Hell's bells, can't wait to feel it. I remember the change to the SLC, whooping speed. And now another 3/2 of that !!!

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It's all down to how aero. There is so much talk about stiffness. Now When you have been around for a few decades you realise that bike frames get stiffer every year. Now, even if they do get stiffer, the fact is they were stiff in 1960. It doesn't matter how fit, how strong, even Sir Chris Hoy can only exert his full force on a bike frame when out of the saddle and pulling up on the handle bars.

Think about this, how much force can even the biggest heaviest cyclist let alone a tri athlete generate on a bike frame?


So take a big bloke say 190lbs who has good upper body strength, ask him to apply maximum effort, the most he can exert on the pedal is 190 lbs, plus some extra force where he is pulling up on the handle bars. Think about this, some skinny triathlete who has an FTP of 200 watts who weights 170 lbs is seriously worrying about the stiffness of a bike frame?

There were some really big powerful blokes back in the 1960s and 1970s and you know what, the flimsy, floppy really flaccid bikes of the time didn't break or twist.

The fact is the average little triathlete generates so little force on a bicycle frame there is absolutely fuck all power lost on the most flaccid frame compared to the stiffest.


Sir Chris Hoy might need to consider the stiffness of a frame, there isn't a triathlete on the planet who generates enough force to lose even one watt due to lack of frame stiffness.

NICE!!!...in a single post you used.. 'stiff', 'stiffness' ,'stiffer'...'stiffer' (again) and ended with 'STIFFEST'....with 'flaccid ' tossed somewhere in between :)

I'll play along.

I get stiff just looking at this bike
:)



.

.. ever tried to eat something on a 55mph decent after 100mls on the road for the next 20mls climb on a italian steel frame 30 years ago? I'm not a triathlete for example ..

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Hi Richard,

I like the way you think. Once I plotted the measured stiffness of frames over the decades. We didn't go all the way back to the '60s, but we did include a 1985 Bianchi lugged Columbus SL frame. Might even be more flexible than a 1960s frame...?

Sure enough, with small changes over a long time, frames have gotten stiffer, to the point that today's stiffest frames are literally twice as stiff as a traditional lugged frame.

Bottom line: people "like" the feel of a stiff bike, but in reality (as you've said), speed is all down to how aero it is.

Cheers,

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

Hi sausskross,

Keep in mind, the old S5 white paper reports drag with fast aero wheels already installed on all the bikes, so the improvement with the new bike is only the 4.4 Watts (at 40 km/h) of the new Cervelo aero drop bar.

Cheers,

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

.. copied to next post ..

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Hi Damon,

I agree that there is a "stiff enough" for each use and each of both frame parts mostly in focus. On a time trial, a technical course, a fast descent with sharp turns and ore bad surfaces, a sprint with one hand between the competitors .. not every rider has the gifts of Thor in power, power release & handling.

For some reason I did save aero wheels for later .. so I'll get them on the new S5 together with another saving of 20+ Watts at appropriate speed :-)

Cheers,

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But when you say twice as stiff it isn't as if the least stiff frame wastes much power.

I doubt you could measure the difference in power loss between the stiffest and least stiff frames. A twice as stiff frame doesn't transfer twice as much power.

I would be interested to see evidence of power loss.

Should be possible with a crank based power meter and a Powertap, use same wheels and running gear and measure the power at the wheel compared to the crank, the least stiff frame should show less power reaching the Powertap.

Are there any tests which show greater power transfer of stiffer frames?

I feel like it's worthwhile to remember that this is not a tri bike. I agree wholeheartedly on the statements regarding stiffness and the skinny triathlete or the TT course, but this is a road bike. Stiffness takes on a different meaning cornering hard in a crit, a sprint powered by a human rhinoceros, descending a mountain, or a variety of other tight situations. Even if the perception of stiffness is a placebo as I have heard at other points, it's whatever helps you sleep at night. The people that I see harping on stiffness the most are sprinters, aggressive roadies, and track riders. I have had a bike flexing under load going into the corners at a track and it's not cool. Advertising the improved stiffness is not really a carrot for the people in this forum. The more aggressive geometry, the bar, and the slight improvement on the frame are probably more relevant to this audience, but the stiffness matters and matters a lot to a large portion of the people that will be making a decision to buy this bike.

