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Trek TTX is Faster Than the P3C
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Xavier
Dec 21, 07 15:23
Post #176 of 236 (1957 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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Katsanis says as much in The use of CFD in the chase of Olympic Gold, although it seems as though they focused more on just the interaction with a disc wheel. The UKSI forks look like this
The question I've wanted to try and answer though, is whether a thin monoblade fork (eg. if you just cut off one of the legs) would be faster with a composite spoked wheel, and if so how thick would the monoblade have to be before you lost the benefit
Xav
SuperDave
Dec 21, 07 15:27
Post #177 of 236 (1948 views)
Re: Trek TTX is Faster Than the P3C [Xavier]
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In the case of the UCI bikes it doesn't matter, you can't use monoblade forks.
http://feltbicycles.blogspot.com/
Xavier
Dec 21, 07 15:29
Post #178 of 236 (1945 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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Ah, but I don't do UCI events :)
Xav
SuperDave
Dec 21, 07 15:38
Post #179 of 236 (1935 views)
Re: Trek TTX is Faster Than the P3C [Xavier]
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So now we're back a few posts up, the industry (dealers, consumers, manufacturers) is not interested in making fast non-UCI legal bikes.
Xavier
Dec 21, 07 15:42
Post #180 of 236 (1930 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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But as an hypothetical question?
SuperDave
Dec 21, 07 17:12
Post #181 of 236 (1870 views)
Re: Trek TTX is Faster Than the P3C [Xavier]
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At $15/minute I'll put the question on someone else's budget!
Hypothetically, I'd say having a 1 sided fork would be about a 50% improvement with a molded wheel's spoke pulse/interference drag than a 2 sided fork.
Andrew Coggan
Dec 21, 07 18:16
Post #182 of 236 (1850 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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In Reply To:
AC,
I think you'll forgive me if there was a decision to
not
make a front disc specific fork.
In general:
narrow spaced fork + disc wheel = good
narrow spaced fork + any molded spoked (iO, Hed3, Corima) wheel = very bad
narrow spaced fork + spoked wheel = not so good
wide fork spacing + disc wheel = nearly as good
wide fork spacing + any molded spoked (iO, Hed3, Corima) wheel = not so bad
wide fork spacing + spoked wheel = good
Given those results, you're forgiven. ;-) Thanks so much for sharing them!
Andrew Coggan
Dec 21, 07 18:19
Post #183 of 236 (1845 views)
Re: Trek TTX is Faster Than the P3C [Xavier]
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In Reply To:
Katsanis says as much in The use of CFD in the chase of Olympic Gold
That sounds like a fascinating read - is there a place that a schlub like me might be able to lay their hands on a copy? (EDIT: perhaps this is the cyclingnews article that was the source of the pic?)
In Reply To:
The UKSI forks look like this
I hadn't seen that pic, and it's literally worth a thousand words...thanks!
RBR
Dec 21, 07 19:02
Post #184 of 236 (1822 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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[reply]So now we're back a few posts up, the industry (dealers, consumers, manufacturers) is not interested in making fast non-UCI legal bikes.[/reply]
Does any bike manufacturer make a realy aerodynamic bike that is NOT UCI Legal?
.
The Dude
Dec 21, 07 20:55
Post #185 of 236 (1779 views)
Re: Trek TTX is Faster Than the P3C [Lucky 1973]
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Um... I find just the opposite. And yes, the 9.9 SSL is not available yet because it is a 2008 model. Trek has '07s on closeout right now because they have too many.
*
The Dude abides.
cbritri
Dec 21, 07 21:45
Post #186 of 236 (1760 views)
Re: Trek TTX is Faster Than the P3C [Lucky 1973]
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I also vaguely remember the P3C (and every Cervelo for that matter, hell for that matter every high end product of any kind) having availability problems at first and/or being released behind schedule.
The TTX 9.9 SSL might be behind because Sram Red are the components and those are pretty hard to come by right now.
guywithabike
Dec 21, 07 22:56
Post #187 of 236 (1750 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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[reply]Isn't the softride & Zipp reported faster than any double diamond frame? Why doesn't the public, the dealers and industry as a whole use them? [/reply]
Because they look like tampons on wheels? :)
--
"Rock and roll, dude." -- Dave Z., on winning TTs in all 3 Grand Tours.
Xavier
Dec 22, 07 1:45
Post #188 of 236 (1723 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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In Reply To:
At $15/minute I'll put the question on someone else's budget!
Hypothetically, I'd say having a 1 sided fork would be about a 50% improvement with a molded wheel's spoke pulse/interference drag than a 2 sided fork.
Cheers - I think I'll have to do my own neanderthal testing then, cue lots of broken bones ... :)
Xavier
Dec 22, 07 1:47
Post #189 of 236 (1720 views)
Re: Trek TTX is Faster Than the P3C [Andrew Coggan]
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In Reply To:
In Reply To:
Katsanis says as much in The use of CFD in the chase of Olympic Gold
That sounds like a fascinating read - is there a place that a schlub like me might be able to lay their hands on a copy? (EDIT: perhaps this is the cyclingnews article that was the source of the pic?)
