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Old 07-17-17, 01:55 AM   #51
ColonelSanders
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There were a lot of problems with that video before it can be taken as gospel.


Leaving aside the more aero wheels of the rim braked bike, in both instances the rider went first on the disk brake bike, meaning he would likely know the lay of the land better on his 2nd run, which in both instances was on the rim braked bike.


Additionally, I would like to know if the results that one gets from such "experiments" changes much, if the rider weighs 220lbs/100kgs vs 154lb/70kgs.


Also, is there any difference in how many miles you can rack up before you have to change your pads in either style of braking?


When I get around to building my next bike, as it will be rim brake equipped, it will give me a chance to do some very rough comparisons myself, but unfortunately it will be on two different frames and two different sized wheels.
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Old 07-17-17, 02:45 AM   #52
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Originally Posted by FBinNY View Post
Disc brake advocates fail to note one key detail.

Braking power isn't limited by the brakes. It's limited by the maximum g-force that can be tolerated before causing an endo.

Agreed, with provisions.




Quote:
Originally Posted by FBinNY View Post
...ALL arguments about braking power are moot.

I think you're not considering the human part of the brake "chain" enough.


Maybe you should separate between "ultimately/theoretically available braking power" and "generally or easily used braking power".


There may well be people skilled and confident enough to manage as short, or perhaps even shorter, braking distances with rim brakes than with discs.
Personally I consistently get shorter braking distances on my disc brake bikes than I get from my rim brake bikes.
There's something in the characteristics/linearity/feedback - particularly from decent hydros - that allows me to brake harder with discs than with rim brakes at the same level of confidence.




It's comparable to the summer I spent tinkering with different canti setups. Some of them were quite horrible in actual use.



It'd be interesting to see a comparison on the linearity or characteristics of rim vs disc brakes.
I.e. how much braking do I get for a certain amount of hand effort.


Doing a static test would be easy enough. Determine at what torque the wheel starts to turn at a certain force applied to the lever.


But there might be dynamic effects due to heat and brake pad abrasion that one would miss out on.
A static test might not say enough.
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Old 07-17-17, 04:34 AM   #53
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Originally Posted by corrado33 View Post
In the case of a really long hill with a stop sign at the bottom.

Disc brakes are absolutely the WRONG choice. Disc brakes overheat and lose braking power over long steep descents where as rim brakes do not. Given ample braking time, rim brakes always come out on top. The only "advantage" discs have is the "modulation" provided by them (and proven wrong by Simon in the video). Modulation only comes into play when you're panic stopping or running at the edge of the grip of the tires.
Huh...

How many times have you actually faded your discs? And did you feather / drag them the whole way down? Because I recall exactly once I've faded a mechanical disc brake (and even then I still had decent power, just less than usual) and that was when I did a quick full stop from 50mph after a twisty alpine descent from 4000 feet to 600 with a fully loaded touring rig which weighed with me on top around 330lbs. Mind you this was using 100% front brake since my rear brake is a rim brake and I don't like using it. If I had had both rear and front as discs I doubt I would have faded them even then.

Also when I was a lot more inexperienced and went riding mountains with a loaned rim brake bike I managed to pop a tube due to the rim heating up so much. I doubt I'll see that happening with discs.

Usually bad technique is enough to defeat any brake system. You drag rim brakes down a technical descent and you'll melt the pads, which in turn will leave you with no brakes. You can also boil brake fluid with the same technique with largely same effects with the difference, that after you let the discs cool you'll have brakes again.
But even if you do overheat and glaze disc brake pads, you'll still have braking power, it'll just be not as much as you'd have in an optimal situation.
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Old 07-17-17, 06:10 AM   #54
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GCN tested it again.
They certainly proved that controversy drives readership.

Just add "versus" in the title and hits go up exponentially.


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Last edited by TimothyH; 07-17-17 at 11:41 AM.
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Old 07-17-17, 06:40 AM   #55
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Disc brakes work for me.

Quote:
Originally Posted by FBinNY View Post
Disc brake advocates fail to note one key detail.

Braking power is limited by the brakes. It's limited by the maximum g-force that can be tolerated before causing an endo.

Do you or have you ever owned, rented or borrowed a bike with disc brakes? Or do you just go by what you read on the internet? I have 2,000 miles on a Roubaix with disc. Rim brakes I have much, much more.

The fact that rim brake users have been doing endos in panic stops for decades proves the point.

Apples and oranges. How you go from one point to another makes no sense. It has to do with several factors.

