Originally Posted by
cyccommute
You are missing the third scenario…not dragging the brakes at all. In the scenario where you are pulse braking…i.e. brake hard, then no braking, then brake hard, ad infinitum…you are putting the same energy into the system but there are periods of high energy input and periods of no energy input or even negative energy input as the air pulls the heat away. At the end of the descent, pulse braking rims will be cooler than if you drag the brakes all the time.
This is exactly slinky braking you're describing right here. I'm sorry but if I had to ride like that I would go insane.
You just don't get it. Pulse braking, you're braking hard some of the time and completely off the brakes at the other times. Drag braking, you're never off the brakes, but you're applying less force than in pulse braking so you're putting heat into the rims at a slower rate. End of the day you put the same total amount of energy into the rims. Therefore it makes no difference what technique you use. Same temperature.
Applying the brakes doesn't put a magical blanket on the rims that stops them from losing heat. What you're saying is the same as saying, during the time you're sitting down to eat, you body is losing no calories. No mister, your body doesn't care if you happen to be eating at any given moment. It's burning the same 85 calories per hour all day long. Your rims don't care if you're adding heat to them at any given moment. They're losing heat continuously the entire descent. When or how you add the fixed amount of energy into the rims doesn't matter. The only thing that matter is the total amount of energy you put in. Drag lightly the entire time vs brake hard pulsing, doesn't matter. Same total heat energy.
very telling sentence here.
I get it Yan, you've toured in mountains and have gone down big descents successfully a lot, but this comment shows that you are not really comfortable with speed and your assessment of danger is different than mine.
Internet discussions are great, but every descent is different and how fast one can go down a descent and how much one needs to control speed will depend on lots and lots of factors, and one factor is the individuals riding skill and competence at speed, not to mention judgement.
of course, all the real world factors prevail--
-line of sight
-your eyesight and reaction time
-your experience going fast and competency with high speed bike handling
-how you brake, ie using front brake HARD for effective bleeding off speed, (back brake too) and letting off fully to let heat dissapate.
-road surface
-grade
-upcoming turn radius
-possibility of side arriving traffic
-potholes, no potholes
-wind, especially side gusts
-any and all traffic
-intimately knowing the condition of your tires and bike in general
-knowing how to manage your braking system ie proper braking, and constantly assessing the possible changing effectiveness of your braking system and adjusting for that
so one riders "completely comfortable" can easily be another riders "terror filled descent", with death looming, as your blanket comment does seem strongly to suggest your view.
BUT, this aint a pissing contest or who has bigger balls, descend as you are comfortable and competent at, who cares? As long as one is safe and is able to assess from experience what is safe, then its all good.
Improper use of braking though can have serious implications, and that's what this usual discussion always leads back to.....but interblabs writing will never really know how one person brakes.......
Yes that's the thing about touring. You're always riding on unknown roads, by definition. Unless you consider riding the same loop every week around your house to be "touring"? The world has many countries, life is short. I don't waste my life touring somewhere I've already toured before. Therefore the road conditions are always unknown to me.
You have no idea what's coming up on the road. You can be bombing down a descent in a wealthy country with the best roads in the world, but there was a rock fall the previous week and it smashed a hole in the pavement. You have no idea what's in front of you.
I don't have the balls to bomb down a 8000 ft descent without touching the brakes. If you do, good for you. I don't think you're lying. I believe you. Enjoy your exhilaration. Try not to do a
Fabio Casartelli.
Originally Posted by
staehpj1
As far as certain death from a 50mph crash. That is nonsense. The biggest danger would be from going over the side of a dangerous drop off at any speed even a lower one, or blowing a turn and hitting a stationary object. From your description it sounds like the liklihood of that is low there.
The danger would be from crashing on a curved section of road, hitting something stationary, and going splat like a bug. If you're going at motorcycle speeds you will have a motorcycle style aftermath. If you feel curious there are plenty of motorcyclist decapitation / delimbing / disembowelment videos on the cesspool of R*ddit. If you haven't watched any of these videos I highly suggest you do. Modern society is so insulated from death that most people have no idea how weak the human body is. We are meat jello. Land in the wrong way and it doesn't take much energy to break your back. But yes it's situational. Ideally you would just have a bunch of road rash. Yikes.
And by the way, motorcycles have suspension and big tires, touring bikes don't.