So why are disc brakes bad on a road bike? My Cannondale Cycolcross works good and stops but why is it hard to find a replacement wheel set??
OJF

I believe it is mainly due to weight more than anything else, your typical road cyclist is a weight weenie at heart so frown upon disc brakes plus I don't think they offer any real benefit in the majority of conditions unlike they do with MTB's.

Bent rims. It makes for rough stopping. I'm suprised that I didn't trash my rims last saturday when the club went over two sets of railroad tracks that had four inch gaps. The next day the rr crossing was closed for repairs, and today the crossing was smooth. The Mavic Open Pro rims seem to be in good shape.

Drag, and weight.

So why are disc brakes bad on a road bike? My Cannondale Cycolcross works good and stops but why is it hard to find a replacement wheel set??
OJF
On a road bike tire traction is mostly biggest limiting factor in braking, not braking power so discs aren't required. They do make sense considering braking in wet weather and rim wear though.

One german guy has had different approach to disc brakes on a roadbike though: http://www.smolik-velotech.de/bilder/hydraulikbremse/ (pictures)
http://www.smolik-velotech.de/news/smolik/user_archiv.php?mode=show&id=4 (Explanation in German)
- smaller discs for control
- dual disc setup to control fork twist
- dropouts can handle hot discs & brake saddle
It's a interesting concept but might be 5-10 years away from production?

Here are a few considerations -

1) The main benefit of discs is use in wet, muddy conditions. A disc rotor will stay cleaner and drier than a rim. However, in rain alone, both the rim and rotor get wet and require several wheel revolutions for the brake pads to clear the water. Contrary to popular belief, discs require longer stopping distances when wet just like rim brakes. So, you are much more likely to encounter conditions that favor discs over rim brakes while mountain biking than road biking. Disc brakes will not offer any better braking performance in the dry.

2) Disc brakes require a dished front wheel which is inherently weaker than a non-dished wheel. Some consider this a bigger problem on a front wheel than the rear because of greater lateral loads on the front.

3) Disc brakes require reinforced forks which reduce ride quality.

4) Under heavy, prolonged braking, disc brakes are more likely to suffer heat-related failure than rim brakes. Failures seen during testing include fade, melted plastic components, fluid leaks (hydraulic systems), and warped rotors. On the other hand, when a rim brake fails due to heat, it is usually a tire blow-off which might be considered more dangerous than the disc failures. Large rotor discs and those with large fluid resevoirs are more immune to heat-related failures, but these are not common on road bikes.

5) Weight. This includes the extra weight of the brake plus the extra weight required in the frame and fork.

6) Cost.

7) Rotor drag.

Remember that rim brakes *are* disc brakes. The disc rotor is the rim, and the swept area of the brake is much larger than current disc brakes. This means greater potential braking force. There are advantages to discs over rim brakes. However, in most road applications, the disadvantages are greater.

So why are disc brakes bad on a road bike? No more radial lacing at the front wheel.
No more front wheels with a low spoke count :-(

So why are disc brakes bad on a road bike? My Cannondale Cycolcross works good and stops but why is it hard to find a replacement wheel set??
OJF
Others may find them of no value, but for me, they are GREAT! If I'm coming to an intersection at speed, a car runs the stop sign and 20 feet is the difference between stopping and getting hit, it's disc brakes or death. And that's dry. Rim brakes (including cantis and Vs with Travel Agents) will not stop me. - TF

Others may find them of no value, but for me, they are GREAT! If I'm coming to an intersection at speed, a car runs the stop sign and 20 feet is the difference between stopping and getting hit, it's disc brakes or death. And that's dry. Rim brakes (including cantis and Vs with Travel Agents) will not stop me. - TF

Wow. I've done emergency stops with side pull brakes that lifted the rear wheel from the pavement. Any more braking power would produce an endo.

Others may find them of no value, but for me, they are GREAT! If I'm coming to an intersection at speed, a car runs the stop sign and 20 feet is the difference between stopping and getting hit, it's disc brakes or death. And that's dry. Rim brakes (including cantis and Vs with Travel Agents) will not stop me. - TF

The two times I I've tried a true full-on panic stop on my road bike I've done endos... and that was with the old single pivot calipers. I would have crashed anyway, but still... I've observed others do the same. No need for more stopping power than that.

