the new hydraulic road brakes are nice, in the past the BB7 mechanical had a tendency to drag a little on one side. They work fine on a road bike, the wheel changes seem a bit slower but maybe it's just a need for practice. If one were using disc on the cross bike, it would be nice to have the same setup on the road bike so the equipment could be shared.

Electric shifting and disc road brakes will be the standard in a couple years, over this season they are getting sorted out in cyclocross and will be a much more mature road technology come spring.

Is it this huge improvement? No, neither is electric shifting. Since the advent of clipless pedals and STI shift levers, there have not been any real significant "must have" changes in road bikes, despite the price of a new bike tripling.

I should know better then to assume ;)

Although that I agree that the disc at 0-degree will hardly have any aero-impact. I would think that the difference between upstream from the appearant wind (ie wind from the left) and downstream from the appearant wind is where there are differences. But most of these would not need to come from the rotor itself, but more likelly from the increase in spokes with the wind-facing side being the worst. The increased hub-diamter would be non-impacting since it sits inside the spokes and that is a very turbulent area. The rotor-mounting structure (Shimano or 6-bolt) is completely covered by the disc-rotor and probably has biggest impact at zero-yaw (which I would think is minimal). The biggest impact could be the point-of-pressure which most likely shifts due to the disc. If only we would find a drag-chart that compares the Zipp 303-FC-CC and the 303-FC-CC-Disc ;) The ZIPP 303-disc set weighs in at 1660gr by the way, heavier then the DT-Swiss MTB 29" wheels, defenitly more aero though...). Probably some low-hanging-in-house-fruit between Zipp and DT-Swiss right there.

On your comment regarding power-to-rotate, also here, I would think this is not so much caused by the disc-rotor itself (decent alu-spider 140mm discs weigh <100gr) but come from the added weight due to increased spoke-count, disc-specific lacing and hub-strengthening. I don't know the weight from the top of my head, but competition-level carbon-rim 29" MTB-XC wheels come at around 1450-1500gr/set which is pretty darn light given the abuse they have to tolerate.

S.

Power-to-rotate at a constant speed isn't a function of weight.

---

http://bikeblather.blogspot.com/

1) Disc brakes are less aero

2) Disc brakes are not legal for road racing. Not sure about triathlon but no one makes TT disc brakes, possibly because #1?

3) refer to #1 & #2

---

Robert Dao
ATC Racing - Austin, TX
Gold's Gym Triathlon Coach
@speedao1
@daotraining

I've seen a test in a german bike magazine in which layers
of some disks were melted, when in a descent and when the person
is not a lightweight.
The biggest problem though seems to be a sudden loss of brake power
when on a long descent and when the person
is not a lightweight.

I do not know if these problems have already been solved, but it
seems that the system is not yet matured for racing bikes.

I wonder, could a road bike with mechanical disc brakes be upgraded later to a hydraulic system?
It appears the new disc-equipped Roubaix models are now using hydraulics (and now also come in 11-speed versions).

Is it this huge improvement? No, neither is electric shifting. Since the advent of clipless pedals and STI shift levers, there have not been any real significant "must have" changes in road bikes, despite the price of a new bike tripling.

Agreed.

I've ridden some of the new mechanical disc braked road bikes. There is a difference in the feel. However, I really could not say there was a huge difference between that, and a well set up set of Ultegra quality or better, rim caliper brakes. I've ridden the latter in all manner of conditions and terrain, and never had a problem. I've never said, "Wow, if I only had better brakes".

---

---

Steve Fleck @stevefleck | Blog

Yes, should be no problem upgrading down the road except for maybe minor cable/hose routing issues.
I've just put the new Sram Red hydraulic discs on my bike and so far they're great. I've used the BB7 brakes for a few years and these new ones are way nicer to use.

for cyclocross i imagine the discs would be nice. In muddy conditions, the amount of metal that gets worm off the rims is pretty remarkable, plus the braking is just dreadful after a while. This is one season of cross

for cyclocross i imagine the discs would be nice.

Yes - this is the one application where I can see real advantages. I was talking about road use.

