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Re: P5 news today... brace yourselves! [gtingley] [ In reply to ]
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gtingley wrote:
matto wrote:
[quote AlexG
Where is the wind tunnel data that says you guys have to have your faces closer to the front wheel?


This is not a bad question. It seems like having your head down and out of the wind would be faster... but is there any data out there? Has anyone measured their drag at various levels of drop?


Yes, at LSWT[/quote]
I did a WT session. We found that at a certain point there wasn't anything, other than discomfort, to be gained from going lower.

The funny thing is that looking at the pictures (front view) from the wind tunnel demonstrates that reducing frontal area was the best predictor of drag (i.e., less A = less drag). Other than raising the bar angle slightly, there weren't any changes that made me faster that you couldn't figure sitting in front of a mirror on your trainer (i.e, not much I could do to change the Cd of CdA).
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Re: P5 news today... brace yourselves! [gtingley] [ In reply to ]
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Looking at the picture on this ad, it appears to be a seat tube/snippet of top tube/seat stay. If the picture is accurate, it looks like the S5. The surprise would be more in the front end of the bike/steering as a guess. Possibly a sloping top tube like the S5 as well. Gerard must be getting a kick out of the guesswork on what it will look like in this forum...any other guesses?
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Re: P5 news today... brace yourselves! [Rocky M] [ In reply to ]
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My guess is a S5 rear with horizontal DO and BB brakes. Front similar to S5 in stack and design but the fork has a dedicated brake. I expect a dedicated aerobar assembly. No nosecone, no inframe hydration but a widened downtube to fair a waterbottle. Tradional forward geometry, UCI compliant, tradional steering no hinge, no hydraulics .

Styrrell
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Re: P5 news today... brace yourselves! [styrrell] [ In reply to ]
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My guess is a brake like the Tektro Aero V-brakes that have been popping up lately and that have been integrated into a few new frames. Designed into the chainstays and not sure about the front brake. I can see it designed into the fork but I am not sure if it is the front or back.

Whatever they do, it will be interesting.
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Re: P5 news today... brace yourselves! [grumpier.mike] [ In reply to ]
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I had a similar experience at the UWAL tunnel with regard to head height. Pushing my head down as low as physically possible compared to where I would comfortably ride added 17 grams of drag to baseline @28 mph and 29 grams at 30mph. My repeat runs were within 4 grams of each other as far as statistical significance. I would disagree slightly with the mirror and Area principle. I found significant interactions between my arm, elbow, thigh, and hand positions that would not change frontal area overall. Also found significant differences in helmets and skinsuits (that all fit well). What looked fast wasn't always so. All total I was able to reduce my tunnel drag by 7.5% at 30mph, 0 yaw, through minor position tweaks and equipment choices. Overall fantastic experience. Yet to see if it will translate to the road as this was at the end of this season.
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Re: P5 news today... brace yourselves! [gtingley] [ In reply to ]
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gtingley wrote:
Sounds like increased stack http://triathlon.competitor.com/...oon-cervelo-p5_44617
Better not be too much stack over a 51cm P3. Anymore than 10 or 15mm would rule it our for me.
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Re: P5 news today... brace yourselves! [Andrew69] [ In reply to ]
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Andrew69 wrote:
Better not be too much stack over a 51cm P3. Anymore than 10 or 15mm would rule it our for me.
What bars are you using? Part of the reason for my figure of 8cm was comparing against my Transition where I used USE Tula bars. Compared to many bars, they put the pads several cm lower.
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Re: P5 news today... brace yourselves! [Steve Irwin] [ In reply to ]
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Vision alloy's, not sure what size spacers but the pads touch the bar.
Currently running a -6 stem with 1, 5mm spacer, so I could get a lower profile top cap , drop the spacer and get a -17 stem if I needed to, except that Im still thinking about dropping a bit lower as I havent found my point fo diminishing returns yet, so if the P5 has a whole lot more stack I could be in trouble...
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Re: P5 news today... brace yourselves! [matto] [ In reply to ]
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matto wrote:
gtingley wrote:
Sounds like increased stack http://triathlon.competitor.com/...oon-cervelo-p5_44617


triathlon.competitor.com wrote:
The P1 and P2, their lower-priced tri bikes, have geometry schemes designed for more upright riding styles than the P3 and P4. The dramatic differences in geometry between the more aerodynamic models and the cheaper versions implied...


