wasatchcnc

A few summers ago I read an article that Velo News did on braking performance of carbon rims on road bikes; it did a comparison of several makes and models and ranked them. I cannot be the only person that chuckled at the concept..I kept thinking about the coefficient of friction standing on a car's chromed bumper on a rainy day.
Anyhow, it got me thinking, why is it REALLY that road cycling doesn't embrace disc brakes?
I am a builder and designer and a well known anti-establishment advocate, but perhaps there is some input out there on the topic?
doug

fietsbob

Bike Consumer.. they are now sold, racers at the high levels , No,

Stopping wont get you first on the Podium, and they tend to weigh more..

Then, again, .. the rim is a disc.. really .. so they have been so for 100 years.

The Gearheads at cyclingnews were surprised when, taking pictures for the website, they found ,

for a Paris-Roubaix a race bike had taken out the same set of 32 spoke wheels that they
had used on previous years ..

A significant part of what the pro's bikes are using is about sponsors proving their stuff ,

for bragging rights to use in the Ad copy, to sell to the General Tifosi Public..

using a carbon rim is more about getting You to buy one.

Retro Grouch 

Brakes are over rated. All they do is slow you down.

dynaryder

Weight,for the most part. In the past they would have added too much weight,but nowadays bikes have so much CF that they can make it work by skimming weight in other places.

Also,the rules are the final determining factor. No sense building a race bike with discs if it's not legal to race. CX used to only allow canti's,now they allow discs and everyone is making a disc CX bike. Prolly only a matter of time before we see discs in the TdF,if only on the rainy days and mountain stages.

knobster

I think you'll see that changing. They really make sense. While I've never had this happen to me, I've read many stories of people on long decents where braking ended up causing a blowout. Not good when going 45mph down a mountain. Braking performance in wet weather is also an advantage. Another nice thing is the lack of wear on the rim itself. This being especially nice on carbon wheels. I think the wheels look nicer when there is no braking surface on them also.

johnny99

Road bike disc brakes must be complicated to engineer or manufacture, judging all the recent SRAM and Shimano road bike disc brake safety recalls in the recalls forum: https://www.bikeforums.net/forumdispl...-Announcements

dynaryder

No,those problems are with mating hydro discs to brifters. Cable road discs aren't an issue.

cafzali

Rim wear is really only an issue on CF wheels, which generally only racers use frequently. You can also get aluminum brake tracks on CF rims and eliminate that issue. Racers and serious cyclists know how to descend such that they're not generally hitting the brakes constantly at 45 mph on CF wheels. Honestly, if you're riding the brakes hard down a descent, you should either have scouted it first or not be on it period. Most people don't live near descents that would easily see them going 45 down a hill.

knobster

Apparently you've never ridden during the rainy season... I've wore out several wheels on my commuter bike due to brake pad wearing the braking surface. You usually don't see it on fair weather bikes, but one that has to endure rain and road garbage this is a issue that you'll sooner or later have to deal with.

Come to Oregon, I can show you several decents that can have you at 45 mph for 10-15 minutes at a time. I had to brake to keep it at 45. Can't imagine how fast I'd go if I didn't brake. Lots of friction heat built up at that speed if braking. Personally, I don't care to go faster than that, especially with other people around me and not knowing their skill levels.

But yes, you don't frequently see CF wheels on non-race bikes, but it does happen on those "racer wannabe" types and for those people, disc brakes do make sense.

fietsbob

there is a lot more speed coming down off alpine passes and trying to gain time for the GC .


neutral race support can cope with a couple different wheels 4 or more kinds.. IDK ..

Looigi

Been dealing with hydro discs on my mtbs for years. Way more hassles and issues than with the traditional rim brakes on the road bikes. For my purposes, I'd much rather stick with the cable actuated rim brakes on the road bike.

rdtompki

Cable actuated disc brakes have been around for years, are reliable and easily adjusted. I've recently switched from BB7s to the TRP HY/RD discs and really appreciate a)the effortless braking on long descents and b)the modulation. The modulation gives me more latitude in getting more braking out of the front brake. That being said if I weighed 140lbs with a good caliper/pad combination I might not feel the need to go with discs, but they do have a place in the recreational cycling scene.

rekmeyata

I see no reason for disk brakes on a road bike unless you ride in mucky conditions. On normal dry days disk brakes will not stop you faster than caliper brakes, the equation of stopping fast is all about tire adhesion to the pavement, and all brakes, even cheap Walmart brakes, can stop you just as fast if the tires and the pavement and the brake pads are all the same. Some designs of brakes may take more hand pressure to activate the brakes hard but the actually stopping power is the same.

cplager

That's assuming that you have the same feedback on both.

I agree that for most well-adjusted brakes, it is possible to lock the wheel, which meets your definition of "stopping power."

But some brake designs make it much easier to brake hard without locking the wheel than others, thereby giving you better braking.

fietsbob

... the well adjusted thing is the Unknown ..

how good are you at adjusting the brakes and the rest of your bike's components ?

rekmeyata

I disagree, I have old school single pivot brakes and new school dual pivots, I have ridden bikes with disk brakes, I have old school cantilever brakes too and found what you said to be completely wrong, you're quoting marketing hype brought to you by the cycling industry to sell you something new. However disk brakes are superior to any other braking system when the wheels get mucked up. You control the amount of force needed with any braking system to stop fast, all wheels will lock up if pushed, some allow better modulation which is what I think your trying to say, in fact I find the old school single pivot brakes to be the best at modulation ability then dual pivots, but modulation is just that modulation, it doesn't increase braking power.

