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Why are disc brakes so desirable?

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Why are disc brakes so desirable?

Old 05-21-11, 07:06 PM
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Why are disc brakes so desirable?

If you aren't riding through water four to six inches deep, are disc brakes even needed?

Don't they warp under heat?

Just curious.
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Old 05-21-11, 07:15 PM
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Same reason they're desirable in cars--they work better & are more consistent in wet/muddy conditions.
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Old 05-21-11, 07:17 PM
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after installing front disk brakes on my 1 bike i would not want to go back. it seem to always work at a constant rate even if it is wet out. i have some bikes that barely stop when it is wet out till the pads seem to dry off.
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Old 05-21-11, 08:31 PM
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If your out on a trail and bend one or both of your rims you'll wish you had disc brakes because they'll still work.
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Old 05-21-11, 08:48 PM
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I can really understand it in the case of warping a wheel, and I plan to upgrade because they do perform better, but in general I don't think they're needed. My V-brakes will lock up the front wheel just fine. They squeal a tiny bit for a few minutes sometimes when they get wet, but still stop well. I can definitely flip myself over the handlebars pretty easily if I want, so I don't see a huge need to go disk until it's convenient.
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Old 05-21-11, 09:21 PM
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Like most innovations in the sport that takes hold, its because people see a value in it. There are always exceptions, but most people I know that give disk brakes a try tend to stick with them. I know people that still run V brakes and are happy, I was until I got a bike with disks, now I cant imagine my MTB bikes with out them. They are a big improvement all the way around. I am sure V-brakes will never go away, and thats cool if thats what you like. I have a friend who rides a steel, full rigid single speed, he sees no value in gears, disk brakes and front or rear suspension. He has his reasons and I am quite sure thats how he will roll till the day he stops riding.

I would say give them a try if you ever have the chance.
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Old 05-21-11, 11:04 PM
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Originally Posted by johnMATX View Post
Like most innovations in the sport that takes hold, its because people see a value in it. There are always exceptions, but most people I know that give disk brakes a try tend to stick with them. I know people that still run V brakes and are happy, I was until I got a bike with disks, now I cant imagine my MTB bikes with out them. They are a big improvement all the way around. I am sure V-brakes will never go away, and thats cool if thats what you like. I have a friend who rides a steel, full rigid single speed, he sees no value in gears, disk brakes and front or rear suspension. He has his reasons and I am quite sure thats how he will roll till the day he stops riding.

I would say give them a try if you ever have the chance.
I'm running here with:

Cantilever Brakes
Single speed 32/18
Platform Pedals
700cc x 35 cyclocross tyres

I find v brakes to be trouble, I went stock on my bike and never looked back

If I was going to get a new bike I would go disk, but only higher quality then the cheap set you sometimes get.

Now with hydraulic brakes is the question at hand, why?
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Old 05-22-11, 08:53 AM
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Hydraulics = more for less (more brake for less effort). Don't know the full or even basic physics behind why they work the way they do, but it's a greater mechanical advantage than regular cable brakes. Take a bike with well-tuned BB7's & put it up against a bike with well-tuned Juicy 3's. Pull a brake lever on each bike with the same amount of force, & you'll get more braking power from the Juicy 3's. People like hydraulic brakes for the same reason they like power steering--it's easier.
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Old 05-22-11, 09:17 AM
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Originally Posted by samburger View Post
Hydraulics = more for less (more brake for less effort). Don't know the full or even basic physics behind why they work the way they do, but it's a greater mechanical advantage than regular cable brakes. Take a bike with well-tuned BB7's & put it up against a bike with well-tuned Juicy 3's. Pull a brake lever on each bike with the same amount of force, & you'll get more braking power from the Juicy 3's. People like hydraulic brakes for the same reason they like power steering--it's easier.
The reason being is that cables can and do stretch (Just a little mind you, under heavy breaking) but hydraulics work with a fluid which can't be compressed (Fluids act like a solid under compression) so under heavy breaking all the energy from the brake lever is transfered to the pads ( via the hydraulic line to the calliper). Quite simple but genious, in it's application.
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Old 05-22-11, 09:54 AM
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Originally Posted by Fairmont View Post
If you aren't riding through water four to six inches deep, are disc brakes even needed?
For some, yes. For others, no.

Originally Posted by Fairmont View Post
Don't they warp under heat?
No, at least not the amount of heat generated in a mtb application.

Originally Posted by Fairmont View Post
Just curious.
Try a search. The comparison of discs vs rim brakes has been beaten to death on this forum, especially 5+ years ago.