This isn't to say that disc brakes don't have better initial response in wet conditions, but ALL arguments about braking power are moot.

Effective braking is several factors, with either rim or disc. Weather conditions, tires and condition, air pressure, road surface, user interface, speed and angle of decent. I have never gone over the handle bars with either disc or rim brakes, and I have had some panic stops, and have had to brake hard on descents in excess of 45 mph. Modulation cannot be passed off as a "preference". In a pace on this last Sunday, I had 3 other strong riders, and we were doing 22-24 mph along the coast next to the ocean. Narrow bike path, so as you are 6-12 inches wheel sucking off the guy in front, modulation of disc allows me to just use the rear, (less stopping power than the front) to slightly feather off speed and stay at a consistent distance. Safety for the guy behind me that is doing the same. Much better and easier with disc. I am at 205lbs, so having the strength and modulation of disc is phenomenally safer in my opinion.

BTW- expect makers to very carefully engineer the maximum braking power for disc brakes, because too much brake can be as or even more dangerous than not enough brake. Trying to find ways to ensure adequate braking power yet, preventing endos from too much braking has long been a challenge, and historically makers have faced more suits over brake induced endos than over inadequate braking power.
You make so many "absolute" statements here, I wont even bother to respond. Data? How many endos have you done? Rubbish.
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Old 07-17-17, 07:16 AM   #56
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Originally Posted by manapua_man View Post
...I'm still running 26" wheels...and triples.
My MTB has a triple, 26" wheels ... and hydro discs. While I ride it I can feel myself passing through time warps between the past and the future.
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Old 07-17-17, 07:59 AM   #57
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The only benefit I can see is with disc brakes on a road bike is that the brake track on a carbon rim always looks new.

Quote:
Originally Posted by manapua_man View Post
...I'm still running 26" wheels...and triples.
Probably still wear your pants around your waist as well

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Originally Posted by DrIsotope View Post
Who the hell is braking on the way down? I'm using the brakes in the last 75 yards before the intersection. I've never been in a situation where I needed to apply enough brake for a period long enough to induce fade. But then again, I tend to brake very late and quite hard, so for me modulation comes into play... a lot.
Maybe not where you are but I can think of more that a few hills many miles long with tarmac not fit for a wheelbarrow. You are right though, most times slowing down from 40 or so for a corner does not take all that long in good conditions on most bikes in good conditions.
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Old 07-17-17, 10:09 AM   #58
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Quote:
Originally Posted by corrado33 View Post
In the case of a really long hill with a stop sign at the bottom.

Disc brakes are absolutely the WRONG choice. Disc brakes overheat and lose braking power over long steep descents where as rim brakes do not. Given ample braking time, rim brakes always come out on top. The only "advantage" discs have is the "modulation" provided by them (and proven wrong by Simon in the video). Modulation only comes into play when you're panic stopping or running at the edge of the grip of the tires.
OTOH rim brakes can over heat a rim that has an over inflated tire and cause it to blow up. At high speed this could even kill you.
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Old 07-17-17, 10:17 AM   #59
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I dunno, I put a fully loaded touring bike in the rain on the line coming down some decent descents. I had cheap $3 Tektro OEM V-brakes coupled with $10 Kool Stops, pushing north of 35MPH. It stopped just fine.

I wouldn't shun a bike with them, road or otherwise, just haven't found a situation where I think I need them.
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Old 07-17-17, 10:24 AM   #60
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Touched on slightly is the deal of rotational enertia. A rim designed for a bike with disc brakes can be more aero, lighter, and stronger if a brake surface is not needed. Therefore a bike with discs, and a proper disc brake rim will accelerate faster, because of less rotational enertia. If you are racing a bike that will accelerate faster in the ending sprint, you will be the winner. Think about that.
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Old 07-17-17, 10:32 AM   #61
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Quote:
Originally Posted by ColonelSanders View Post
There were a lot of problems with that video before it can be taken as gospel.


Leaving aside the more aero wheels of the rim braked bike, in both instances the rider went first on the disk brake bike, meaning he would likely know the lay of the land better on his 2nd run, which in both instances was on the rim braked bike.


Additionally, I would like to know if the results that one gets from such "experiments" changes much, if the rider weighs 220lbs/100kgs vs 154lb/70kgs.


Also, is there any difference in how many miles you can rack up before you have to change your pads in either style of braking?


