Stan's makes a set in he 1400 grams range, but that does not include the discs, disc bolts, skewers. Also, it has a lot of air grabbing spokes compared to a road wheel and has a 170 lb. weight limit since hard braking with a 200 pounder would probably pull the spokes. Even if you used the lightest available 140 mm discs front and rear and Ti bolts without skewers it would still be well north of 1600 grams which is the weight of a middling road wheelset. Also, for all you engineers out there, the limit for how small you can go on the rear and still have room for the hub, stays, etc. is around 140 mm and that is just way way too powerful for a road bike rear. I guess you could make a really small caliper and matching disc, but it is still going to have alll the previous problems discussed.

I am actually happy about the 4 bolt crank idea assuming it is one of the standard sizes, but more than likely, Shimano will be different in order to try to sell you chain-rings for 3 times normal price and nobody ever buys them anyway since the aftermarket will have to stock yet another standard size. And before everyone starts saying how their strong legs will be bending chainrings all the time, let's just remember that the strongest mountain bike riders in the world including Lance and Levi have never bent a chainring to my knowledge in competition. If you are not currently earning a living by riding a bike then I don't want to hear about your strong legs and instead of typing on your computer you should be auditioning for Team Sky!

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For certain parts stiffer is more important than lighter.

For several years I rode a Morati SC 1.3 with disc brakes. You can find some discussion about it here, viewtopic.php?f=3&t=32177&p=399762&hilit=morati#p399762" onclick="window.open(this.href);return false; .

The disc brakes were awesome! The bike was not a weight weenie, but was the most comfortable bike I had ever ridden until going to a custom build. Whatever penalty there was going uphill, was more than worth the quality of braking going back down long, twisting descents.

Considering most cyclists are not racers and most are not weight weenies, I think disc brakes are the future for all recreational cycling. If they become UCI legal, I think they will become the standard. You just can't beat the performance of disc brakes in any conditions.

The only downside I see to disc brakes is that it is easy to lock up the wheel and, with the small contat patch of a road tire, you are very likely to skid or slide when unfamiliar with the brakes. But a little time on the bike and feathering the brakes becomes second nature.

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TED ESSENFELD
Schoorl, Noord-Holland, Nederland
Bike Pics
English Custom Steel Internal di2
Litespeed Ghisallo

Interesting that they are keeping the 24mm spindle and ignoring BB30 & BB386EVO and using proprietary shift cable.

Typically and technically speaking, a mountain bike will descend as fast as a road bike under the same rider.
What are the differences?

-A mountain bike on a dirt road will see massive and abrupt changes in speed. Dirt roads in the mountains are typically ridiculously steep (ever wonder why they aren't paved?). In a typical descent in the Santa Monica Mountains a rider can go from 10mph to 45mph in a matter of seconds, then needing to go back down to 15mph about 30 seconds later. Disc brakes are remarkable for the needs here, as terrain can change very rapidly. Dirt road descents are typically not very long, and not very straight - although those do exist, they are rare. Often after a few seconds of descending the terrain will change rapidly, necessitating a dramatic reduction in speed and/or trajectory.

-A road bike is often able to descend at a fast speed for a longer period of time as the roads are comparatively more gradual and descents are significantly longer, allowing the rider to accelerate with gravity or pedal strokes until a terminal velocity is achieved.

-A good comparison would be a mountain bike and road bike descending a very steep, very technical road with off-camber turns, changing radii, and other hazards. If you put both on slick tires, my money is on the telemetry of speed being relatively close in top speed, delta values, and slowest speed. Local examples include Tuna Canyon (down) and Las Flores (down). Of note: RedBull staged a downhill TT/race on Tuna many years ago.

-A road bike with slick tires on a dirt road will not be as fast as a mountain bike with dirt tires on that same road, and vice versa. "Horses for courses" as the idiom goes.

Continue talking amongst yourselves.

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Exp001

There are 970-980gr 29er tubular disc wheels with a 240lb weight limit (for MTB use, for road use it would be even higher). Skewers are the same ones. Two Ashima 140mm rotors with ti bolts weigh 145gr

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BIKE DESIGN AND +

http://cds-0.blogspot.com/

I'm not sure how valid the 4 arm rumor is. In Shimano's Tech Doc the picture of the crank shows 5 arms. Of course that could just be a place holder.

I'm pretty sure it's still 5 arm as per the tech doc

I wouldn't use that as the basis for it being four or five armed. The direct mount brakes in the tech doc are the same as the the caliper style, when it clearly looks much different, as per the drawings further down the article.

Does anyone really use different chainrings with Shimano cranksets anyways? They never match up and usually end up looking pretty bad.

I thought the diagrams later on show the mounting points for the brakes, not the brakes themselves

are this really 29" or 26"? does the weight includes rotor? if price is no object the some enve built can be under 900 grams with the right parts
980+145=1125
sub 900gram wheelset= 900 grams
that is 225 gram difference
plus the extra weight on the fork and the extra weight of pads and calipers vs rim calipers and pads?
is braking that much of an issue
i ride carbon tubulars with kcnc cb1 brakes and i find the quite aduquate for their job. i do not thik that you can make the rim any lighter specially clinchers.

I'm a little concerned about wheel compatibility here, hopefully we can just replace the freehub body and not need a whole new hub/wheel.

what was the spacing on the new giant tcr sl? it was supposed to be wider? if so this will indicate the diredtionm that shimano will follow as i believe giant is a strategic partner.

Nope, you need a new hub. The freehub body is getting longer with the same 130 OLD, so the DS flange is moving in 2mm.

It is the same spline pattern though, so you can use your 8/9/10s cassettes on the 11s freehub body with a spacer.

Have you ever actually put this 'limit' to the test on at least a computer model ? On paper, I see a 110mm disc design being theoretically possible, with some changes to the current mounting standards.

Oh yah, talk about which, someone did a 100mm dual-disc front not that long ago I believe ?

You're right, that's what I get for looking at it on a phone screen.

The hub spline thing seems a bit silly. If there was a time to redesign the splines to work better with aluminum cassette bodies, it seems like it would be now