Inoplanetyanin

Ok, so I read often how bike travelers like ride with a tail wind and that it helps a lot, especially if thebike is bulky.
Well, wind makes it a little easier to pedal. So, why not make a big sail, that will push the bike fast without even need to pedal, or maybe will significantly help pedaling up the hill.
If they say, tail wind blows approximately 25% of the time, it could be a noticable help.

What do you think?

SipperPhoto

Do ya think the UCI will approve that for Time Trials ?

Jeff

Inoplanetyanin

Sure .
As long as you are on the bike and not using any motors, nobody prohibited changing the aerodynamics for your advantage.

deliriou5

if only the tailwind blew 25% of the time!!!

murphy's law of cycling - whatever direction you pedal in, the wind will blow the opposite way.

joking aside.... any wind other than directly behind you will compromise the steering handling of the bike - this is a HUGE safety issue. and don't forget about the hairiness of wind gusts!!

Inoplanetyanin

This is not even a point, solar powered systems don't expect the sun to shine at night!


Superstitious approach. If the wind doesn't blow in the favorable direction, just take the sail down, it will weight not more than 3 lbs...

You can still roll if the wind blows from the angle less than 90º perpendicular. Remember, all sail ships need is SOME KIND of wind, they will adjust the sails. Loaded bike is heavy, and you can adjust the tail size to come to a compromise between handling and wind power assistance.

Safety is important, that's why the sail would have to be clear, in order to be able to see what's coming from behind, but we are talking about reasonable conditions on where to use it, something like lonely highways of Saskatchevan...

deliriou5

well see the thing about sailboats is that they have something called a keel, to provide lateral stability to combat the effects of crosswinds. they also have a very low center of gravity. consider the relatively high center of gravity of a bike with a rider on it. and also consider the low moment of inertia of a lightweight racing bike. these two can add up to a deadly combination... rendering the bike very tossable this way and that.

case in point: disc wheels are known for their extreme aerodynamic efficiency compared to their spoke wheeled counterparts. but it is common knowledge that these wheels are not to be used on courses with strong crosswinds, because you can literally be blown off the road!!

Inoplanetyanin

Well, we have several theories at hand. Now it's time to conduct an experiment.

MKRG

I know that when I ride my bike I'm never feeling a breeze from behind. The wind is always coming from in front of me therefore a sail would slow me down all the time. I suspect it is the same with everybody here that doesn't live in an area that has sustained winds of >20mph. The thing to remember here is that sailboats don't excede the speed that the wind is blowing.

mechBgon

If all that happens is that you get blown off the road, you're doing great. Being blown into the path of a semi is not a pleasant idea.

I've logged many hours of highway cycling between Spokane and Pullman, and being passed by heavy trucks travelling 60mph (100kph) results in a powerful draft. As the shockwave off the front of the truck arrives, you are pushed outward. As the rear of the truck passes, you are treated to a powerful but turbulent tail-blast. The turbulence is much more severe if the prevailing wind is somewhat crosswise to your line of travel.

Under those circumstances, I sometimes got kicked around quite a bit even on a conventional bicycle, and certainly would not want a sail that might pull me out into the traffic lane (and into the path of the next semi, they frequently run in groups around here).

Of course, I've seen from your Wal-Mart Bike thread that you are going to ignore peoples' advice, knowlegeable or not, if you don't like what they're telling you... but that's my contribution to this topic By the way, this has been done commercially before (anyone remember the Viking sails from the 80's?)

Inoplanetyanin

MechBgon - strong arguments. And no, I never heard of anything like that done commercially.
MKRG wrote:
Maybe that's because you are MOVING, regardles of the wind direction, you should be able to feel some breeze

Definitely, it's not the most safy device, but sometimes it could be useful, I believe. Sometimes there are no vehicles for hours, especially if traveling somewhere other than US, or on dirt, secondory roads, such as along the fileds of KAnsas. And even if you see a vehicle coming every once in 30 minutes, you can pull the tread and let the saild down, untill the offender is gone.

deliriou5

actually... LOL you hit the nail right on the head.... I was overthinking this LOL... basically the sail will turn into a parachute (kinda like the ones on dragsters or the space shuttle) at any speed above the speed of the tailwind. the only time that the sail will be of any help is if you're pedaling so slow that the wind is moving faster than your bike is. and as MKRG pointed out.... there are very few places in the world with sustained winds greater than 20mph.

with the sailboat, you only have the wind to move you. if you turned the motor on with the sail still raised, to the point you were going faster than the speed of the wind.... the sail would essentially turn into a drag chute!! having the motor on with the sail raised would be a total waste of energy, becauase not only does the motor have to propel the boat through the water, it also has to supply the power needed to overcome the aero drag of the sail!!

chip

A little bit of help might be o.k. but to have a sail for fast bicycling won't work cause you'll loose control of your bicycle?

