I have a road disc brake project to complete.
What would be the optimal disc diameter size front and rear, and what is the lightest/best function caliper available ?.
I plan on either using Di2 or EPS. it will also have a cable to hydro converter for brake function.
Thanks in advance.
cyman.

If I were you I would use a 160mm front, and a 140 rear disc for a light road bike. In terms of the lightest caliper, I think the Hope Race Evo X2 is currently the lightest lever/caliper combo, not sure of the lightest caliper only though I'm affraid. The Formula R1 gets a very good write up so could be worth a look.

Hope SAW two-peice rotors in 160mm come in ~85 grams and the Hope Race X2 are ~60grams in 160 but if you are in the US, they are very hard to find. There is also some ultra pricey lightweight two-piece rotors from Scrub Components and AbsoluteBlack.cc

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Michael - The Anaerobic Threshold is neither...

carbon-ti?

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CARPE DIEM
Colnago C59 Italia GLBK
Up coming custom steel cyclocross

Ill vouch for the Formula R1s. once bedded in they brake really well! Ive worked with hope before and found it a struggle where as the formulas seemed nicer. Not convinced on their seriously drilled out rotors though...

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http://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=100739

Thanks for your replys, gives me something to work on..
cyman.

avid cable disc and save the weight of the converter plus work really well

The BB7 is a very good brake. What frame are you using, please tell.

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www.thecycleclinic.co.uk

Enve is coming out with a carbon road disc fork in Aug / Sept.

Enve carbon road disc fork
Axle-to-crown height = 367mm
Disc tabs = 140mm?

I think the tabs will be 140mm. I think they have discussed 140mm vs 160mm a lot, and I think the decision was close and they went for 140mm. The decision is not set in stone. I suggest to call them if you really think they should do 160mm before the go into full production. It's a smallish company and they are open to talking to people about this.

Please provide some more detail re the frame and groupset selection.

I'm currently riding a Kona Honky Inc which is heavy, but works, and am working towards a Di2 equipped carbon framed bike as the next step (may even be Ti), but must be a road bike, not CX.

I use the RT-86 Shimano IceTec rotors and whilst not the lightest, they are very good and are comparitive in weight to the G2 Cleansweep rotors for the same size.

I use a 180/160 combo, as Im a bit bigger, but a 160/140 combo would suit most people (as long as sensible discs are used).

Cheers

Michael B

Very Very interested in how this works itself out but...

140mm discs on road bikes seem to be gaining momentum. And there has probably been a lot of talk in the bike industry of which size discs would become the norm on road bikes. I, myself, was thinking of doing 160/160, but am open to other possibilities. Certainly smaller rotors look better, but bigger rotors have a mechanical advantage.

Colnago's carbon bike with discs uses 140 rotors front and back if I am not mistaken. And 140mm does seem to be gaining some traction from other manufacturers too.

Kona's road bike that is coming out soon, the 2013 Kona Rove, has 140mm discs front and rear.
http://cog.konaworld.com/archives/12172