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Disc brakes on road bikes...

Which tyres for Paris-Roubaix? Whose time trial bike is fastest? Suspension mountain bikes or singlespeeders? Talk equipment here.

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Re:

24 Dec 2016 02:17

Felice Gimondi wrote:Disc brakes or not, lack of grip on tires on wet or dry surfaces is still a bigger obstacle, changing to disc brakes does not improve this situation significantly.


Yes is does, and that is precisely why people are making the switch.

After all these years, all the info, all the bikes to test, I'm still totally perplexed as to why the most ardent critics of disc brakes on road bikes have the least, mostly zero experience with it. Awfully strange conundrum to throw yourself into.
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Re: Re:

24 Dec 2016 10:27

MWC wrote:
Felice Gimondi wrote:Disc brakes or not, lack of grip on tires on wet or dry surfaces is still a bigger obstacle, changing to disc brakes does not improve this situation significantly.



Yes is does, and that is precisely why people are making the switch.

After all these years, all the info, all the bikes to test, I'm still totally perplexed as to why the most ardent critics of disc brakes on road bikes have the least, mostly zero experience with it. Awfully strange conundrum to throw yourself into.


I have disc brakes on my CX and have ridden disc brakes there for many years both hydraulic and mechanical in snow and ice conditions in down to -20 c for instance. I can therefore say that on CX the tires still represent a great challenging part and efficiencies gained from disc brakes is not without connection to grip on variable surfaces. The total gain is much more significant on CX than on my road bike due to different properties on the various surfaces, but the more slippery it gets; mud, wet grass, snow or ice, the lesser the benefit of disc brakes become.

Otherwise there wouldn't have been studded tires;) You try and race your opponent on icy conditions with disc brakes without studded tires and they would outpreform you even with bad v-brakes with travel agents.
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24 Dec 2016 17:21

Sooo... brakes don't work well in conditions where brakes don't work well?... Hmmm, this changes everything.
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Re: Disc brakes on road bikes...

24 Dec 2016 17:26

Felice Gimondi wrote:
I have disc brakes on my CX and have ridden disc brakes there for many years both hydraulic and mechanical in snow and ice conditions in down to -20 c for instance. I can therefore say that on CX the tires still represent a great challenging part and efficiencies gained from disc brakes is not without connection to grip on variable surfaces. The total gain is much more significant on CX than on my road bike due to different properties on the various surfaces, but the more slippery it gets; mud, wet grass, snow or ice, the lesser the benefit of disc brakes become.


Ok Felice, what are you some sort of self-deprecating disc braker? :p Tire grip is the result of tread choice and pressure for the given course, being a deft bike handler doesn't hurt either. Since you have many years of experience on disc for CX, how are you missing the point that our brakes have better control and modulation of that grip over a pad on a rim in all surface and weather conditions? Everything else being equal the rider with the better brakes wins. So the entire World Cup complex is doing it wrong?

Otherwise there wouldn't have been studded tires;) You try and race your opponent on icy conditions with disc brakes without studded tires and they would outpreform you even with bad v-brakes with travel agents.


This example makes perfect sense for disc. Since most icy patches are usually floated over, no brakes applied, I'm still going to have the better brakes for the rest of the lap and my opponent is riding much heavier tires with lesser brakes. Not to mention, how many people out there are really dealing with icy cross racing on a regular basis? Are we really talking about racing, or commuting all year round in places that actually have a Winter? I started racing CX in the mid 90's in icy and frigid Minnesota and nobody ever used studs for the 1 maybe 2 late season races that featured ice, not even when disc brake bikes started showing up in 07, or when Dugast started producing the Diavolo for Sven in 2010.

Back to disc brakes on road bikes?
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24 Dec 2016 19:18

Grip is not entirely up to tire choice, on my road bike I can block the wheels whenever I want, at what ever speed , on CX the brakes were simply not powerful enough.
Last edited by Felice Gimondi on 24 Dec 2016 19:30, edited 1 time in total.
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Re: Disc brakes on road bikes...

24 Dec 2016 19:24

MWC wrote:This example makes perfect sense for disc. Since most icy patches are usually floated over, no brakes applied, I'm still going to have the better brakes for the rest of the lap and my opponent is riding much heavier tires with lesser brakes. Not to mention, how many people out there are really dealing with icy cross racing on a regular basis? Are we really talking about racing, or commuting all year round in places that actually have a Winter? I started racing CX in the mid 90's in icy and frigid Minnesota and nobody ever used studs for the 1 maybe 2 late season races that featured ice, not even when disc brake bikes started showing up in 07, or when Dugast started producing the Diavolo for Sven in 2010.