Wow. I've done emergency stops with side pull brakes that lifted the rear wheel from the pavement. Any more braking power would produce an endo.
With any rim brake on a road bike, my hands are not strong enough to lift the rear wheel on the flat. Maybe I automatically shift my weight back and you don't, or maybe my hands just aren't strong enough (or both). Whatever the reason, THEY DON"T STOP FOR ME, so the rest is irrelevant.

I also disagree (again) with this 'lift the rear wheel' as max stopping power. I can shift my weight back and slide both wheels (usually with dire consequences). The max braking power is just before the wheels (usually rear first) lets lose.

TF

I also disagree (again) with this 'lift the rear wheel' as max stopping power. I can shift my weight back and slide both wheels (usually with dire consequences).

On clean dry pavement, this is extremely doubtful. Given the traction coefficient of bicycle tires (nearly 1.0) and the typical height of a cyclist's center of gravity, you'd have to get your center of gravity well behind the rear axle to skid the front wheel - a difficult feat with your hands on the handlebars and feet on the pedals.

Just as an experiment, several times I have tried to skid my front on clean dry pavement, either in my regular seated position, or with my weight as far back as I could. In all cases I have failed - the rear wheel started to rise up without any front wheel skidding.

About the only way to skid a front wheel on a road bike is on loose or slippery surfaces (sand or gravel, wet manhole covers or painted stripes). But in these cases, it is tire traction that limit braking, not the brakes them selves, and the braking rates that the skidding occurs in these situations is well below the maximum braking rate on clean dry pavement.

Here's Sheldon Brown's take on braking:

http://www.sheldonbrown.com/brakturn.html

Maybe it's cause I MTB and also ride motorcycles but I think the day will come when we will have disk brakes that are better & lighter then our rim brakes right now.

I am not sure, it seems like there are some misconceptions about disk brakes... AFAICT Discs are:

- Way less likely to fade & overheat
- If they do overheat you do not blow out your tires
- Far better modulation
- Far better power (yes it is noticeable)
- Far far far better in bad weather

Go down an extended 10% grade on your road bike and you basically have to let the bike run and save the brakes for corner entrances and possible emergencies. Try dragging the brakes for 1 mile down a 10% grade just "because" you don't feel like bombing 40+ mph for whatever reason and you will just about melt your rims brakes if you don't blow out your tires. There are many, many disk brake systems already on the market which can easily handle that kind of duty.

Also on top of the bad weather performance, rim brakes get all crudded up in the bad weather, and they don't regain their stopping power until you stop to clean the pads & rims of all the goop. Disks really don't have this problem anywhere near as badly.

Another potential advantage IF disc brakes are developed and mature for road bikes is the rim should be able to be made lighter, reducing moment of inertia. Further you would have no issues with Carbon rims & finding brake pad material which works on carbon.

Another item that is nice (especially hydraulic discs, which also appear to be lighter since the fluid is lighter then cables) is that they are extremely low maintenance. The pads last forever and there is minimal adjustment required once the system is set up right.

If someone chooses to I can only imagine it is possible to build something interesting like a 4" rotor hydraulic brake system for road bikes which would beat our current rim brakes in all areas, especially power, reliability, durability, etc.. and weight could arguably be competitive given a good enough wheel/rim design.

There are certainly a lot of other things on road bikes which people are spending huge $$ on which are not nearly as much of a functional improvement as disk brakes *could* be. (They are certainly not there today)

I would really like a proper front disk for my fixie... it would allow me to go down big hills and control my speed without the fade issues of rim brakes. It would allow me to carry more weight for commuting, etc.. and still have the same margin of safety. I would definitely love having disk brakes on a touring bike.

I'm with you Ben.

I have Disks on my Cannondale & love them.