Originally Posted by JoeBear50 View Post
The reason being is that cables can and do stretch (Just a little mind you, under heavy breaking)
No they don't - not under the loads they see in a mountain bike application. Mechanical brakes lose efficiency in two main areas - friction and housing compression.
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Old 05-22-11, 10:48 AM
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Before I got my Stumpjumper I felt like disc brakes were not very important. Now that I've used these ones (Avid Elixirs) I can't imagine going back to rim brakes. The difference is huge.
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Old 05-24-11, 04:22 AM
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Originally Posted by cryptid01 View Post

No they don't - not under the loads they see in a mountain bike application. Mechanical brakes lose efficiency in two main areas - friction and housing compression.
This is the first time I've actually realized I hadn't ever thought about why hydraulics work better (when compared to cable disc). What do you mean by housing compression? I understand how friction is a now-obvious reason for considerable power loss. But when you think about it, it's all about leverage, which is easy to solve (considering frictionless, for the sake figuring out the remainig loss), so where does the remaining force disappear to? What 'gives' (bends), so to speak?
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Old 05-24-11, 06:49 AM
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This reminds me of the debate over suspension forks and frames back when they where first introduced. Until you think about where and how you ride, and then try them where you ride, you won't really know what you need.

I have bikes with V-brakes and disks, and with front suspension and with solid forks, and with rear suspension and a hardtail. Each was built for a different purpose and each works well for what it was built for. So if you are commuting, trail riding, bombing down hill, or doing trials, you need to think first about how and where you ride.

BTW: I prefer the power of a hydraulic caliper but like the feedback of a cable caliper better for some uses. You just need to try each option to know what will work best (or acceptably) for your use.
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Old 05-24-11, 08:12 AM
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^^
Spoken like a man with experience, very well put.
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Old 05-24-11, 11:41 AM
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Originally Posted by 3speed View Post
My V-brakes will lock up the front wheel just fine.
That there are still people who adhere to this tired and totally debunked truism amazes me.
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Old 05-24-11, 12:01 PM
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Originally Posted by dminor View Post
That there are still people who adhere to this tired and totally debunked truism amazes me.
Reminds me of the old guys who daily drive classic cars getting 5mpg under the defense of "I don't trust these new cars, there's no way that plastic bumper is gonna save me in a crash!"

Once you rationalize an irrational idea to yourself, you're the only one who can change your mind. No amount of outside reasoning will do any good.
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Old 05-24-11, 02:43 PM
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Originally Posted by kenb View Post
If your out on a trail and bend one or both of your rims you'll wish you had disc brakes because they'll still work.
When you are on the trails and you bend your one or both of your rotors, you will wish you had V-brakes
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Old 05-24-11, 02:49 PM
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Originally Posted by Skankingbiker View Post
When you are on the trails and you bend your one or both of your rotors, you will wish you had V-brakes
Consider your wheels are almost always in contact with the ground whereas your rotors never should be, I think disc brakes are the safer option.
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Old 05-24-11, 03:42 PM
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Originally Posted by Stealthammer View Post
I have bikes with V-brakes and disks, and with front suspension and with solid forks, and with rear suspension and a hardtail. Each was built for a different purpose and each works well for what it was built for. So if you are commuting, trail riding, bombing down hill, or doing trials, you need to think first about how and where you ride.
Out of curiosity, what are the circumstances under which you think V-brakes are preferable?
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Old 05-24-11, 04:29 PM
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Originally Posted by Bikernator View Post
What do you mean by housing compression?
When a control cable is placed under tension, the cable stops exert a compressive force on the cable housing. This phenomenon is frequently and incorrectly termed "cable stretch." With the proper housing, and after break in (get it?), it's not that big a deal.

Originally Posted by Bikernator View Post
I understand how friction is a now-obvious reason for considerable power loss. But when you think about it, it's all about leverage, which is easy to solve (considering frictionless, for the sake figuring out the remainig loss), so where does the remaining force disappear to? What 'gives' (bends), so to speak?
The force doesn't really "disappear" - it's just that it is much less with mechanical systems as opposed to hydraulic. It's a lot easier to increase forces hydraulically than it is mechanically (see: backhoes) I suppose you could make a V brake lever that exerted similar leverage to a hydraulic system, but it'd be 8" long and it'd be too far from the bar for you to reach.

Hope this answers your question?
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Old 05-24-11, 04:38 PM
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Originally Posted by dminor View Post
That there are still people who adhere to this tired and totally debunked truism amazes me.
I know. I get tired of trying to think of new, witty ways to stem the flow lest my insults become equally trite.
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Old 05-24-11, 05:50 PM
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Originally Posted by Skankingbiker View Post
When you are on the trails and you bend your one or both of your rotors, you will wish you had V-brakes
when you are on the trail and bend or dent one or both your rims you will wish you had disk brakes. i know i have had to limp my bike off the trails with practically no brakes before because i have damages a rim.
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Old 05-24-11, 05:57 PM
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As a recent switcher from cantilever (or whatever those notoriously difficult-to-adjust brakes are called) to disc, I love disc brakes so much better. I really had to clamp down with all fingers going down steep hills on the old brakes, now it takes just one finger on each hand. On long hills I even had to stop and give my hands a rest cuz they were cramping up. No more.
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Old 05-24-11, 07:26 PM
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This is a refreshing and new thread topic.
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Old 05-24-11, 09:03 PM
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Originally Posted by dminor View Post
That there are still people who adhere to this tired and totally debunked truism amazes me.
No, no, he is right. They will lock up his wheel just fine. It's the rest that is iffy.
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