What a bunch of crap spewing that is. The P2 isn't that much less aggressive than a P4. The P2 is more aggressive than the Trek Speed Concept and way more than the Shiv.

That's exactly my point. The SC and Shiv are less aggressive yet they are faster. So why do we have to have such aggressive positions?
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Re: P5 news today... brace yourselves! [jackmott] [ In reply to ]
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jackmott wrote:
heres some perspective
a p3 with old zipp 808s on it is about 5 minutes of drag per 40k

a p4 with new 808s drops that by like 20%, so 4 minutes of drag per 40k

if the frame and wheels and components all were 0 drag you would only save 4 minutes per 40k



pito00 wrote:

I agree, but my guess is it'll have to be some wild beam style bike a-la the ZIPP or softride frames. I'm guessing they're maxing out the double diamond frame given the rules they currently operate with.

Frames shape affect cyclist's drag so there is more to do than "simply" building 0 drag bikes, the Litespeed Illicito is a good example

http://cds-0.blogspot.com
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Re: P5 news today... brace yourselves! [Rocky M] [ In reply to ]
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I think we can certainly count on a faired water bottle, and an asymmetric bottom bracket.
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Re: P5 news today... brace yourselves! [SavageHouck] [ In reply to ]
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SavageHouck wrote:
I think we can certainly count on a faired water bottle, and an asymmetric bottom bracket.


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Re: P5 news today... brace yourselves! [AlexG] [ In reply to ]
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Personally, I think the issue with geometry isn't necessarily abut aggressive position. True, you can get a more "aggressive" fit with a P4 than a SC, etc, but some of us just don't fit on the new super bikes. I'm an outlier (?sp) on the fit scale, with short legs and very long torso. To get anywhere near horizontal (notice I said near, not to), I'd have to run a ridiculously long stem on all the super bikes. With the integrated front end that companies are going to, that makes impossible to replicate my P3 fit on most new models. I was hoping the P5 would stay in the same geometric range. For people like me, it's necessary. For everyone else, you can add spacers if you need a higher stack, or just get a different bike.

What can I say, I'm a selfish asshole. But I'm happy with my current ride and can always find a P4 on the cheap, or move to a felt or Shiv TT. This move would mean Cervelo is out for me, but I'd be surprised if, at the end of the day, there is a significant amount of added stack to the P5 vice P3/4.
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Re: P5 news today... brace yourselves! [Epic-o] [ In reply to ]
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Quote:

Frames shape affect cyclist's drag so there is more to do than "simply" building 0 drag bikes, the Litespeed Illicito is a good example

not that much under even triathlon rules, and Litespeed didn't make the Illicito, and the Illicito doesn't have any astounding rider interaction that we know of anyway.



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
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Re: P5 news today... brace yourselves! [jackmott] [ In reply to ]
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jackmott wrote:
Quote:

Frames shape affect cyclist's drag so there is more to do than "simply" building 0 drag bikes, the Litespeed Illicito is a good example


not that much under even triathlon rules, and Litespeed didn't make the Illicito, and the Illicito doesn't have any astounding rider interaction that we know of anyway.


My mistake, Quintana Roo Illicito. Jackmott, you shouldn't be so categorical, there are many design choices yet to be improved/discovered

http://cds-0.blogspot.com
Last edited by: Epic-o: Dec 13, 11 9:37
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Re: P5 news today... brace yourselves! [Epic-o] [ In reply to ]
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Aren't QR and Litespeed under that same umbrella?

