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Old 06-02-05, 02:02 AM   #51
Raiyn
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Originally Posted by lisitsa
Does the weight of the disk brake mean the front wheel has to be dished to the side? I honestly think that rim brakes are a much sleeker and aesthetically pleasing braking solution, and roadies are all about aesthetics.
The weight has nothing to do with it, and the dish is extremely minor far less than say a standard rear wheel.
As for aesthetics. Argue with this
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Old 06-02-05, 06:57 AM   #52
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Originally Posted by Rowan
You all do know that the limiting point for either disc brake system (rim or rotor) is the adhesion of the tyre on the road surface? It doesn't matter a hoot how much stopping power one or the other can theoretically provide, once that point of adhesion is exceeded, you're in lock-up mode.

I like the rim disc system -- it's simple, efficient when properly adjusted for mechanical advantage and with pads that are of appropriate compound.

The only distinct advantage I can see for disc brakes is the heat factor on very steep downhills with sharp, low speed corners. But I have not encountered melted tubes from that yet, so I am happy with my current set-ups.
Wet weather?????????Snow,ice,road salt etc etc etc, all of the things most roadies hide from, hence, no disc brakes.Form follows function with bikes, it isnt rocket science.
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Old 06-02-05, 07:25 AM   #53
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Originally Posted by Rowan
You all do know that the limiting point for either disc brake system (rim or rotor) is the adhesion of the tyre on the road surface? It doesn't matter a hoot how much stopping power one or the other can theoretically provide, once that point of adhesion is exceeded, you're in lock-up mode.

I like the rim disc system -- it's simple, efficient when properly adjusted for mechanical advantage and with pads that are of appropriate compound.

The only distinct advantage I can see for disc brakes is the heat factor on very steep downhills with sharp, low speed corners. But I have not encountered melted tubes from that yet, so I am happy with my current set-ups.
What you're missing is one of the primary advantages of disc brakes, a better ability to modulate. It allows you to get closer to the critical point of adhesion, without exceeding it. You can brake harder because you don't have to worry so much about over-braking.
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Old 06-02-05, 12:32 PM   #54
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What you're missing is one of the primary advantages of disc brakes, a better ability to modulate. It allows you to get closer to the critical point of adhesion, without exceeding it. You can brake harder because you don't have to worry so much about over-braking.

exactly: You can stop the bike faster if you can remain on that fine line of not quite loosing traction.
Just another way to say it.
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Old 06-03-05, 09:46 AM   #55
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Originally Posted by FarHorizon
Please post feedback once you've talked with your friend. I'd be very interested in his comments. Thanks!
My friend has owned his own bike shop for about 20 years and was in the bike business all his working life. He was working on these things in the 70's. I saw two of them at his shop when I was working for him once. One of them was a Sears "Freespirit" The disk was on the rear wheel only, as the fork was not stiff or strong enough. They were not high end bikes, they were 10 speed road, almost entry level, bikes. The brakes did not generally stop the bike well, and the customers always complained about them being noisy. I think the rotors were plain steel too. I’m not positive. They were cable activated. The other one I
saw was on an old 10 speed of another brand, neither one of us can remember what it was. It was also only on the rear wheel. I think the possible rusting of plain steel, the weight, the fact the they were on the wrong wheel for most of the stopping power, and maybe just poor leverage on the activators, made them not right for the bikes of the time. He says there were adjustable and had a worm gear to work them. It was probably hard to sell them at the time.

I think disk brakes sold well on mountain bikes because the typical mountain bike ride consists of dirt, water, mud, and a steep downhill. Often one right after another. Most riders can actually understand the difference in a few rides, even if they are not technical or really into it. You can feel it right away and it is not difficult to sell them. The customers perceive a real benefit from it. And the forks need to be beefier than a road bike anyway.

The problem with a well designed modern disk on a road bike is that a lot of riders never go in the rain, many don't go on large downhills, and the bikes don't get as dirty. I don't mean it never happens, I'm saying the amount of riders that do that is much smaller than on mountain bikes.

Even if a disk can be made to be a better product, I think it will be hard for the customer to perceive a benefit, even though it's there. I think the sales of a road bike disk would be more of a problem than making a nice small quality one. In the end if it does not sell, it does not matter how good it is. No one in their right mind will keep making them.