Go down an extended 10% grade on your road bike and you basically have to let the bike run and save the brakes for corner entrances and possible emergencies. Try dragging the brakes for 1 mile down a 10% grade just "because" you don't feel like bombing 40+ mph for whatever reason and you will just about melt your rims brakes if you don't blow out your tires. There are many, many disk brake systems already on the market which can easily handle that kind of duty.

The only actual test data that I have seen does not support this view. In fact, it says quite the opposite. The testing was done with prolonged downhill braking on tandems. The disc brakes available at the time, several years ago, all failed at lower temperatures than the rim brakes. I believe that some of the downhill brakes currently available would fare better because they feature larger diameter, heavier rotors.

If someone chooses to I can only imagine it is possible to build something interesting like a 4" rotor hydraulic brake system for road bikes which would beat our current rim brakes in all areas, especially power, reliability, durability, etc.. and weight could arguably be competitive given a good enough wheel/rim design.

There are two factors which primarily affect brake performance. The first is the size of the swept area of the brake. The larger the area, the more braking power. Since rim brakes have a much larger diameter rotor than traditional discs, they have a greater swept area and, thus, the potential for greater braking power. If a small diameter rotor is to be effective, it must have a much wider brake track to increase the size of the swept area.

The second factor is heat. What you do when you brake is turn velocity into heat. The way to increase the heat capacity of a disc is to increase its mass. A heavier rotor can dissipate more heat without warping. You can use an alternative material, like a ceramic composite, to allow the rotor to get hotter without warping, but you will also have to make the other components more heat-resistant. In the tests mentioned above, plastic parts melted and fluid leaked under high temperatures. Increasing the amount of fluid used in the system increases its ability to tolerate heat, but it also increases weight. Other materials can be substituted for the plastic, but these would likely increase cost.

Yes, it is possible to design a disc brake system that would perform better than a rim brake for most road applications, but you would increase cost and/or weight. Given the current product offerings, most road cyclists are better served by rim brakes.

Have you done your own comparison? Are you a road only guy or do you ride a MTB as well?

I recently went out and test rode the Shimano, Hayes, and Sram (Avid) disk brake setups in order to choose one.

I've had 105, Dura Ace, and Ultegra setups on my road bikes as well as most of the Shimano V-brake lineup, several sets of Cantilever brakes, and I've had the high end Avid V-brakes as well.

There is not even any comparison, the road brakes are not even in the same ballpark with the current disk setups. I regularly ride the same roads on each of my two bikes, my local twisty descent the road brakes are fading almost instantly and there is absolutely no way you could stay under the speed limit and descend slowly on the road bike, you basically have to run the bike and brake hard for each corner, allowing the bike to dissipate the heat between the corners. On the MTB you can put one finger on the rear brake alone and descend the whole road at 10-15mph with absolutely no sign of fade, and even if you heat up the rotor it cools in seconds, far faster then a rim can cool off. Using both forget about it, you're not even heating the rotors.

In terms of weight you can already build up a MTB drivetrain with 6" Hydraulics to be quite competitive with Dura Ace on weight.

I think the only reason we haven't seen it happen on the road is it's banned for racing. If it wasn't banned rim brakes would be history pretty quickly.

Have you done your own comparison? Are you a road only guy or do you ride a MTB as well?

Yes, I ride MTBs and motorcycles, too. Up until the end of 2004, I also owned and operated a full-line bicycle shop. So, I've had the opportunity to ride lots of bikes. It sure was interesting riding bikes with brand-new disks. With most of them, we could ride around the parking lot with both brake levers bottomed against the handlebars. They don't work so hot until they are broken in.

My own personal MTBs have not had disks, but I've ridden many with disks off-road. If I get a new MTB, it will probably have disks on it.

There is not even any comparison, the road brakes are not even in the same ballpark with the current disk setups. I regularly ride the same roads on each of my two bikes, my local twisty descent the road brakes are fading almost instantly and there is absolutely no way you could stay under the speed limit and descend slowly on the road bike, you basically have to run the bike and brake hard for each corner, allowing the bike to dissipate the heat between the corners. On the MTB you can put one finger on the rear brake alone and descend the whole road at 10-15mph with absolutely no sign of fade, and even if you heat up the rotor it cools in seconds, far faster then a rim can cool off. Using both forget about it, you're not even heating the rotors.