Styrrell
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Re: P5 news today... brace yourselves! [Epic-o] [ In reply to ]
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Quote:
heres some perspective
a p3 with old zipp 808s on it is about 5 minutes of drag per 40k

a p4 with new 808s drops that by like 20%, so 4 minutes of drag per 40k

if the frame and wheels and components all were 0 drag you would only save 4 minutes per 40k

So that means to update to a P4 with new wheels from my P3, assuming a cost of about $10,000, I would be spending $167 per second? I would expect any reasonable performance number by the P5 would still work out to be over $100 per second saved. Not the best bang for the buck.

That would be very tough to get past the wife! :(
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Re: P5 news today... brace yourselves! [Epic-o] [ In reply to ]
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Epic-o wrote:
My mistake, Quintana Roo Illicito. Jackmott, you shouldn't be so categorical, there are many design choices yet to be improved/discovered

given usat and uci rules, and modern fluid dynamics software tools, I'm not sure that is really true =)

I'm sure bikes will get faster, but the p5 isn't going to drop ~40 seconds off the p4 like the p4 did to the p3, etc.



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
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Re: P5 news today... brace yourselves! [jackmott] [ In reply to ]
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But it might if it has a downtube that shields a standard water bottle, and you compare a P5 with water bottle to a P4 with water bottle like what CA used at the 70.3 worlds. This would actually be an important consideration to me because I like to have a frame mounted water bottle even if it is not Slowtwitch approved. Don't even get me started on Total Immersion, Powercranks, or functional strength training :-)
Last edited by: Scott_B: Dec 13, 11 11:09
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Re: P5 news today... brace yourselves! [jackmott] [ In reply to ]
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jackmott wrote:
Epic-o wrote:

My mistake, Quintana Roo Illicito. Jackmott, you shouldn't be so categorical, there are many design choices yet to be improved/discovered


given usat and uci rules, and modern fluid dynamics software tools, I'm not sure that is really true =)

I'm sure bikes will get faster, but the p5 isn't going to drop ~40 seconds off the p4 like the p4 did to the p3, etc.

No bike will get down to zero drag, so that is a hard limit that can only be approached but not exceeded. Of course, it will require increasing levels of engineering effort to do so.

Expecting a lot of improvement from bike/rider interaction is unrealistic unless we start allowing fairings as part of the bike.
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Re: P5 news today... brace yourselves! [Scott_B] [ In reply to ]
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Why would we compare bikes as they are actually ridden vs bare? Performance in a race isn't nearly as important as who wins the WT testing;-)

Seriously though, as more and more testing becomes available it seems to open up more questions. Specialized has said that repeatability in a one tunnel in the same day is very difficult, let alone comparing different tunnels with different testing protocals on different days. I don't know that we will see a big jump in just frame drag, but frame / body / wheel / accesories in total, in real world situations are just starting to be explored.

Look at the speeds that HPVs attain. Obviously fully faired bikes wont be allowed in tri, but things like the down tube shifted over to sheild the drivetrain, fork legs designed to move the air around your legs, gearbox transmission hidden in the frame, etc have all been barely examined.

The other issue is yaw angle. Right now makers are looking for bikes that perfrom well at all reasonable yaws and some of the best bikes do better a low and worse at high. What happens when a company says to hell with it, we are coming out with a high yaw bike and a low yaw bike along with a simple wind guage and guidlines as to what to ride in various conditions.

I wouldn't be surpised at all if its possible to come up with a bike 40s faster than the P4 under certain conditions, heck the SC is pretty close at high yaw.

Styrrell
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Re: P5 news today... brace yourselves! [styrrell] [ In reply to ]
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http://twitter.com/tomfowler2
All I can say is, it better damn impress me with all the hype
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Re: P5 news today... brace yourselves! [justkeepedaling] [ In reply to ]
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Trouble is I don't think anything will impress most peple these days if its a UCI legal design. I'm assuming its UCI legal and I'd be surpised if it has any design feature that makes anyone go Wow. That not a criticism, just the realities of building anything to a narrow set of specs.

I would like to see an all out non UCI TT bike, but i don't think thats the P5s goal.

Styrrell
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Re: P5 news today... brace yourselves! [styrrell] [ In reply to ]
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Yeah I agree. Pretty much every UCI-legal superbike looks almost the same besides a couple different lines and curves here and there.
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