It is reasonably easy to boil the fluid on a real-world production car if you do a few hot laps at a race circuit. If we're going to talk real-world conditions, try a few reasonably hard stops in your car and watch the pedal feel change.
But that really is beside the point. From what I understand it is possible to heat your discs up enough that they can boil the fluid and make the brakes fade. While dot4 fluid has a fairly high boiling point (446 deg celcius), it absorbs fluid so the boiling point does decrease in real world conditions. It's a phenomenon that is acknowledged to occur on mountainbikes. So I am curious as to if and how it is dealt with on road bikes.
I imagine we would put a fair deal of stress on a disc brake on an extended downhill, and to be honest I'm not sure if I'd rather risk blowing a tyre or losing my brakes all together due to fade. If I could pick I'd probably say lets blow the rear tyre up, haha!
On the whole I think it's a technology that will become fairly mainstream but with the riding I do (lots of climbing [and descending] fairly steep stuff) I'm not going to be an early adopter.
The change in pedal feel will have more to do with the pad material being outside of the optimum operating limits.
It is rare for even a race car to boil it's fluid, and that is with massive rotors glowing red/orange hot and dissapating a lot more energy than a road car can even try to.
Granted, it can still happen, but I'd say it's rare.
Will it happen on a road bike - in my experience (13,000+km), you'd have to be trying hard to do it.
biker jk wrote:There are disadvantages of disc brakes which appear to have been glossed over in the frenzy to embrace this new offering on a road bike. The torsional braking forces put more stress on the spokes which will require more of them and also of thicker gauge (offsetting some of the weight savings from not needing an alloy braking surface). Beefier forks will also be needed (again, adding weight). The rear wheel will be weaker due to the need for dishing on both sides.
And then offset by some other weight savings.
From my Volagi, the 57cm frame is 1,225g, and this has full internal cable routing, clever little plates to make it neater as well which adds to the weight, so not bad. The fork is 482g with 380mm of uncut steerer tube.
Overall, those weights are 200 or so grams over a reasobnably light frame, but I'm not going to compare with a VWD Cervelo, as that is a completely different frame.
My wheelset, using 29er carbon rims (24mm wide) with 28 spokes front and 32 rear comes to 1,421g which is not bad.
Overall the bike will shave in just under 8kg, and for a bike with some mid tier parts, is pretty damn good for a double disc road bike.