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Why choose disc brakes over rim brakes for a road bike?

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Why choose disc brakes over rim brakes for a road bike?

Old 02-21-19, 03:30 AM
  #51  
deepakvrao
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Originally Posted by gregf83
+1. I was wearing out rims in about 18-24 months commuting through the winter. The crud from the road forms a grinding paste on the wheels and it doesn't take long to wear through a rim. I don't see any advantage to discs on my summer bike but for the 4-6 months of wet roads I ride on switching to discs is a no brainier. Consistent braking down hills in the wet and not having to rebulid wheels every couple of years is worth it to me. Zero downsides for the winter.
I'm not sure what it's like to travel with hydraulic disc brakes so I'm going to stick with rim brakes and pickup cheep wheels from all those who convert to discs.

Why would travel be an issue with hydraulics? I am just about to buy a hydraulic disc brake bike, which I plan to use for travel too.
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Old 02-21-19, 06:25 AM
  #52  
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Because they stop far better. They do what they are supposed to do in a superior manner. There is no need to justify it because you live in a flat or hilly environment. Why choose electronic shifting over mechanical? Same analogy. Some things just do a better job for what they were designed to do.
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Old 02-21-19, 06:29 AM
  #53  
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Reading this taught me why you all have trouble with rim brakes. If you set the brake pads some small fraction of a millimeter away from the rim it is not just a problem removing a wheel. Initial brake response is going to be weaker too. Overall brake power is going to be weaker. Set the brake pads 3,4,5 millimeters away from the rim. Your brake lever has plenty of travel and plenty of cable pull. Wonder why that is. Why is every brake lever ever made set up for ten times the cable pull you are using? With brakes set wide you just drop the wheel w/o even thinking about quick release. Your hand is in a smaller and stronger fist when you brake. When you need sudden power or to quickly get through the film of water on the rim you pull those pads through air fast and hit the rim with the pad.

Some poster above said something about how the only choices to accomplish something were dual pivot, v-brake or disc. What? If you don't know what a centerpull or sidepull is, sure you could end up wishing for disc. Almost no one has ever experienced the power and ease of a centerpull with brazed-on pivots. Because those brazed on pivots are a super ultra custom feature. Too expensive and rarefied for any but a handful of elite cognoscenti. And instead of brazing some pivots the industry completely redesigns the entire bike.

Rim wear is real. The industry is not selling disc to the entire market because of hardcore riders in PNW. They're selling to sell.
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Old 02-21-19, 06:46 AM
  #54  
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Originally Posted by deepakvrao
Why would travel be an issue with hydraulics? I am just about to buy a hydraulic disc brake bike, which I plan to use for travel too.
Im not sure if its an issue. Maybe you just need to include a spacer between the pads to prevent the pistons from extending too far. I wouldnt want to fool around with bleeding brakes on my vacation. Its better for someone with direct experience to comment.
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Old 02-21-19, 07:34 AM
  #55  
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Originally Posted by 63rickert
Reading this taught me why you all have trouble with rim brakes. If you set the brake pads some small fraction of a millimeter away from the rim it is not just a problem removing a wheel. Initial brake response is going to be weaker too. Overall brake power is going to be weaker. Set the brake pads 3,4,5 millimeters away from the rim. Your brake lever has plenty of travel and plenty of cable pull. Wonder why that is. Why is every brake lever ever made set up for ten times the cable pull you are using? With brakes set wide you just drop the wheel w/o even thinking about quick release. Your hand is in a smaller and stronger fist when you brake. When you need sudden power or to quickly get through the film of water on the rim you pull those pads through air fast and hit the rim with the pad.

Some poster above said something about how the only choices to accomplish something were dual pivot, v-brake or disc. What? If you don't know what a centerpull or sidepull is, sure you could end up wishing for disc. Almost no one has ever experienced the power and ease of a centerpull with brazed-on pivots. Because those brazed on pivots are a super ultra custom feature. Too expensive and rarefied for any but a handful of elite cognoscenti. And instead of brazing some pivots the industry completely redesigns the entire bike.

Rim wear is real. The industry is not selling disc to the entire market because of hardcore riders in PNW. They're selling to sell.
There are a lot of variables when setting up rim brakes, lever travel, pad type, caliper type (v-brake, canti, single, dual pivot caliper etc.) and most importantly stopping power.