Does your username BenInMA indicate that you live in Massachusetts? I don't know what roads you've been riding, but I've been riding in Massachusetts for nearly twenty years, and I've never had a problem with braking on descents anywhere in Massachusetts (or New Hampshire or Vermont either, for that matter). My road brakes allow me to ride at any speed I choose, with no fade. I have no problem decelerating at the limits of braking (i.e. just below the rear wheel lift off point) when the need (or whim) arises. And I still use single pivot calipers. I don't know any other experienced riders around here who have any kind of probem, either. If you're having a problem with road brakes on descents, it sounds more like a grip strength or technique problem, not an equipment problem.



In terms of weight you can already build up a MTB drivetrain with 6" Hydraulics to be quite competitive with Dura Ace on weight.

What do you mean by "quite competitive"? Comparing Dura-Ace with XTR, the levers and cables/hoses are nearly the same weight, but the Dura-Ace calipers at 314 grams are about 1/3 lb lighter than XTR disc calipers (208 gm/pair) and rotors (278 gm/pair). In addition, disc hubs are heavier - for example, DT Swiss 240s disc hubs weigh 427 gm/pair, whereas the equivalent non-disk hubs weigh 346 gm/pair. When you add it up, the disc brakes are about 1/2 lb. heavier. Why lug around that extra weight on a road bike, when rim brakes work just fine?


I think the only reason we haven't seen it happen on the road is it's banned for racing. If it wasn't banned rim brakes would be history pretty quickly.

I really, seriously doubt that has any thing to do with - especially here in the US. Firstly, most cyclists don't race, so that only restricts a small portion of the population. And even then, disc brakes are only banned for UCI races - they are still perfectly legal for the vast majority or US road races (most races in the US are run under USCF or local organizations such as as BRAC, OBRA, etc.). So, the disc brake ban only affects maybe a couple of hundred of US based racers who do UCI races, and not the tens of thousands of other cyclists who race, and definitely not the other hundreds of thousands of cyclists who don't race.

Maybe road cyclists haven't embraced disc brakes because they are not fashionable - or maybe because they just aren't needed by most road riders.

I'm curious. Are disc brakes (a fairly recent fad) necessary on mountain bikes? Or, are they just cool? It's a serious question. I think my cantilever braked mountain bike will stop faster than is safe, just like my road bike will with its side pull brakes.

Or perhaps the issue is the difference between riding in Colorado and riding in Indiana. We have steep hills but not long ones. I can't imagine a MTB rider in the Midwest actually needing disc brakes. But then what do I know. I'm just a roadie.

I'm curious. Are disc brakes (a fairly recent fad) necessary on mountain bikes? Or, are they just cool? It's a serious question. I think my cantilever braked mountain bike will stop faster than is safe, just like my road bike will with its side pull brakes.

Or perhaps the issue is the difference between riding in Colorado and riding in Indiana. We have steep hills but not long ones. I can't imagine a MTB rider in the Midwest actually needing disc brakes. But then what do I know. I'm just a roadie.

The biggest advantage in my neck of the woods (north central Illinois) is mud clearance. The clay here sticks to everything. Rim brakes are easily packed with mud. Disks don't have that problem. For riding in dry conditions, there's not much difference to me.

For fmw

I live in the PacNW, and as you know it rains alot here (which is why I'm sitting here typing and not out riding). I highly doubt those cantilever brakes would be considered safe after going through a couple inches of mud and a few mud puddles. You can squeeze those brake levers as hard as you want and you are probably still going to slam into that tree. Disc brakes were a huge advancement for MTB's and I would never go back to rim brakes. You can get your disks wet so they lose power, but the only time I ever did that was by submerging them in the lake. Disks require way less grip, better modulation and stay clean in the muddiest conditions. They aren't necessary unless you want the best performance you can get in severe conditions.

I have to agree with most that they may never make it on road bikes. Just not any real advantages considering the conditions we usually ride in.

