Why didn't cannondale do a proper job i.e. A lefty style areo fork with an intregated caliper ?

WD :-)

Hi Mugen_EP,

Whole bike drag numbers will come in due time.

I think you already understand that those numbers will answer a different question, about whole bike designs, not the smaller question about disc vs. rim brakes. Arguably that is the more important question, since we ride whole bikes, not just brakes.

The wind tunnel test we did was to illuminate one comparison between disc vs. rim brakes, as we design our next bikes.

Cheers,
Damon

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Tom, "in the aggregate" -- you may not realize you haven't seen all the other tests. Unfortunately I can no longer get permission to share them publicly.


I'm actually surprised at you here Tom. There is data (and CFD) which hints which components create how much drag, across the yaw range. It surprises me that you're apparently willing to take a stand on your intuition here, when you must know this can be simulated and tested. (Unfortunately we can't share it yet.)

Cheers,
Damon

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Thank you pk.

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Hi Josh,
Luckily, I escaped the Taiwan trip this time. :-) Have fun and let's connect later.
Cheers,
Damon

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Thanks for your input Damon. I know you already mentioned you were testing just the brake variation but just curious, since normally new bikes are compared to the older ones especially when it comes to marketing, why wasn't the slice-rs given a run at the same timeframe? At least it would show bike vs bike on how it performs vs the new design right? It should be easy to drag that one setup really well and get some numbers compared to the new D-Slice. Then again maybe you guys already did and don't want to release the info right now until the bike is ready to roll out....

My opinion follows, so obviously it is right:

This is a forest vs. Trees situation.
I don't care if discs are faster than rim brakes.

I care if bikes are faster.

I find it ironic that TomA, who has created a co-mingled (tubular, open tubular, clincher) spreadsheet of tire crr, is so strongly against a construction difference.
Why isn't there a column of subjective rating on the tire spreadsheet? Because it doesn't matter. What matters is the tire that rolls fastest.
I believe that is the route we should follow.

We need to pit bikes against each other.
We need to make a list.
On that list can be a little "D" or "R" so that we know if it is a disc or rim brake. Then people can integrate what is important to them, as an individual. The rest of us do not need to tell them if they are right or wrong.

In the beginning Tubulars were fastest. Clinchers caught up and surpassed.
In the beginning Rim brakes were fastest, Discs are catching up...

When I see things like the Cannondale article (or any source of information), I take in the information and I say "huh, interesting" and I add it to my knowledge base. It's neither right nor wrong, it just is. It's something to learn from and something to integrate. Is research ever perfect? No, but we can always learn from it.

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I talk a lot - Give it a listen: http://www.fasttalklabs.com/category/fast-talk
I also give Training Advice via http://www.ForeverEndurance.com

The above poster has eschewed traditional employment and is currently undertaking the ill-conceived task of launching his own hardgoods company. Statements are not made on behalf of nor reflective of anything in any manner... unless they're good, then they count.
http://www.AGNCYINNOVATION.com

It was.
Exactly.
:-)

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Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)

Lots of things matter about tires. Rolling resistance is one. Aero is another. I'm not sure you could use Tom's list to find the fastest tire for a race. Flo used a method that could maybe do that, but it was so intensive they could only test a small subset of tires, and then only on their wheels (of course).

And neither measured things like puncture resistance.




I'm not so sure it was really more about our knowledge catching up, not clinchers catching up. Clinchers have probably always been more aero (generally). And comparable in Crr. This just wasn't well tested until the last 15 years or so (publicly, at least).




Similarly, I'm not sure we can really do what you suggest. The differences between super-bike frames are getting down to the level where it's a big jumble of lines around the P5-level. The most you can say is that some are high-yaw bikes, vs. low-yaw, etc. There is no clear "fastest bike." And as soon as you start the customization process and deviate from the tested equipment and geometry, those differences may all go out the window. Personally, for my next bike I'll likely pick whatever bike in that jumble of lines looks the best and hasn't jumped the $10K shark. And brakes well. It's got to brake well, because I'm tired of crap brakes on TT bikes.

This Cannondale will be in the running as long as they don't jump the $10K on me. It's dead-sexy (from the one photo). And with no data yet, I have good intuition that it'll be in the P5 line jumble.

yes, if cannondale want to go down the disc route then that is their choice. if the bike they come up with as a result of that is fast then great, we'll all be happy (if we can afford it). if it isn't then everyone except cannondale can ignore it (aside from bitching on ST) and only cannondale (and their sponsored athletes) will suffer.

of course it won't necessarily be the brakes that make it fast or slow. what this test shows is that discs and rim brakes are not in a different league with regard to aero performance. either one can potentially be part of a fast bike given good design of the rest of the package which discs may or may not facilitate. we'll never really get a clear answer to which is inherently faster but we will get a new generation of bikes, most of which look like running discs, which may or may not be faster than the current rim braked bikes.

what we are certainly seeing with the P5X and Andean leading the way is bikes that are close to race-ready as standard off the shelf, including with brakes that work well. while the ST crowd doesn't necessarily need this, being quite capable of setting up our own aero storage and nutrition, what we do get from this is a clearer ability to compare each bike's true race aerodynamics. we can then choose which one we want based on realisable aerodynamics, storage/nutrition practicality, price, appearance etc and of course whether the brakes actually work which will likely be more often a yes, fewer of the bikes we've seen that might tick the other boxes but have brakes that you can't live with (literally)

the problem is just that spending $XK on a new bike may also mean spending $YK on new race wheels. frame and wheel manufacturers pushing discs had better get together to do some sharp package deals if they want discs to take off

