Feltup

Yeah, wiping those rims off with a damp cloth takes forever.

Why can't you have discs on a road bike? Can you not build your own wheels. Is it because you would have to use a flat bar?

mtbikerinpa

Because to do so on my current student budget and means would require custom producing mounts on my frame(not impossible, just not practical for me at the moment).

What is this about a flat bar?

swifferman

hurrah for dual pwnage

Flat bars are basically mtb bars and drop bars are the ones with curved hadnels pointing down on road bikes.

I think it has something to do with weight on road bikes maybe.

mtbikerinpa

I know what they ARE, but what is the slight of hand that I am not seeing?

crgowo

I think he's hes trying to say that you would need a flatbar for discs brakes since they dont make road brake levers in hydro.

mtbikerinpa

A little custom work, no big. lol. Honestly, I would just get the road mechs instead. The conditions are not as demanding of them as a trail race would be.

Dannihilator

Then how come companies are switching to discs Mr. I'm too caught up in the purple annodized craze from the late 80's to early 90's to notice that the industry has evolved rapidly.

It's a rider's choice to select between discs and V's. It also depends on the person's budget and intentions for the bike. I can see a person using vee's where it is flat and/or the rider is very light and does not need the power of discs. But if you are average weight and live in a hilly region, disc brakes are the way to go. Ironically disc brakes are the only way to go if you have a bike that won't accept v's. Me, another Downhiller and Freerider, V's would be suicide, and very costly. I don't want to change rims every two/three weeks because the pads wore through the rims at those speeds.

I'm also an urban rider, discs allow for more tire clearance.

Raiyn

V brakes work for me. On my commuter. On my Trail bike I run a set of Avid Mechanicals. I don't know what kind of riding you do, but I have seen MTB rims come in that have had to be retired due to having their sidewalls worn concave so this generalizatiion that the wheel will be destroyed by another means before the sidewalls are worn out is largely incorrect.
Your preference. Personally I think mine are (to quote a rather obese Austin Powers character ) Dead Sexy.
The only reason you may never see disc brakes on a road race bike (notice the word may) is due to the weight penalty.

Why are discs better than rim brakes?

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. The surface area of the rotor 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. The fact that rubber compound rim brake pads can only sustain so much heat and pressure before they break loose is another key point as is the fact that disc pads, being made of a more durable substance, are not prone to the same failures.
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.

side note: Watch out roadies there's rumors of a composite / ceramic rotor in the works with a new ultra light caliper.

Dirtbike

im no roadie but that sounds quite interesting. would a ceramic rotor really be strong enough?

Raiyn

They've used ceramics in many different applications over the years from jet turbine fan blades to armor systems. Hell I even had a knife that had a ceramic blade on it. Trust me it can be done.

Feltup

I don't ride down hill. I am talking about mountain biking. You know where you have to pedal as much as you have to brake. I think some of the problem is that new riders ride the brakes all the time. I have been MTBing for 17 years and have never worn a rim out with Vs. I actually have a couple of old wheels sitting in my shop that are 11-12 years old and still have life in them. One set has went through 20+ pad changes. Now I do go through pads especially on one local trail when wet/raining. I keep reading modulation, modulation. I ride different. I am using them hard or not using them at all. I agree if you got the pad always scraping the surface of the rim you can wear something out. But that is just rider error. Basically riders need to learn how to use their brakes.

You will never see them in the Tour.

mtbikerinpa

Ever read Mountain Bike Action? The are constantly saying how heavy braking, 'on-off' braking is bad technique and anything that would cause a skid other than in a race is bad. Modulation is good. Control.

Ever notice what you DON'T find in a tour? It wasn't until a few short years ago you would find helmets in the tour. TdF(or any UCI controlled even) is no reference for technology in my book other than bike wieghts.

