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Please explain why road bikes don't have disc brakes

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Please explain why road bikes don't have disc brakes

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Old 07-19-17, 10:24 AM
  #226  
Phil_gretz
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Originally Posted by dwing View Post
I just recently experienced the delayed braking response with rim brakes when I got caught in a pop-up storm on a downhill descent. Started raining heavily and I was almost to the bottom of the descent coming into a corner... I started applying brake at a distance I thought was conservative before the corner but slowed barely which alarmed me because I then realized I needed to be on it earlier and harder. Then, more brake pressure.. slowing but not enough to make the corner or stop.. ... then, as much pressure as I could apply.. and barely made the corner. I was close to bailing. That delayed braking response doesn't happen with disc.
^which is exactly why I have disc brakes on my commuter...
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Old 07-19-17, 10:25 AM
  #227  
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What's the over/under on electronic discs? You know they are coming ... because they will be needed for ABS, which will be next.
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Old 07-12-18, 03:06 PM
  #228  
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its cheaper, high end bikes all have disks
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Old 07-12-18, 03:18 PM
  #229  
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If you are not adjusted well, get ready for an endo. Calipers are lightweight and allow for a great deal of flexibility in stopping power, you are more in control. And the best part is they are stinkin' simple.

Endos are not something you're going to get as much of on a cruiser that weighs twice as much, even more. Otherwise, learn to love flying?
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Old 07-12-18, 05:06 PM
  #230  
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Originally Posted by jungzest View Post
its cheaper, high end bikes all have disks
Not quite yet. At our shop, half of our high-end ($5000+) road bikes have disc brakes. Approx 80% of our $700-800 road bikes have discs.
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Old 07-12-18, 06:24 PM
  #231  
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Jan Heine of Bicycle Quarterly just put up a blog article looking at the benefits of various brake types. TL;DR version is that disk brakes have no real performance advantage on bikes using narrow tires, but the wider the tire, the more more material is needed to provide strength in the caliper to prevent excessive flex. A disk brake only needs to clear the brake rotor, which is the same thickness regardless of tire width, and thus can perform better with wide tires and rims.

https://janheine.wordpress.com/?utm_...eid=850bec5fab
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Old 07-12-18, 06:30 PM
  #232  
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Originally Posted by JohnDThompson View Post
Jan Heine of Bicycle Quarterly just put up a blog article looking at the benefits of various brake types. TL;DR version is that disk brakes have no real performance advantage on bikes using narrow tires, but the wider the tire, the more more material is needed to provide strength in the caliper to prevent excessive flex. A disk brake only needs to clear the brake rotor, which is the same thickness regardless of tire width, and thus can perform better with wide tires and rims.

https://janheine.wordpress.com/?utm_source=Retail+Customer+Newsletter&utm_campaign=61c3c406a0-EMAIL_CAMPAIGN_2017_11_29_COPY_01&utm_medium=email&utm_term=0_f74fbd5ca8-61c3c406a0-32968617&mc_cid=61c3c406a0&mc_eid=850bec5fab
That seems like an argument that is designed to work only if everyone forgets about cantis and V brakes.


Originally Posted by Heine
And modern carbon forks are stiff anyhow – carbon delaminates if it flexes too much – so adding disc brakes doesn’t result in a loss of shock absorption.
Geez, Jan, do you actually believe what your typing?

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Old 07-12-18, 06:38 PM
  #233  
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Originally Posted by Kontact View Post
That seems like an argument that is designed to work only if everyone forgets about cantis and V brakes.
He doesn't ignore them. From the blog post:

There are ways around the flex issue. Instead of beefing up the caliper until it gets so heavy that nobody wants it on their bike, you can use the very stiff fork and frame as part of the brake. Cantilever and centerpull brakes do that, and well-designed ones offer plenty of stopping power, even in the wet.
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Old 07-12-18, 06:38 PM
  #234  
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Originally Posted by Kontact View Post
That seems like an argument that is designed to work only if everyone forgets about cantis and V brakes.
Obviously Heine is aware of cantilevers, since he's a cantilever brake salesman. His commentary about discs being used to accommodate wider tires on road bikes was specifically in the context of how performance-oriented road bikes pretty much always use caliper brakes.
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Old 07-12-18, 06:51 PM
  #235  
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Originally Posted by JohnDThompson View Post
He doesn't ignore them. From the blog post:

There are ways around the flex issue. Instead of beefing up the caliper until it gets so heavy that nobody wants it on their bike, you can use the very stiff fork and frame as part of the brake. Cantilever and centerpull brakes do that, and well-designed ones offer plenty of stopping power, even in the wet.
I was replying to your post on the subject rather than Jan's article.