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Coach Brain: Accelerate 3 ; Incoherent Ramblings

On a bike it is a kind of fusion between mechanics and biology. The mechanic part is the vehicle and the biology the engine. If mechanics are measured with instruments you will find technical summaries. They are helpful to optimize all the graphs of input to output. These method doesn't comply with the engine, otherwise there wouldn't be any competition between athletes outside printed magazines ..

There is no doubt that aero is always on if you move through air, but at speed over distance and time criteria all power release & direction control is driven by feedback of the vehicle to biological sensors and adjustments ..

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I am a big sprinter (size 58 frame, 1,500 watt 5 second power) and the old, less stiff S5 always felt rock solid to me. Thor was able to out descend the entire pro tour on one, and he is a big guy too.

At some point though there are legitimate downsides to a less stiff bike. The old steel frames were more prone to speed wobble, for instance.

Most brand name modern frames, stiffness differences are probably very rarely substantive.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

I'm actually not disputing that. I'm just pointing out that it's not fair to fault the company for bragging about this when it is very important to many potential buyers. Whether or not it SHOULD be important to them is a point for another debate and not one I have enough knowledge to contest. My comment about the placebo is regarding the need to believe in your equipment under pressure. When I read forum conversations or talk to people about it, the desire for stiffness is nearly always from roadies and attributed to those situations. Even if it is "whatever makes you sleep at night", that still holds it's own value for the marketing team and without the engineers pressing that standard forward, we would all still be on those old wobbly bikes. The only reason I made that comment was a tendency in this thread to value the stiffness out of context (applied to use in triathlon) and I didn't really find that fair to the company, the bike, or Damon. IF all other things are equal, wouldn't you want a stiffer (or lighter or more aero) bike.

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Coach Brain: Accelerate 3 ; Incoherent Ramblings

Oh for sure, and if you find tricks to make the tubes wider with no aero penalty, you might as well.

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Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

the new AR is better

So...tell me more :-)

Are you saying that hands in the drops "shields" more of the bar from the airflow, or vice versa? In other words, it takes all those round drop bar sections "out of play" aerodynamically...and then couple that with a bar with aero "tops"...

But, that doesn't work when the bar position results in a drops position with straight, locked arms like shown in this "test" below, right?

http://www.bikeradar.com/...riding-harder-42744/

Instead, the drops position should look more like this, correct?

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http://bikeblather.blogspot.com/

Starting to ride the SLC did not convert me to aero, it was a very, very big add. With the S5 they put more of that add to the bike, the implementation made me stunning with one question left. Is a tapered steering tube really slower than a straight with exposed brake calipers ..

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At a point everybody lives his dream ..

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Hi sausskross,

We learned during P5 R&D that, especially at yaw, a wider airfoil shape can delay separation, so the head tube can be wider. And to your point, the new S5's wider fork and head tube are a good aero match with standard brakes, which means no proprietary brakes are required.

Cheers,

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

Here's the position. This was years ago, when Cervelo and Zipp tested with theam CSC in the San Diego tunnel. This is the test session after which Fabian famously said "808 is the new 404."

You might also remember Gerard's blog post on how high (or low) the bars should be:
http://gerard.cc/2011/09/27/worlds-bar/

Cheers,

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

Good to see you're in tune with what we've done. We studied the ergonomics quite a bit while designing the curve of the drop. As you can imagine, we bench marked a bunch of bars too, including the two you mention, as well as other current popular bars. I think a lot of folks will like this bar's ergonomics.

Damon.

My apologies.

I had forgot that the bar on the NEW S5, is your proprietary Cervelo bar. But I can see that you've taken the best aspects, of your close work with 3T & FSA over the years, and combined that with your own aerodynamics and engineering expertise to come up with this new handle bar for the S5

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Steve Fleck @stevefleck | Blog

Hi Steve, no apology necessary. On the contrary, I apologise, as I see now that my words could have been read as sarcastic.

Cheers,

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

Hi Damon,

thanks for the pic, it's a good model for the position to get on the new S5 next season. Here is my favorite of Jensie. To keep this position for 20 minutes means some gym during winter for me!



This picture is posted at the roadbikereview.com forum .. http://forums.roadbikereview.com/...s-voight-181581.html

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"Too much dude...not enough bike." Seriously.

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http://bikeblather.blogspot.com/