See my post above...but, in short, I'll say "prove it" :-P

---

http://bikeblather.blogspot.com/

When (not if) the big S releases a disc Shiv that's faster than the current rim version, everyone is going to say the current Shiv is a brick.

Now if that new disc Shiv is faster than the IA/Speed Concept/P7 or whatever is the fastest existing bike, you don't get to hide behind saying that the rim versions could/should be faster.

Instead of worrying if the disc Venge is faster than the rim version, we should be asking if it is faster than a Madone/S5/Aero Camino.

---

/kj

http://kjmcawesome.tumblr.com/

"Beauty is in the eye of the beer-holder", I guess...

One ironic thing (among many) about that product is that braking power on a REAR wheel isn't really an issue for any bike. Due to weight shift in braking, the vast majority of braking power is from the front wheel, not the rear. There's a reason that Campy often has offered a single-pivot rear brake in their gruppos: it saves weight and it's plenty of braking capacity.

It's funny...someone mentioned after seeing this that a drum brake might be a more appropriate technology for a rear aero disc...and you know what, they're probably right!

In the end though...is the braking capability of just clamping to the outer edge of the disc that's 3X larger in diameter really not enough for excellent performance? Really?? Why the extra complexity?

Oh, that's right...because some think it "looks cool". I'm sorry...I keep forgetting that the bike industry is really a fashion industry...my mistake... :-/

---

http://bikeblather.blogspot.com/

Not everyone wants to ride HED Jet's Tom. I love my 808 and Super 9 and wouldn't go back to aluminum brake track wheels. This argument will go on and on and on about proper braking surfaces. If the new bikes are faster and they can prove it, I'm getting one.

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

I'm fine with you spending your money however you wish...but, why wouldn't you "go back to aluminum brake track wheels"? What's the problem?

Besides, have you ever found your 808 and Super 9 lacking in braking performance? Do they have the NSW textured surfaces?

---

http://bikeblather.blogspot.com/

I've ridden HED Jets before. I have no issue with braking in the dry. Raining....well that's a different story haha. It rarely rains at any of my races so that's not much of an issue.

Carbon wheels are here to stay. I've argued in the past with you that you can shape carbon wheels differently than an aluminum brake track with a fairing but you disagreed.

I don't have the NSW 808.

Are HED wheels fast? Sure. Does the fairing look cheap and thin? Yep. I wouldn't go back to aluminum rims and a fairing because I like carbon clinchers even though I know their limitations.

There is no denying that discs are coming and will be here to stay. There are technical benefits and disadvantages to rim and disc. That's why I'm going to sit back and wait and see.

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

Bullshit. Show me the data.

---

Suffer Well.

What type of phone do you have?

Do you own a computer? If so, what kind and how old?

When did you get your first CD player? Do you still use CDs?

Do you know what streaming music apps are?

Where's the due process?!

---

"One Line Robert"

Since I sweat like a pig, my rear brake (internal) cable is always stuck, and if I were to use my rear brake, it would remain closed on the rim. So, I literally have not used my rear brake in many, many years. That's all my training and all my racing.

What am I missing here that a *rear* disc brake would address?

---

----------------------------------
"Go yell at an M&M"

The fact the 808 has a disc brake and the Super 9 needs one too so that a disc brake tri bike can run an 808 and Super 9.

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

One ironic thing (among many) about that product is that braking power on a REAR wheel isn't really an issue for any bike. Due to weight shift in braking, the vast majority of braking power is from the front wheel, not the rear. There's a reason that Campy often has offered a single-pivot rear brake in their gruppos: it saves weight and it's plenty of braking capacity.
It's funny...someone mentioned after seeing this that a drum brake might be a more appropriate technology for a rear aero disc...and you know what, they're probably right!
In the end though...is the braking capability of just clamping to the outer edge of the disc that's 3X larger in diameter really not enough for excellent performance? Really?? Why the extra complexity?
Oh, that's right...because some think it "looks cool". I'm sorry...I keep forgetting that the bike industry is really a fashion industry...my mistake... :-/

It's correct that for max stopping power, the rear brake isn't needed, as the rear wheel will be at the point of lifting.

If you TRULY want to know which is faster aerodynamically, then you can't compare any future "disc optimized" bikes to current frames that are not to the same level of integration...AND you need to make sure that you take advantage of OTHER features which one or the other system allows in order to reduce the overall system drag. For example, it's silly to do a rim vs. disc comparison with wheelsets with the same amount of spokes in each since the rim brake setup allows the use of less sic spokes due to the spokes not needing to transfer braking torque. The number of spokes in a wheel affects both the translational AND the rotational drag (don't forget to measure "power to rotate" in these tests!) Now then, we're talking about a disc wheel here, so that example isn't exactly applicable...but it IS applicable to whatever front wheel you use in the total system comparison.

Note that Fulcrum's Racing Quattro Carbon DB disc braked wheel has 21 spokes front & rear, so disc braked wheels don't seem to be particularly handicapped compared to rim braked wheels.

With triathlon bikes not needing to meet restrictive UCI rules, the use of disc brakes should allow companies to produce designs that wouldn't be possible with rim brakes, e.g.