Inoplanetyanin

Well, the person equipped with this firm device designed by me , might be no faster than convinient bike, and will perhapse be passed by colorfull "fit cyclists" on 2 lbs gold bicycles....
BUT, .... when tornado comes
He will be passing SUZUKI HAYABUSA at 200 mph

stridercc

Not to be the barrer of bad news, but in order for the sail to help you would need a direct tail wind at least as fast as the speed you are traveling at, other wise it would only create more drag.

-Matt-

Chris L

Hmmm.... I still think that would be too much hassle for me. I'd say 90% of the places i've ridden have slighty more traffic than that (even the quieter ones). To be honest I don't think I could be bothered even putting it up or pulling it down ever 30 minutes, never mind 15 or five or whatever.

Although I have thought about it for headwinds. Now that would be interesting!

Rowan

A Batman-style jacket with webs attached to the arms and side seams would be a better proposition than a sail like this -- at least it would be more convenient. Just extend your elbows!

R

jcivic00

Ummm...I'm no rocket scientist, but in order for the sail to acually be able to move you, I think it would need to be almost 3-4 times the size you have. In order to catch enough of a breeze anyway. I mean most boats are 75% sail and 25% boat right?

roadfix

THAT'S BECAUSE YOU'RE GOING THE WRONG DIRECTION!

Rowan

In that case, land yachts were invented ages ago. Good fun by all accounts.

Pat

Well not a good idea.

1) 20 mph is not that fast to cruise (depending on the rider) and how often does one have a tail wind greater then 20 mph? So the effectiveness of a sail would be slim to none.

2) Sail and boom would weigh a lot. Also, how do you balance whilst holding a mast?

3) Wind resistance would increase and act even when all the gear was stowed.

4) As mentioned above, being passed by a semi with a sail out would be very dangerous. You would probably be blown off the road.

Bobatin

You should be able to use the sale where the wind is anything but 45deg of dead ahead. Boats can sail faster than the wind they are using. Ice boats get up to 85mph without much trouble. Your wheels are your keel. Balancing in gusts would be the biggest problem but if you used a trike you coulb probably work around that. A recumbent trike would probably be the optimum vehicle to do this with.

L Lortami

dude-you try ridin something like that over the brooklin bridge, an your gonna go for a swim

Pete Clark

Ino, I like the way you think (is that a sketch by Leonardo DaVinci? )

Actually, there are landsailing vehicles already, but no human power...

https://www.nalsa.org

:thumbup:

Here's an excerpt from the website:

November 2001 Speed Trials
Ivanpah Dry Lake

Bob Dill
November 28, 2001

With three days of wind this was one of the best speed trials in recent memory. As usual, it was an informal affair with a lot of sailing and a couple hours of speed trials each day. On Thursday the wind stayed around 20 for most of the day. During speed trials it ranged from 18 to 24. Dennis Bassano got the Green Machine to 71.6 mph with his class 5 sail. On Friday, the wind stayed in the upper teens for most of the day. During Friday's speed trials it ranged from 15 to 19. Tye Bayless was the fastest at 65.2 with his class 3 sail. My best guess on boat speed to wind speed ratio for the most efficient boats is a little better than 4:1. This estimate is based on the average over many runs. The best efficiencies are in moderate winds. Most boats had maximum efficiencies of around 3:1.

Riders of faired recumbents report a sailing effect under certain conditions, due to the sail-like ability provided by the fairing.

How about this:

https://www.nalsa.org/champs02/Dscn1524.jpg

chewa

I've seen photo's of Dutch cyclists (they know a thing or two about wind) with kites on their backs acting as sails.

By strapping the kite to their back like a backpack and angling it to the prevailing wind, they got a wind assist.

MichaelW

There is kind of recumbent trike which is powered by a large kite. They go pretty fast, but are not really road worthy.