I've rarely seen two bikes that stop exactly the same, even when new.
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Old 02-21-19, 07:54 AM
  #56  
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I think a car analogy works here. Drum brakes on cars worked fine for decades stopping cars. Disc brakes came along and stop cars even better, and you'll be hard-pressed to find drums on a car today. Disc brakes just work better.
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Old 02-21-19, 08:05 AM
  #57  
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I've got disc brakes for 2 reasons. Better braking in the wet, and it's been a fairly wet winter in the UK. And better braking for when I've got my 20kg dog in her 12kg trailer on the back of my bike. I wouldn't go back to rim brakes in the wet (unless caught out).
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Old 02-21-19, 08:29 AM
  #58  
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Originally Posted by rubiksoval
And dragging your brakes? For a decade?

Okay, so not a legitimate reason.
That is why my rain bike has disc wheels. In Seattle, we can go weeks where the road is not dry. Add to that all the sand that cities and counties use to battle ice and snow, and it really shortens the life of wheels. I would usually get a season and a half out of Mavic Open 4 rims.
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Old 02-21-19, 08:34 AM
  #59  
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Originally Posted by TimothyH
Get on a well maintained mountain bike with 203 mm rotors and you will change your mind the moment you even think about squeezing the levers.

Stopping is frighteningly good. I mean it stops so well it will actually scare you the first time.

After two or three squeezes you will be laughing like an eight year old and getting up as much speed as you can just so you can stop.

I generally don't like to over-dramatize things but the experience for me was mind blowing.
-Tim-
Along these lines, I think that it's a good thing that most people first experience disc brakes on a new bike with pads/rotors that aren't yet properly bedded. It's still an experience the first time you pull the lever, but you're less likely to send yourself over the bars. that bedding process gives you a nice acclimation period.

Also, I haven't read through all of the responses in the thread, but the reduced braking effort is nice, too, and it's not just for the infirm with arthritis - if I can comfortably brake with just my index finger, it leaves the middle wrapped around the bars, providing a little more security when things get choppy.
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Old 02-21-19, 08:36 AM
  #60  
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I live and ride in an area with a lot of 10% and greater hills - some 15% stuff. Descending I will be using my brakes at some critical locations depending on what is on the road surface (sand, little pebbles, etc. I ride both carbon wheels (Boyd) and alloy (Campy and Mavic) as rim brakes. I use Campy carbon pads and their alloy pads. I have tried a number of different pads for the carbon wheels and found the Campy to work better than SwissStop yellow, Deda blue and the stock Boyds. When both are dry, the carbon wheels will stop you sure enough but not as powerfully as the alloy wheels. When wet, I have to pump the carbon and alloy wheels a few times to dry them out. The alloy still outperform the carbon wheels for stopping power, but not significantly so. Would I build a new road, not a gravel or CX bike, with disk wheels for my riding? Probably not because I could not swap wheels between bikes, the rim brakes work really well, and aesthetically I prefer the look of a rim brake road bike over that of a disk brake bike. My gravel bike (Ritchey Outback) has Sram hydraulic disks as does my mountain bike (Tomac). I find the power and control of the disks for those bikes preferable to rim brakes for control on technical and "busy" road or trail surfaces. I can move much more slowly where necessary and control the bike better. All of this said, if I were going with one bike (road), one set of wheels and they would be carbon wheels, I can see the logic of disks vs rim brakes. Thru axles definately hold the wheel very securely. I suppose that the seat stays can be engineered to be more forgiving with a disk rim bike frame. BUT, I also will go with the lightest set of wheels that my wallet will afford so disk wheels for the road make this not as easy to choose or afford a sub 1300 gram wheel set.

Orbea offers a road bike that you can set up with disk or rim brakes, so, that is an options for some to consider.
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Old 02-21-19, 08:49 AM
  #61  
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Originally Posted by SHBR
There are a lot of variables when setting up rim brakes, lever travel, pad type, caliper type (v-brake, canti, single, dual pivot caliper etc.) and most importantly stopping power.

