Why is no one using disc brakes in the tour?

Discuss light weight issues concerning road bikes & parts.
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Lewn777
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Joined: Thu Mar 09, 2017 5:35 am

by Lewn777

maddog 2 wrote:
Marin wrote:
Braking distance is limited by tire traction, not brake type, ..


The nugget that keeps on giving :roll: Braking distance is down to the rider's ability to modulate braking power. For front end braking (in the dry) this isn't anything to do with tyre traction, as you'll go over the bars before you lock up the tyre. So it comes down to how close you can get to lifting the rear wheel, and discs modulate much better than rim brakes in doing this. Rim brakes are harder to hold on this balance point, and the blocks get hot and so their consistency suffers.

Marin wrote:and I can brake hard enough to lift my rear wheel on almost all of my bikes, rim or disc.


I wouldn't dispute this. But you can hold it at this point with more control on discs.


Sorry but I don't understand this point. Simply on a road bike you have a tiny contact patch. You can easily lock up either wheel with any road bike with a well maintained rim or disk brake on any dry road. You can also modulate that perfectly well with either brake type. I could do a 'no way endo' with any kind of modern rim brake or disk brake on a good dry road surface, and that is all down to understanding how to pull the brake lever correctly. The point should be made however that a 5800 brake or above will help as will new pads and a very good quality brake track. For example in nearly every way I prefer my Campy wheels to my DT Swiss, except that I massively prefer the modulation feedback on the DT Swiss rims. There are so many variables that making bold statements about how rim brakes behave is liable to hideous generalizations.

Yes, all things equal I prefer disk brakes, but alas they add somewhere between 600 grams to a kg to your bike. Last time I switched my heavy 1900 gram wheels for 1300 gram aftermarket wheels kit changed the entire feel of my climbing bike, something a cold day in hell before I add that weight back on to my wheels whilst adding probable brake rub and increased maintenance.
Last edited by Lewn777 on Thu Jul 20, 2017 3:58 pm, edited 1 time in total.

MoPho
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Location: NorCal/SoCal

by MoPho

Marin wrote:
Braking distance is limited by tire traction, not brake type, and I can brake hard enough to lift my rear wheel on almost all of my bikes, rim or disc.

The one bike where I can't is my BMX. It doesn't have a front brake.



Well it seems you have plenty of traction then. 8)



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by Weenie


Hexsense
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Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

Are you all sure you can lock up front wheel?
I know, rear wheel is easy to lock up. But front?

I saw some novice tend too brake to hard they fly over the bar. That's kind of locking up the wheel with the brake but the wheel doesn't stop rotating. Thus rider flip over the bike. This is due to bad weight balance. And it tell us that the traction on front wheel is so great (due to being rotation point, unlike rear wheel that'll just lift and skid). Even more than the force that lift people up and throw over the bar.
Then if they learn to move center of gravity far back on braking (sit by the far back end of the saddle) so they won't flip over the bike when brake hard. Then in this case front braking is very hard and doesn't flip over. I've yet to see anyone at all can lock front wheel up with proper weight balance. Maybe there are, i just never seen one.

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Lewn777
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by Lewn777

Hexsense wrote:Are you all sure you can lock up front wheel?
I know, rear wheel is easy to lock up. But front?

I saw some novice tend too brake to hard they fly over the bar. That's kind of locking up the wheel with the brake but the wheel doesn't stop rotating. Thus rider flip over the bike. This is due to bad weight balance. And it tell us that the traction on front wheel is so great (due to being rotation point, unlike rear wheel that'll just lift and skid). Even more than the force that lift people up and throw over the bar.
Then if they learn to move center of gravity far back on braking (sit by the far back end of the saddle) so they won't flip over the bike when brake hard. Then in this case front braking is very hard and doesn't flip over. I've yet to see anyone at all can lock front wheel up with proper weight balance. Maybe there are, i just never seen one.

I my opinion you can't really use a front brake properly unless you learn to endo, rolling endo being the ultimate mastery of the skill. A heavy progressive squeeze of the brake. This can be done on almost any bike, motorcycle, mountain bike, road bike and on almost any surface. You can also lock up the front wheel by yanking gobs of front brake. Whether you go over the front bars or not instead depends on the pitch of the road surface, body positioning and surface quality.