That's just my guess.
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Old 06-03-05, 10:19 AM   #56
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That or there won't be any benefit but people will buy them anyway for aesthetics or some other silly reason. Markets are fickle.

Seems like some road bikes were marketed with suspension forks not that many years ago after they became popular on mountain bikes. I believe one of the claims made was less fatigue because of the more comfortable ride. Like disk brakes on road bikes, an answer to a question nobody asked.
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Old 06-03-05, 11:52 AM   #57
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I like rim brakes just fine on the roads too. I ride in the city, I'd be replacing my rims with the same frequency with or without wear to the braking surface. I'm sure if road discs can be made to be as light but more expensive than high-end calipers that BLLs will buy them. To me the aesthetics of the current high end road bike would be marred by anything but the very finest in disc brake evolution, I'd need the cable inside both the fork and the frame, especially if hydraulic. The mechanical component would need to be extremely low-profile and polished. The rotor wouls need to be small, as small as a high flange hub. It had better be pretty and it had better be adjustable enough for me to continue using front brakes only for 97% of my braking i.e. not locking up, has to be ABS.

Someone posted a picture of a dirty RockShok with a midrange disc brake and a sawblade rotor on it and asked people to argue against its aesthetics? It's dirty, tied on with a ziptie and completely overbuilt for road applications. From a MTB perspective, it's fine, certainly not great, just okay. From a road perspective it's dirty, primitive, heavy and entirely unneccesary. Miles from anything as pleasing as this:
From a road perspective.
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Old 06-03-05, 12:06 PM   #58
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I'm not a roadie, but damn SamHouston...that's sweeeeeeeeeeeeeeeeeeeeeet
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Old 06-03-05, 02:35 PM   #59
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Originally Posted by cydewaze
you don't need the stopping power in the mud and such because (hopefully) you aren't riding through the mud and through streams on a road bike.
well dont they need more stoppping power? less wheel touches the ground meaning more force needs to be used?

am i right or is it just me?
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Old 06-03-05, 02:36 PM   #60
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well dont they need more stoppping power? less wheel touches the ground meaning more force needs to be used?

am i right or is it just me?
I don't think it's a question of more power, most rim brakes will lock up in premium conditions with a ride of any weight on them. a disc brakes just allows the power to be used more effectively in ill conditions.
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Old 06-03-05, 04:27 PM   #61
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It just seems that most of these road bikes are sub 20 pounds, and it would be difficult to do that with disc brakes. For most instances, you just dont need discs on the road, its that simple. How often do you hit real mud on the road? Even if they made the calipers as light as Campy record brakes or whatever with tiny rotors, you need beefier wheels to withstand it as well as a fork.
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Old 06-03-05, 04:37 PM   #62
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Quote:
Originally Posted by SamHouston
Someone posted a picture of a dirty RockShok with a midrange disc brake and a sawblade rotor on it and asked people to argue against its aesthetics? It's dirty, tied on with a ziptie and completely overbuilt for road applications. From a MTB perspective, it's fine, certainly not great, just okay. From a road perspective it's dirty, primitive, heavy and entirely unnecessary. Miles from anything as pleasing as this:[IMGkilled]http://www.campyonly.com/images/history/deltas/carbon_deltas.jpg[/IMG]
From a road perspective.
Oh my stars and horrors! Someone's afraid of getting dirty!
That SOMEONE was me Sparky.
The zip tie is there to help route the cable much like you use them to route a computer wire for when you're trying to match Lance's cadence in your spandex roadie fantasies.
I mock your carbon brake as it is totally impractical for any real world application. Primitive? Ha! Let's see who can stop better you elitist hack.

Just as a side note how about you post a picture of your REAL bike.
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Old 06-03-05, 07:08 PM   #63
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Gotta love all the excuses, its not pretty enough, its too heavy, I dont need it.