I've rarely seen two bikes that stop exactly the same, even when new.
How odd. I've seen endless bikes that stop exactly the same. Coasterbrake Schwinns are pretty much all the same. Varsities are all the same if and when they are working. Etc.

There certainly are variables. This morning today's bike has Tektro cantilevers. Big clearance is one of the reasons to even have cantis, these brakes sit too close to rim and nothing to be done for it. Oh well. They do stop and it is a basic bike.

When mechanics have to cope with an ever-expanding array of wholly different brake systems it does get difficult. As brakes become ever more esoteric there are consequences. Tried -and-true is better for most riders than new and improved. When it is a matter of safety systems it gets problematic when no two are seen to be same.
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Old 02-21-19, 08:55 AM
  #62  
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Originally Posted by gregf83
I’m not sure if it’s an issue. Maybe you just need to include a spacer between the pads to prevent the pistons from extending too far. I wouldn’t want to fool around with bleeding brakes on my vacation. It’s better for someone with direct experience to comment.




It's very much not an issue. There are little spacers that slide between the pads, even a folded business card will work, but if you don't have them, the pistons still aren't going to extend far enough to be problematic. Worst case is that you have to remove the pads and wedge a plastic tire lever between the pistons to push them back in a bit, which is a 2 min per caliper operation - nothing that would warrant bleeding. Once you reset the pistons and mount the wheel, one lever squeeze and you'll be back in business. If, for some reason, you were to squeeze the lever with completely bare calipers (no disc, no brake pads), then you could cause yourself some problems with the pistons pushing out too far, but I don't see why you'd remove the pads for travel.

Edited to add: on both ends of a recent trip, other than removing the pad spacer and mounting the wheels, my bike required no additional attention to be ride-ready.

Last edited by WhyFi; 02-21-19 at 09:00 AM.
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Old 02-21-19, 09:06 AM
  #63  
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For those who say that wearing out rims isn a non issue, this article says otherwise.

https://cyclingtips.com/2018/05/comp...d-disc-brakes/

I have no clue, as I am a fair weather rider ;-)
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Old 02-21-19, 09:07 AM
  #64  
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Originally Posted by 63rickert
How odd. I've seen endless bikes that stop exactly the same. Coasterbrake Schwinns are pretty much all the same. Varsities are all the same if and when they are working. Etc.

There certainly are variables. This morning today's bike has Tektro cantilevers. Big clearance is one of the reasons to even have cantis, these brakes sit too close to rim and nothing to be done for it. Oh well. They do stop and it is a basic bike.

When mechanics have to cope with an ever-expanding array of wholly different brake systems it does get difficult. As brakes become ever more esoteric there are consequences. Tried -and-true is better for most riders than new and improved. When it is a matter of safety systems it gets problematic when no two are seen to be same.
Its not as foolproof as it might seem, most of this depends on who worked on the brakes, and how worn they are.

Some brakes have the same lever feel, yet stop differently, rims are also part of the equation.
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Old 02-21-19, 09:16 AM
  #65  
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Originally Posted by JasonD67
I think a car analogy works here. Drum brakes on cars worked fine for decades stopping cars. Disc brakes came along and stop cars even better, and you'll be hard-pressed to find drums on a car today. Disc brakes just work better.
Exactly,

I'm not sure what all the discussion is about with regard to wet or dry conditions or living in a hilly environment. Makes zero sense.
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Old 02-21-19, 09:20 AM
  #66  
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All this discussion really doesn't matter. Within the next 5 years all good bikes (not department store bikes) will be disc brakes. Disc brakes are superior in every manner.

https://road.cc/content/buyers-guide...ped-race-bikes

https://www.bikeradar.com/us/road/ge...g-point-51685/

Last edited by prj71; 02-21-19 at 09:24 AM.
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Old 02-21-19, 09:57 AM
  #67  
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Originally Posted by prj71
All this discussion really doesn't matter. Within the next 5 years all good bikes (not department store bikes) will be disc brakes. Disc brakes are superior in every manner.
I think you're probably right that almost all high-end road bikes will be available only with disc brakes in the near future. But I don't think disc brakes are superior for road racing bikes in every manner.