I don't think that's true regarding Crr. There was a period of time (the 60's, 70's, into the 80's) when tubulars were manufactured much as they are today: Thin, supple fabric casing, thin rubber tread glued on by hand (not vulcanized), latex tubes. During that same period, clinchers were heavier, vulcanized construction using thicker rubber and lower tpi casings, along with heavy wire beads. That's why for years the idea of racing on clinchers was scoffed at. It was not until lightweight "folding" beads were introduced, companies like Michelin, Avocet and Specialized started making lighter, faster vulcanized clinchers, and then companies like Vittoria started making clinchers ("open tubulars) using the same materials and methods as their fast tubulars that clinchers approached the performance of tubulars. I think that was sometime in the 80's, but I'm going off memory.

...and then people realized using latex tubes inside the clinchers made them as fast, or faster, than equivalently constructed tubulars :-)

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http://bikeblather.blogspot.com/

I agree. When somebody makes a bike substantially faster (>5W with a proper yaw weighting with a rider onboard) than my Speed Concept I'll buy it :)

Except in reality your list is a pipe dream. Tom tested all the tires himself using the same protocol. All these bikes are tested at different sites by different people paying attention to different details, spinning things in their best interest. There will never be an objective list for bikes like there is for tires as long as wind tunnel time remains so bloody expensive.

That is glossing over the fact that tubulars with latex tubes were faster than clinchers with latex tubes for a long time. Clincher tech caught up. If you had taken up the tubular fight 10 years ago you would have just been advocating for better tubulars.

I'm pretty sure "open tubular"-style clinchers were available more than 10 years ago...I guess you don't understand that part where I said "equivalently constructed" :-/

Besides, I'm also fairly certain that Jobst Brandt did the roller testing that indicated the inherent glue losses in tubular system WAY before then...

So, I'm really not seeing your point.

But, if you want to look at tires as an analogy for the current discussion, I think you have it backwards. I looked at those 2 main systems and realized people were focusing on performance qualities that were lower order (wheel/tire weight for example) and willing to put up with hassles to obtain that...while I looked at what actually makes a rider faster overall (and apparently Tony Martin, among others, agrees ;-) In the case if the brake discussion, people are valuing a performance property (braking...although it's unclear if hub-discs actually do perform "better" when compared to well-designed rim-disc setups) over other properties that actually make a rider faster (for pavement racing applications). On top of that, they're advocating a system change that inherently requires a "sea change" in equipment due to incompatibilities. Again, I'm looking at the overall system to make a judgement.

I find it funny that because I'm insistent on pointing these things out that I'm perceived as a hub-disc hater, when I'm not. In fact, I embrace them for activities where it makes sense, such as activities where tires that are significantly wider than the rim are a preferred setup (e.g. MTB, CX, "gravel", etc.) and where aerodynamics, and to a lesser degree mass, aren't as important (e.g. commuting, training, etc.) With "go-fast" bikes on pavement though, the better systematic approach is to take advantage of all the things that rim-discs have to offer due to them being a more highly integrated implementation. If you're unhappy with the braking performance of rim-disc though, that's not a flaw of the configuration, it's a flaw in the implementation somewhere. It's that simple.

What's ironic is that in the first implementations of rim-disc braking, we unknowingly (at the time) skipped past the awkward hub-disc phase and proceeded straight to the more system integrated phase. Yeah, it's a technology that has been used for a long time on road bikes, but that doesn't mean it's not a more advanced configuration for the "racing on pavement with fractional hp" task. Moving to a hub-disk system is in many ways a step backwards, technologically speaking.

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http://bikeblather.blogspot.com/

Hello Tom A. and All,

To your point ....

It is interesting that ..... phone texting has become so popular when voice mail was already available .... seems bass-ackwards from an evolution viewpoint .... but trends are not always logical .... or the logic is not readily visible.

A test posted recently showed least brake drag by eliminating brake apparatus from the airflow ..... which seems reasonable.

Therefor we need a system that keeps the braking apparatus out of the airflow ... or streamlines it so that the drag induced by the brakes is minimal.and still provides adequate cooling.

For improving rim-disk brakes .... streamlined brake pads would be a start ..... but with the current pad location in the fork crown or chain/seat stays the pads would still create some 'choking' effect .... and still not be as aero as no brake pads ..... but .... would offer compatibility with most existing bike/wheel systems.

It may be possible with some venting in the area of the brake pads to reduce or eliminate most of the brake pad drag. Brake pads could be contoured to fit most any rim shape ... but may require an insulated brake track on the wheel so the heat of braking does not adversely affect the rubber tire/tube if there are very long and steep down hill runs.

For me and the near term ... rim-disk brakes look like the best choice .... My hydraulic rim-disk brakes on the P5 seem more than adequate .... and perhaps I could eke out a bit aero set up with streamlined brake pad/attachments.

For hub-disk brakes and hub-shoe brakes ..... they offer possibility of new designs that divorce the brakes from the outer wheel rim ... moving them to the hub where they can be enclosed and streamlined ... becoming part of the wheel .... although requiring stronger wheel and fork designs ... making many current bicycle wheels partially obsolete .... and most likely with structures being a bit heavier than rim-disk brakes.

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Cheers, Neal

+1 mph Faster