Discs or no discs for pros

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by Weenie


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Mr.Gib
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by Mr.Gib

Fiery wrote:
Mr.Gib wrote:
Fiery wrote:
Mr.Gib wrote:
Fiery wrote:Let me rephrase that: Mr. Gib, are you actually capable of locking up the front wheel and making it slide while riding in a straight line on dry pavement? Alternatively, are you capable of consistently braking so hard that the only way to avoid endoing is by decreasing the braking force?


The simple answer is yes.

What's the modulation like when being at that limit?


Seems good to me - never stacked it. As you get to that limit you are slowing down quite a bit, the front end is heavily loaded, giving good front wheel traction, so even though you are already squeezing hard, it takes significant additional force to decelerate ever further. These big differences in hand effort, while taxing the sense of feel in the hand, seem to allow for more "fine tuning". The severe downward force also results in really good feedback about what your front tire is up to grip wise.

I think it is a great exercise to find a 10 or 15 percent grade, get the bike up to 50 km/h and practice how fast you can stop. Seen too many good riders with not the slightest clue of how to use their brakes. I live at the top of a 18% grade. I do this at the beginning of every ride. (My cool down at the end of the ride sucks though :D )


My experience is quite different: I don't remember ever being in a situation where I felt I would lose the front wheel or flip over it if I squeezed any harder while braking hard on dry pavement (weight as far to the back and as low as possible, of course). I also find the modulation to be quite bad when near the limit. It is hard to brake harder, but it is also hard to ease off just a little, which results in jerky braking. For the record, I have been using caliper rim brakes most of my life and I don't really have any experience with hydraulic disc brakes - and while modern rim brakes are indeed very good, I'd love more power and modulation.


Interesting - it sounds to me like this is an issue with brake caliper, brake pad, and/or rim. I have ridden bikes that gave me the feeling you describe about not being able to increase braking any further, but it was always due to inferior equipment/set up. The very fact that you are in on this thread suggests that you probably have decent brakes so :noidea: Even with my body all the way back and low, I can still get the rear end to hop a bit. Granted this has only been on steep down slopes so that is a factor.

As for the difficulty in easing off, this comes from the way the human hand works. Great at gripping but poor at opening with power and control. It's a challenge but doable.

To keep this on topic - for many riders a lot of these issue will be addressed by discs. The pros when they are racing? I don't see much of an advantage in any situations.
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.

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CBJ
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by CBJ

One thing I have learned is you need a lot less power with dics than I initially thought. Less fingers has given much better control of both brakes and bike. Actually too much force can sometimes make the fork chatter.

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Mr.Gib
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by Mr.Gib

CBJ wrote: Actually too much force can sometimes make the fork chatter.


There should be no such thing as too much force. Maximum force up to the point of lock up over the shortest time duration is theoretically the fastest way to descend and also theoretically where discs could provide an actual racing advantage to those with skill and nerve. The problem isn't too much force, it is underbuilt forks.

I test rode a gravel grinder recently that was completely free of chatter. The fork was beastly stiff and as a result the front end rode like a brick - harsh, even with big tires. The few better riding bikes that I have tried all chattered to varying degrees at the point of lock-up. My Boone disc is not good in this regard. What is good for ride quality, handling, etc. may not be necessarily good for disc braking at least with regard to the fork.

I am curious to know what the weights of these new disc forks will be. How light can they get and still be useful (no chatter)? 400 grams? Anybody weighed the fork off the Domane?
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.

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by efeballi

Can this chattering be due to the brake acting only on one fork leg? It could be bending, pushing the wheel off-axis, and come back to normal, and so on.
Nobody would like dual disc brakes, especially on a road bike, but I'll love it. Throw in 330 mm rotors and 6-pot Brembo calipers too, please.
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CBJ
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by CBJ

Mr.Gib wrote:
CBJ wrote: Actually too much force can sometimes make the fork chatter.


There should be no such thing as too much force. Maximum force up to the point of lock up over the shortest time duration is theoretically the fastest way to descend and also theoretically where discs could provide an actual racing advantage to those with skill and nerve. The problem isn't too much force, it is underbuilt forks.

I test rode a gravel grinder recently that was completely free of chatter. The fork was beastly stiff and as a result the front end rode like a brick - harsh, even with big tires. The few better riding bikes that I have tried all chattered to varying degrees at the point of lock-up. My Boone disc is not good in this regard. What is good for ride quality, handling, etc. may not be necessarily good for disc braking at least with regard to the fork.

I am curious to know what the weights of these new disc forks will be. How light can they get and still be useful (no chatter)? 400 grams? Anybody weighed the fork off the Domane?