Translation------I ride only when its sunny and nice and part time at that, and I spend more time ogling over my bike than riding it

difference in weight is about 1 pound- 1.5lbs if that

stock normal rims are just fine,its just a hub and fork change, only need a disc up front where its gonna do some good anyway

Now if you ride like the typical roadie and only ride a couple thousand miles/yr in nice weather then NO, you wont need a disc,it wont help you.Ride in the rain,snow,ice, and salt and you'll fall in love with it and wonder how you got by without it.Its an extra pound or two, sheesh, in real world conditions that equates to almost nothing unless your racing AND in great physical shape to begin with.
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Old 06-03-05, 07:52 PM   #64
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Originally Posted by Raiyn
Oh my stars and horrors! Someone's afraid of getting dirty!
That SOMEONE was me Sparky.
The zip tie is there to help route the cable much like you use them to route a computer wire for when you're trying to match Lance's cadence in your spandex roadie fantasies.
I mock your carbon brake as it is totally impractical for any real world application. Primitive? Ha! Let's see who can stop better you elitist hack.

Just as a side note how about you post a picture of your REAL bike.
Well don't get em' all in a twist over a response that wasn't insulting. I've probably posted a few pics of my own different rides in the fixed forum, and no it's not mine, my road bike costs about half as much as any kind of carbon campy delta setup.

However you asked someone to argue the aesthetic of your arrangement and that's what happened. Like I said, from a MTB perspective it's fine, from a road perspective it's not and the thread is about -road- disc brakes. I don't use a computer btw, I'm not a roadie, I'll ride anything and have. I do wear lycra not spandex in road and off-road races when I'm lucky enough to participate but then again I believe in the right tool for the right job. For instance if I did as you and decided to argue with someone on the internet I might mention that riding the road is a real world application and then falling back on the whole "right tool for the right job" invite you to attempt a race on the road from 50yds to 100 miles you on your MTB and a rider of equal ability on a road bike and see how it turns out. How;s this for a real world application? I picked and dropped 14 packages today logging around 27k then went home had lunch and went to work at my other day job. I was on the road and surprisingly enough on a road bike although I've done the job in the real world on MTB(11), cyclo(1), fixed(1), road(5), touring(1), SS(1), hell I even once commuted into downtown on my wifes SS cruiser. You want to limit yourself that is your business.

relax, remember the question, breathe....you asked aesthetics, no one was out to get you.
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Old 06-03-05, 08:42 PM   #65
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Originally Posted by SamHouston
I like rim brakes just fine on the roads too. I ride in the city, I'd be replacing my rims with the same frequency with or without wear to the braking surface. I'm sure if road discs can be made to be as light but more expensive than high-end calipers that BLLs will buy them. To me the aesthetics of the current high end road bike would be marred by anything but the very finest in disc brake evolution, I'd need the cable inside both the fork and the frame, especially if hydraulic. The mechanical component would need to be extremely low-profile and polished. The rotor wouls need to be small, as small as a high flange hub. It had better be pretty and it had better be adjustable enough for me to continue using front brakes only for 97% of my braking i.e. not locking up, has to be ABS.

Someone posted a picture of a dirty RockShok with a midrange disc brake and a sawblade rotor on it and asked people to argue against its aesthetics? It's dirty, tied on with a ziptie and completely overbuilt for road applications. From a MTB perspective, it's fine, certainly not great, just okay. From a road perspective it's dirty, primitive, heavy and entirely unneccesary. Miles from anything as pleasing as this:
From a road perspective.

NOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!!! Not Campy Deltas!!!!

















Wait a minute, didn't I mention Shimano AX a while back???
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Old 06-04-05, 02:44 AM   #66
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The friction loses on Disk brakes are real. The V-Brake has no contact with the rim thus no friction loss. If you ask a racer what what would they choose? A bike with friction loss or one without, the choice is obvious.

Furthermore, a pro-cyclist is not going to spend a lot of time on the brakes. This is not a spot that requires you to dive deep into a corner again and again like Nascar. A pro-cyclist who spends lots of time on the brakes is probably at the end of the pack. I suspect the brakes on Lance's bike look almost new after the race.

Until we see zero friction loss, the V-Brake is not going away from racing. Unless the UCI mandates disks for safty reason, I see no pro-rider willing to compromise his ride for even minimal friction loss. We'll probably see disks made for road bikes but only for recreational rider.
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Old 06-04-05, 05:10 AM   #67
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Originally Posted by Dahon.Steve
The friction loses on Disk brakes are real.
Hi Steve!