BlazingPedals

Road bikes are already lighter than the UCI permits for racing; so the extra weight of discs is becoming a moot point. I've been saying for years that sooner or later they're going to be the standard, and they're slowly getting to that point. I've got them on both of my lowracers. I can wish they were lighter (and someday I'm sure they will be,) but I sure have no complaints about their power and modulation.

rekmeyata

UCI is so out of touch with reality when it comes to bike weight it's just plain nuts; they should lower that down to 13.999 pounds for awhile until technology gains happen again and they can safely lower it again, but 14.999 pound limit is just plain stupid in today's world. There are people riding on surface streets with bikes lighter then the UCI limit without issues, it's time to shed a pound.

rydabent

With calipers rim wear is the main problem. IMO it is a great sin to wear out a vital bike part, the rim, when there is a better solution. First of all discount professional riders. They have teams that give them bikes to ride. For the rest of us wearing out a rim is a big deal. The cost of a new rim and a rebuild is high. Again for the rest of us, most of us here can do a full brake replacement on a disc brake equipted bike, but cant do a full wheel rebuild unnecessary with disc brakes. Then there is the fact that with out the braking surface the rim can be designed to be stronger and more aero.

As for UCI rules that personally I think are stupid, as someone here pointed out the weight of a disc brake system is not relevant. Bikes can be built light enough that they NEED the weight of the disc brake system.

Disc braking is simply a more elegant engineering solution.

Looigi

If tires, chains, cogs, rings, bearings, cables, and brake shoes are vital bike parts, I'm definitely going to hell.

As far a disc being an elegant solution, I guess it depends on your definition of elegant. Mine is lighter, simpler and fewer parts to perform the same function. Elegant combines functions into fewer systems and components rather than adds more independent systems and parts. IMO, rim brakes are elegant compared to disc brakes.

fietsbob

For Lincoln Nebraska.

cplager

Certainly I've noticed a large difference in ability to stop when switching from "default" brake pads to, say, Kool Stops. The original brake pads had no problems locking the wheel, but I was able to have a lot more control with the better pads. (I'm sure we agree that the goal isn't to lock the wheel.)

So, yes, brake manufactures do in fact say this, but I do find this to be true as well.

(You'll note that no where in my post did I mention disc brakes being better than rim brakes. It's not that I don't think that, in general, that is probably true - largely for the reason you highlight, but rather that wasn't at all the point I was trying to make).

dynaryder

Do you beat your road bikes as badly as your MTB's? Unless ridden in the same conditions,it's hardly a fair comparison. Pretty sure Jeeps are built tougher than Ferrari's,but if used for four-wheeling I bet they require more wrenching.

Only issues I've ever had with discs are from damage during shipment of the bike and playing polo. Zero issues from street riding.

rekmeyata

Yeah rim wear is real high, I use to race in the mountains of S Calif and I can attest with all the heavy braking mountain riding requires due to fast descents getting 30,000 to 40,000 miles on a set of rims is just plain expensive. And the cost to have new rims rebuilt is nuts too, who wants to spend $140 to for one rim rebuild? that kind of money over a 30k + mile period can just drive a person to bankruptcy.

Right now the lightest and lowest costing brake option is rim brakes, disk brakes will add about 150 to 350 grms of additional weight to the bike over rim brakes, plus it puts more stress on the spokes so how long will spokes last vs rim brakes spokes? What about the fact that a more beefy fork is required with disk brakes, or the fact that they make the rear wheel weaker, no mention of those costs. On hot days doing fast mountain riding those small rotors can get red hot which in turn can destroy hub seals and bearings, no mention of that small problem either. And why is no one is talking about the rotor wearing out? They only last 2 to 3 years depending on use and they cost $25 to $80 each...in the long run the cost of rotor replacement alone will far exceed the cost of a new rim!! No one is talking about the pad wear either, pads have been known to wear out in a day of rainy riding to as long as 2,000 miles...as long as 2,000 miles? and those pads aren't cheap at about $30 each; my rim brake pads last at least 10,000 when I was riding mountains!! and a set of Kool Stop Salmon pads are only $6 each!

I've ridden bikes for over 40 years with nothing but rim brakes in all sorts of weather except snow and never had an issue stopping, if I had I wouldn't be on this forum today, and there are plenty of guys on this forum that are at least as old as me and they too are still alive from using rim brakes.

So no, disk brakes are not going to be less expensive in the long haul, in fact they will be a great deal more expensive, but we all buy into the marketing hype to get us to spend more of our money faster.

rydabent

looigi

When you can combine parts and systems into one the does save weigh material and makes the whole machine simpler, that is good. I have seen too many machine that they tried to combine functions, and if one part of a multi function machine breaks, the whole machine is down.

However I disagree with you that wearing out an expensive part like a rim is an elegant solution. Look at true life adventures. On crazy guy on a bike, there have been several instances of a rim failing due to brake pad wear. If this happens clear out in the middle of no where with no bike shops near, it ruins the whole tour until you can get to a bike shop. However if a caliper or disk fails the bike is still rideable. Making the wheel rim part of the braking system is a fail.