It's interesting that you mention that deep dish aero wheels dont have a positive effect on aerodynamics. the "Tour" tests of various aerodynamic bikes such as the lotus and cheetah (which were done at a velodrome at 45 km/h) report that rider position and wheels have a greater effect then even the frame on aerodynamics. the results are at www.catbikes.ch

re. the data on the cheetah page, you may notice that all the bikes have values between 314 to 320w. That is a 1.5% difference.

However, SRM cranks, powertap, computrainer have an error margin of at least 5%. which means none of the data available there is any significant.

..... also, if you look back a few years when Hellreigel really smoked the bike course, he was riding his Centurian with 650 wheels so that doesn't seem to be an issue for him. I think that Zack's softride has the little wheels too. It is probably an issue regarding exposure of the European triathlon bike model.

"Dan, I'm curious, why just a clock and PE?"

two reasons: trying to calibrate your ride to a specific power and HR is very hard. these two parameters, esp watts, jump all over the place. there's not enough precision. second, HR is only a measure of aerobic performance, and neuromuscular performance is an important component of cycling fitness and fatigue. you can do an awful lot of work on the bike and have it not show up on a HR monitor. for example, you might ride a reasonably hard effort at 60rpms for 15 minutes and generate the same watts with the same heart as if you ride at 90rpm. if you rode a medium effort over 4 or 5 hours, tho, then you'd be able to see the folly of riding at 60rpms vs 90.

as is the case in swimming, i believe stripping away everything but PE and time will do the trick, and you'll find the truth through a lot of repetitions.

---

Dan Empfield
aka Slowman

Here are my best guesses

1. The shape of the crown on a fork is incredibly important, as the aerodynamic effect of the wheel going through it is twice the speed of the bicycle. Cannondale hyped the keyhole shape of their time made slice forks as allowing the top of the wheel to slip through the fork blades more efficiently. Of course there might be a crosswind, weight or handling issue as well.
2. Just yesterday I spoke with the Cannondale rep about their multisport bikes, it was his belief that the frame tubes were primarily cosmetic. I am not sure if this was from the engineers or just his opinion. Dan’s informal aero tube analysis showed the Cannondale being significantly wider than most other manufacturers, perhaps showing that they placed greater priority on preserving the stiff ‘Cannondale’ ride than on aerodynamics. Since the standard and aero tubes are of such similar frontal area I would guess that their aerodynamic efficiencies would be more similar and if the argument that aero tubes are detriments in cross-winds is sound then the round tubed bikes might even be aerodynamically superior. Of course it might just come down to weight. As far as I know Cannondale is still using plain ol 6061 aluminum in the Multisport frames, whereas the standard tubes are available in the much lighter, and in my opinion, better riding, Optimo tubeset. My guess is that the weight difference is close to a pound. If someone has more accurate numbers I would like to hear them. I should note that Cannondale is bringing back their custom program so if you want steep angles on round tubes the world is your clam (the new custom colors are supposed to be killer, or so I am told)
3. The many water bottles might be a result of needing to carry ample amounts of both water and a sports drink

4. I have no idea

Now that C'dale has filed Chap. 11 bankruptcy it may a be a moot point.

Sorry, but I can´t find any english papers on the aerostuff. But I remember a test in the german version of triathlete back in 1995 where they tested a hole lot of (rotating) wheels. They found a Carbotec 12 spoke low rim wheel to be the fastest.

An interesting conclusion was that just minor failadjustments of aerospokes ruined the performance of any wheel - that happened, as far as I remember to the Zipp-wheels tested and showes the importance of proper treatment and installation of the wheels.



And Dan, with regard to the SRM cranks as a measuring device in the Tour test: I think the pro model is a lot better than +/- 5%. The germans also tried to ensure constant poweroutput by using the same professional 6day biker for the test. Those guys know how to spin at a constant high pace! But of course you´re right - 100% accuracy is impossible to achive. Anyway the results were interesting, and deep profile rims should, if they were a significant force, separate from the rest of the bunch, and clearly they didn´t (they were´nt bad either) . The main conclusion in the german Tour was:

The fewer spokes, the more aero. Deep section rims are of no other importance than allowing the use of fewer spokes. If this can be acchived without a deep rim, then you often get a lighter, as aero and therefor faster wheel.

Oh, and guys, I´m just typing this out of what I remember. I read the magazines a few month ago (again) because I was looking for new wheels for my Vamoots. The reason why I choose a normal roadbike is the versatility and my main focus on hilly bikecourses = Zofingen!