I wouldn't want to say you're wrong here, but I haven't had any friction loss on my bike at all. I've got Avid road discs. Every once in a blue moon, I notice pad drag (I can hear it instantly), but a quick click on the pad adjusters makes all right with the world again. I also believe that I haven't had any friction loss because I can pick up either wheel off the ground, spin it by hand, and watch it slowly spin down with no visual or audible loss, and no irregularity to the spin.

I'm not saying that my experience is universal, but so far I have no friction loss. In your opinion what brands and styles (MTB, road, hydraulic, mechanical) of discs cause friction loss? Also, what percentage of that brand/style would you think have friction loss?

Thanks!
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Old 06-04-05, 05:58 AM   #68
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Like most everthing disks and road riding are compatable, but it depends on the bike use and in some cases the terrain. IMO they have disadvantages on road bikes designed for racing venues.

The friciton issue is bogus. However, the aerodynamic and weight issues are paramount. Newer dual pivot calipers brakes with good pads work in racing applications. Unlike their single pivot older siblings, they stay adjusted and require some but minimal maintenance.

Not all riders, in fact many avid distance as well as some speed crazed recreational riders and dedicated commuters could benefit from disk equipped road bikes bikes. The difference in the performance level of the bikes as to weight and aerodynamics would hardly be noticed by most.

The term road bike used in these forums and others, tends to mean a road racing or crit machine or possibly a TT bike. No disks on these.Tri bikes either.

They can be found on Cyclocross, Touring and some really nice flat bar road bikes. There is a new generation of bikes that many manufacturers are touing with that are sort of compacts but with a slightly shorter sloping top tube and a longish headtube. These dropped bar bikes provide a more heads up positioning and the varied hand positions of dropped bars. Some of these could benefit from the addition of disks.
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Old 06-04-05, 11:12 PM   #69
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That makes sense. A rim brake has a much longer 'arm' than a disc brake. Therefore, to create the same amount of torque, a rim brake has to create forces that are 5 to 10x as much. Depending on where the brake pads are, applying a force 5 to 10x your breaking force could pull the wheel right out.
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Old 06-05-05, 01:16 AM   #70
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Quote:
Originally Posted by Dahon.Steve
The friction loses on Disk brakes are real.
On a poorly setup system maybe. I have no such losses on mine or on any that I setup for others
Quote:
Originally Posted by DiddlBiker
That makes sense. A rim brake has a much longer 'arm' than a disc brake. Therefore, to create the same amount of torque, a rim brake has to create forces that are 5 to 10x as much.
Actually that's backwards the leverage force of the outside of the wheels acting on the hub is greater. We've all stopped a moving wheel at the rim with our fingers - no big deal. Try that at the hub or by grabbing hold of a disc rotor and you'll lose a finger.
Code:
I'm reposting my reply to an earlier debate on the subject http://www.bikeforums.net/showthread...087#post833087
Rim vs Disc What's the difference?
The difference is friction. Friction is of course the force acting against the momentum. Friction under all circumstances will be greater in a disc system than a rim system. Not even ceramic rims and their pads can compare to the sustainable friction of a disc system. Not to mention the effects of inclement conditions on rim brakes.

Let's start by taking a look at the physics involved. There's a law of physics that states how an object in motion has a certain amount of energy due to its momentum. This energy is called kinetic energy. In order for this object in motion to stop or slow down, it must lose some or all of its kinetic energy. It does this by converting the kinetic energy to heat.

It's pretty simple. At your wheel you have a metal disc and a set of friction pads. The pads squeeze or push onto the metal. When this happens, you create friction. Friction generates heat, of course. Since the wheel is turning, then the kinetic energy of your momentum is converted to heat at this point and discharged harmlessly into the atmosphere (with a slight loss of pad material), and your bike slows down. The faster it is going, the more heat is needed to stop it. The more pressure you apply to the pads, the faster it can discharge the kinetic energy. The disc aids in the discharge of the heat generated it's surface area allows heat to dissipate harmlessly. A larger disc aids the process of heat dissapation.
Rim brakes work well, but they have a hard time shedding heat well enough to prevent fade when used really hard. Brake fade occurs when the brake overheats dramatically and braking power is vastly reduced.
Facts
  • Disc brakes handle heat load and dissipation better than calipers.
  • They don't transfer the heat generated directly to the rim, like calipers.
  • Disc rotors are MUCH cheaper to replace than an entire rim (as low as $15).
  • As far as being able to lock a wheel: yes you can lock a wheel much easier with a disc than you can a caliper of any type, however if your brakes are PROPERLY setup, you also have greater modulation with less effort than any caliper system ever invented.

