Go Back  Bike Forums > Bike Forums > General Cycling Discussion
Reload this Page >

Please explain why road bikes don't have disc brakes

General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Please explain why road bikes don't have disc brakes

Reply

Old 06-06-17, 10:20 PM
  #26  
LesterOfPuppets
cowboy, steel horse, etc
 
LesterOfPuppets's Avatar
 
Join Date: Sep 2008
Location: Rock Springs, WY
Posts: 31,110

Bikes: everywhere

Mentioned: 43 Post(s)
Tagged: 1 Thread(s)
Quoted: 3063 Post(s)
Originally Posted by Ty0604 View Post
Yar-e

Yar like in "yard" and "e" as in eat

haha I'm ashamed because I graduated with a masters in communication and took an IPA class (International Phonetic Alphabet) to get my journalism/broadcasting certificates but I don't remember any of the IPA guidelines.
So it's a Scandinavian thing?
LesterOfPuppets is online now  
Reply With Quote
Old 06-06-17, 11:25 PM
  #27  
Ty0604
Banned.
 
Join Date: Nov 2015
Location: Pacific Northwest
Posts: 1,157

Bikes: 2017 Fuji Jari

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 227 Post(s)
Originally Posted by LesterOfPuppets View Post
So it's a Scandinavian thing?
I have no idea the origin of the word or anything.
Ty0604 is offline  
Reply With Quote
Old 06-06-17, 11:37 PM
  #28  
MikeOK
Yo
 
MikeOK's Avatar
 
Join Date: Aug 2002
Location: Ozark Mountains
Posts: 1,596

Bikes: 2003 Yeti AS-R, 2018 Waltly ti

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 420 Post(s)
Originally Posted by Mark42 View Post
Why is it that road bikes have V brakes, and mtn have disc? Why not put disc on road bikes? I thought disc were better. I know the set of BB5 calipers on my bike weigh more than a set of V brake levers, but does squeezing the rim make up for the few grams saved over a disc? Someone must make a light weight magnesium alloy or carbon caliper that would negate that weight advantage. Or maybe I'm totally missing the relationship of brakes to bikes.

The reason I ask is because after looking at lots of alloy and carbon road frames on alibaba/aliexpress, noticed that no road bikes had IS or PM caliper mounts on the chain/seat stay. All were setup for V brake.
Some road bikes do come with discs. The main reason why you dont see more is that you don't need the braking power of discs on a road bike. I rode my old Trek over 40,000 miles and didn't have to replace the pads one time. On my mountain bike with discs I had to replace them at least once a season. Another disadvantage of discs on a road bike is the added weight. Roadies can get pretty anal about every gram of weight.
MikeOK is offline  
Reply With Quote
Old 06-06-17, 11:39 PM
  #29  
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 36,045

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 120 Post(s)
Tagged: 1 Thread(s)
Quoted: 4317 Post(s)
Originally Posted by LesterOfPuppets View Post
.....and decided that it should be always be said preceded by Fuji and very quickly, so they sound like one word.
Fujiyari? Isn't that the dormant volcano west of Tokyo?
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline  
Reply With Quote
Old 06-06-17, 11:44 PM
  #30  
wgscott
VectorPotential sensitive
 
wgscott's Avatar
 
Join Date: Jul 2013
Location: The Timbers of Fennario (CL77)
Posts: 3,305

Bikes: Steel

Mentioned: 41 Post(s)
Tagged: 0 Thread(s)
Quoted: 1711 Post(s)
Originally Posted by Ty0604 View Post
and took an IPA class (International Phonetic Alphabet) to get my journalism/broadcasting certificates but I don't remember any of the IPA guidelines.
Yeah, but at least that enables you to make a good beer.

PS: Hope you are healing well!
wgscott is offline  
Reply With Quote
Old 06-07-17, 12:02 AM
  #31  
Ty0604
Banned.
 
Join Date: Nov 2015
Location: Pacific Northwest
Posts: 1,157

Bikes: 2017 Fuji Jari

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 227 Post(s)
Originally Posted by wgscott View Post
Yeah, but at least that enables you to make a good beer.

