I wouldn't try 1st-generation road hydraulic brakes down a huge mountain descent just yet. Braking in cyclocross (low speeds on gravel/mud) is a bit different to braking at 70 km/h on tarmac.brett.hooker wrote:I am too far past it to worry about being elite speed, but I would love a fairly light road bike with discs just for the stopping improvement; particularly coming down places like MT Coottha and mt Nebo.
Shimano Di2 hydraulic road disc brakes spotted
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby __PG__ » Fri Feb 22, 2013 7:25 am
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby kunalraiker » Fri Feb 22, 2013 9:07 am
__PG__ wrote:I wouldn't try 1st-generation road hydraulic brakes down a huge mountain descent just yet. Braking in cyclocross (low speeds on gravel/mud) is a bit different to braking at 70 km/h on tarmac.brett.hooker wrote:I am too far past it to worry about being elite speed, but I would love a fairly light road bike with discs just for the stopping improvement; particularly coming down places like MT Coottha and mt Nebo.
I completely agree, remember the MTB Demo by GIANT I had been to, was too scared to brake as it would just lock the bike.
I once had to jump of the bike at high speed to avoid a fall.
Imagine the same braking efficiency on Road Bike.I don't want to Slide or Dive into something, please spare me
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Mulger bill » Fri Feb 22, 2013 9:27 am
There's been years of dev work done on them, the only salient difference is the lever.__PG__ wrote:I wouldn't try 1st-generation road hydraulic brakes down a huge mountain descent just yet. Braking in cyclocross (low speeds on gravel/mud) is a bit different to braking at 70 km/h on tarmac.brett.hooker wrote:I am too far past it to worry about being elite speed, but I would love a fairly light road bike with discs just for the stopping improvement; particularly coming down places like MT Coottha and mt Nebo.
I've made those sort of silly speeds on 1" slicks on my old Giant XTC on road using 1st gen Avid Juicy7s. They howled like wolves at a full moon and the pads were smoking at the bottom of the descent but I never felt (too) worried.
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby barefoot » Fri Feb 22, 2013 9:33 am
But but but...Nobody wrote:Weight is overrated in the real world. Aero is more of a problem but I doubt any of us could ride a bike fast enough on the flat to notice the difference (all other thing being equal)kunalraiker wrote:They will be heavier, much heavier really as compared to my cable brakes.
At the moment, rims are compromised by the requirement to provide a braking surface.
Take that requirement away, and they can be significantly lighter and more aero.
It won't happen immediately, but I'd expect to start seeing some very tasty disc-specific carbon rims hitting the market not long after hydraulic brifters make their presence felt.
tim
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Mulger bill » Fri Feb 22, 2013 9:45 am
OY!Nobody wrote:Weight is overrated in the real world. Aero is more of a problem but I doubt any of us could ride a bike fast enough on the flat to notice the difference (all other thing being equal)
Why are you trying to start another round of where's when there's still a game in progress?
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby clackers » Fri Feb 22, 2013 11:14 am
Yep, I've got some BB7s, just about the best cable discs around, but my hydros are even better, Kunalraiker - power, graduated control, and self-adjusting for pad wear.kunalraiker wrote: What's the point, given the cable brakes are excellent at stopping.
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby MichaelB » Fri Feb 22, 2013 11:15 am
kunalraiker wrote:
2. Points made
First- Weight
Second- Cosmetic-Looks
None of these have anything to do with trying a road bike with Disc.
Counter point
Weight : You have no idea of the weight, so how can you comment ?
Looks : Beauty is in tyhe eye of the beholder. Personally, i favour safety and being able to stop over a minor cosmetic issue.
Actually trying : Before you make disparaging comments, you need to try. Then you will realise the added weight (4/5ths of stuff all) when compared to the added weight of a rider, lights, spares etc is really a furphy, and so is the aero.