When I get around to building my next bike, as it will be rim brake equipped, it will give me a chance to do some very rough comparisons myself, but unfortunately it will be on two different frames and two different sized wheels.
All good questions. Although a few are the opposite for me. I'm usually faster the first time down a hill because I overestimate the grip of my tires. After a good scare or 3, the second time I wise up and go slower. haha

Also, I'm pretty sure the rims are the same, just with different decals. The black tire + black rim of the rim brake bike makes the rim look "larger" and more aero, but I think they're the same depth. If anything I could argue that the disc rim SHOULD be more aero because of the lack of a brake track.

My question is this.

When considering the downhill AND the resultant 20-50k flat ground before or after it, which bike would come out on top? My guess is the more aero one. Disc brakes help for the very limited amount of time when you are actually braking. There are very few road races where the entire race is downhill with sharp curves. (However, that IS why disc brakes are superb for mountain biking, because it's really just one big downhill race with lots of curves.)
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Old 07-17-17, 11:24 AM   #62
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Originally Posted by Tape2012 View Post
On my bike, I installed both rim and disc brakes and 4 levers. I like having choices.
Quote:
Originally Posted by AlmostTrick View Post
Me too!

But I ended up with both because after reading all these threads on BF it was just too hard to choose.
PICTURES! (or it didn't happen)

IBTL
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Old 07-17-17, 11:28 AM   #63
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PICTURES! (or it didn't happen)

IBTL
I would, but am still recovering from the last sudden stop.
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Old 07-17-17, 11:35 AM   #64
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Mountain bike discs, road bike rims. You don't need discs on your road bike, it's overkill.
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Old 07-17-17, 11:46 AM   #65
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Mountain bike discs, road bike rims. You don't need discs on your road bike, it's overkill.
You don't NEED dual pivot rim brake calipers, either.
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Old 07-17-17, 12:09 PM   #66
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You don't NEED dual pivot rim brake calipers, either.
Whoa! Let's not get carried away here.
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Old 07-17-17, 12:19 PM   #67
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I even have v brakes on my mountain bike, but it's more of a xc bike than a downhill bike. I occasionally wish it had discs especially when it's wet.
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Old 07-17-17, 01:04 PM   #68
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I even have v brakes on my mountain bike, but it's more of a xc bike than a downhill bike. I occasionally wish it had discs especially when it's wet.
Well ... then ... dry your bike before you ride it.
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Old 07-17-17, 01:18 PM   #69
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You don't NEED dual pivot rim brake calipers, either.
Should have seen my old parachute-brake setup...
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Old 07-17-17, 01:32 PM   #70
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Originally Posted by MikeOK View Post
Mountain bike discs, road bike rims. You don't need discs on your road bike, it's overkill.
I'm curious whether you use or have ridden disk brakes.


-Tim-
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Old 07-17-17, 01:37 PM   #71
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I'm curious whether you use or have ridden disk brakes.


-Tim-
Yes hydraulic on my Santa Cruz Bullet, mechanicals on another mountain bike I can't remember the brand of.
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Old 07-17-17, 02:19 PM   #72
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Quote:
Originally Posted by ColonelSanders View Post
There were a lot of problems with that video before it can be taken as gospel.


Leaving aside the more aero wheels of the rim braked bike, in both instances the rider went first on the disk brake bike, meaning he would likely know the lay of the land better on his 2nd run, which in both instances was on the rim braked bike.


Additionally, I would like to know if the results that one gets from such "experiments" changes much, if the rider weighs 220lbs/100kgs vs 154lb/70kgs.


Also, is there any difference in how many miles you can rack up before you have to change your pads in either style of braking?


When I get around to building my next bike, as it will be rim brake equipped, it will give me a chance to do some very rough comparisons myself, but unfortunately it will be on two different frames and two different sized wheels.
This is the point I have wondered about no one takes in account the heavier rider, I am over 275 and noticed a big difference, but have no science to back it up.
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Old 07-17-17, 02:28 PM   #73
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I wouldn't mind having mech discs on my Yeti. I might just do that this winter along with Di2. It has XTR on it now but even top of the line mech shifters require a lot of maintenance. But this is a brake thread...
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Old 07-17-17, 02:34 PM   #74
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Has there EVER been an advancement in technology which was completely embraced? In reading through these comments I'm reminded of an argument my grandfather had with my father about why he "doesn't need electronic ignition." He was trying to claim that the old points/condenser style of ignition was in no need of improvement. I seem to recall he made the same argument about fuel injection too. My father swore he would never need a computer "because the typewriter works just fine."

I should email my dad the link to this thread.


-Kedosto
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Old 07-17-17, 02:44 PM   #75
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It's amazing how all these disc brake threads go to multiple pages when absolutely nothing new is said.
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