Regards



Martin

I can confirm what Kreutzer says - we dont not give that much emphasis to aerodynamics in Europe.It has been quite fun to follow the aero discussion in USA, when there is no hype over the topic here. We go for a powerfull position and good powertransfer on the bike and a lightweight bike as well - Aerodynamics is most limited to bodyposition on the bike off-course with an aerobar, allthough wingtype aerobars like the Cinelli Angel is very popular among triahtlets. However the majority is on a standard roadbike with a clip-on aerobar. The saddle will be pushed a bit forward on the rails, perhaps combined with a straight seatpost resulting in approx 74 degrees or so. The elite like Sandvang and Sindballe will have a dedicated competition bike in aerodress like the Principia TT2 or Bernardi Aliante (Sandvang rides a Italian ROSSIN with standard geometry but with aerotubing) but mostly with standard roadgeometry or not steeper than 74-75 deg..

The testing in TOUR is mainly amied at BB and front end stiffness, stiffnes-to-weight ratio(STW-value) and ride characteristics of the frame. Not much mentioning of aerodynamics, in fact TOUR often reports that the use of aerodynamic tubing is hurting the overall stiffness of frames, as round tubing create a much stiffer frame. The winner of their testing for about 2 year in row of the STW-value has been the danish Principa REX Pro, edging out Klein, Cannnondale and the German Storck frame. The frames are also tested for durability of the paintscheme and the craftmanship of the frame is rated. A lot of well-known frame manufactures has been given poor evaluation in this department with badly made welds, incorrect alignments of the bearingcups, dropouts that are not straight, forks with a rake that do not match the frametype, seatstays that are not of the excact same lenght on left vs right side etc. etc. Not very encouraging reading.

Likewise the wheeltests which they generally perform every 2 years, last in the spring of 2002, shows that you should avoid box type rims but does not show much difference between deep and shallow rim types. Like Kreutzer reports it is the spokecount and aeroshapes of the spokes that matter according the Germans. A 32 spoke wheel faired quite well in the test and beat several real aerowheels, which TOUR did find very strange themselves but concluded that the reason was the use of aerospokes which combined with the high spokecount created sort of a disc effect.

The HED 3 was highly praised as a true aerowheel, but was not the fastest in direct headwind. Here it was beating by several wheels, among others Mavic Cosmic Carbone, Corima Medium and similar wheels. However as soon as they moved the wind direction to a sidewind the HED3 was very superior over all of them. The Lightweight wheel also was among the winners due the low weight and stiffness but was not the most aero due to the relatively many thick and round spokes. Zipp 303 was high up there and mentioned as a choice for both aerodymanics and durability for everyday riding in the clincher version. The German Citec 3000 wheels (which Hellriegel rode in Hawaii Ironman) had great aerodymanics and are very stiff but somewhat heavy and did get a low rating on the acceleration test - these and the HED3 are the wheels i bought myself, the Citec wheels are so stiff and straight that you fell like riding on rails.

The February 2003 issue is quite interesting as TOUR takes on integrated headsets and reports several incidents where integrated headsets combined with a carbonsteerer has caused the bearings to lock-up in critical riding situations. They claim that in hard conditions the carbon steerer can flex/vibrate and cause momentarily the steerer to lock / tighten in the bearings. Likewise it is reported that some European manufacturers stay away from integrated headsets and use only the old non-integrated type or semi-integrated headsets. Ernesto Colnage has publicly announced that never will a integrated headset be installed on a Colnago bike and has even launched an advertising campaign in the italian press stating the facts and that there is no reason for integrated headset whatsoever.

Something to think about ! ( i should mention that i own 2 frames with integrated headsets myself and i will continue riding them)

Wow. Thank you very much for the European perspective. I think this will blow a few minds over here or at least set off some very interesting debate. As for myself, I've been very skeptical of the windtunnel/math formula approach to bicycle aerodynamics from the beginning, particularly since only a few individuals are involved and most of the results are kept secret since these people have commercial affiliations. We're only told what they want us to hear it seems. I find the posts from you Danes quite fascinating. Please keep posting.

It should be noted that TOUR is not focusing on triahtlon even if the do run articles now and then on Leder, Hellriegel etc and the Ironmans they participate in .

TOUR is highly influenced by the European bicycle/roadrace heritage that dates back to the start of 1900. As are we all that live here - the bikeshops does not carry 26" bikes at all anymore and it is difficult to get spares for them. Mavic has even stopped making the 26" version of the Carbone wheel.