Originally Posted by HTupolev View Post
Obviously Heine is aware of cantilevers, since he's a cantilever brake salesman. His commentary about discs being used to accommodate wider tires on road bikes was specifically in the context of how performance-oriented road bikes pretty much always use caliper brakes.
How wide a tire would a performance oriented road bike have to have before a rim brake would need to get larger than they are? The mechanism of a short reach caliper could easily fit a 35c tire as it is, they just aren't mounted in a good place to do so.
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Old 07-12-18, 06:56 PM
  #236  
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Break a couple of spokes on a rim brake bike in the middle of no where, and you have to back off the pads to where they are useless. Your disc brake will still work fine, and get you home like nothing happened.
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Old 07-12-18, 07:00 PM
  #237  
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Originally Posted by rydabent View Post
Break a couple of spokes on a rim brake bike in the middle of no where, and you have to back off the pads to where they are useless. Your disc brake will still work fine, and get you home like nothing happened.
Now there is one good point about disc brakes.
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Old 07-12-18, 07:06 PM
  #238  
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Originally Posted by Kontact View Post
How wide a tire would a performance oriented road bike have to have before a rim brake would need to get larger than they are? The mechanism of a short reach caliper could easily fit a 35c tire as it is, they just aren't mounted in a good place to do so.
Most short-reach calipers are still rated for around a 28mm max. While some can technically fit a 35 if they're mounted high enough, you usually have some very uncomfortable clearances, plus bad interference between tire and brake pad would be pretty inevitable on wheel changes. It "works", but not in a way that bicycle manufacturers actually spec.
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Old 07-12-18, 07:07 PM
  #239  
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Originally Posted by rydabent View Post
Break a couple of spokes on a rim brake bike in the middle of no where, and you have to back off the pads to where they are useless. Your disc brake will still work fine, and get you home like nothing happened.
Not if the tire is now rubbing the stays.
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Old 07-12-18, 07:14 PM
  #240  
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Originally Posted by HTupolev View Post
Most short-reach calipers are still rated for around a 28mm max. While some can technically fit a 35 if they're mounted high enough, you usually have some very uncomfortable clearances, plus bad interference between tire and brake pad would be pretty inevitable on wheel changes. It can "work", but not in a way that bicycle manufacturers actually spec.
That's exactly what I was saying - if you redesigned the way a short reach caliper was mounted, you wouldn't have to make any of the lever arms longer to go around a much bigger tire than we currently use it for. So you really need a pretty darn large tire (and a bike that fits it) before you say "This caliper has to be too big to work correctly!" No one is using a tire that large on competitive road bikes that this limitation is even close to being an issue. If you don't need fender or mud clearance, you don't need a big caliper for even a fairly large road tire - you just need everything to line up correctly.
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Old 07-12-18, 09:13 PM
  #241  
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Originally Posted by rydabent View Post
Break a couple of spokes on a rim brake bike in the middle of no where, and you have to back off the pads to where they are useless. Your disc brake will still work fine, and get you home like nothing happened.
A legitimate point, but I honestly can't remember the last time I've broken a spoke on any wheel I've built myself.

N.B. I'm not a fan of low spoke-count wheels.
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Old 07-13-18, 01:23 AM
  #242  
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I'm pretty sure I could get home with one of two brakes. What happens if you break a disc brake cable?
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Old 07-13-18, 02:38 AM
  #243  
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People love to argue about disc vs rim brakes so much that they don't even notice that this is a year old thread.
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Old 07-13-18, 07:42 AM
  #244  
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Originally Posted by Kontact View Post
Not if the tire is now rubbing the stays.
And here's a good example of why you should carry a proper sized spoke wrench in your kit.
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Old 07-13-18, 08:28 AM
  #245  
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Uh, because not everyone wants disc brakes?
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Old 07-13-18, 08:48 AM
  #246  
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They shoot horses, don't they?

BTW...Interesting troll here. The person who bumped this thread has bumped four other threads where the last post had been on either 7/12 or 7/13 of 2017. If you think that's a coinkydink I have a slightly used bridge in Brooklyn for you.

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Old 07-13-18, 08:58 AM
  #247  
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This thread has gone on so long that you can buy one, now, or not, it's up to you .

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Old 07-13-18, 08:29 PM
  #248  
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Because they are not necessary. Mountain bikes ride though mud and water, which can get on the rims, which contaminates the rims and the brake pads. When I got into mountain biking when the sport was still fairly new, I used drum brakes, which are even more protected than discs when it comes to mud and water.

Road bikes are supposed to be light and nimble. A road bike caliper, lever, and cable weigh less than a disc brake rotor, caliper, hose, and master cylinder. Having the caliper on the rim allows for the breaks to have great leverage when clamping against the rim, and wheel changes are much faster. I like disc brakes on mountain bikes or commuting bikes, I know how to adjust and maintain them. But for my road bikes, I like the simplicity of rim brakes. They are not sexy or trendy, but they work perfectly.
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