Sorry, I was being needlessly elliptical, here we are, I also got the original author wrong but it's Katsanis' work that he was quoting:
www.fluent.co.jp/contents/news/bknumber/images/Hart_Olympic-Sport-Paper.pdf
Xav
(This post was
edited
by Xavier on Dec 22, 07 1:55)
Rappstar
Dec 22, 07 5:59
Post #190 of 236 (1665 views)
Re: Trek TTX is Faster Than the P3C [Xavier]
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IIRC, ultimately it's been found that because of the additional strength, you need substantially more material than for a dual-bladed fork. So much so, that the aerodynamic savings were actually less. The dual-blade design is very sound structurally. I don't think the monoblade is really going to help you, until more substantial material improvements come along.
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Xavier
Dec 22, 07 6:43
Post #191 of 236 (1637 views)
Re: Trek TTX is Faster Than the P3C [Rappstar]
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Totally - if you look at the example of the Burrows monoblades they are much deeper and also thicker than normal, depends to what extent the fork blade interference is having an effect I suppose. The other problem is the hub/fork interface, you need a much wider diameter axle than normal and therefore a modded wheel, which may or may not be worth it! You could fudge it with a quick release and a spacer on the missing fork side to press against but it would be very dangerously flexy
Xav
Trigeak13
Dec 23, 07 14:12
Post #192 of 236 (1515 views)
Re: Trek TTX is Faster Than the P3C [ShawnF]
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I used to work on a bike shop that sold the TTX and I own a p3c. I can tell you that I'm faster on the p3c than the TTX. Also, the ttx is very sluggish in and out of turns. I like a very quick and responsive bike, that is not the TTX.
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GregX
Dec 23, 07 15:30
Post #193 of 236 (1487 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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Isn't the softride & Zipp reported faster than any double diamond frame?
from what i recall reading years ago, based on some pretty good tests, the zipp 2001 series frame was quite a bit faster than a traditional (i think, round-tubed) double diamond frame, but that was when each test bike had a
rear disc wheel.
but if each bike had a
spoked
rear wheel then, interestingly enough, the zipp did worse than the double diamond frame.
how a zipp 2001 with a disc would compare to an equivalent size p3c with a disc is anybody's guess. but i think the cervelo would do better than the zipp because its tubes are much narrower, and since the seat tube basically 'disappears' in front of the rear wheel. because of the p3c's special seattube, i think the p3c is effectively not really a double diamond frame, or at least not in the eyes of the wind.
Where would
you
want to swim ?
SuperDave
Dec 23, 07 16:36
Post #194 of 236 (1456 views)
Re: Trek TTX is Faster Than the P3C [GregX]
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Just because the seat tube is curved doesn't mean it acts as the same frontal area as the wheel. There is interaction between the tire and the tube itself and of course the tube has to be at least 25mm wide, (I think its around 28mm on the bike you mentioned) whereas the wheel can be 19mm.
I'm not suggesting that one frame is faster than the other, but overcoming missing frame members on double diamond aerodynamics is very difficult, and mirroring the shape of a wheel doesn't make the frame member dissappear aerodynamically.
-SD
GregX
Dec 23, 07 16:48
Post #195 of 236 (1448 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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In Reply To:
Just because the seat tube is curved doesn't mean it acts as the same frontal area as the wheel. There is interaction between the tire and the tube itself and of course the tube has to be at least 25mm wide,
no, i am not saying that just because a seat tube is curved means it has the same frontal area as the rear wheel. but what i am saying is that
if
the shaping of the seat tube is done very well (as is the p3c's seat tube), then it can
approach
the same frontal area of the rear wheel and the seat tube begins to
nearly
disappear.
as that's the main goal of that p3 design feature and that's why they end up with such good drag numbers.
Where would
you
want to swim ?
(This post was
edited
by GregX on Dec 23, 07 17:02)
SuperDave
Dec 23, 07 17:11
Post #196 of 236 (1431 views)
Re: Trek TTX is Faster Than the P3C [GregX]
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Doesn't a straight leading edge on a tube have less surface area than a curved tube?
What happens to the wheel/tube interface?
-SD
Rappstar
Dec 23, 07 17:39
Post #197 of 236 (1419 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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It does, but frontal area and surface area are not the same thing. Think about the surface area of an airplane wing - very large - but the frontal area is quite low. By curving the seatpost, you will increase the surface area, but you won't necessarily increase frontal area.
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SuperDave
Dec 23, 07 19:56
Post #198 of 236 (1377 views)
Re: Trek TTX is Faster Than the P3C [Rappstar]
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Agreed,
In this application, what do you think is
better,
surface area or frontal area?
-SD
Rappstar
Dec 23, 07 20:52
Post #199 of 236 (1347 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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frontal area is much more dominant for aerodynamics. An increase in surface area is not inherently bad at all. Consider this bike, which you may have heard of:
Here, the additional surface area is on the sides. I.e., this has more surface area on the sides due to filling back to the seattube. So I wouldn't be too concerned with surface area, since we all know how this bike tests. I actually think the DA has more surface area on the seattube from backfilling to the wheel with a straight leading edge than the P3C does from curving the seattube. The frontal area in each case is basically equivalent. The question is which offers better aerodynamics. I suspect you know the answer. But in both cases, you have two bikes that choose an increase in surface area to achieve superior aerodynamics. Either design is going to test better than a simple airfoil shape that does not fair the rear wheel at all.
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SuperDave
Dec 23, 07 20:54
Post #200 of 236 (1342 views)
Re: Trek TTX is Faster Than the P3C [Rappstar]
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I have nothing to add except that the seat tube width on that bike you've pictured is only 25.5mm wide.
Otherwise, can I have the publication rights to your comments? :)
-SD
http://feltbicycles.blogspot.com/
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