PS: Hope you are healing well!
haha Pebs likes IPAs. I'm more of a cider person. Am doing much better, thank you! Heading out next week to begin an ~800 mile tour of Yellowstone & Grand Teton. Oddly enough I feel in better shape now than I did before the accident.

Here's a story from late last year regarding disc brakes in road racing for anyone who wants to read...Disc brakes to return to road racing in 2017 | Cyclingnews.com
Ty0604 is offline  
Reply With Quote
Old 06-07-17, 02:11 AM
  #32  
coominya
Senior Member
 
coominya's Avatar
 
Join Date: Aug 2016
Location: Brisbane Aust
Posts: 1,644

Bikes: Giant ToughRoad Giant talon

Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 703 Post(s)
Originally Posted by hillyman View Post
check back in a few years after The Tour allows disc brakes and then somebody wins with them. Then you will be an idiot not to have disc brakes on a road bike.
Yes, once they are the "fashion", everyone will be lining up.
coominya is offline  
Reply With Quote
Old 06-07-17, 06:33 AM
  #33  
DomaneS5
Fredly Fredster
 
DomaneS5's Avatar
 
Join Date: Jan 2017
Posts: 480

Bikes: Trek Domane S5, Trek 1.1c, Motobecane Omni Strada Comp, Trek X-Caliber 6

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 167 Post(s)
Originally Posted by MikeOK View Post
Some road bikes do come with discs. The main reason why you dont see more is that you don't need the braking power of discs on a road bike. I rode my old Trek over 40,000 miles and didn't have to replace the pads one time. On my mountain bike with discs I had to replace them at least once a season. Another disadvantage of discs on a road bike is the added weight. Roadies can get pretty anal about every gram of weight.


Jeeez. I had to replace the rear brake pads on my Trek 1.1 after 1.5K, but I do ride a lot of hills. Must be the entry level brakes.
DomaneS5 is offline  
Reply With Quote
Old 06-07-17, 06:37 AM
  #34  
Garilia
Senior Member
 
Garilia's Avatar
 
Join Date: Sep 2010
Location: South Park...ing Lot
Posts: 721

Bikes: Fantom 29

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 49 Post(s)
OP, please explain why you think road bikes do not have disc brakes.
Garilia is offline  
Reply With Quote
Old 06-07-17, 07:18 AM
  #35  
DomaneS5
Fredly Fredster
 
DomaneS5's Avatar
 
Join Date: Jan 2017
Posts: 480

Bikes: Trek Domane S5, Trek 1.1c, Motobecane Omni Strada Comp, Trek X-Caliber 6

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 167 Post(s)
Funny how I could have had disc brakes on my latest road bike for an extra $500.
DomaneS5 is offline  
Reply With Quote
Old 06-07-17, 07:37 AM
  #36  
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 35,638

Bikes: 8

Mentioned: 129 Post(s)
Tagged: 0 Thread(s)
Quoted: 5087 Post(s)
We shall see, You may buy Road bikes limited tire clearance, or Cross, able to fit bigger tires, Now.

Both with Disc Brakes, But...

the Pro' s in the TdF, etc. may stay with rim brakes due to easier quick spare wheel support on the road,
During the races when they puncture... and they do have dozens of spare wheels..
fietsbob is offline  
Reply With Quote
Old 06-07-17, 08:35 AM
  #37  
wphamilton
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 13,718

Bikes: Nashbar Road

Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 2094 Post(s)
Four years ago http://www.bikeforums.net/bicycle-me...ike-discs.html we figured that marketing was the main force pushing road bike disc brakes.

Weight, mechanical complexity, cost, increased size/drag, and the stronger rear triangle needed are the downside. Better modulation at the handles is the advantage. Not wearing out rims is another.

At one time, I figured that discs would allow you to develop anti-lock on back, and anti-pitch-over on the front. But outside the box, you could also do that with rim brakes and a solenoid or motor pulling the cable if you really wanted to. Nobody has gone that route yet, so it's probably not as useful as I had imagined.
wphamilton is offline  
Reply With Quote
Old 06-07-17, 08:46 AM
  #38  
Maelochs
Senior Member
 
Maelochs's Avatar
 
Join Date: Oct 2015
Posts: 9,779

Bikes: 2015 Workswell 066, 2014 Dawes Sheila, 1983 Cannondale 500, 1984 Raleigh Olympian, 2007 Cannondale Rize 4, 2017 Fuji Sportif 1 LE

Mentioned: 107 Post(s)
Tagged: 0 Thread(s)
Quoted: 4404 Post(s)
Originally Posted by wphamilton View Post
At one time, I figured that discs would allow you to develop anti-lock on back, and anti-pitch-over on the front. But outside the box, you could also do that with rim brakes and a solenoid or motor pulling the cable if you really wanted to. Nobody has gone that route yet, so it's probably not as useful as I had imagined.
I think the forces involved are too small and the dividing line too narrow.