Feltup

No I don't read Mountain Bike Action. How is it bad when training but good while racing? Do you really need a magazine to tell you how to brake? I don't lock up my wheels unless going around a tight turn. But I do use the brakes when I need them and stay off when I don't. I see it all the time riders keep the brake levers half open and brakes rubbing all the time. I call that bad rider skill. Modulation is usless unless you are riding down hill.

catatonic

I don't know how it is in racing, but when I had my V-brakes, on some of the downhills on road I've seen around San Jose, I had both my front and rear pads practically burning after the descent. You could smell the plastic for hours after....god it stunk.

BTW, the v-brake arms were hot to the touch when that descent was done. Since then I've loved my discs...far, far better heat dissipation.

I would love to see copper alloys find their way into disc brakes though...since copper is better at heat dissispation.

bbarend

Would engineering a thin carbon road fork for a disc mount be feasible? What if we all switch to fixed gear and then we won't need brakes.

Maelstrom 

Only problem with copper would be during a crash situation. They would bend like butta, I already go through a rotor a year, I can't imagine crashing using an oversized penny for stopping.

I don't have any issues with current heat on the rotor, my problem is when the oil in the line heats up rendering the brake useless

BBarend, my freewheel broke one time on a dh run. This meant essentially I was fixed. Worst experience of my life, at least in a dh bike

a2psyklnut

Guys remember the original posts. This isn't a question as to what system provides better braking force or modulation but rather the application of the system to the specific rider.

I'm with Mael on this one. You don't "need" discs for the type of riding you stated that you do. You'll save weight which is more advantageous to you and under the conditions that you ride, the linear pull (V's) will work just fine.

I don't need discs. Honestly, I don't. I however would not ever give them up. I like the feel, I ride in muddy conditions, I love to get rained on. I like riding drops and chutes. My descents are short, but steep. I like being able to ride home on a tacoed wheel banged almost straight. For ME, I'll ride discs.

For what you've described, save your money and get a set of good linear pulls and some better pads (as referenced early on).

The_Convert

LOL!

that should be enough to keep us from wasting ourr time on this guy.

By the way, they are not going to be in the Tour (anytime soon anyways) only because they are not permitted by the UCI. They have also been banned from ''Cross.

bac

There are more advantages to discs than just the ability to stop well in in wet/muddy/snowy conditions. Really, the ONLY disadvantage to discs are the little bit of extra weight. If you don't race, that is a non-issue. If you do race, you'll get more braking power, and much less fatigue from braking. The bit of extra weight is worth it for me. You'll also get:

-Disc brake pads that last MUCH longer than V-brake pads
-Great modulation
-WAY more power (one finger braking)
-If you bend your rim, you can still go (and stop!) with discs

Good luck with your choice, but for me, there really isn't a choice @ this point.

sparks_219 

I totally agree with what you said before. However, this guy already has avid mechanical disc brakes. To me, it just doesn't make sense to spent the extra money on V brakes because he doesn't sound too much like a weight weenie.

However, if he's willing to spend some money to save a pound or so off his bike, then definitely go to V-brakes.

Cheers

Ming

jayson

Maelstrom mate the guy was asking about XC brakes not DH or FR, and secondly i live in yorkshire where we have some of the finest terrain anywhere in the world with 'ups' and downs i.e. XC so sorry to pi$$ on your bonfire I stand by what i said, V brakes are crap and should killed off soon as. I only hope the mountains aint as big as your ego mate or you really are in trouble with your fading brakes. Over to you....

Maelstrom 

No ego my friend. I just disagree with your point. I stand by my point proven. Discs's aren't required.

telenick

Geez, it's just a brake question. I have both and love then equally.

telenick

You mean like this?


You have a point bbarend. But some might need new knees after many miles of fixed gear riding. I'd like to keep mine in tip top shape for turning in fresh milk. That's powder skiing to those of you who don't know the sumptuous feel of dropping a knee in three feet of freshies like I did this weekend.

swifferman

Take 3 seconds and look at his location...

yes, thats right.

Oh but of course, the world famous Yorkshire! How can we contend with that!?