Hyrdaulic Disk Brakes

Discuss light weight issues concerning road bikes & parts.
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bikebike
Posts: 13
Joined: Mon Aug 08, 2016 9:38 pm

by bikebike

Looking for any feedback on Road bike hyrdaulic disk brakes. Many people speak about the wet weather benefit. How about on even sunny and dry conditions? What are possible negatives about disk brakes, other than aerodynamic concerns or esthetic concerns?

MichaelB
Posts: 438
Joined: Tue Apr 22, 2008 4:31 am

by MichaelB

Thje worst bit for me is the noise that you can get in the wet.

Meh.

The MAIN advantages are the consistency and modulation (nee control).

As a user for some time now (cable & hydraulic), they are great. Simple.

jeffy
Posts: 1255
Joined: Sun Oct 05, 2014 11:51 pm

by jeffy

Descending fast, tight corners. One finger, gentle braking. Exceptional control.

I have heard said, from someone with rim brakes to someone with hydraulic discs "you start braking when i start praying"

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Fixie82
Posts: 353
Joined: Mon Mar 18, 2013 3:45 am

by Fixie82

Agree with consistency and modulation - negatives in the application of the system on the road are very few. Emergency stops for me usually result in a skid at the rear as I still ride both disc and rim brake variants so haven't yet totally adjusted how hard I apply the brakes in an 'oh shit' moment. Installation and maintenance could throw not so much negatives up but compromises. You may have to invest in a couple of new tools and some time learning to bleed the system when installing and for maintenance, although with the closed system maintenance will be at much longer intervals. If something happens on the road spare parts may be harder to find at small bike shops but with MTB pretty much all having hydraulic systems now it shouldn't pose a massive problem unless you are in the middle of nowhere.

Aerodynamic concerns are interesting, I've stayed out of most of the debate however they are pretty much drag neutral at 0 degree yaw and increase drag due to their side profile. What people don't seem to take into consideration is the amount of time we spend at different yaw angles, it's not the be all and end of all of studies but FLO have shown that we spend the majority of time at 0 degree yaws when riding. As such the negative effect to aerodynamics would be negligible and what effect it did have would be negated by the ability to hold more speed approaching corners and potentially finer control over that speed.

Each to his own really but unless you are racing there are no major drawbacks to a disc bike for me. Of course you may have other considerations such as wheels you already own not fitting, not liking the aesthetic, preferring rim brakes because it's what you know ect

Cheetahmk7
Posts: 69
Joined: Sat Aug 20, 2011 2:09 am

by Cheetahmk7

Fixie82 wrote:Aerodynamic concerns are interesting, I've stayed out of most of the debate however they are pretty much drag neutral at 0 degree yaw and increase drag due to their side profile. What people don't seem to take into consideration is the amount of time we spend at different yaw angles, it's not the be all and end of all of studies but FLO have shown that we spend the majority of time at 0 degree yaws when riding. As such the negative effect to aerodynamics would be negligible and what effect it did have would be negated by the ability to hold more speed approaching corners and potentially finer control over that speed.


What you are forgetting is what happens when experiencing high yaw angles. This is the time in the race when there is a strong crosswind, the strong riders have put it into the gutter and riders are being dropped like flies. Often it is for only a tiny period of a race but it is the defining moment of the race.

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Fixie82
Posts: 353
Joined: Mon Mar 18, 2013 3:45 am

by Fixie82

Nope not forgetting that at all - I'm simply saying that the aerodynamic penalty is small at high yaw angles, I've seen the figure of 4 watts bandied about, and it's negligible/no penalty present at low yaw angles. In the context of deciding between a disc and rim brake model, aerodynamics of the braking system shouldn't even be a consideration in my opinion. There are other differences and compromises to be made that would affect the decision making process before you start splitting hairs on aerodynamics.

