[Cadent]

The motorcycle world has a truism: "Any engine gets you to 80 MPH, after that, it is all aerodynamics."

To the extent that the Suzuki Hayabusa had at one time (I don't know about now) small wings on the forks to keep the front wheel in contact with the road at higher speeds, and apparently this was functional, not affectation.

And the reason that all motorcycles look the same way now is due to the aerodynamics..this is the most efficient way to design a motorcycle.

Now, you can map this only so far to a bicycle, which is a pretty narrow profile, but the body, I would assume, is the big air dam in the system. I would assume that bikes have been built with fairings, but for good reason, they are not so produced now.

What experiments have been conducted with aerodynamics, and why have they all gotten us to the same point, that of the crouched rider vs. some other solution?

thx!

Don

 

[wooglin]

Not so fast. I chased a recumbent for 100 miles not too long ago.

http://www.recumbents.com/home/

And http://www.ihpva.org/, which seems to be down right now.

 

[Marc]

There are more aerodynamic positions than drop bars or current TT bikes.

Google "Graeme O'Bree" to learn how the UCI bit-by-bit banned more aerodynamic riding positions and frames from competition and records.

 

[Nimitz]

Don the difference between bikes and a motorcycle is compromise...

the most aerodynamic position may not be the most powerful one and vice versa

OR the most aero/powerful position isn't realistically sustainable for a long period of time.

its ALL about compromise on a bike

no fairings are allowed in UCI competitions but the fastest "bikes" are 2 wheel'd full fairing almost land speed bullet shaped.

https://www.wired.com/culture/lifestyle/news/2007/03/bikerecord_0330

wind tunnel testing would be the main big tests, as well as power output tests.

Chad

 

[Cadent]

Not so fast. I chased a recumbent for 100 miles not too long ago.

http://www.recumbents.com/home/

And http://www.ihpva.org/, which seems to be down right now.

84MPH? Geesh....

OK, let me be more specific then -- BTW, would love to try a recumbant, hard to find in this area... -- anyway... back to the motorcycle analogy. Most road motorcycles have some type of fairing that deflects the air from around the rider, doing two things, making a still pocket of air for the rider to reduce buffeting, and to provide a slipprier profile for air and lessen resistance.

I can see banning fairings from racing (well..I can't but I will acknowledge the power to do so...) but do the rules and regs of the racing federations then drive development for "civilian" bikes? Hmmm..I guess so.... if you have club races, they would conform to the union rules, and that would be a huge part of the market for that class of roadbikes. That then leaves the outliers, where the recumbants live... OK, guess I answered my questions then. It isn't then a function of physics, its a question of union rules, correct?

Thx!

Don

 

[Mr. Versatile]

UCI and USCF rules allow a certain amount of aero modifications, but not many. Any kind of fairing, windscreen, etc is specifically banned. Because of this very few fairings have made it to 'regular' road bikes. They'd likely be very expensive, easily broken, and minimally effective for (no offense to anyone) everyday riders, especially when riding in groups. The exception seems to be recumbents. I've seen quite a few of them with fairings, and on the flats they can be fast as hell. Unfortunately they don't handle or climb well. Recumbents are also ineligible to race under UCI and USCF rules.

 

[Kerry Irons]

Fairing problems

Now, you can map this only so far to a bicycle, which is a pretty narrow profile, but the body, I would assume, is the big air dam in the system. I would assume that bikes have been built with fairings, but for good reason, they are not so produced now.

Over the years, numerous fairings have been offered for both "normal" and recumbent bikes. There are a couple of recumbent riders in our area that use some type of fairing. However, there are serious tradeoffs and that is why fairings have never made much of a dent. First, they are hell in crosswinds. They block cooling wind, and therefore make it much harder to keep cool in hot weather. They add a lot of weight. They can effect bike handling, even in calm winds. Depending on the design, they can make mounting and dismounting the bike a bit of a challenge.

If you go back to the 1890s, most of the "great ideas that never seem to catch on" were patented: out of round chainrings, cam/activated crank arms, shaft drive, belt drive, fairings, solid tires, etc. etc. etc. In the 45 years I've been cycling, most of these have come around more than once, each time threatening to disrupt the technology of bicycles, but each time fizzling out in a few years. People new to the sport seize on these ideas as if no one has ever thought of them before and think what great innovations they are.

 

[Marc]

Recumbents are also ineligible to race under UCI and USCF rules.

To be more specific, ANY non-double-traingle geometry frame is forbidden under UCI rules.

 

[Cadent]

... They block cooling wind, and therefore make it much harder to keep cool in hot weather. .. .

If you go back to the 1890s, most of the "great ideas that never seem to catch on" were patented: out of round chainrings, cam/activated crank arms, shaft drive, belt drive, fairings, solid tires, etc. etc. etc. ....QUOTE]

I figured out this weekend that the bicycle has an air-cooled engine that needs a supply of wind to keep it at normal operating temperature... a realization that didn't dawn on me until it became very obvious 20 miles into a 35 mile ride.

Shaft drive I can see would have weight issues, but I loved shaft drive on my MC when one was so equipped. But I can see that belts would be too wide to really work for a bike.

At least we have gotten away from the tall front tyre.... er.... tire.

 

[ziscwg]

Over the years, numerous fairings have been offered for both "normal" and recumbent bikes. There are a couple of recumbent riders in our area that use some type of fairing. However, there are serious tradeoffs and that is why fairings have never made much of a dent. First, they are hell in crosswinds. They block cooling wind, and therefore make it much harder to keep cool in hot weather. They add a lot of weight. They can effect bike handling, even in calm winds. Depending on the design, they can make mounting and dismounting the bike a bit of a challenge.

If you go back to the 1890s, most of the "great ideas that never seem to catch on" were patented: out of round chainrings, cam/activated crank arms, shaft drive, belt drive, fairings, solid tires, etc. etc. etc. In the 45 years I've been cycling, most of these have come around more than once, each time threatening to disrupt the technology of bicycles, but each time fizzling out in a few years. People new to the sport seize on these ideas as if no one has ever thought of them before and think what great innovations they are.

Rotor does these out of round chain rings. They make it easier to pedal in the weak areas of you pedal stroke. I tried them on my mtb and they worked once you got used to them. They were not to good on those real steep pitches, which mtb sees a lot of.

I also thought Shimano did some licensing deal with Rotor to use on their Dura Ace line.

 

[milkbaby]

Enthusiast road bike styles/fashion seem to be often driven by what the pros ride, so we usually see the same kinda stuff on the local ride instead of faired recumbent bikes...

You can always draft in a group if you want to lower the effect of aerodynamic drag.

 

[Cadent]

Rotor does these out of round chain rings. They make it easier to pedal in the weak areas of you pedal stroke. I tried them on my mtb and they worked once you got used to them. They were not to good on those real steep pitches, which mtb sees a lot of.

My wife's Raleigh MTB has a "power oval" chain ring... no great evidence it does any good, but then I don't ride her bike. We didn't buy the bike for that feature, it just was there. But this bike is.... 15 yrs old now - bought in the mid-90s, IIRC.