The fine control needed to manage forces across so small a contact patch with braking times already being so short .... the gear would be more on the line of laproscopic robot surgery than automotive. The costs would be commensurate. And the gains would be minimal.
Maelochs is offline  
Reply With Quote
Old 06-07-17, 08:55 AM
  #39  
wphamilton
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 13,718

Bikes: Nashbar Road

Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 2094 Post(s)
Originally Posted by Maelochs View Post
I think the forces involved are too small and the dividing line too narrow.

The fine control needed to manage forces across so small a contact patch with braking times already being so short .... the gear would be more on the line of laproscopic robot surgery than automotive. The costs would be commensurate. And the gains would be minimal.
I don't follow the reasoning, but you're probably right about minimal gains which makes it moot. Sliding on the back isn't very urgent an issue, and the front won't slide (on straight braking on the road), which mostly rules out anti-lock anyway. Maybe wet surfaces, ice? I'm not certain if it would help, or not help.
wphamilton is offline  
Reply With Quote
Old 06-07-17, 09:11 AM
  #40  
leob1
Senior Member
 
Join Date: Jul 2006
Location: Middle of the road, NJ
Posts: 2,878
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 158 Post(s)
Originally Posted by FBinNY View Post
The reality is that caliper and/or cantilever brakes have worked well for a century or more, and while they're npt perfect, neither are disc brakes.

Each has advantages and drawbacks, and the balance is different for road and off road applications.

So, given the proven history and discounting your erroneous assumption that disc brakes are somehow "better", a more interesting question might be, why rework road bikes to make disc brakes work on them?
You sound like Sheldon Brown more and more. When v-brakes started becoming popular because they where 'better' than cantis, his position was well set up cantis are better than poorly set up v-brakes, and visa-versa.
The same hold true for caliper vs. disc for road bikes now.
leob1 is offline  
Reply With Quote
Old 06-07-17, 09:19 AM
  #41  
Maelochs
Senior Member
 
Maelochs's Avatar
 
Join Date: Oct 2015
Posts: 9,779

Bikes: 2015 Workswell 066, 2014 Dawes Sheila, 1983 Cannondale 500, 1984 Raleigh Olympian, 2007 Cannondale Rize 4, 2017 Fuji Sportif 1 LE

Mentioned: 107 Post(s)
Tagged: 0 Thread(s)
Quoted: 4404 Post(s)
Reasoning. This is BF, why would i use "reasoning"?

I just figure that a car has a contact patch of maybe 100 square inches, and a bike, about two. And a bike's braking event is really quick. A bike ABS system would need to be super-sensitive and super-quick.

It would have to cycle really quickly or it wouldn't really "cycle." It would just release the brakes once and squeeze again (judging by the pulse through the pedal on my car's ABS.)

Also, the distance it would need to move such a very light brake arm ... literally a fraction of a millimeter. That kind of precision reminded me of robot surgery.

I could have said "NASA-like precision" or something.

The forces involved with a car, where a single wheel's braking system probably weighs more than my bike, versus the tiny pads on my bike ....