I think Avid recently held an event where they put there new road disk brakes on some bikes and invited a bunch of pro's to go at it on a long, steep, twisty road. I don't remember how it went, but I do believe that they're finish times were faster with disk than rim. I think it was called the Red bull road rage or something like that.

I do ride road and mtb and love both. so I'm not about to chastise either one.

If you want to feel the difference there are cyclcross frames built with disk tabs. My friend is riding a Redline conquest disk and is always saying how much he loves the disk brakes. He only rides it on the roads and at about 240 lbs needs all the stoping power he can get

I have to agree with most that they may never make it on road bikes. Just not any real advantages considering the conditions we usually ride in.

I think Avid recently held an event where they put there new road disk brakes on some bikes and invited a bunch of pro's to go at it on a long, steep, twisty road. I don't remember how it went, but I do believe that they're finish times were faster with disk than rim. I think it was called the Red bull road rage or something like that.

Guess again. Avid, maker of rod disk brakes, did sponsor the Red Bull Road Rage. However, the top two finishers in the Time Trial, Myles Rockwell (1st) and Dave McCook (2nd) both used standard road bikes - with rim brakes. The 3rd place finisher, Brian Lopes, did use disk brakes, but he also used a modified MTB (with suspension fork), so it is likely that he had no choice but to use a disc brake (MTB frames and suspension forks are not compatible with road rim brakes).

For, the other two competitions of the day, Myles Rockwell won the pack race (still with his rim brakes) and Dave McCook won the Speed Trap prize for the fastest top speed of the day of 58 mph (with his rim brakes).

I think the only reason we haven't seen it happen on the road is it's banned for racing. If it wasn't banned rim brakes would be history pretty quickly.

Addendum: Upon reviewing UCI equipment rules, it appears that disc brakes are not banned from road racing. The only mention of disc brakes in the UCI rules (http://www.uci.ch/imgArchive/Rules/1gene-E.pdf)is under section 1.3.025:
"Freewheels, multiple gears and brakes are not permitted for use on the track during competition or training. Disc brakes are forbidden in cyclo-cross traiing and competition."

So I guess is the only thing standing in the way of disc brakes on the road are fashion, personal preference, or (lack of) function.

Guess again. Avid, maker of rod disk brakes, did sponsor the Red Bull Road Rage. However, the top two finishers in the Time Trial, Myles Rockwell (1st) and Dave McCook (2nd) both used standard road bikes - with rim brakes. The 3rd place finisher, Brian Lopes, did use disk brakes, but he also used a modified MTB (with suspension fork), so it is likely that he had no choice but to use a disc brake (MTB frames and suspension forks are not compatible with road rim brakes).

For, the other two competitions of the day, Myles Rockwell won the pack race (still with his rim brakes) and Dave McCook won the Speed Trap prize for the fastest top speed of the day of 58 mph (with his rim brakes).
"(MTB frames and suspension forks are not compatible with road rim brakes)." They may not be compatible with road rim brakes, but they certainly are compatable with (inferior) rim brakes. - TF

"(MTB frames and suspension forks are not compatible with road rim brakes)." They may not be compatible with road rim brakes, but they certainly are compatable with (inferior) rim brakes. - TF

Not really. More and more MTB frames and forks are now made without cantilever studs, so they can't mount rim brakes even if you wanted to. If you look at the photos from the Red Bull Road Rage (http://www.redbull-photofiles.com/Photofiles/PhotofilesModule/ShowEventImages?eventID=1127749347284-1012007691), you'll see that Brian Lopes' bike has no cantilever studs, either on the suspension fork or on the rear swing-arm of his suspension frame, so he could not have used rim brakes even if he wanted to.

Upon reviewing UCI equipment rules, "Freewheels, multiple gears and brakes are not permitted for use on the track during competition or training. Disc brakes are forbidden in cyclo-cross traiing and competition."

