Will road racing be dominated by bikes with disk brakes and lighter carbon wheels in the future? Having owned carbon wheels (Lightweight Standards/ Enve 45 Clinchers) in the past, I appreciate their lower rotating mass with almost instantaneous acceleration and higher performance. Going back to a high quality aluminum wheel set (HED Ardennes) reminded me of the superior braking and control offered by alloy rimmed wheels. It was suggested that the higher number of serious crashes in the Tour de France over the past few years has been partially a result of carbon wheels. Specialized is offering a high end road bike this Fall with disk brakes. It seems that this will offer the best of both worlds: superior braking and control and the ability to use even lighter carbon wheels without fear of overheating rims and braking issues. Will a very light bike weight still be achievable? Do you think that this will be the dominant design in the future?

Most of the crashes in the tdf are at the end of the flat stages where everybody its fighting for position and on rain stages. I do not think that disc would help on either scenario. There is always a rider that disrupts the sprint trains and disc brakes would not alleviate those problems. On rain stages it might but as out is a lot of riders use alloy rims for this occasions and I personally do not think that disc
brakes are going to make cancellara or gesink better our worse than they already are. On to of that there is going to be an adjustment period for the teams and riders that start using these first.

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Although I know little about rim strength, I can only guess that the weight of the rim cannot be reduced too much due to the additional stress placed on the spoke eyelets which will be trying to pull from the rim even more on a disk braked bike. Plus spoke strength/count cannot be optimized too much either I wouldn't have thought?
Only guessing from basic engineering principles, but I am sure someone will know more than me.

As far as spokes go, in my experience(with mountain bikes) you can use the same spokes as rim brake wheels. All of my wheels are built with Revo's or Laser's. I've also had good luck with using as few as 24 spoke disc wheels. And this is for a mountain bike. You won't be able to use sub 20 spoke wheels or radial lacing, but honestly different spoke patterns and lengths add very little weight...although this is weight weenies!

Plenty of MTB wheels build with CX-rays so disc brakes on road bikes only mean no more radial lacing.

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Perhaps the future could bring full carbon aero bladed wheels with hub inserts (like there is with the BB cartridge system). It could slot in like a free wheel hub on the DS and lock-in on the NDS. The slide-in Hub assembly could hold the disc mounts or be attached after insertion and locking. This would remove issues with the DS spoke bracing angle and produce a very strong/light wheel ... maybe, just a thought. Perhaps the patents are being lodged and processed even as we write

Can road bike hydraulics cope with braking forces on mountain descents at 70 km/h +?

Here is a new road race bike model from Foundry bicycles with dual disk brakes. Sadly can't be raced yet.
http://velonews.competitor.com/2012/08/ ... dry_232846

Rush, hydraulics have been used by tandem tourists all over the world for a decade or so, descending mountains at similar speeds whilst weighing far far more. There will not be an issue. Brake rub might well be though.

I've been riding mechanical discs in the Alps this Summer on and off and have been impressed with the modulation but not with the pad wear rates - the latter is easily fixed.

I see discs where Specialized do - on bikes aimed at the keen amateur and sportive rider. Particularly in the UK, there are a lot of riders crossing over from MTB's - and the weather is almost endlessly wet. Both good reasons to offer discs on a selection of road bikes.

For racers the rub will have to be sorted I suspect. I'd be interested to know just how light a tubular rim could be however without the need for a braking surface. Like you, that's the bit I'm looking forward to as I spend a lot of time going up mountains.

With regards to race accidents, I would say that too many riders are choosing extra small framesets with 140mm stems and high profile wheelsets.

I think that we will see an increasing number of bikes with disc brakes in the future, for better or worse.

I don't think that you are going to see any weight savings though. True, rims could get a little lighter without a brake track, but more/longer spokes and beefed up spokebeds, plus heavier hubs, calipers, forks and the addition of the disc itself mean that the system is going to be heavier.

I'll be running disc on my CX this year, but it may be a while before you see my road race bike with discs.

Not to mention, what happens in that first big tour sprint with everyone on discs and a big crash with a rider almost losing an arm to a sharp, hot disc? those things can take huge fillets of flesh.

I think there's a 38 page thread on road disc already?