Disc Brakes



jwroubaix

Member
Jun 6, 2007
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Looking at new bikes and trying to determine if I should go with Disc Brakes. I am someone who actually uses the brakes. One question I have is regarding upgrading wheels with disc brakes. Is there anything that has to be taken into consideration with wheels and disc brakes or will any wheel fit?
 

Gelsemium

Active Member
Feb 17, 2015
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I have disc brakes for the first time and I feel that the braking process is more safe because the wheel slide less. It does make sense, the whole mechanism is better.
 

maydog

Well-Known Member
Feb 5, 2010
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What kind of bike?

There is some controversy regarding the benefits of disc brakes on road bikes. They work, but some wonder if they are more fashion than function.

Disc brakes only work with wheels built around disc brake compatible hubs. This does limit your selection, but it is still pretty good.
 

Volnix

Well-Known Member
Feb 19, 2011
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I had a go with a higher-end mtb fitted with some good disc brakes. The braking performance was right down scary! :eek:

I also had the same experience with a road bike fitted with Ultegra stuff (calipers)...

At the moment I am using a pair of 2300brifters, some tektro brake calipers and a pair of Swisstop blue pads. Braking is more then enough. :)

There seems to be a slight advantage in disc brakes in terms of braking in the wet, as they probably dont pick up too much road muck. But they are heavier.

They also don't ruin your rims.

There was an article somewhere about disc brakes not working well with quick release skewers. Apparently because of vibration or something, they were causing the QR skewers to become undone, resulting in the wheel becoming detached. Haven't seen that getting mentioned much around though.


An interesting article about Disc brakes can be found in this link from Sheldon Brown's website:

http://sheldonbrown.com/disc-brakes.html
 

Gelsemium

Active Member
Feb 17, 2015
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OK, so I am not an expert, I bough my bike on sales and they happened to have disk brakes, so I really can't tell full specs. I do know they brake really safely.

That link is not opening for me Volnix.
 

MotownBikeBoy

Well-Known Member
Nov 24, 2012
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I really like the disc brakes on my hybrid, Personally they just seem more "reliable" than caliper breaks.
 

Gelsemium

Active Member
Feb 17, 2015
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That's what I feel as well, I feel it's a more solid braking, sliding disappeared with disk brakes for me.
 

Gelsemium

Active Member
Feb 17, 2015
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Actually this last one you posted works fine, but not the first one. Thanks for posting it again, interesting read!
 

sixxup

New Member
Feb 27, 2015
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After long use brakes do get hot, since it is their friction surface that makes brake work. Disc brakes have the ability to cool back faster hence more resistant to heat fade. Disc brakes have more stopping power than drum brakes. They are also compact than drum brakes.
 

Gelsemium

Active Member
Feb 17, 2015
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Yep, they are more advanced in all the senses I think sixxup, so the only disadvantage I might see in them is the price because in terms of performance and safety they are better.
 

CAMPYBOB

Well-Known Member
Sep 12, 2005
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I like the guy that said, "A racing bike with disc brakes is...not a racing bike.".

Less aero.
Heavier.
Wheels are heavier with more spokes and longer, crossed spokes.
Wheels are less aero with more and longer crossed spokes.

Brake fluid still boils.
Rotors still warp and sandwich construction rotors can come undone.
Organic disc pads can wear away in ridiculously short periods of time. Like one race or one day of descending.
Pads can have the backing pad glue let go.

Cyclo-Cross racers are killing pads in two laps on muddy courses. Two. Laps.