As soon as Shimano figures it out, we will see it in the TdF, and then we all will want it .... i guess.
Maelochs is offline  
Reply With Quote
Old 06-07-17, 09:25 AM
  #42  
prathmann
Senior Member
 
Join Date: Nov 2008
Location: Bay Area, Calif.
Posts: 7,179
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 619 Post(s)
Originally Posted by wphamilton View Post
At one time, I figured that discs would allow you to develop anti-lock on back, and anti-pitch-over on the front. But outside the box, you could also do that with rim brakes and a solenoid or motor pulling the cable if you really wanted to. Nobody has gone that route yet, so it's probably not as useful as I had imagined.
A very simple mechanical anti-lock braking system is illustrated in the book "Bicycling Science." The rear caliper brake is mounted on a post so it can slide forward when actuated and a spring returns it to the normal position when released. The front brake cable is mounted so it's pulled by the sliding action of the rear brake rather than being controlled directly by the rider. This provides very strong front braking just until the rear wheel begins to skid a bit due to the weight shift thereby relaxing the pull of the rim on the rear brake. The article in the book indicates that the system worked very well in testing until eventually they broke the front fork due to fatigue from all the hard stops. But it did provide consistent minimum distance stops with no danger of pitch-over regardless of how hard the rider applied the brake lever.

Obviously there are some issues with this system. No ability to independently operate the front or rear brakes depending on surface conditions and also a single point of failure - if the rear brake cable snaps you lose both brakes. But it could be supplemented with the addition of a third independent brake with its own cable.
prathmann is offline  
Reply With Quote
Old 06-07-17, 09:41 AM
  #43  
wphamilton
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 13,718

Bikes: Nashbar Road

Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 2094 Post(s)
Originally Posted by prathmann View Post
A very simple mechanical anti-lock braking system is illustrated in the book "Bicycling Science." The rear caliper brake is mounted on a post so it can slide forward when actuated and a spring returns it to the normal position when released. The front brake cable is mounted so it's pulled by the sliding action of the rear brake rather than being controlled directly by the rider. This provides very strong front braking just until the rear wheel begins to skid a bit due to the weight shift thereby relaxing the pull of the rim on the rear brake. The article in the book indicates that the system worked very well in testing until eventually they broke the front fork due to fatigue from all the hard stops. But it did provide consistent minimum distance stops with no danger of pitch-over regardless of how hard the rider applied the brake lever.

Obviously there are some issues with this system. No ability to independently operate the front or rear brakes depending on surface conditions and also a single point of failure - if the rear brake cable snaps you lose both brakes. But it could be supplemented with the addition of a third independent brake with its own cable.
Fascinating, combining the two ideas into one mechanism and the operating principle makes perfect sense. Probably for another thread, lest I hijack this one, but you've given me something to mull over. Thanks.

ps, I was envisioning leaving the front cable in place, so you could just pull more on the lever if the electronic mech failed.
wphamilton is offline  
Reply With Quote
Old 06-07-17, 09:53 AM
  #44  
rydabent
Senior Member
 
Join Date: Apr 2010
Location: Lincoln Ne
Posts: 7,201

Bikes: RANS Stratus TerraTrike Cruiser

Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1129 Post(s)
The OP needs to read up on the latest offering from almost all bike mfg, and he will see that indeed disc brakes are most certainly available on road bikes. Even Campy has released a line of disc brakes for road bikes. The single biggest reason is the fact that with disc brakes, rims are not worn out and scabbed up, and the rims can be made stronger and more aero if they dont have a brake surface.

Last edited by rydabent; 06-07-17 at 10:03 AM.
rydabent is offline  
Reply With Quote
Old 06-07-17, 10:28 AM
  #45  
LesterOfPuppets
cowboy, steel horse, etc
 
LesterOfPuppets's Avatar
 
Join Date: Sep 2008
Location: Rock Springs, WY
Posts: 31,110

Bikes: everywhere

Mentioned: 43 Post(s)
Tagged: 1 Thread(s)
Quoted: 3063 Post(s)
Originally Posted by leob1 View Post
You sound like Sheldon Brown more and more. When v-brakes started becoming popular because they where 'better' than cantis, his position was well set up cantis are better than poorly set up v-brakes, and visa-versa.
The same hold true for caliper vs. disc for road bikes now.
V-Brakes aren't even significantly "better" than cantis. They are almost infinitely easier to set up for a beginner factory or bike shop worker, however.
LesterOfPuppets is online now  
Reply With Quote
Old 06-07-17, 10:35 AM
  #46  
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 36,045

Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter

Mentioned: 120 Post(s)
Tagged: 1 Thread(s)
Quoted: 4317 Post(s)
Originally Posted by leob1 View Post
You sound like Sheldon Brown more and more. When v-brakes started becoming popular because they where 'better' than cantis, his position was well set up cantis are better than poorly set up v-brakes, and visa-versa.
The same hold true for caliper vs. disc for road bikes now.
I knew Sheldon well, and I guess I should be flattered. In fact, he and I probably agreed more than we disagreed, and the canti vs. "V" brake question was one where we didn't agree.

