On Friday, October 23, 2020 at 1:16:27 PM UTC+1, Sepp Ruf wrote:
Andre Jute wrote:
On Thursday, October 22, 2020, Frank Krygowski wrote:
Handlebar bags: Some of us like them.

For some reasons, see "My PBP Bike: Rack and Bag" at
https://www.renehersecycles.com/journal/

-- - Frank Krygowski

It's wishful thinking. Actually, there is one position where the bag
might have some aero-effect, and it is the position Franki-boy's champion
ignoramus assures us it would have no effect -- and where Ridealot tells
us experience is it works. That's behind the saddle, where the bluff
sides of the bag would form a sort of Kamm tail to shortcut the
turbulence of the passage of the cyclist and his bike, which translates
directly into reduced drag. See the work of Professor Kamm between the
big wars, and the graphic of both my Lancia Fulvia (the Zagato Kammback
and the standard factory 3-box coupe) at speed with the skeins of wool
streaming behind it in my Building Special Cars (Batsford, London and
Robert Bentley, Boston are the most accessible editions).

Andre Jute
Sleek & sophisticated
Would you like to comment on this classic?

https://drivetribe.com/p/in-1998-luigi-colani-presented-CVoUYr2pRvymeEWJfOj2fg

At this link my attempt to look at the photograph was stymied by a demand to let them invade my computer at will and forever. **** that for a lark.

Or this one?
https://it.wikipedia.org/wiki/File:Schauff-Fahrrad,_Prototyp_Colani_(2019-10-07_Sp).jpg

Maybe that sort of shell would be worth something on a racer. I really couldn't tell without time in a wind tunnel. I suspect that bike might have been difficult to control on a fast downhill, what with those hollow wings covering the handlebars creating a shifting pressure differential dancing around the top of the steering column, with a likely steering input, perhaps even consequent lift, with the result of a light front wheel, perhaps air between tyre and road, not great for roadholding and handling. A further stability problem on that bike will be created by the forward centre of aerodynamic pressure, which even academics didn't know so much about just after the war. I would have made the fairing longer over the back of the rear wheel or put up a fin or something to give more side area near the back to, as it were, draw the CoAP backwards for greater resistance to crosswinds or even mild crosscurrents set up by passing another rider, or being passed by him.. On the whole, I might have been impressed with the state of knowledge available in 1949, but today -- not so much. I liked Colani's V16 ultra-long Jaguar XK 150 lookalike hotrod better, but there is no escaping the fact that Colani was a flashy industrial designer, not an aerodynamicist. That bike shell you directed me to is a result not of a fascination with real aerodynamics but rather of his love affair with the fluid shape-properties of the then new glass-reinforced plastic (GRP), what Americans call fiber reinforced plastic or FRP.

Generally speaking, I'm not overcome with admiration for efforts to improve bike aerodynamics. Most bikes are in fact as aerodynamic as they can be, and their total resistance to the air is only a small fraction of the dynamic resistance of a speeding bike, which always has a rider on top. It seems to me that people who worry about bike Cd have forgotten the part played by front area (as in CdA), and of course the frontal area of the rider is several times that of his bike. The most effective way to make a bike go faster at speeds where aerodynamics come into play in the results -- is for the rider to lose weight and become narrower.

Andre Jute
Svelte, fast, hungry