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Trek TTX is Faster Than the P3C
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Rappstar
Dec 23, 07 21:07
Post #201 of 236 (3000 views)
Re: Trek TTX is Faster Than the P3C [SuperDave]
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Exactly. the 25.5mm width is a big part of why the frontal area is so minimal, which is also part of why the bike is fast. So again, it's about frontal area, not surface area.
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gregclimbs
Dec 24, 07 0:19
Post #202 of 236 (2979 views)
Re: Trek TTX is Faster Than the P3C [Rappstar]
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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:
<pic snipped>
that thing looks looks like a fat pig with those wide base bars, wide ass cranks, ugly brakes....
deep in it's heart it wants to look like this:
g
greg
www.wattagetraining.com
(This post was
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by gregclimbs on Dec 24, 07 0:21)
starless
Dec 24, 07 0:44
Post #203 of 236 (2964 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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Does Greg ever descend as well?
zebragonzo
Dec 24, 07 2:35
Post #204 of 236 (2950 views)
Re: Trek TTX is Faster Than the P3C [Rappstar]
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[reply]frontal area is much more dominant for aerodynamics. An increase in surface area is not inherently bad at all. [/reply]
Bigger frontal area tends to result in pressure drag due to separation, surface area results in surface drag. While pressure drag is around 10x worse than surface drag, it's still an issue.
gregclimbs
Dec 24, 07 6:41
Post #205 of 236 (2915 views)
Re: Trek TTX is Faster Than the P3C [starless]
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That's funny...
Gregclimbs is a bit of a misnomer and a joke all at once. I climb like a brick and descend like one as well...
G
greg
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nocalclimber
Jan 15, 08 23:25
Post #206 of 236 (2758 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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A great deal of bikes are desgined, or should I say styled, to look fast. Anyone with any kind of aerodynamic knowledge can spot the bikes designed by an industrial designer, as opposed to an engineer with knowledge of aerodynamics. The geometries are far from "clean" with styling features that quite frankly disturb the airflow and increase the drag rather than reduce it. If you look at an F1 car, where downforce is the main driver behind aerodynamic design, not drag, there are many external aerodynamic devices with a great deal of complex interactions between them and the rest of the car. I feel many, not all, bike manufacturers style their bikes with F1 cars in mind with the idea that it must look fast or revolutionary to sell. There are detailed interactions between the various parts of the bike and rider but at the end of the day a clean bike is a fast bike.
Some manufacturers make all kinds of exhorbitant claims about how much time they spent in the wind tunnel and on CFD analsysis . They'll publish "non-partisan" comparisons against other bikes where miraculously their bike ends up being the fastest. This has become a marketing battle without quality engineering to back it up. As a racer, with a degree in aeronautical engineering , over 15 years of experience in aerodynamics ,including wind tunnel testing and CFD, this devalues the work that some bike companies truely put in. I'm not a bike company employee with any particular affiliation, but if you look at the bikes each one produces you can tell which companies genuinely use the engineering tools they claim and those who just market themselves as using them. Wind tunnel testing and CFD is expensive, a stylized design and some marketing spin is a lot cheaper.
Shane D
Jan 16, 08 2:04
Post #207 of 236 (2693 views)
Re: Trek TTX is Faster Than the P3C [nocalclimber]
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By your highly trained eye, what bike frames do you consider to be the fastest aero wise??
Your top 5 list would be nice :-)
Shane D
UK Gearmuncher
Jan 16, 08 2:05
Post #208 of 236 (2693 views)
Re: Trek TTX is Faster Than the P3C [nocalclimber]
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This is probably the most accurate post on this subject I have ever read and I definetly agree.
One of my favorite modern examples was the new Pinarello design shown in the UK's cycling weekly. When asked if it had been taken to the tunnel they replied 'that they didn't need to as they obtained the aero design knowledge off their previous designs'. the cycling reporter stated in his appraisal that ' going by their previous results they're obviously right in this policy'. With this king of of ignorance, it's no wonder we have half the dross on the market we do.