Here are the drawbacks for me:
1. Their initial bite is grabbier than rim brakes -- it's harder to very lightly feather off a tiny amount of speed. A rim brake is kind of a disc brake, with the largest allowable disc, and there are some advantages to those physics -- the larger the braking disc, the less clamping force needed to slow the wheel. A rim brake will always carry this advantage over a 140mm or 160mm disc because of the ratio of lever pull to braking force.
2. They make wheel changes more complex. A good disc brake system needs a thru axle.
3. They require the frame to be stiff in areas where otherwise you wouldn't want to stiffen the frame, and it's asymmetric
4. The pads need to be replaced more frequently
5. They are heavier
6. They are less aerodynamic

In 10 or 15 years, I hope that there's a common easy axle standard that allows road, cyclocross and xc mtb 29ers to swap disc brake wheels, everything is running a nontoxic hydraulic fluid that doesn't gel or freeze, and brake pad technology gets totally dialed in to road racing standards.

For now, I'm very happy with rim brakes on a road racing bike. Rim brakes beat all the speed advantages offered by, say, every Ceramic Speed upgrade, and a whole lot more in terms of performance and ease of maintenance and use.
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Old 02-21-19, 10:07 AM
  #68  
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Originally Posted by ljsense
A rim brake will always carry this advantage over a 140mm or 160mm disc because of the ratio of lever pull to braking force.
This is incorrect. Hydraulic disc brakes have a higher mechanical advantage and require less force to apply full braking. The lever pull for a rim brake needs to accommodate brake pad wear which limits the available mechanical advantage. Higher mechanical advantage means more lever travel for equivalent pad movement. If the mechanical advantage is too high you'd need to continually adjust your pads as they wear or risk the levers bottoming out. Hydraulic discs are self adjusting so the lever travel does not need to accommodate pad wear.
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Old 02-21-19, 10:10 AM
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Originally Posted by ljsense
1. Their initial bite is grabbier than rim brakes -- it's harder to very lightly feather off a tiny amount of speed. A rim brake is kind of a disc brake, with the largest allowable disc, and there are some advantages to those physics -- the larger the braking disc, the less clamping force needed to slow the wheel. A rim brake will always carry this advantage over a 140mm or 160mm disc because of the ratio of lever pull to braking force..
So much nonsense
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Old 02-21-19, 11:02 AM
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Originally Posted by ljsense
I think you're probably right that almost all high-end road bikes will be available only with disc brakes in the near future. But I don't think disc brakes are superior for road racing bikes in every manner.

Here are the drawbacks for me:
1. Their initial bite is grabbier than rim brakes -- it's harder to very lightly feather off a tiny amount of speed.
My (admittedly limited) experience is exactly the opposite: I find it MUCH easier to "feather off" speed with discs.

(My experience with discs brakes is limited - my experience with the various kinds of rims brakes is not.)
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Old 02-21-19, 11:20 AM
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Anyone tried hydraulic rim brakes? I imagine they provide a pretty elegant experience.
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Old 02-21-19, 11:21 AM
  #72  
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Once you get used to them, good disc brakes allow feathering just fine. It's a different touch.

Last edited by Bikesplendor; 02-21-19 at 02:55 PM.
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Old 02-21-19, 11:36 AM
  #73  
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I've been cycling for almost 50 years and I never heard of wearing out the rims because of braking with rim brakes. That said, I think the best reason for disc brakes is the additional clearance for wider tires. Rim brakes have always worked fine for me, but my newest bikes have discs so I can ride wider tires, which I like.
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Old 02-21-19, 11:45 AM
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I wore a decent Al rim on a heavy, commuting bike to the point where it cracked at the brake track and was thinned to a scary degree on inspection. That probably took about 20,000 mi. of fair weather riding.
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Old 02-21-19, 11:48 AM
  #75  
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In the MTB universe, the superiority of discs is never questioned, at least that I am aware of. Road cycling is performed in much narrower parameters in that we can eliminate many variables compared to MTB conditions.

Are rim brakes perfectly adequate? Yes.
Are discs superior? Yes.

I wish that road bikes would just stick to rim brakes, but it is what it is, and my next road bike will go disc.

ETA- I have been mountain biking since the 80's and when disc brakes first came out, I was thinking they were a marketing gimmick, and actually thought it was a passing fad. Boy, was I wrong!
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