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby MichaelB » Fri Feb 22, 2013 11:19 am
Yes it's different. So you brake different. What does the 'method' of braking have to do with it.__PG__ wrote:I wouldn't try 1st-generation road hydraulic brakes down a huge mountain descent just yet. Braking in cyclocross (low speeds on gravel/mud) is a bit different to braking at 70 km/h on tarmac.brett.hooker wrote:I am too far past it to worry about being elite speed, but I would love a fairly light road bike with discs just for the stopping improvement; particularly coming down places like MT Coottha and mt Nebo.
I've been running the pre-production TRP Parabox from before the local Aussie distributors had them.
I have done many high speed descents with 15 - 25km/hr hairpins in succession, and at 95kg, had no issue whatsoever.
They key is the correct rotor for the road.
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Xplora » Fri Feb 22, 2013 12:38 pm
Early stage R&D is hardly the time to bag the tech, that's for sure.
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Nobody » Fri Feb 22, 2013 12:51 pm
It was BikeRumor.com.Xplora wrote:Yeah, the Road.cc (?) reviewer put himself into the meatwagon using the lightest CX rotor available and then blamed the discs for his failure to descend safely. It could very well be that a huge 200mm rotor could be ideal for big descents. Or not.
Early stage R&D is hardly the time to bag the tech, that's for sure.
http://www.bikerumor.com/2012/02/14/roa ... they-work/" onclick="window.open(this.href);return false;
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Xplora » Fri Feb 22, 2013 1:12 pm
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby MichaelB » Fri Feb 22, 2013 1:50 pm
There was also the unanswered question of the quality of the bleed, as he had shortened the lines as well.Xplora wrote:Yeah, that's the one. Garbage article... I can't believe the website editor allowed it onto the site, because it showed the writer to be a prize twit
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby barefoot » Fri Feb 22, 2013 2:11 pm
Two things for certain:Xplora wrote:Yeah, the Road.cc (?) reviewer put himself into the meatwagon using the lightest CX rotor available and then blamed the discs for his failure to descend safely. It could very well be that a huge 200mm rotor could be ideal for big descents. Or not.
Early stage R&D is hardly the time to bag the tech, that's for sure.
1) Energy in (kinetic / potential energy) = energy out (heat).
Can't be created or destroyed, and all that.
If the rotor can't dissipate the heat generated by the brakes, it will get hotter. Hotter things are better at dissipating heat, so whatever the disc (be it 140, 200 or 700mm), it will reach an equilibrium temperature. The less effective the rotor is at rejecting heat to atmosphere, the hotter that equilibrium temperature will be.
2) Disc brakes can operate at much higher temperatures than rim brakes.
I work in automotive braking. We have brakes in the lab working just fine with the rotors glowing, well over 600°C. That's with resin-based pads, on hydraulic brake systems, which is what 100% of cars use.
I don't know much about sintered metal, but I know they go there for motorcycles, trains and industrial applications where the brakes get really hot.
I also don't know anything about the friction materials currently used in bicycle disc brake pads, but I really find it hard to believe we're pushing hard against the temperature limits of the best friction material technologies in existence. As a very crude indication... I've never seen a bicycle disc brake glowing red like I regularly see car disc brakes.
By comparison, rim brakes. Alloy rims, filled polymer pads. Alloy melts at <700°C... loses plenty of strength before that. And it's a very good thermal conductor, so whatever temperature your braking surface is getting to, your tyre bead and tube will be in contact with almost the same temperature. Rubber isn't good with temperature... especially when it's trying to contain 100psi air.
So, combining - a disc brake system WILL get hotter than a rim brake system, because it isn't as good at rejecting heat. But a disc brake system is MUCH better at coping with high temperatures than a rim brake system - and IMO has the potential to be significantly better than the current implementation.
As above, I'm not convinced the friction materials currently in use are all that good. And that's aside from all the work that could be done to improve brake cooling. Why can we cool the processor of a laptop computer, but can't cool a (significantly hotter) bike brake? Calipers don't even have cooling fins yet...
tim
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Daccordi Rider » Fri Feb 22, 2013 2:18 pm
That being said I'd be happy to give it a go.