Leonard Zinn states:


Dear Lennard,
If the peloton would switch to disc brakes, the heat would not be a problem anymore!
— Todd
Dear Todd,
That is not entirely true. Yes, the overheated rims and tires we saw in Oman would cease to be a problem with disc brakes. In those conditions, I believe the heat at the caliper and rotor would be a problem, however, and, as I said in my column about Oman, could lead to total brake failure.
Even if the UCI were to allow disc brakes in road racing, for them to gain wide acceptance, road racers would insist on superlight versions that are also low in profile. Racers are not going to be interested in brakes that render their $10,000 aero road bike less aerodynamic than road bikes of the 1970s. Calipers and rotors sticking out in the air create drag, as do the crossed spoking patterns and more spokes required with disc brakes.
But answering some of these demands by reducing the size and weight of the calipers and rotors means there will be very little thermal mass in the system, making them subject to overheating. Too much heat in the caliper can boil the fluid and can burn through the resin pads that good performance with tiny rotors requires.
If hydraulic fluid boils in a brake system, the brakes do not work. Hydraulic brakes work because fluids are essentially non-compressible, so pushing on one end of a column of fluid will result in just as much push at the other end of the column of fluid. Gases, however, are compressible. That’s why we ride on pneumatic tires. So if the fluid boils, gas bubbles will appear in the fluid, and the push from the master cylinder piston in the lever will not push the pistons in the calipers out hard enough to stop the bike.
We’ve discussed this here in the past. Different brake fluids have different boiling points, but all of them do have a boiling point.
As for the pads, resin pads get a stronger initial bite on the rotor than do metallic, a.k.a. sintered, pads. And if the rotor size is going to be tiny, like 140mm (or smaller yet) in order to satisfy the desires of road riders for low weight and low wind drag, you will need a lot of brake bite. But resin pads will rapidly be destroyed with the kind of heat that slowing down a road bike on a steep, fast descent in high ambient temperatures requires.
As an example of the issues involved, I can point to experience with a super strong, super-tall, 330-pound customer of mine who owns five custom Zinn titanium bikes we’ve built for him here in Boulder. The last two have been with hydraulic disc brakes, because he had so many brake and tire problems with rim brakes similar to the ones I discussed in my article about Oman.
This man rides a lot, all over the world, and he does things like back-to-back six-week riding camps in the Alps in summertime. (He gets stronger and stronger, but, contrary to what you might expect, his weight does not change significantly.)
With Shimano hydraulic road disc brakes, he was getting just one day (!) out of organic (a.k.a. resin) pads, even on cool days, and that’s using XTR rotors, 180mm front, 160mm rear, not the 140mm rotors that come with the Shimano Di2 road disc brakes. Yes, his disc brakes work way better for him than rim brakes ever did, and they eliminated the tire problems he was having, but daily pad replacement was overly burdensome for him. So he switched to sintered pads, and on his trips to the Alps, he now goes six days between pad changes. He’s not overjoyed about the hassle, but he can deal with weekly, rather than daily, pad replacement. He also has to forgo the nice initial bite of a resin pad.
Despite Shimano’s insistence that he should need neither the large rotors nor the sintered pads, that is what he ended up with, because he could not stop with 140mm rotors. Imagine the braking power it takes to slow his bike down while descending the Col du Tourmalet. He and his bike weigh 350 pounds, the same as a 175-pound man and his 135-pound wife on a 40-pound tandem. If you’ve ever ridden a tandem down a steep descent (like the Tourmalet!), you know how fast it picks up speed. I know from personal experience how terrifying exactly this circumstance can be. Now imagine the minimal sense of security you would feel if all that stood between you and your partner and flying off a cliff in the Alps were a pair of road disc brakes with 140mm rotors.
It is my opinion that prolonged braking in 120-degree Fahrenheit (49C) temperatures would bring about similar brake problems for a rider of a more average weight.
Cable-actuated disc brakes could solve some of these problems, but they are not likely to be used by road racers. When coupled with sintered pads, cable-actuated disc brakes would eliminate most heat problems at the rim and at the caliper, other than perhaps warped rotors (or even melted sandwich-style rotors). But they are bulkier, heavier, and less aerodynamic than hydraulic discs can be, and they have less power and modulation.
My point is that I don’t think a magic bullet yet exists for being able to do prolonged braking on a steep descent at 120-degree temperatures. The best thing you can do in the meantime is not hold onto the brakes but instead brake harder and let off for a few seconds in between, rather than letting them continue to heat up. Or alternate front and rear braking to let one cool at a time if you have to maintain a slow speed, like in a neutralized descent.
― Lennard
Read more at http://velonews.competitor.com/2015/03/bikes-and-tech/technical-faq/technical-faq-di2-options-hot-brakes_362056#gkVoPdwuOfV1xAer.99


For some types of riding and for some riders there are benefits to using disc brakes. There are also drawbacks that are significant for other types of riding.
 