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nocalclimber
Jan 16, 08 21:37
Post #209 of 236 (2461 views)
Re: Trek TTX is Faster Than the P3C [Shane D]
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Shane,
Hey, I thought my comments would be dismissed as the rantings of an engineering snob. You know I thought about this and I cant come up with 5 current production frames (from different manufacturers)where I think knowledgeable aerodynamic design was actually employed in the up front design process (as opposed to after the fact benchmarks and the like). The fact that I only genuinely believe one manufacturers claims (aside from the work the University of Sheffield did on the British Cycling track bike) regarding the level of engineering in their products would also make me appear bias.
Cheers
NextMerckx
Jan 17, 08 1:11
Post #210 of 236 (2378 views)
Re: Trek TTX is Faster Than the P3C [nocalclimber]
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With your aerodynamic experience, can you perhaps explain the double standard of Trek's when it comes to LeMond and their Aeolus wheels? They claim the 'trip strip' on the forks of LeMond tri bikes reduces overall drag by reducing surface contact with the air and virtually creating a larger airfoil shape. When comparing their wheels to Zipp, however, the 'larger airfoil' then becomes a 'low pressure wake' on the trailing edge of the rim (out in front of the bike) and increases aero drag. So...err...which way is it?
And can you at least affirm (and thereby commit ST heresy) that proper rider positioning on even the most aerodynamically deaf and dumb --well, not the MOST, but one that's poor...say, a tri on a Cannondale SystemSix-- is going to be more beneficial than riding on the sleekest bike with an aerodynamically useless position?
QuintanaRooster
Jan 17, 08 6:05
Post #211 of 236 (2279 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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Very interesting bike set up you have there.
Looks like you took the minimalist approach with no basebar and no pedals.
I ride with a guy who races with only one aerobar extension. He is an interesting character.
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Deus ex Machina
Jan 17, 08 7:10
Post #212 of 236 (2225 views)
Re: Trek TTX is Faster Than the P3C [QuintanaRooster]
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Interesting, yes. That, and they both probably share the same destiny of crashing...Badly.
(This post was
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gregclimbs
Jan 17, 08 7:34
Post #213 of 236 (2200 views)
Re: Trek TTX is Faster Than the P3C [Deus ex Machina]
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Wow, you make a lot of assumptions (about me, my abilities, the bike's difficulty in turning without a basebar, etc.)
The reality is, I rode this position/setup for a whole season of racing and training before committing to it (search my old posts for more info on my "hot swap" setup.
I had one close call last year on a training ride where a car cut me off (left turn in front of me) that the setup worked fine and the outcome wouldn't have been any different with full bars - I avoided the car.
G
p.s. The lack of pedals was due to needing another pair of x1s as they are narrower than the stainless versions.
greg
www.wattagetraining.com
Deus ex Machina
Jan 17, 08 8:14
Post #214 of 236 (2151 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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If my personal hero, Natasha, can crash, then I don't believe anyone else is immune. She is a total bad ass.
wasfast
Jan 17, 08 8:17
Post #215 of 236 (2142 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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Where are your hands when starting from a standstill and need to pull on the bars? I've seen some UK TTers use this approach but am having a hard time imagining how you get underway.
gregclimbs
Jan 17, 08 8:17
Post #216 of 236 (2142 views)
Re: Trek TTX is Faster Than the P3C [Deus ex Machina]
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Yeah, you are right. If you don't look down the road, you will hit shit.
Doesn't mean it was the bar setup's fault. Doesn't mean that I or anyone else has a "destiny to crash".
:)
G
greg
www.wattagetraining.com
gregclimbs
Jan 17, 08 8:25
Post #217 of 236 (2127 views)
Re: Trek TTX is Faster Than the P3C [wasfast]
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Starts are a lot like braking, choke up on the bars (hands inside the brake levers) and support forearms on the armrests.
