Disc brake advantages?

Discuss light weight issues concerning road bikes & parts.
TobinHatesYou
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by TobinHatesYou

Cemicar wrote:
Sat Feb 09, 2019 9:19 am
sparklywheels wrote:
Sat Feb 09, 2019 8:54 am
Well my rim bike was 6.8kg ready to ride, I don’t see any disc bike hitting that weight with mid section wheels, pedals, sensors, cages and Garmin.
Emonda with XXX4.

Yep, my Emonda SLR Disc with deep ENVE 5.6s, Vector 3s (or Assiomas,) cages and computer is right around 6.8kg. With 202 NSWs it's ~175g lighter.
Last edited by TobinHatesYou on Sat Feb 09, 2019 10:27 am, edited 1 time in total.

by Weenie


sparklywheels
Posts: 36
Joined: Fri Dec 07, 2018 6:12 pm

by sparklywheels

TobinHatesYou wrote:
Sat Feb 09, 2019 10:10 am
Cemicar wrote:
Sat Feb 09, 2019 9:19 am
sparklywheels wrote:
Sat Feb 09, 2019 8:54 am
Well my rim bike was 6.8kg ready to ride, I don’t see any disc bike hitting that weight with mid section wheels, pedals, sensors, cages and Garmin.
Emonda with XXX4.

Yep, my Emonda SLR Disc with deep ENVE 5.6s, Vector 3s (or Assiomas,) cages and computer are is right around 6.8kg. With 202 NSWs it's ~175g lighter.
Well, how much was it though ? :D Lucky you to have such a nice bike!
guyc wrote:
Sat Feb 09, 2019 10:09 am
But there’s a cognitive dissonance here.

On the one hand you’re saying that 500g is critical because it costs you 3-4 seconds on a climb.

On the other hand the weight penalty is worth it.

Both can’t be right if both conditions are true.

Btw - I’m absolutely not having a go at you here. I know this is WW and weight is the MO, but when people are now regularly riding 7+kg bikes because of aero and/or discs then bikes that would have been laughed off the page 3 years ago are now the norm.
I said that they were supposedly worth the weight penalty. Not my personal opinion however. I’m not a weight weenie, and I will take a weight penalty if there’s an advantage to it. I prefer sprint stems, stiff parts all around and heavier saddles if they’re more comfortable. I would give up 100+g of crankset weight savings for better front shifting. I’m just not convinced that disc brakes are really much of an advantage performance wise, excepting rim wear in dirty conditions and heat issues with some rim braked carbon wheels. I don’t think I’m biased since I have had both, and it’s the new bike that has discs.
Last edited by sparklywheels on Sat Feb 09, 2019 10:22 am, edited 1 time in total.

guyc
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by guyc

I think you’ll find a lot of people who agree with you on that.

sparklywheels
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by sparklywheels

guyc wrote:
Sat Feb 09, 2019 10:19 am
I think you’ll find a lot of people who agree with you on that.
I guess we do agree on something after all. :D I’d like to know why people prefer discs though, I just don’t get it personally :? I’m trying to hear different sides and opinions.

guyc
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by guyc

For me they’re clearly at an advantage in rain, and they remove the risks with carbon clinchers on very long descent. Plus a lack of rim wear of course.

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zebragonzo
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by zebragonzo

Advantage - you don't need to verbally let the rest of your group* know if you're braking sharply in the wet.
*or anyone within several hundred meters
Dimples: Laminar flow separates more easily from a surface than turbulent air. Delayed separation reduces drag. A groove perpendicular to the flow triggers laminar to turbulent conversion. A spinning object uses dimples so an edge always faces the flow.

neeb
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by neeb

Although it sounds as if the OP's issues are to do with setup, I also completely don't get it (or rather I do, discs on road bikes have more to do with trends and marketing than with practicality).