Well I am basing this on actually riding my bike over the last two months and how you apply the brakes makes a big difference. I have ridden dics on my mountain bikes since the early 2000s so its not lack of experience. There are difference in braking situation that calls for difference in how you use the brakes. Its under hard braking chatter can happen especially on rough surface actually I have only had it happen on rough very uneven tarmac. The theory you mention does not take these other factors into account. Take a look at this chatter is not uncommon:

"Brook Macdonald's Trek Session is equipped with a prototype version of a harmonic damper that's designed to prevent any chattering from the rear end under heavy braking. Combining a light frame with big powerful stoppers like Shimano's Saint brakes can occasionally lead to unwanted vibrations, which is where a device like this comes in handy. Two pieces of rubber with a brass center piece are found inside the unit, technology that Trek originally developed for their hardtail customers, as well as for cyclists seeking a way to reduce the amount of high frequency vibrations transmitted from the road. "

Image

Source: http://www.pinkbike.com/news/randoms-fr ... -2015.html

I will much rather have a more compliant fork and some "risk" of chatter than some crazy stiff overbuild fork.

cl9k24la
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by cl9k24la

Disc brakes on road bikes (and for that matter the PRO peleton) is the stupidest thing ever!

Nefarious86
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by Nefarious86

cl9k24la wrote:Disc brakes on road bikes (and for that matter the PRO peleton) is the stupidest thing ever!

Ignorance is bliss [emoji14]

Peleton, yes it's overkill.
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Mr.Gib
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by Mr.Gib

CBJ I am with you on all of this. Glad to hear that I am not in a tiny minority when it comes to dealing with brake chatter. Yeah, all the bad stuff, chattering, etc. happens at the hard and fast limits, and it sounds like this may affect a lot of current equipment. And yes, I can avoid chatter on my Boone in all but near full power braking.

I assume it's possible to completely build chatter out of the equipment, but then we probably wouldn't like the equipment very much (or be able to lift it lol). Hey - none of my cars' brakes chatter so we know its doable. For me - I didn't buy my disc bike for the improved braking, I bought it to keep from destroying rims during winter training and in that regard mission accomplished.

I guess I'm just pointing out a potential downside that comes along with the benefits of discs, and wondering if it is worth the increase in expense, complication, and weight? Each individual will have to decided based on their priorities. However I am steadfast that discs are not a pure win-win and hopefully we get some honest feedback from the tour pros.
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.

jeffy
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by jeffy

Mr.Gib wrote:
CBJ wrote:I am curious to know what the weights of these new disc forks will be. How light can they get and still be useful (no chatter)? 400 grams? Anybody weighed the fork off the Domane?


a TCX Full Carbon CX Disc Fork is under 400g

Nefarious86
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by Nefarious86

Unsure of the weight of my tarmac fork but 0 chatter in 3500km of use.
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pushstart
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by pushstart

Yeah, the Whisky No 9 (road) fork is chatter-free and under 400g (mine weighs ~400g but official weight is 370g, so mine must have been one of the heavy ones).

OTOH, I have had brake shudder on my CX bike (Spot fork, ~450g) when using some rotors. My Avid HSX rotors seem to be much better than TRP rotors, for example. On that bike it hasn't been significant enough to be a practical concern. And it is so much better (at stopping + less shudder) than the crap cantis on my previous edition of that bike.

OJ
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by OJ

Browsing through this very entertaining thread...
- disc brakes are coming, suck it up!
- Road rim brakes are quite excellent. Or at least my Ultegra brakes on aluminum rims are very good. Enough power to do a nose manual at 60km/h and enough control not to eat shit as a result. I would even say that the feel of Ultegra 6800 brakes with aluminum rims is better than my new Ultegra disc brakes on my CX bike.
- If you are racing, and need spare wheels or do races with neutral support, discs will really throw a curve ball at you. Most racers in the world are non-professional and do not have cash to solve the standards/compatibility issues. Some of you may not even remember or may not have experienced the time when neutral support had to figure out who had 9-spd and who had 10.
- Rotors get hot rally quick and can cut like a razor. I've burnt my hand twice this summer (first time ever though) on a brake rotor while tweaking the brakes after riding up and down a flat driveway/backlane wearing flip flops, so very slow and very little braking. Emergency braking before a pile up is for sure enough to heat up the rotor enough to burn. I've also seen a rotor cut a finger to the bone after accidentally touching the rotor. The bike mechanic didn't even notice the cut at first as it happened so fast and cut through like a sharp box cutter. You may discount these hazards all you want, but they do exist.
- I do like disc brakes in general, but the added value doesn't seem to be quite the same as on MTB or even CX. Performance in in high speed descents is also something I would like to learn more about. I've experienced some sketchy brake loss on my MTB in seemingly not demanding situations. On a MTB I can hug a tree or something, but on a road bike brake reliability is bigger thing for me. I have descended quite a bit on single pivot calipers and even Campy Delta brakes, so maybe it's just that from my perspective we've come a huge way already when it comes to braking.

BTW, never had brake chatter on a road bike with road calipers. Plenty of times on cross and MTB...that shit just sucks a big one.
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Mr.Gib
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by Mr.Gib

Good post OJ.

And regarding the quote below, this is a data point that along with my first hand experience that has me thinking there is not a great deal to be gained for all the trouble, complication, and expense. Good for the industry but a bit of pain for some portions of the market.

OJ wrote:- I would even say that the feel of Ultegra 6800 brakes with aluminum rims is better than my new Ultegra disc brakes on my CX bike.
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.

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eliflap-scalpel
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by eliflap-scalpel

ok for the heat of a rotor ... but try to stop from 50 km/h to 0 with a carbon rim with rim brakes and touch the rim surface ...
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