It does require using appropriate gearing (no starting in the 54x11), but that is a good thing.
G
greg
www.wattagetraining.com
bpq
Jan 17, 08 8:35
Post #218 of 236 (2115 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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What... no bento box? Just kidding... that is on SICK ride. This is, like, the third time I have found myself LUSTING after a bike you've posted. We must be drinking from the same koolaid since you keep buying my dream rides. The difference is that I dream about them while you're riding them.
A couple of quick questions: Are those Blackwells or old school (ie non-dimpled) 808s? Just wondering about your choice in wheelsets. Why no disc? Also, you seem to have your saddle adjusted pretty far back. Are you riding slack?
Also... can you post a pic of the drive side. Just for curiosity's sake.
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Deus ex Machina
Jan 17, 08 8:40
Post #219 of 236 (2098 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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Well, God speed to you and keep the rubber side down.
MarkyV
Jan 17, 08 8:49
Post #220 of 236 (2074 views)
Re: Trek TTX is Faster Than the P3C [bpq]
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Why no disc?
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gregclimbs
Jan 17, 08 8:49
Post #221 of 236 (2074 views)
Re: Trek TTX is Faster Than the P3C [bpq]
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A couple of quick questions: Are those Blackwells or old school (ie non-dimpled) 808s?
actually, they are dimpled 808s (pt2.4 rear)
Quote
Just wondering about your choice in wheelsets. Why no disc?
'cause that wheel also has a wheelbuilder disc cover (almost, but not quite as fast as the sub9). actually, the wheels, powermeter, crankset aren't really "sorted" yet.. that is just current running trim. Obviously the 808+cover won't work @ masters nats.
I have the fsa cronos on there now as the low q-factor. If the quarq comes out anytime soon, I will test it on these cranks and run a sub9. if not, I might try going back to my vista integrated crankset (which kills the crank based powermeter) and forces the 808 rear (or a replacement with the 1098!), but there is an overlap issue with the crank and the thick bb shell.
if I don't like the quarq, the SRM goes back on with sub9.
maybe with custom crankarms that match the narrow fsa crank...
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Also, you seem to have your saddle adjusted pretty far back. Are you riding slack?
yup. I am not a triathlete and so my saddle position matches my road bike. I have no reason to ride steep as 1) I am flexible enough to hold the position and 2) there is no discernable drop in power despite the "closed" hip angle that the slack+LOW position creates.
I attribute that to years of specificity and trining/racing in essentially the same position for a long time.
g
greg
www.wattagetraining.com
tomp
Jan 17, 08 9:43
Post #222 of 236 (2013 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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Do you route the powertap wire internally, or does it go down the downtube? (or is it wireless?)
enjoy,
tom
gregclimbs
Jan 17, 08 10:24
Post #223 of 236 (1975 views)
Re: Trek TTX is Faster Than the P3C [tomp]
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As mentioned above a pt2.4 (wireless).
Whatever solution I ground out on will be wireless - pt, quarq or srm...
As probably the slc-sl will be eventually as well so the cabling doesn't bugger up aerodynamics.
G
greg
www.wattagetraining.com
tomp
Jan 17, 08 11:13
Post #224 of 236 (1947 views)
Re: Trek TTX is Faster Than the P3C [gregclimbs]
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Ah, sorry, missed that. I saw the rear brake cable down by the bottom bracket and thought that was an internally routed PT cable. Nonetheless, nice bike! :)
tom
In Reply To
As mentioned above a pt2.4 (wireless).
Whatever solution I ground out on will be wireless - pt, quarq or srm...
As probably the slc-sl will be eventually as well so the cabling doesn't bugger up aerodynamics.
G
53x12
Jan 17, 08 15:32
Post #225 of 236 (1790 views)
Re: Trek TTX is Faster Than the P3C [bpq]
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Why no basebars?
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