Mr. Boardman says it works so I agree.

Interesting concept and it is much easier to make a little piece of plastic compared to cutting a new mold (mild sarcasm).

What really surprises me is how flat the top of the fork crown is. The question I have is how the hell is that suppoosed to work? Next to a parachute a flat plate is as bad as it gets.

This is my opinion from a mechanical engineer's prospective. The test is trash. They're comparing a truncated section to a 'surface trip' section WITH a sharp trailing edge. The test should be redone with the truncated section being replaced with a sharp trailing edge section. That way they can actually test what the surface trip is actually doing. Also, those 23 seconds are at 13 m/s (over 29 mph) at 10 degrees yaw. First of all, you will never be doing that sort of speed for that time and secondly, if you're going that fast, your yaw angle is going to be crazy small. The faster you go, your relative wind is going to shift forward. 10 degrees would be an appropriate yaw angle for let's say 20 mph.

lol; l am sure he knows his stuff, he certainly has some mates that do such Mike Burrows et al.

The science is sound l just don't understand why if it translates into real world gains others don't follow suit?

I have never really understood why tests are not conducted at real world speeds but that is a whole other post.

I was thinking about trying some model glider turbulators but l doubt l would ever be able to detect the difference outside of a lab; still never underestimate the placebo effect :)

Great questions. I don't know anything about science. All I know is I am a slavish fanboy of Mr. Boardman going on 25 years now and trusts everything he says because he is Mr. Boardman.

It's funny that you bring that up. One of the mechanics at my LBS was telling me how they put (used to put?) turbulator tape on the front of the headtube of track bikes. He said it was supposedly faster. Who knows.

I helped do some testing on him in the Labs back in the day; his sustainable power was monstrous; Respect!

Agree. They take a sub-optimal foil and test it against an optimized one... Seems like one of the most blatantly misleading presentations of results I have seen.

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

In theory it can work. That said, unless I saw some sort of 3rd party testing I wouldn't be inclined to go out and buy one.

You met my beloved! Oh fortunate human! (I am not kidding by the way. I am a total fanboy.)

When I was in the tunnel with Len brownlee at U of W he had some special 3m perforated tape which he was using On leading edges (bars, fork etc)

He said it wasn't always a slam dunk but could work in some cases. There is a Ted talk out there about how he used it on the front of the sled of the Canadian guy who won the skeleton gold in whistler 2010.

Cheers,

Probably because, as 10 other threads have mentioned in the last few months, the Reynolds number difference between 20 and 30 mph is small and therefore the time savings scale. Therefore, because it is easier to differentiate the frames at higher speeds and the previous sentence is true it's better to test at faster speed.

Paul Lew did this awhile ago with his Swirl lip generator.

Ridley did it on the Dean with a rough surface treatment.

BMC did it on the last generation TM01 as well.

The science "works".

How it is similar/different with standard airfoils vs. truncated or any other additional variable, I don't know.

I think the point of the test was to show that (given the 3:1 constraint) a UCI legal tube shape with the trip layer added can be made faster than a truncated airfoil of the same dimensions with a much higher length:chord ratio.

The rest of the claim's details are probably not that relevant, but IME, real airfoils work better than truncated airfoils at slower speeds.

But the only point in doing a "cam tail" is to shorten the chord and keep the tube profile UCI legal. If you do not care about UCI legal you would never do a cam tail.

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

I personally agree.

But a lot of people who make money designing these bikes seem to believe otherwise.

Felt IA for example, and obviously Trek SC on the trailing edge of the seat tube and seat post.

Diamondback Andean in the wallet holder, seat post, etc.

TriRig Omni seat post.

Not quite true. There are at least two other potential design benefits to using a truncated airfoil. First, that flat back wall can help improve stiffness for a given aspect ratio. Second, the truncated airfoil can, when designed correctly, offer better high-yaw performance (see Trek's excellent CFD data showing the virtual tail bending at high yaw). And given the design application, there are a couple other benefits that sometimes apply related to cable routing, mechanical mates, etc.

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TriRig.com

Doesn't some forms of Cam profiles help where you are shielding something like a bottle.

Boardman knows his stuff.

In my limited experience, trips are often best applied to bluff shapes - hence skinsuits and trip socks. As mentioned above, trips have been applied before to bikes. They're also discussed in Burrow's book.

I read this in part as saying, 'our 3:1 aerofoils are the wrong shape. Kamm tail aerofoils are a better shape. We can improve ours by adding trips.' If they'd compared the clean Boardman tube shape it would have been better.

I wonder how accurately they need to apply the tape.

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Developing aero, fit and other fun stuff at Red is Faster

Agreed, it's hardly new news.

My rather ancient Ridley Phaeton has trips, in the form of approx 2mm thick strips of tape, on the HT and ST.

It's also been used on rowing on the oar shafts, an engineer reasoning that a round tube of some diameter travelling substantially faster through the air than the unit could benefit from trips.

Anywhere you're likely to have laminar flow in a pressure gradient liable to cause separation, a boundary layer turbulator like this sort of trip should provide performance improvement. Laminar flow provides low drag but is less robust than a turbulent boundary layer and will separate earlier. A trip may not be advantageous in all conditions but at higher angles it certainly have the potential to delay flow separation. There's absolutely nothing revolutionary about this, it's pretty basic aerodynamics.

Thanks l think you have me convinced to try some DIY trip strips on my bike (below). After doing a little research (inc reading Burrows book) l will add some turbulators to the forks and seat post; any suggestions about other locations?

http://tri-passion.com/...com/REAP/REAP_02.jpg

Cheers