Do I have V brakes on my road only commuter? Yes, due in no small part, to the fact that both my frame and fork are not disc compatible. As I plan on eventually (after my shock upgrade on the trail bike) swapping out the fork on my commuter for a rigid model that has disc tabs I will not be without the added all conditions stopping power of discs for much longer. It is also possible that I may even just get a fork with V-brake bosses as the current setup is adequate for most everything I encounter while commuting in Florida, but it's funny how things can change.
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Old 06-05-05, 01:50 PM   #71
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Why would you want discs on a road bike?
Current technology provides more than enough stopping power in most conditions. Sure, braking in the rain is sketchy - but if you had discs, your lack of friction (read traction) would simply be transferred to your tires. Ouch! Yes, your rims get marred, but you'd have to do a lot of miles in the rain down lots of hills to wear through the rim flanges.
And why would you want a brake that has the disadvantage of far less mechanical advantage? Just spin a wheel in your hand and try to stop its rotation by the hubshell. Hard. Now grab the rim/tire and it's easy to stop. Using beefy, heavy hardware needed to create the clamping forces needed to stop a mountain or downhill bike or tandem makes sense - the benefit is worth the cost for sure. But on a road bike? Why fix something that isn't broken?
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Old 06-05-05, 01:54 PM   #72
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I was going to have disc brakes on my road bike, then again, I'm like 2x the average rider.
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Old 06-05-05, 02:06 PM   #73
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"The larger disc aids in the discharge of the heat generated the increased surface area allows heat to dissipate more quickly
Rim brakes work well, but they have a hard time shedding heat well enough to prevent fade when used really hard. Brake fade occurs when the brake overheats dramatically; braking power is vastly reduced.
Facts
Disc brakes handle heat load and dissipation better than calipers.
They don't transfer the heat generated directly to the rim, like calipers."

Discs HAVE to handle heat better because they create much more heat in the process! It's solving a problem created by the solution. Doesn't make sense to me! A road rim doesn't get very hot under most riding conditions. And I've never blown off a clincher on ANY road descent. (Tubulars present a different problem, but I don't think worth addressing.)
Now, I can't back this up with testing, but it would seem to me that a rim would be better at dissipating heat due to larger surface area moving through the wind -especially at the top of the wheel where it's moving faster opposite to the direction of travel. And if I remember, aluminum (rims) transfers heat better than steel (rotors). (Aluminum has a lower heat capacity, but higher conductance.) And it's true that a rim does directly heat the tire, it dissipates what little heat it generates very quickly.
And you say "larger disc." Larger than what, a smaller disc? Any rotor is much smaller in radius than the rim. So, what's your point?
Tandems, downhill, mountain and cross bikes are a great application for disc brakes. But road brakes work just fine; don't fix a nonexistent problem.
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Old 06-05-05, 02:16 PM   #74
PWRDbyTRD
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8" rotors work a ton better than 6"
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Old 06-05-05, 02:38 PM   #75
slvoid
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Honestly, now that I have some sanded down koolstop brake pads on my litespeed, that thing grabs much better than my giant ocr with disc brakes. Stopping distance is just about the same but I can consistently do that with discs and not have to worry, the modulation is much better with discs.

For road riding, road brakes are just fine.
But if I'm commuting year round, I want discs, they work better in the rain, they stay away from the grime on the road when I ride through the industrial park, it's cleaner, the squeal makes me sound like a truck which is pretty cool, and it looks cool.

As far as heat dissipation is concerned, the only areas where you will need to is if you plan on dissipating a lot of kinetic energy, and I mean a LOT, like several hundred pounds of tandem or if you plan on descending a 20 mile 10% grade and you don't want to die.

What I want to see is a really strong and thin 2.5" wide carbon brake disc. I just want to see my brake discs glow at night. Forget dissipation, I want heat retention.

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