So, just how is it that they enforce riders not using disc brakes when training for CX? Leave it to those techno-worms at the UCI :)

Not really. More and more MTB frames and forks are now made without cantilever studs, so they can't mount rim brakes even if you wanted to. If you look at the photos from the Red Bull Road Rage (http://www.redbull-photofiles.com/Photofiles/PhotofilesModule/ShowEventImages?eventID=1127749347284-1012007691), you'll see that Brian Lopes' bike has no cantilever studs, either on the suspension fork or on the rear swing-arm of his suspension frame, so he could not have used rim brakes even if he wanted to.
The modified bike was designed for disc brakes, not burdened with them. "More and more MTB frames and forks are now made without cantilever studs..." for a reason.

Why have you developed such a bias against disc brakes when they obviously work for a lot of people on and off the road. If not for you fine, but we are not all you. - TF

I think one of the best benefits of disc brakes is that rim manufacturers are unburdened by the necessity of building a large heavy braking surface on the rim. By deleteing the braking surface, they can concentrate on building a lighter, stronger rim, offsetting some of the weight of the heavier hubs.

Also, the statement about disc brakes only being good for conditions that road bikers rarely see is incorrect. I live near Seattle, and we get lots of water / mud all year long.

I just purchased a cyclocross frame with disc mounts, and as soon as I can afford them, I'll be putting some on.

I think one of the best benefits of disc brakes is that rim manufacturers are unburdened by the necessity of building a large heavy braking surface on the rim. By deleteing the braking surface, they can concentrate on building a lighter, stronger rim, offsetting some of the weight of the heavier hubs.

This might be true in theory, but we have yet to see such rims hit the market. Brake tracks are not heavy. Parallel sidewalls do not limit the engineer in designing a strong, lightweight rim. In fact, many of the "disk-only" rims have been virtually identical to "rim brake" rims except for the lack of a machined brake track.

This might be true in theory, but we have yet to see such rims hit the market.

This is true - disc brakes are a fairly new phenomena in biking - and particularly to road-biking - but there is no doubt that it is a possible direction that the market is heading.

While it's not normally smart to draw parallels between the mt. bike market (which is driven primarily by recreational riders) and the road bike market (which is driven by the racing community), those who predicted that things like disc brakes and carbon fiber were just passing fads in the mt. bike market have been proven wrong. The reason? In order to continue to sell bikes, the market demands that this year's product be perceived as significantly more "advanced" than last years - even if the advancement is purely from a marketing perspective. That's why the high-end mt.bike market has inexorably moved forward on disc brakes and full suspension - it is perceived by the marketplace as the next level of advancement.

So, as the road market eventually moves toward disc brakes, and demands them to be lighter and more "aero" for the road bike market, the manufacturers will have to respond to meet those demands, including taking advantage of lower-weight disc specific rims (the same direction that they are in the mt. bike market).

Granted, the road biking community is already well established, stuck in tradition and much less responsive to change than the mt. bike market, but that only makes the transition slower. The fact that Avid owner Sram has introduced a road-gruppo will almost certainly expidite the transition.

An example: I asked Greg Lemond a few weeks ago why his company uses less and less steel. His answer was that the market was demanding carbon fiber and titanium now, even if steel provides certain superior ride and economic characteristics. So, it doesn't matter if disc brakes are a vastly superior technology or not - if it becomes the chosen technology of the marketplace, mfgs will respond if they want to sell more bikes.

Personally, besides the advantage they provide me in my personal climate, I prefer the feel of discs - all of my mt.bikes are disc equipped, so it's only natural for my cyclocross bike to be similarly disc-enabled as well.
:)

What's wrong with disk breaks??? NOTHING! Not one thing, unless you're a "weight wenie"....
1. They pack way more stopping power.
2. They work better in wet and muddy conditons.
3. they clean themseves almost instantly

When I did the conversion on my MTB the front break alone stopped it better than both of the old rim breaks. And I'm using the mecanical disks, not the hydrolic ones.
Ok, maybe my MTB disk experiances have me a little bias, but if my roadie had mounting points for disks, they'ed be on it to.

Drag? not if you have them adjusted right...
Weight? How much difence is there realy? (not counting hydrolic units)

"So why are disc brakes bad on a road bike? My Cannondale Cycolcross works good and stops but why is it hard to find a replacement wheel set??"
.
1) Not bad, but not needed
2) CX bikes w/ discs are not "mainstream" yet, so you must buy a "custom" wheelset.
.
Discs make sense for CX bikes, because of the dirt and clay that can get on rims.
Discs do not make sense for road racing bikes because rim brakes work just fine 99.99% of the time. Having them on a touring or training bike could be argued for.