For CX the two chief advantages would be as you noted, less wear and tear of the rims ( but some of this would be transferred to the rotors!), as well as better clearance in areas on the bike that in REALLY muddy conditions, clearance can be an issue.

---

---

Steve Fleck @stevefleck | Blog

Same experience here. I'm not at all opposed to owning a bike with disc brakes except for the one troubling mention by here about how easy it is to lock the wheels. As if that were some sort of virtue. I don't want to lock up my wheels. I don't want it to be too easy, either. I don't want to have to learn and automatically remember to have some soft touch. Next thing you know we'll need to add ABS systems to our disk brakes

Yes, but how cleanly that is done depends on the cable housing stops vs cable housing guides (for full run housing). I make all my disc-brake equipped frames with open cable guides for that very reason.

---

---------------------------------------------------------------------
Some are born to move the world to live their fantasies...

https://triomultisport.com/
http://www.mjolnircycles.com/

I guess you have been lucky. I have gotten caught a few times in the mountains when started to rain. I basically lost my brakes on the downhills!

I then blew off a tire at IMLT in the hills I assume from too much braking, and heating up the rims.

So I really could care less about the weight and aero stuff, just seems they are more safe which is why I would really really consider a set on a new TT bike.

.

---

Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

and yet people have been riding disc brakes on mountain bikes for years, in conditions where traction is much more limited than on the road.

---

Swimming Workout of the Day:

Favourite Swim Sets:

2020 National Masters Champion - M50-54 - 50m Butterfly

I thought your primay goal was to go against the ST wisdom?

With much wider tires, not on pavement, not at the same speeds

right. mtb's are ridden in worse conditions, easier to lock up wheels, and yet people do it all the time without locking up the wheels and skidding around (unless they want to).

my point is that the fear of locking up your wheels and heading over your handlebars at the slightest touch is rather unfounded. If you are "really" worried about it, just run a smaller diameter disc. That'll give you pretty much the same braking in dry conditions as a good rim brake, but more predictable braking performance in the wet. more predictable braking in the wet means you can draft closer when riding in a bunch, or brake later in corners.

---

Swimming Workout of the Day:

Favourite Swim Sets:

2020 National Masters Champion - M50-54 - 50m Butterfly

Anyone saying that doesn't actually understand how disc brakes work, and probably hasn't ridden much in the rain. It's far easier to lock up a rim brake in the rain, particularly the rear--since the modulation isn't as good. That's why I pretty much abandoned using my rear brake on my road bike all together after moving to a wet climate. You're much less likely to lock up a disc brake than a rim brake, as long as you're going more than 1-2 mph.

If you're locking up the back wheel on a road bike, in general it means you're applying too much front brake and lifting your weight off the back wheel.

---

---------------------------------------------------------------------
Some are born to move the world to live their fantasies...

https://triomultisport.com/
http://www.mjolnircycles.com/

Based on most comments on this thread, getting discs on a TT bike is against ST wisdom.

.

---

Dave Campbell | Facebook | @DaveECampbell | h2ofun@h2ofun.net

Boom Nutrition code 19F4Y3 $5 off 24 pack box | Bionic Runner | PowerCranks | Velotron | Spruzzamist

Lions don't lose sleep worrying about the sheep

i like to go against the conventional ST wisdom too. which is why I swim, do flip turns, and refuse to lose any weight.

---

Swimming Workout of the Day:

Favourite Swim Sets:

2020 National Masters Champion - M50-54 - 50m Butterfly

Well said!! Being at race weight all year is a boring and pointless way to live ;-)

Either that or they just read the posts of 3 people on this thread stating how much easier it is to lock the wheels of their bikes with disc brakes. Take your pick.

I'm not locking up the back wheel and I'd buy a bike with disc brakes in a second. (I hope people get the bit about ABS was tongue-in-cheek). I just found it a little offsetting that people think that being easily able to lock up your wheels is a good thing.

They served me well in cyclocross this season. Two muddy/nasty races and I easily had more control over my bike and had consistent breaking capabilities from start to finish. I know there is still hesitancy for some individuals in the world cup series to jump on the boat, but once hydraulic discs brakes have the bugs worked out of them they will definitely be the new standard for cyclocross in the future.