Hydro discs mod for roadies...?

Looks good.

The problem is having an STI lever not just a 'vertical' lever. People want to keep integrated shifting and braking and none of the big 3 have integrated a hydraulic master cylinder into their lever body (yet). I think it's a no brainer for 2013/14 on electronic groups as they have the space required without much of a redesign needed, not sure if it will filter to mechanical groups, there are already cable-to-hydraulic converters that provide a solution there (from TRP, Hope etc.) can't see much business sense in the big 3 radically redesigning their mechanical levers for a what will be a fairly niche market for a while.
Weight-wise I think we'll end up with something equivalent to rim brakes, you don't have to beef up forks that much (there's already light road carbon disc forks out there) and what you gain with the disc you can loose a lot of at the rim by having no braking surface.

The RT8 TT is for solo time trial riders. I wonder what advantages better braking has during a time trial?
The most advantageous use of disk and hydraulic braking is found in the worst conditions ie cyclo-cross, commuting and winter training. Manufacturers should break with convention and introduce a hydraulic system at a low price point then the technology can trickle up. If they introduce hydraulic disks at the pro end, riders will try it, see that it offers little advantage for going fast in the dry, and lose interest. There will then be no trickle down to the riders who really could use it.

I'm waiting to see what they do about brake reaction forces, and the disc ripping the wheel out of the dropouts.

Lawyer lips and through axles are no good on a race bike because of quick wheel changes. MTB bike and fork manufacturers haven't advertised the problem (and have settled out of court with non-disclosure on the few court cases that haven't happened), but if you look you'll find that simple road style dropouts no longer exist.

The simple solution is to put the disc caliper on the front of the left fork blade so the axle is forced into the dropout rather than out, but I see no sign anyone doing this.

this is true but the main problem that normal qr levers cant hold them, the friction trying to rotate the brake pads is proportional to the diameter of the brake surface. give discs are several times smaller you have to generate several times the force at the pad to stop the same, the main problem made worse by repositioning the brake. so its not irrational madogg, just an engineering brain can see obstacles. understand im not saying it cant be done, just not as efficiently as calipers.

maddog 2 wrote:

the engineering for dropouts to hold the wheel in place is straightforward, and it works, as said. Sure, traditional dropouts (made for caliper brakes) aren't ideal with discs but so what..... the engineering just need to suit the application.

There is no engineering argument against discs. The only rational argument I can see against discs - and by that I mean one with some data to support it - is that they are slightly heavier, but this will become less of an argument over time, and anyway plenty of bike parts are heavier than they could be but are still good designs - Di2, two-ring setups, adjustable saddles/stems etc...

On all other aspects discs are better - more power, consistency, better modulation, better in the rain, less rim wear (and less danger from split rims as a result), better pad wear, easier pad maintenance, possibly even more aero overall, rims can also be re-designed as no braking track needs to engineered into them (which suits carbon down to the ground) and so can be lighter, and again, possibly more aero.

with enough development theres no reason not to have heater/blowers for those icy cold winter rides. they only need to make a battery the size and weight of a fag packet with 30KW/h capacity.

maddog 2 wrote:

The only rational argument I can see against discs - and by that I mean one with some data to support it - is that they are slightly heavier.

Rim brakes are mechanically simpler and easier to adjust (though need more adjusting to start with) and vastly less annoying when refitting wheels. Also, the narrow clearances of discs makes them prone to squeaking and potentially dragging and there isn't much you can do about that if it happens on the road. This could presumably be designed out but it doesn't seem as though anyone has seen fit to do this so far!

As MichaelW says, the advantages of discs are mainly when conditions are poor. In the dry I found braking distances on my road bikes not much longer than that of my disc equiped MTB - and most of that difference I suspect was the weight of the MTB keeping itself planted more. Any more brake on the road bike and I'd have been over the bars so I suspect discs would make little difference.

Given that road bikes can't use as much stopping power as MTBs anyway, I'm not quite sure what the obsession is with looking at hydraulic discs. From what I understand, good quality cable discs can be very good indeed. I suspect they may be a more logical route for raod bikes than hydraulics.

On that basis, there is little technical advantage in me having discs on my road bikes. On my commuters, on the other hand, there clearly is.

Any more brake on the road bike and I'd have been over the bars so I suspect discs would make little difference

Again, sorry, this is a duff argument. Just because you can yank on the brakes and lift the rear wheel doesn't mean you have 'good enough' brakes - the key is can you do it controllably?

Having the power and modulation to brake hard enough to lift the rear controllably is hard with rim brakes because the power they produce under hard braking is less consistent than discs, due to the blocks getting very hot, very quickly and doing nasty things to the friction coeffs (especially on Alpine type descents). Tis true that discs suffer fade too, but nowhere near as bad IME.

Your argument is like saying: all car brakes can lock the wheels, so all car brakes are the same. They aren't. Some have more power and control and feel and modulation.

Now clearly quite a chunk of riders never brake that hard anyway... which is a different issue. If you don't need good brakes then that's fine.