Back to disc brakes on road bikes?


Not much experience in icy and snowy conditions I see:) That floating over does not require disc brakes and is not an argument for disc brakes in particular. Btw, studded tires are not allowed in CX races, but if they were legal, riders would frequently use them and on snowy conditions they would go much faster than normal cx tires.

You talk about better brakes when the limiting factor is ground friction, the sudded tires example was to show you that point, alas you wouldn't listen to reason.

Modulation is interesting, as if you're able to analyse ground surface more accurate at +50 kph with disc brakes.
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Re: Disc brakes on road bikes...

24 Dec 2016 19:35

"Everything else being equal the rider with the better brakes wins."

Not correct, if both disc brakes and rim brakes function beyond the forces of grip, disc brakes will not be the deciding factor. That's my point.

Rim brakes is also a variant of disc brake, where the disc is 700c
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Re:

24 Dec 2016 19:41

VeloFidelis wrote:Sooo... brakes don't work well in conditions where brakes don't work well?... Hmmm, this changes everything.


Meaning you really don't get significant improvements from either choice, welcome to this realization:)

As I said, tire friction is a bigger issue.
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Re:

24 Dec 2016 21:09

Felice Gimondi wrote:Grip is not entirely up to tire choice, on my road bike I can block the wheels whenever I want, at what ever speed , on CX the brakes were simply not powerful enough.


You couldn't lock up CX canti brakes? How much do you weigh?

Not much experience in icy and snowy conditions I see:) That floating over does not require disc brakes and is not an argument for disc brakes in particular


It's not an argument for brakes at all, it's the rest of the course that does.

Btw, studded tires are not allowed in CX races, but if they were legal, riders would frequently use them and on snowy conditions they would go much faster than normal cx tires.


Sure, illegal for UCI racing. When was the last time anybody here raced a UCI sanctioned event with technical inspection? You're only going faster with studs if the majority of the course is ice, which is, well... never.

You talk about better brakes when the limiting factor is ground friction, the sudded tires example was to show you that point, alas you wouldn't listen to reason.


I listened, I gave you a reply, and you chose to strawman.

Modulation is interesting, as if you're able to analyse ground surface more accurate at +50 kph with disc brakes.


Brake modulation has nothing to do with analyzing ground surface at speed. You're really getting Twilight Zone here.

Felice Gimondi wrote:"Everything else being equal the rider with the better brakes wins."

Not correct, if both disc brakes and rim brakes function beyond the forces of grip, disc brakes will not be the deciding factor. That's my point.


All you are accomplishing with that point is stating the obvious, that you can hit the deck on a slippery section limited by tire grip regardless of brakes. Sure, but there's clearly more to it. What about the 99% of the rest of the course? These slippery sections that will take down anybody on any kind of brake is such a small percentage of races per year, if at all for most amateurs or pros. Disc brakes allow you to brake later and adjust speed into a really bad section, the result is faster laps for 45min. Yeah of course all else being equal, the very reason you don't see a mixed field at the World Cup level anymore.

Rim brakes is also a variant of disc brake, where the disc is 700c


This is one of the original old wives' tales that people used to bring up when disc brakes were new to road almost 10 years ago. Can't believe you (a disc user?) brought it up. Cantis, V, center pull, side pull, rod actuated are all "variants" of rim brakes. Disc brakes are an entirely different 'system'. You said that you made the switch to disc for cross for more power. So why don't you elaborate on why you feel you have more stopping ability with with disc? It will totally contradict the 'rim is a disc theory', but whatever at this point. :rolleyes:
Last edited by MWC on 25 Dec 2016 19:10, edited 2 times in total.
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Re: Re:

25 Dec 2016 02:59

Felice Gimondi wrote:
Meaning you really don't get significant improvements from either choice, welcome to this realization:)

As I said, tire friction is a bigger issue.


I think the bigger problem is cranial rectitosis... in that situation friction is most definitely an issue ;)
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Re: Disc brakes on road bikes...

25 Dec 2016 18:15

Disc brakes on road bikes will save the world and bring peace and good will to all mankind.

Merry Christmas

MWC
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25 Dec 2016 19:20

Santa must have not had Disk brakes on his sleigh as he skipped my house...............
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Re: Disc brakes on road bikes...

26 Dec 2016 10:58

MWC wrote:Disc brakes on road bikes will save the world and bring peace and good will to all mankind.

Merry Christmas

MWC

Not for me they won't.