Losing 4 watts in the small context of high yaw angles (which FLO aptly shows is a minimal percentage of ride time) doesn't strike me a massive issue compared to what discs bring to the table in other situations. 4 watts when you're chasing a split in a cross wind isn't going to be the deciding factor of you making it across or not.

Of course this point relies on being able to use them racing - which unless you live in the U.S shouldn't factor into the discussion just yet.

joeg26er
Posts: 62
Joined: Thu Aug 28, 2008 3:40 am

by joeg26er

What about weight differences? I've used super lightweight caliper rim brakes KCNC CB1 on vintage Zipp 202 rims for many years. For example in 6 Gap Century where you climb 6 gaps LOL with combined climbing total of about 12,000 feet over 104 miles.
Descents are upwards of 50mph. One descent I hit 56mph. But not super twisty. Brakes worked well.

pushstart
Posts: 445
Joined: Sat Jun 16, 2012 3:12 am

by pushstart

Hydros are great. I use cable discs (Spyres) on my road bike and they work fine but are not nearly as nice as the SRAM hydros on my commuter. In general for me there are very few disadvantages to disc brakes (loud when wet, more difficult to setup) and the benefits of massively better braking vastly outweigh the disadvantages. The braking control is much better. The ability to brake with a single finger from the hoods makes for extremely confident control in technical situations -- especially nice off-road, but nice in some road situations too.

I love that disc brakes let me run carbon rims without worrying about braking performance or risk of delamination on descents. And let me run rims with wider tires (frame allowing) or swap wheelsets without adjusting rim calipers. It is no surprise that road bikes are moving in this direction. You don't hear many stories of people who ride hydro road disc and decide to go back to rim brakes.

bikebike
Posts: 13
Joined: Mon Aug 08, 2016 9:38 pm

by bikebike

Your feedbacks are very helpful. Any comment on most common mechanical issues, maybe mal-alignment of disk to pads? Someone already mentioned fluid maintenance.

Cheetahmk7
Posts: 69
Joined: Sat Aug 20, 2011 2:09 am

by Cheetahmk7

Fixie82 wrote:Nope not forgetting that at all - I'm simply saying that the aerodynamic penalty is small at high yaw angles, I've seen the figure of 4 watts bandied about, and it's negligible/no penalty present at low yaw angles. In the context of deciding between a disc and rim brake model, aerodynamics of the braking system shouldn't even be a consideration in my opinion. There are other differences and compromises to be made that would affect the decision making process before you start splitting hairs on aerodynamics.

Losing 4 watts in the small context of high yaw angles (which FLO aptly shows is a minimal percentage of ride time) doesn't strike me a massive issue compared to what discs bring to the table in other situations. 4 watts when you're chasing a split in a cross wind isn't going to be the deciding factor of you making it across or not.

Of course this point relies on being able to use them racing - which unless you live in the U.S shouldn't factor into the discussion just yet.


Image

Maybe 4 watts compared to standard brakes, but it would be more when compared to the hidden brakes like you find on many aero bikes. I'd say that when you are in the gutter fighting to hang on that 4+ watts could absolutely be the difference between hanging on or getting dropped. I'm typically talking handicap races here when scratch or block catch your group, there is a crosswind and they put it into the gutter. If you can hang until the road changes direction there is a good chance of figuring in the prize money. It doesn't matter that this occurrence is for just a small percentage of the ride as it is the critical time that decides the race outcome. I have seen this happen time, after time after time.

