynamic friction, which requires less force to maintain. Beginners typically only use one leg as if with a coaster brake.

Force = Mass x Acceleration. That being said, if your wheel's mass is constant and you can decelerate (negative acceleration) your wheel fast enough, you can create MORE force than the Static Friction force and switch over to dynamic friction. Try using both legs by pushing down with the back leg and pulling up with the front leg (can't do this with platforms).

But wait, boys and girls, there's more. You can lower the Static Friction force that you need to overcome by decreasing the force used in the binding of the two objects of the friction. Do this by shifting the weight off of your back wheel to the front by leaning forward or hop up (skipping).

This static and dynamic friction are determined by the two surfaces, the tire and the road. Hart tires, grass, wet roads, etc...will slide easier. Soft tires, porous roads, etc...will be harder to slide on.

So, if you want to skid, generate a lot of force, move weight off of the back wheel, and combine two surfaces that make little friction. It's that's simple.










Also, if you want to be invisible, just figure out a way for light to not bounce off of you.