People want to ride the bikes they see in the Tour and other roadraces, which is the type of bike the shops stock. If you go to a LBS as a new triahtlete they will sell you a roadbike with a clip-on bar, some will push for a profile fast-forward stem.

Triahtlon is very small in Denmark and the market is not big enough for a trispecific shop.

Anyway - i can fax you the test articles from TOUR if you wish. I probably still have the wheeltest, roadbiketest and tribiketest (Principia TT2, Quintana Roo, CUBE lightning, FELT TRI). Technical german is hard to read - even for me and i have worked in a german company for 7 years.

feel free to ask me if you have any difficulties understanding the german pages. I grew up in Germany, so translating minor parts shouldn´t be a problem.

Another thing - even though Tour is focusing on roadracing earlier tests in Triathlete Germany showed the same results.



"De bedste hilsner"



Martin

speed comes primarily from the engine. Most of the aero losses come from the body. Speed comes from the optimum combination of aerodynamic shape of the rider and optimum power. One may have to sacrifice a little power to improve aerodynamics or a little aerodynamics to improve power to get the optimum speed. And what is optimum on a mostly downhill or in a headwind may not be optimal on a mostly uphill course or in a tailwind (where power may be more important than aerodynamics). This requires a little experimenting by the rider and lots and lots of miles to figure this out.

Lance could probably kick all our butts riding a properly fitted 1960's Schwinn Continental.

---

--------------
Frank,
An original Ironman and the Inventor of PowerCranks

Dan, I'll grant you some of what you wrote, but I still disagree with you. For one thing, you mention different rpms. I maintain that in order for a test to be valid ALL external variables need to be held to ZERO. Same RPMs, same rider, same time of day, same hydration rate prior and during the testing, same fuel rate, same, same, same, same, EXCEPT the variable one is testing, be it wheelsets, forks, frames, combination. Project 96 got about as close as anyone ever has to cutting out all extraneous variability in the testing. The best that can be said out of that project is that it produced or reinforced trends that are in place today. However, much has changed since then with respect to the bike world, some of it hyped to ideas out of Project 96, but not really adhering to the science behind it. The best we can do is look to people like LA or Deboom or Hellriegel for answers. LA spends a lot of time in the wind tunnel getting himself and his bike as aero as possible. From that I take it that for him, using the Trek TT, the disc and H3 front is fastest. However, there may be things about my position, bike, etc that make that a poorer choice than others.

As for your assertion that it would take several iterations to determine an answer (no matter how one conducts the test, but in your case time and PE), well, lets say I do a 30min TT five times, average the time and get a "score" for one setup. Then I need to do it five times with the other setup I'm testing. I can probably do those tests accurately by doing one per week. Well, you just killed 3 months just to determine which is faster. And I don't think many of us AG'ers could talk the LBS or web shop into letting us keep items that long for comparison, let alone use them that much. And as for variability in PE, well this week's long run was exactly the same (time, time of day, HR avg, distance, wind speed, wind direction, temp, clothing, shoes, etc.) but it felt a lot easier than last week. So what are we to do? No offense Dan, but I trust a Pro SRM's 2.5% variability a lot more than I trust your personal PE, no matter how long you've been at the game. If I'm really splitting hairs I'd get the Pro/Med version which is even more consistent (notice I didn't necessarily say accurate).

Thanks, but i am all right - it just takes longer to read than english.

Had problems with the word "beschleunigung" for some time though : found out it means something like: acceleration index, the energy in kilojoule you need to take the wheels from 0 up to a certain speed, in the test 30kmt.

am i right ?

Anyway i wondered about your "Vamoots", had not heard of that before and wondered if it was just a neat petname for your bike - searched the net for it and found a very nice titanium frame. Looks cool.

Hvor dælen har du støvet sådan en fyr up ?

hilsen

Jesper - ps. det er sgu koldt at cykeltræne i DK i dag.......

Hi Jesper



You´re totally right about "beschleunigung"! And yes, it is cold here in Denmark - that´s why I´m riding my good old italian Battaglin roadbike or my mtb and keep the Moots in the bedroom. BTW - anyone here in Denmark can get this lovely titanium frame through the european, germanbased distributor. The only problem is the frameprice of 3500 Euro - that´s almost double up on the US price. But who cares :-) (I got mine at a special but still expensive price)



Hilsen



Martin