Gelsemium

Active Member
Feb 17, 2015
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Yeah, if you are considering competition all the details count so it would make it a lot heavier, but for the purpose I use it I really feel that the disc brakes are safer.
 

Kiprasn

New Member
Mar 7, 2015
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Disc brakes are definitely safer and better. If you're the one who stops and uses them, than you should invest in disc brakes. Not only they have more stopping power, if the ground is wet, normal brakes will work much slower, while disc brakes will ussually work almost the same. If i'd have an extra dollar, I would definitely invest in them:)
 

amalfatima

New Member
Mar 8, 2015
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From that list, it looks like you should be most worried about yourself! I suppose it's even worse when you're on a bike--you have to resist the urge to swerve in front of a large truck.
 

Gelsemium

Active Member
Feb 17, 2015
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One thing I miss about the old brakes is that with the disk ones I am unable to slide, it seems that the disks make the braking more soft and effective the same time.
 

oldbobcat

Well-Known Member
Aug 31, 2003
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It appears that more riders have opinions about disc brakes than have actually used them.

That said, I'll share my secondhand observation. Around October our shop received about a half-dozen carbon-framed disc-brake-equipped road bikes. Lots of customers asked about them, mostly commuters and mountain bikers, and we sent a few on test rides. And when the test rides returned they asked to try a similarly equipped or similarly priced bike without the disc brakes. And that was the one they usually bought.

We are selling a few lower priced alloy- or steel-framed disc-equipped road bikes, mostly to guys who already have a "nice" bike and want something for exploring dirt roads and mucking around on bad weather days.

While the braking performance is impressive, I think they're discovering they don't use brakes as much as they thought they would, and that road discs are just too much overhead (weight, overbuilding, wind resistance, and expense) for the utility they're getting from them. I'm open to seeing that impression change, because I'd hate to see these bikes gathering dust on the floor in August, but it's going slower than anyone would have expected.
 

Gelsemium

Active Member
Feb 17, 2015
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Yes, I don't doubt that they are not competitive because they add more weight and wind resistance, but at the same time for those cycling for fun they are just fine.
 

rotaryrocket

New Member
Dec 24, 2014
17
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I am an avid commuter in the pacific northwest and making the switch from rim brakes to hydraulic disc brakes was easy. I test rode one with mechanical disc and one with hydraulic disc, I bought the hydros. I don't compete, don't care about drag, have fenders, often wear a backpack that will be upwards of 30lbs...I ride in the wet, dry, whatever. People who commute daily and swear by rim brakes must live in AZ, or simply don't ride in the wet. As far as people competing, I can understand their concern, but for everyday use in all weather conditions...disc is my choice.
I cant imagine how fast these guys are going that they are talking about boiling the fluid in their bicycles brakes...that's like automotive racing talk man...wow.
 

Volnix

Well-Known Member
Feb 19, 2011
2,883
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rotaryrocket said:
People who commute daily and swear by rim brakes must live in AZ, or simply don't ride in the wet.

Amen, Dura Ace brake-pads are sh^t. Thank you Jesus. :D

I settled for a pair of these: They still brake worst then an Ultegra-set up but at least they do actually function in the wet. :D

Bringing Out the Dead [SIZE=15.0799999237061px]([/SIZE][SIZE=12.0900001525879px]1999[/SIZE][SIZE=15.0799999237061px])[/SIZE] Ambulance Crash
http://cli.ps/bDWmX
Swissstop-FLASH-EVO-BXP-SH-SRAM-PAD-Rim-Brake-Pads-Blue-P100003763.jpg


rotaryrocket said:
I cant imagine how fast these guys are going that they are talking about boiling the fluid in their bicycles brakes...that's like automotive racing talk man...wow.

"Trippy" :D


https://www.youtube.com/watch?v=lNsv4RYFt5U