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby barefoot » Fri Feb 22, 2013 2:31 pm
Hehe.Xplora wrote:Yeah, that's the one. Garbage article... I can't believe the website editor allowed it onto the site, because it showed the writer to be a prize twit
This bit says it all, really:
Numerous cases of severe brake fade on his MTB, and never pondered whether he might be doing something wrong? I don't remember ever fading MTB discs. Started running out of grab on cantis and Vs a few times, but discs tend to hold up a bit better IMO. But most people don't do a long continuous drag on both brakes at the same time - rim or disc; road, mountain, or car - and expect the brakes to still be there when you need them.TFA wrote:The brake fade that led to my accident is something I’ve experienced on my mountain bike on several occasions with multiple brands of brakes.
The story can pretty much be summarised: "If you're going to ride like a kn0b and crash your bike, it's safer crashing at MTB speeds than road speeds. Hey look, disc brakes on road bikes, howaboutthat?"
tim
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Mulger bill » Fri Feb 22, 2013 4:59 pm
Damn right. A poor workman always blames his tools.barefoot wrote:This bit says it all, really:Numerous cases of severe brake fade on his MTB, and never pondered whether he might be doing something wrong? I don't remember ever fading MTB discs. Started running out of grab on cantis and Vs a few times, but discs tend to hold up a bit better IMO. But most people don't do a long continuous drag on both brakes at the same time - rim or disc; road, mountain, or car - and expect the brakes to still be there when you need them.TFA wrote:The brake fade that led to my accident is something I’ve experienced on my mountain bike on several occasions with multiple brands of brakes.
tim
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby alex » Fri Feb 22, 2013 8:42 pm
but ill still buy them... and so will everyone else
campy 11 speed - I DONT NEED THAT! 50 PAGE FORUM THREAD! everyone bought it/wants it
dura ace 7900 - OMGosh SO UGLY! 50 PAGE FORUM THREAD! everyone bought it/wants (wanted) it
di2 - CABLES WORK FINE! 50 PAGE FORUM THREAD! - everyone bought it/wants it
and so on and so on and so on, the same thing happens with every new and different product
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Nobody » Fri Feb 22, 2013 9:07 pm
I haven't found 23s limiting for braking on good roads. I doubt I could even get the front wheel to lock on a good wet road. But then I only run 85psi in the front.alex wrote:when the limiting factor for braking is the common 23mm tyre, i am not sure why we all think we need disc brakes
According to the reviewers of disc brake road bikes, in general, even cable disc brakes offer better modulation than rim brakes.
http://www.bikeradar.com/gear/article/d ... kes-32770/" onclick="window.open(this.href);return false;
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Uncle Just » Fri Feb 22, 2013 9:11 pm
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Timeonabike » Fri Feb 22, 2013 9:13 pm
Was expecting sogginess that I'd come to expect from (albeit really poorly maintained) rim type cable operated brakes.
If these are out in a year, then I've got a year to save for the road bike I've been thinking about getting.ACE.
Cheers,
Time
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Xplora » Fri Feb 22, 2013 9:26 pm
I don't think it is possible to argue against the superiority of hydraulic for all but the most minor of reasons. We'll have internal routed hydro brakes in time. We'll have aero brakes in time. We'll have less dangerous discs in time (could be a while though). Considering the cost of replacing discs versus rims, I don't know why anyone would even raise the question of "better".
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby il padrone » Fri Feb 22, 2013 9:39 pm
Now that is one very positive advantage for discs I reckon, but not for the reason you are suggesting, rather for descending long steep descents without risk of blowing your tyres off the rim due to brake-induced heating. A really big plus. This was the big problem I had when I rode up, and down, Baw Baw.Uncle Just wrote:Lastly try coming down Baw Baw in the wet on the best dual caliper brakes as even in the dry you'll have to be very cautious.
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Mugglechops » Fri Feb 22, 2013 9:51 pm
Never had an issue with them and I can brake as hard as I want without going over the bars or the world ending
Will probably upgrade to hyd road calipers in the future.
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby kunalraiker » Fri Feb 22, 2013 11:45 pm
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Re: Shimano Di2 hydraulic road disc brakes spotted
Postby Mulger bill » Sat Feb 23, 2013 12:00 am
London Boy 29/12/2011
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