I race, can only afford one bike at a time and bought a new bike last year.
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26 Dec 2016 13:48

I'm 176cm and my weight is 65kg, still can't get the CX brakes to block at all times, even mechanical disc brakes, cause they're simply not powefull enough on all types of surfaces. My hydraulic however, they can and also my rim brakes on my road bike.

Modulating the brakes has lot's to do with analysing and feeling the effect your braking has, and at higher speeds the human perception is just not good enough.
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26 Dec 2016 13:57

"Disc brakes allow you to brake later and adjust speed into a really bad section"

If your existing road bike brakes already will block the wheels, or even better, brake just up to the point before blocking, there are no improvements in braking capabilities. If you ride on a bike with or without disc brakes, it is the same amount of energy one has to dispose with, if that energy is not possible to get rid off on a shorter distance because of tire friction being the limiting factor, disc brakes will not shorten the braking distance. That's only physics.
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Re:

26 Dec 2016 17:00

Felice Gimondi wrote:"Disc brakes allow you to brake later and adjust speed into a really bad section"

If your existing road bike brakes already will block the wheels, or even better, brake just up to the point before blocking, there are no improvements in braking capabilities. If you ride on a bike with or without disc brakes, it is the same amount of energy one has to dispose with, if that energy is not possible to get rid off on a shorter distance because of tire friction being the limiting factor, disc brakes will not shorten the braking distance. That's only physics.


I did a little experiment this year. Went back and re-rode most of the long technical descents where I hold KOM's and PR's on Strava with the disc equipped bike, but on my rim brake bike with every intention of making a result on these sections. Guess what happened, no KOM's and no PR's. I even overshot a really tight corner over the yellow line, one that I remember railing on the other bike. I can brake much later into corners with disc, in turn I exit faster. I also have better control and modulation throughout the braking sections at speed. By your definition(?) of physics the combination of disc and road tires I don't have any advantage because you claim that the limiting factor is tire grip. You don't realize for whatever reason that this debate was over years ago? Nobody is still trying to figure out why disc brakes work better than rim brakes. The only problem roadies have with it is that is messes up their traditional aesthetic. So what is your intention by hammering this tire friction thing to death? Doesn't make any sense.

How is it that your physics doesn't add up with everybody else's physics? If what you're saying is true every shop is going to have to pull their 2017 road disc models off the floor, tomorrow! And all the manufacturers are going to have to pay for making false claims for 20 years. Let's see if they got your warning, backed up by physics of course. :lol:
Last edited by MWC on 27 Dec 2016 00:46, edited 6 times in total.
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Re:

26 Dec 2016 17:14

Felice Gimondi wrote:I'm 176cm and my weight is 65kg, still can't get the CX brakes to block at all times, even mechanical disc brakes, cause they're simply not powefull enough on all types of surfaces. My hydraulic however, they can and also my rim brakes on my road bike.


I weigh 14kg more than you and could lock up every mechanical disc I've ever had on a CX bike. How is it possible that you, much lighter, cannot? Oh, I remember, your physics are a little different than normal. My bad. :o


Modulating the brakes has lot's to do with analysing and feeling the effect your braking has, and at higher speeds the human perception is just not good enough.


Maybe you shouldn't ride down hills. Just a suggestion. ;)
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27 Dec 2016 12:10

Disk brakes are a real solution to the heat problem on carbon clinchers. It completely solves the overheated rim problem.
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27 Dec 2016 17:13

The goal of a better braking system is to never 'block' the wheel; hence the existence of ABS braking systems. The improved modulation of disc brakes allow for shorter braking distance without 'blocking' the wheel. Rim brakes with less modulation, and bigger issues with heat build up and pad compatibility will 'block' a wheel more quickly and with less warning. This causes loss of traction, and control, leading to longer stopping distance. Sometimes the extra friction from your lycra, your skin, handlebar tape, the end of your pedal, the edge of your saddle, and the side of your helmet can shorten that distance. But the price for that, makes the cost disc brakes appear to be a bargain.
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28 Dec 2016 03:52

Former tech ed here, now at cyclingtips, James Huang...

Disc brakes offer better modulation than rim brakes, meaning it’s easier for the rider to precisely meter out exactly how much clamping power is generated. Peak stopping power occurs just before the point of lock-up and disc-equipped bikes are better equipped to flirt with that edge without crossing over. Disc brake power also tends to be more linear and predictable than on rim brakes, and it’s far more consistent in varying weather conditions, especially when compared with using rim brakes on carbon rims – a combination that yields notoriously poor performance in the wet and yet is also prone to overheating when dry.


I know he's too smart to chime in here anymore, but dang James, after 20 years of disc brakes ya'd think the debate would be over by now. :rolleyes:
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