• A front 'fork' with a monoblade/lefty for aerodynamics, and no need to remove wheel when puncturing.

• If the road surface is poor - fit 650b wheels with (even) fatter tires.

• Automatic pad wear compensation, so no awkward, dirty under bottom bracket adjustments needed.

• No loss of power with convoluted braking line routeing.

• No cable stretch requiring extra lever travel.

These and other factors are in addition to whether discs are better at braking. So, where are rim brakes better - tradition?

NOT a BlackBerry.



Multiple...from the 1st computer I ever bought (Commodore 64) to an iPad to high-powered PC workstations. The right tool for the job. The Commodore isn't currently used BTW (in case you were wondering).

I also have multiple slide-rules in my collection that I know how to use...you know, in case the power goes out ;-)



1987. Yes, I still use CDs. Why wouldn't I when I have such a large collection and they don't degrade?



Of course. I use them when it makes sense and/or is most convenient.



WTH do all of those questions have to do with the fact that Zipp managed to invert the lipstick:pig relationship?

---

http://bikeblather.blogspot.com/

...and a hydraulically actuated rear rim brake would solve that actuation problem ;-)

---

http://bikeblather.blogspot.com/

Regardless of the data - it does look quite ugly.

I'll probably refuse to buy a disc brake bike because of that alone.

---

"One Line Robert"

You also have to realize that frame manufacturers only have so much man power to design the frames and can sell only so many frames in total. They will not be able to support both idealized rim brake and disc brake models in the long run.

I don't think that the braking benefits of disc brakes overcome the aerodynamic costs, and developing disc brake models is slowing down the overall advancement of TT bikes.

I disagree based on the posts from Damon Rinard of Cannondale and Cam Piper of Specialized.

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

We don't really know much about the durability of that setup yet, do we? In comparison, my front Hed Jet 6 has a mere 18 spokes.



I don't think it's been shown that sort of fork configuration is actually more aero. A traditional fork makes a nice triangulated structure. A mono-fork would necessarily need more structure to accommodate the same forces. So...that's all pure speculation on your part.




One could argue that if you're doing timed races in conditions that require tires fatter than 28-30mm, you might want to reconsider if you should be doing it on a Tri/TT bike in the first place :-/




There is no reason why a hydraulically actuated rim brake couldn't have those exact same properties. Those aren't a function of brake configuration (rim vs. separate braking disc) but of brake lever/caliper system design.




Well...according to SRAM's own data, their hydro rim brake actuating on an aluminum surface is only ~10% less braking torque for a given lever force as compared to their disc brakes on a 160mm rotor. If one then considers the fact that HED claims "25% shorter stopping distances in dry conditions, or 70% shorter stopping distances in wet conditions" for their Turbine brake track equipped wheels as compared to regular aluminum tracks, one can logically conclude that any gaps in braking performance really aren't there. I would really like to see independent data on this...but sadly, nobody in the media appears willing to take it on.

So, after that, they're better in regards to aero, mass, complexity, and backwards compatibility...none of which should be dismissed out of hand considering it's possible for their to be no performance difference.

Food for thought...there are 2 well-known custom tandem manufacturers (Santana and Erickson) who recommend rim brakes (V-brakes) instead of separate braking discs for the front end of their tandems. One should probably contemplate why this is so...

---

http://bikeblather.blogspot.com/

You might want to re-read those posts a bit more carefully...

---

http://bikeblather.blogspot.com/

I did.

To quote Damon Rinard:

If you care about braking, consider disc brakes. If you care about speed, consider disc brakes.

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

He also said:

"It’s tricky to make a blanket statement like “discs have more drag,” because testing different bikes gives different results. For example, a bike optimized for rim brakes, by definition isn’t optimized for disc brakes, so sticking some discs on it doesn’t represent the performance you’d expect from a bike designed from the ground up as a disc brake bike. Same in reverse."

BTW, I would take the word "consider" used in that context in his quote above as meaning to weigh the pros/cons of the choice for the particular application. Nothing more.

---

http://bikeblather.blogspot.com/

Yep, read that one too. Why don't we sit back and wait and see what Damon and others can bring to the market before we judge disc brakes by what they can and cannot do.

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

That's OK...isn't this thread supposed to be about the fact that Zipp managed to invert the normal lipstick:pig relationship on a disc wheel? (Which is quite a feat, actually)

You seem to have driven it off track ;-)

---

http://bikeblather.blogspot.com/

Debate is a good thing but we are debating something that doesn't really exist yet! Let's get some more disc brake tri bikes on the market, tunnel test them, then debate! The Parlee TT disc brake bike is the start.

---

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/

Sorry, missed this before...more evidence supporting my mini wind tunnel testing, and indicating that the ERO Sports testing has overestimated the magnitude of the benefit.

That's interesting, as I would have thought that tandems would be one situation in which a disc brake would make sense - after all, I'd rather overheat and warp a disc rotor than overheat the rim and blow out (or roll off) the tire. Perhaps I'm underestimating the difference in heat dissipation, such that the former is simply much more likely?

(Come to think of it, I've seen reports of single riders warping discs on long descents...so a tandem would almost certainly do so.)