Races in Australia are pretty much devoid of descents so disc brakes bring additional aerodynamic drag and weight to the table without realising any of their braking benefits.

shotgun
Posts: 194
Joined: Tue Dec 30, 2008 3:38 pm
Location: Philippines

by shotgun

Biggest drawbacks

- weight penalty brought about by the heavier components and frameset
- quick tire or wheel changes

Having said that, I ride my hydraulic disc roadie 3/1 over my race road bike. Braking is just sublime.

bikewithnoname
Posts: 999
Joined: Tue Sep 22, 2009 1:29 pm
Location: UK

by bikewithnoname

Pernsonally I'd pass until at least gen 3 of the calipers, they need to open wider in adjustable manner and self return better than an mtb caliper to ensure no pad drag. No manufacturer has a decent contact adjustment yet
"We live in an age when unnecessary things are our only necessities." Oscar Wilde

Pegoretti Responsorium, Parlee Z5i, Donhou Commuter, 1946 MacLeans Featherweight L'Eroica!, 2x MTB 'dales

Broady
Posts: 270
Joined: Thu Jan 03, 2013 5:02 pm

by Broady

Had Shimano hydro discs for 6 months or so now on my Feather, would never go back to calipers, the braking is sublime. Reliable, consistent, controlled and powerful. If you haven't used a bike with them you are definitely missing out.

Brus
Posts: 38
Joined: Mon Apr 25, 2016 1:36 pm

by Brus

i have shimano hydro for about a year and right now i´m looking for new road (race) bike and rim brakes are "must have".

i like the hydro for reliability, consistency, powerful, user-friendly. But i don´t like how it looks, how heavy are they. No nice and light deep carbon wheels available..

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Fixie82
Posts: 353
Joined: Mon Mar 18, 2013 3:45 am

by Fixie82

Cheetahmk7 wrote:
Fixie82 wrote:Nope not forgetting that at all - I'm simply saying that the aerodynamic penalty is small at high yaw angles, I've seen the figure of 4 watts bandied about, and it's negligible/no penalty present at low yaw angles. In the context of deciding between a disc and rim brake model, aerodynamics of the braking system shouldn't even be a consideration in my opinion. There are other differences and compromises to be made that would affect the decision making process before you start splitting hairs on aerodynamics.

Losing 4 watts in the small context of high yaw angles (which FLO aptly shows is a minimal percentage of ride time) doesn't strike me a massive issue compared to what discs bring to the table in other situations. 4 watts when you're chasing a split in a cross wind isn't going to be the deciding factor of you making it across or not.

Of course this point relies on being able to use them racing - which unless you live in the U.S shouldn't factor into the discussion just yet.


Image

Maybe 4 watts compared to standard brakes, but it would be more when compared to the hidden brakes like you find on many aero bikes. I'd say that when you are in the gutter fighting to hang on that 4+ watts could absolutely be the difference between hanging on or getting dropped. I'm typically talking handicap races here when scratch or block catch your group, there is a crosswind and they put it into the gutter. If you can hang until the road changes direction there is a good chance of figuring in the prize money. It doesn't matter that this occurrence is for just a small percentage of the ride as it is the critical time that decides the race outcome. I have seen this happen time, after time after time.

Races in Australia are pretty much devoid of descents so disc brakes bring additional aerodynamic drag and weight to the table without realising any of their braking benefits.


Still going to respectfully disagree that 4 watts is going to be the difference in that situation. You might get dropped but it's not because you couldn't put out 4 more watts. Adding 4 extra watts to your output would increase your speed by such a minimal amount it's simply not going to matter in this situation. At race speeds of 35kmh an increase of 20 watts would get you to roughly 35.5kmh, so how much does 4 watts get you? Good race craft of following the move and position will matter more in this situation, not your braking system.

Just because it's a cross wind also doesn't necessarily mean it's a high yaw angle either, it's influenced by speed and if you are drafting. There is some great info on SlowTwitch about yaw angles if you want to check it out further.

As for gaining the benefits of discs I guess it depends on where you race in Australia and what races you enter. I would love discs for some Crit courses, being able to brake later into a corner and potentially carry more speed because of the finer control would outweigh the small aerodynamic penalty. All else being equal of course. I would also love to use them in wet races as well. My local races here in QLD are quite hilly too.

Funny thing is that as we are in Australia and we can't use them in races so there should be other more pressing reasons for choosing between disc or rim brakes than how they will affect your racing.

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