TurboKoo
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by TurboKoo

I'm just saying that those who can have no problem controlling modulation with rim brakes.
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MoPho
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Location: NorCal/SoCal

by MoPho

Lewn777 wrote:I my opinion you can't really use a front brake properly unless you learn to endo, rolling endo being the ultimate mastery of the skill. A heavy progressive squeeze of the brake. This can be done on almost any bike, motorcycle, mountain bike, road bike and on almost any surface. You can also lock up the front wheel by yanking gobs of front brake. Whether you go over the front bars or not instead depends on the pitch of the road surface, body positioning and surface quality.



By that argument, you don't really know how to pedal unless you can ride a wheelie. Sorry, but an endo or rolling endo (stoppie) is as much about knowing how to shift your weight and balance as using your brake. In fact there are BMX Freestyle guys who can do it (and even crazier stuff) without brakes at all. It's certainly not an indicator of knowing how to use your brake properly or brake performance.
And I would argue that knowing how to hit the brakes hard without doing an endo or locking up a wheel is a more useful life skill, you want both wheels on the ground doing the work. In an emergency stop, doing an "endo" usually results in the bike stopping and the rider not so much.

On dry roads, I have never found [front wheel] traction to be the thing holding back the available braking on a road bike.



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lobuxracer
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Joined: Fri Jun 23, 2017 5:09 am

by lobuxracer

DOUG wrote:
lobuxracer wrote:
DOUG wrote::lol: I'll make sure to run my purchasing decisions past "the Europeans" before buying anything then. Oh wait I already ride a road bike with discs! Hopefully the superior braking in the dry and much better performance in the wet will make up for my lack of experience :roll:

You guys crack me up.


Just curious how you define superior. I've raced bicycles, motorcycles, and cars. Superior means many different things in each of these formats. I'm wondering what you mean by "superior" braking.

Before you say something foolish, you might want to read something by a brake engineer http://www.scirocco.org/faq/brakes/pulpfriction/pfpage1.htmlwhose credentials include http://www.teamscr.com/about-james-walk ... r-jr~.html vehicle stability systems for OEMs.

Suffice it to say, regardless of your religion, the tire determines your braking performance regardless of how you choose to extract heat from forward motion.


Thanks but I understand how braking works, maybe you don't? I'm not going to bother going through all the advantages vs disadvantages as thats been done ad nauseum on here and on every cycling forum in existence but i will say that disc brakes are far more efficient at converting kinetic energy into heat so I guess you're proving my point for me. As a Mechanical Engineer, motorcycle, car, MTB and road racer I'm in a good position to assess the benefits of disc brakes. I've thought about it carefully and have a lot of experience riding both systems in a range of conditions over many years.

I hope I'm not considered "foolish" but thanks for your concern :roll: Have you ridden a disc brake bike for more than 5 minutes? If so what is your perspective on disc vs. rim?


I've been racing something since '76. I consistently stopped my 500+ lb FJ1100 in 13 feet from 25 mph in MSF Instructor training way back in 1985. I've locked a front wheel at 120 mph and managed to continue without interruption or panic. I know how to modulate brakes. You still failed to tell me what you mean by superior. Braking performance isn't defined in a single stop, and the only advantage I can see to a disc system is repeated stops won't (potentially) overheat your tires and cause a rim/bead failure from overpressurization. Since this never even comes close in the riding I do, I don't see any advantage to discs at all. I definitely see a weight and complexity disadvantage, a lot like the woman in the bike shop with a nearly new bike who could not get the wheels to turn because the pads failed to properly retract. It's pretty difficult to have a brake issue with rim brakes the same way, and if you do, correcting it takes seconds, and I don't even have to stop to do it. Not the five hours the shop was quoting to solve her issue. So, I don't see disc brakes replacing the rim brakes on my road bike any time soon. It's nothing like when motorcycles went from drum brakes to disc brakes. That was truly a case of superior technology winning and becoming ubiquitous because you could NOT win with drum brakes against disc brakes. Same story with DCT and even SMG gearboxes - you won't win against them with a manual gearbox.

I totally understand why MTB and cross bikes benefit from discs. I just don't see discs being mandatory to win on the road. Ever.
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