No doubt that they provide a braking advantage in some situations (mainly in very wet conditions), but the trade-off in terms of weight, aerodynamics, maintenance complication, frame geometry compromises, compatibility with rim brake equipment etc just isn't worth it on a road bike unless you are riding off-tarmac, commuting or regularly riding downhill in the rain.

500g is a very minor penalty but a detectable one. It's silly to compare it to amounts by which your body weight fluctuates on a daily basis - would you want your body weight to fluctuate between 63.5 and 65kg instead of between 63 and 64.5kg?

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C36
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by C36

To focus with you initial problem, I do think there is an issue with the set up. As much as I am convinced that disc are a non sense from the bike performance, that the bike feel less responsive... they do offer the ability to brake hard with little effort and you should get it.
- how is your position? With an “extreme” reach the hands will lose grip strength, hoods angle could also be a factor.
- are you sure the discs and pads are free of all contaminants? Riding in circulation may be enough to contaminate them (happened on a ride I did comparing two tarmac (disc and rim brakes).
- for the rest having a good LBS reviewing your braking system may be needed to bring an external professional expertise. If braking degrades 40km after a purge, could you have a leak/air entry somewhere? A friend had a similar problem and appears the calliper had an issue (had to be changed twice but now it’s stable).


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Alexandrumarian
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by Alexandrumarian

Are road discs comparable or worse than mtb? When i get back to road rim after riding my xt mtb, i feel like i am using Flintstones tech. But its jut about feel and lever easiness - i doubt actual stopping is much different. But the feel and response of the xt are great, it must be that op has a setup issue...

spdntrxi
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by spdntrxi

sparklywheels wrote:
guyc wrote:
Sat Feb 09, 2019 10:19 am
I think you’ll find a lot of people who agree with you on that.
I guess we do agree on something after all. :D I’d like to know why people prefer discs though, I just don’t get it personally :? I’m trying to hear different sides and opinions.
My hands go numb .. they go numb a lot later or not at all with disc brakes because I can use 1 finger. If wet performance is not night and day better you are doing it wrong ( vs carbon) I don’t really care about point 2 becauseI don’t prefer to go out in the rain but I’ve been caught out in it a number of times to know the difference.

500g is not going to kill me... I’m not good enough for it to matter and the variation in a whole host of other things is more important. So for me it’s my hands and no it’s not a fit issue.

If you don’t prefer disc ... good for you. You will save 500g , not have to deal with niggles of disc brakes and very soon if not already be able to get some high end carbon hoops cheap on the secondary market. I know I’ve already sold most of my rim brake fleet last year.

sparklywheels
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Joined: Fri Dec 07, 2018 6:12 pm

by sparklywheels

C36 wrote:
Sat Feb 09, 2019 2:04 pm
To focus with you initial problem, I do think there is an issue with the set up. As much as I am convinced that disc are a non sense from the bike performance, that the bike feel less responsive... they do offer the ability to brake hard with little effort and you should get it.
- how is your position? With an “extreme” reach the hands will lose grip strength, hoods angle could also be a factor.
- are you sure the discs and pads are free of all contaminants? Riding in circulation may be enough to contaminate them (happened on a ride I did comparing two tarmac (disc and rim brakes).
- for the rest having a good LBS reviewing your braking system may be needed to bring an external professional expertise. If braking degrades 40km after a purge, could you have a leak/air entry somewhere? A friend had a similar problem and appears the calliper had an issue (had to be changed twice but now it’s stable).


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No it’s not setup, and I’ve fixed the issue myself. The other bikes I tested weren’t set up by me, and were pristine conditions demo bikes. I made the same observation with them.

Mr.Gib
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by Mr.Gib

Jeez, a whole bunch of disc brake philosopy (all percetly valid) that does not address the OP's problem. That problem is clearly related to pads not bedding in or some other issue that is reducing friction. That's all there is to this.