But this is very different. Changing from classic cantis to the newer design didn't introduce any new problems, so there was nothing to offset any benefit.

OTOH - discs introduce all manner of issues, including the need to redesign wheel mounting systems, stiffen the fork, along with increased weight and cost. That's not to say there aren't benefits, especially for people wanting CF rims.

IMO - on balance - disc brakes don't make sense for racing and most sport riding, though they may make sense for other "road" bike applications such as commuting or touring.

I don't have a problem with disc brakes for road bikes, but do have a problem with the notion that they are somehow "better" in an absolute sense. IMO - it's never a question of better or worse, as much is it's a question of better or worse for a specific purpose.

Unfortunately, there are various bike industry factors, mostly economic, driving the effort to create the illusion that disc brakes are the future and convince folks that they are somewhat disadvantaged by not replacing their working bike with the "new and improved" products.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline  
Reply With Quote
Old 06-07-17, 10:47 AM
  #47  
LesterOfPuppets
cowboy, steel horse, etc
 
LesterOfPuppets's Avatar
 
Join Date: Sep 2008
Location: Rock Springs, WY
Posts: 31,110

Bikes: everywhere

Mentioned: 43 Post(s)
Tagged: 1 Thread(s)
Quoted: 3063 Post(s)
Originally Posted by FBinNY View Post
I knew Sheldon well, and I guess I should be flattered. In fact, he and I probably agreed more than we disagreed, and the canti vs. "V" brake question was one where we didn't agree.

But this is very different. Changing from classic cantis to the newer design didn't introduce any new problems, so there was nothing to offset any benefit.
In addition to the easier setup for assemblers, V-brakes also made manufacturers' lives easier by eliminating two cable stops per bike. Total win-win for bike makers.
LesterOfPuppets is online now  
Reply With Quote
Old 06-07-17, 10:49 AM
  #48  
Seattle Forrest
Senior Member
 
Seattle Forrest's Avatar
 
Join Date: Mar 2010
Location: Seattle, WA
Posts: 17,905
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 5712 Post(s)


Seattle Forrest is offline  
Reply With Quote
Old 06-07-17, 11:00 AM
  #49  
Garilia
Senior Member
 
Garilia's Avatar
 
Join Date: Sep 2010
Location: South Park...ing Lot
Posts: 721

Bikes: Fantom 29

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 49 Post(s)
i don't speak to the superiority of one braking technology over another, I don't think about it that much. This post has generated some great discussion though. I will simply say that some people seem to use "road" bike when they really mean "racing" bike. In my mind, Road Bike is a broad category that includes racing/sport, touring, commuting, cyclocross, TT, triathlon, single speed/fixie...

Where do flat bar road bikes fit in, or are they hybrids? What about a drop bar hybrid?

This is why I try not to think too deeply about these things.
Garilia is offline  
Reply With Quote
Old 06-07-17, 11:18 AM
  #50  
rgconner
Senior Member
 
rgconner's Avatar
 
Join Date: Mar 2017
Location: Sacramento, CA
Posts: 1,084

Bikes: Curtis Inglis Road, 80's Sekai touring fixie

Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 436 Post(s)
Originally Posted by FBinNY View Post

I don't have a problem with disc brakes for road bikes, but do have a problem with the notion that they are somehow "better" in an absolute sense. IMO - it's never a question of better or worse, as much is it's a question of better or worse for a specific purpose.
In the IT World, we call "better" a "Non-functional requirement" as it is not measurable unless you know the actual functional requirements behind it. Like:

1. Little to no stopping in the rain is very important.
2. I do long fast descents where I am riding the brakes constantly.
3. I am putting it on a Tandem bike and require the extra braking power.
4. I want the lightest bike possible.
5. I want the bike to be bullet proof and not have to adjust things all the time.

There are of course more functional requirements than that, but they are all well defined and a disc vrs rim braking system could be evaluated against them to decide which is better.
rgconner is offline  
Reply With Quote

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service