What's so bad (or good) is a difent argument from are they necacary....
Is beer a good thing? Yes...
Is it necacary? No...

What's so bad (or good) is a difent argument from are they necacary....
Is beer a good thing? Yes...
Is it necacary? No...

Yeah, well you still have to phrase your argument correctly:

1. The limiting factor in road bike braking is at what point the bike rotates over the front wheel. It doesn't matter how much power disc brakes have, because damned near every brake can cause a road bike to do a stoppie. The exceptions to this would be a heavily loaded touring bike or a bike on a wet or otherwise compromised surface. In those conditions, the rider and how he modulates the brakes is the important factor.

2. Whether or not discs work better in the wet or muddy is either debatable or not relevant. Muddy conditions aren't relevant for a roadie. As for discs being better in the wet.....says who? My ZG brakes worked plenty fine descending Mt. Lemmon last year in a monsoonal downpour. At no time did my lack of disc brakes put me in peril.

3. "They clean themselves almost instantly." This is a subset of argument #2. Define "almost instantly." It'll at least take one full revolution of the wheel to clean the disc--assuming one full revolution will clean it completely--just as one full revolution wipes a rim. What the disc has that trad brakes don't is the ability to build a bit more heat. Disc pads also stand up better to the heat and can work at higher temps. How much that helps....well, I don't know if that's been quantified.

People might prefer discs, and there might be situations where they might be beneficial. The lever ratio of some disc systems might work better for people with impaired or otherwise decreased hand strength. However, that does not mean they are empirically better. And since it now comes down to preference, this debate is no more useful than the bike materials debate.

Yeah, well you still have to phrase your argument correctly:

1. The limiting factor in road bike braking is at what point the bike rotates over the front wheel. It doesn't matter how much power disc brakes have, because damned near every brake can cause a road bike to do a stoppie. The exceptions to this would be a heavily loaded touring bike or a bike on a wet or otherwise compromised surface. In those conditions, the rider and how he modulates the brakes is the important factor.

2. Whether or not discs work better in the wet or muddy is either debatable or not relevant. Muddy conditions aren't relevant for a roadie. As for discs being better in the wet.....says who? My ZG brakes worked plenty fine descending Mt. Lemmon last year in a monsoonal downpour. At no time did my lack of disc brakes put me in peril.

3. "They clean themselves almost instantly." This is a subset of argument #2. Define "almost instantly." It'll at least take one full revolution of the wheel to clean the disc--assuming one full revolution will clean it completely--just as one full revolution wipes a rim. What the disc has that trad brakes don't is the ability to build a bit more heat. Disc pads also stand up better to the heat and can work at higher temps. How much that helps....well, I don't know if that's been quantified.

People might prefer discs, and there might be situations where they might be beneficial. The lever ratio of some disc systems might work better for people with impaired or otherwise decreased hand strength. However, that does not mean they are empirically better. And since it now comes down to preference, this debate is no more useful than the bike materials debate.

Once again, rim brakes may work for you, but the suck for me and I know that there are others out there like me.

1 - I CAN slide both front and back wheels in normal conditions. The 'rotate over the front wheel" does not apply. Maybe I need someone to go in front of me and sweep/dry the road before that semi blows through the stop light and I have to STOP.

2 - Rode in the rain last night using my rim brakes. Everyone there agreed - road brakes suck. I had to change the route to get one rider to go with us for fear of not being able to stop in traffic. As long as you can plan for a stop and have time to wipe them dry for a rotation, they suffice. If it's an emergency and you don't have that extra 7 feet - dead.

3 - My disc equipped bike stops NOW. No pre-braking required.

"However, that does not mean they are empirically better. And since it now comes down to preference, this debate is no more useful than the bike materials debate." This is not a "preference" for me, it is a requirement to stop faster. DISCS ARE BETTER. The "preference" is for you to not use them because you don't need them.

TF