If the pads are semi-metallic and the OP has never really hit them hard, he might just have a glazed pad type situation. I installed new pads recently and it took a few hundred km with some really hard stops until the braking was where it should be - it was near useless immediately after the install. My wife who is tiny always complains that here disc bike does brake as well as her rim brake bikes. I take her little bike for a test and sure enough - not good. I take it to a steep hill and hammer the crap out of the brakes and she's good to go. (I get funny looks - a big man doing hill repeats on a midget bike :D ) In fact, I think most people, as much as they love their disc brakes, are riding around with far from optimal braking performance.

So to the OP - trust me and others when we say you are not getting the best out of your equipment. When working properly, and admittedly that can be a challenge sometimes, discs will provide incredible stopping power and great modulation with the least hand effort. They will be better (though not by that much) then the very best alloy rim brake set-up.

The weight, aerodynamics, expense, maintenance, etc. that is another issue for another thread.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

neeb
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by neeb

Mr.Gib wrote:
Sat Feb 09, 2019 5:34 pm
Jeez, a whole bunch of disc brake philosopy (all percetly valid) that does not address the OP's problem. That problem is clearly related to pads not bedding in or some other issue that is reducing friction. That's all there is to this.
No such thing as a neutral thread about disc brakes, especially if the initial post hints at some opinion as to their advantages or disadvantages.. :D

A recent bike review in a British cycling magazine refered to the disc brake debate as cycling's Brexit (if you are in the U.S. I suppose the equivalent is Trump vs. Obama/Democrats).

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nickf
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by nickf

I have heard many complaints about road disc in both wet and dry conditions. Lack of power, noise, disc/caliper alignment noises. These bikes are coming from different shops so I don't think it's setup. There genuinely seems to be a trend of lackluster performance when it comes to disc brakes. That's in wet and dry conditions. Granted I live in Florida where there are no hills to be worried about when descending. The industry is really pushing disc as a solution to a problem that doesn't truly exist in the world of road bikes. My 4-year-old Bontrager carbon tubs brake tracks look just fine. Also, the wet weather performance thing is a moot point, myself and almost everyone I ride with avoids riding in the rain anyways.


I am on the fence about disc with my next allroad build, my requirements are to fit a 38c. I can fit 38s and even 40c tires between a set of trp mini v's on my Trek Crockett. I have done many many allroad events and 38s have proven to be plenty of tire and offer the best mix of size, weight, compliance, and stability. So other than needing to go with a tire that's 42c+ or 650b there is no true need for disc. But having that option would be nice, but is it worth the weight penalty and so-called improved braking performance? This is weight weenies after all. I for one am not cool with bolting on 500G+- for "improved brake modulation and wet weather performance" said every marketing team.

sparklywheels
Posts: 36
Joined: Fri Dec 07, 2018 6:12 pm

by sparklywheels

nickf wrote:
Sat Feb 09, 2019 7:59 pm
I have heard many complaints about road disc in both wet and dry conditions. Lack of power, noise, disc/caliper alignment noises. These bikes are coming from different shops so I don't think it's setup. There genuinely seems to be a trend of lackluster performance when it comes to disc brakes. That's in wet and dry conditions. Granted I live in Florida where there are no hills to be worried about when descending. The industry is really pushing disc as a solution to a problem that doesn't truly exist in the world of road bikes. My 4-year-old Bontrager carbon tubs brake tracks look just fine. Also, the wet weather performance thing is a moot point, myself and almost everyone I ride with avoids riding in the rain anyways.


I am on the fence about disc with my next allroad build, my requirements are to fit a 38c. I can fit 38s and even 40c tires between a set of trp mini v's on my Trek Crockett. I have done many many allroad events and 38s have proven to be plenty of tire and offer the best mix of size, weight, compliance, and stability. So other than needing to go with a tire that's 42c+ or 650b there is no true need for disc. But having that option would be nice, but is it worth the weight penalty and so-called improved braking performance? This is weight weenies after all. I for one am not cool with bolting on 500G+- for "improved brake modulation and wet weather performance" said every marketing team.
Interesting to hear I’m not the only one.

by Weenie


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