Go Back   EcoModder Forum > EcoModding > Motorcycles / Scooters
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 03-21-2023, 03:34 PM   #1 (permalink)
Master EcoModder
 
Join Date: Dec 2016
Location: Florida
Posts: 380
Thanks: 64
Thanked 160 Times in 135 Posts
Does a windshield help with a bike's aero?

At highway speeds regarding mpg, in a full upright ride posture and at what point is a windscreen too big for mpg improvement? I am not including any weather riding/comfort improvements that a windscreen might provide.

Scanned 5? pages, didn't see this topic addressed.

  Reply With Quote
The Following User Says Thank You to j-c-c For This Useful Post:
aerohead (08-22-2023)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 03-21-2023, 03:38 PM   #2 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,561
Thanks: 7,736
Thanked 8,554 Times in 7,041 Posts
Depends on the shape. Full upright would be worst, compared with semi-recumbent or cafe racer crouch.
__________________
.
.
Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster

____________________
  Reply With Quote
Old 03-21-2023, 05:54 PM   #3 (permalink)
Human Environmentalist
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 12,392

Acura TSX - '06 Acura TSX
90 day: 24.19 mpg (US)

Lafawnda - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Prius Plug-in - '12 Toyota Prius Plug-in
90 day: 57.64 mpg (US)

Mazda CX-5 - '17 Mazda CX-5 Touring
90 day: 26.68 mpg (US)

Chevy ZR-2 - '03 Chevrolet S10 ZR2
90 day: 17.14 mpg (US)
Thanks: 4,189
Thanked 4,378 Times in 3,353 Posts
I don't know that any windscreen is more efficient than just the rider. Unless you're ducking in the little bubble of a sport bike, I don't think they add any aero improvement and are entirely for comfort purposes.

I had a cracked windscreen completely break away at full throttle on the CB750, and I want to say I gained another 10 MPH of top speed after that. It was making that big of a difference in drag.
__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!
  Reply With Quote
Old 03-21-2023, 07:53 PM   #4 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,561
Thanks: 7,736
Thanked 8,554 Times in 7,041 Posts
The folk wisdom on the Salt Flats is that it's not how you make the hole, it's how you close the hole.


2.bp.blogspot.com/_X_tJstZ1fVE/TRILN62i6xI/AAAAAAAAAHk/-h906_09Phw/s1600/spuik.jpg

Were I to expose myself without a cage, I'd want a teadrop helmet with Bluetooth and internal rear-view cameras, an airbag vest in a backpack, and a tailbox. Maybe a bug deflector?
__________________
.
.
Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster

____________________
  Reply With Quote
Old 03-21-2023, 11:35 PM   #5 (permalink)
Human Environmentalist
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 12,392

Acura TSX - '06 Acura TSX
90 day: 24.19 mpg (US)

Lafawnda - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Prius Plug-in - '12 Toyota Prius Plug-in
90 day: 57.64 mpg (US)

Mazda CX-5 - '17 Mazda CX-5 Touring
90 day: 26.68 mpg (US)

Chevy ZR-2 - '03 Chevrolet S10 ZR2
90 day: 17.14 mpg (US)
Thanks: 4,189
Thanked 4,378 Times in 3,353 Posts
Quote:
Originally Posted by freebeard View Post
Were I to expose myself without a cage, I'd want a teadrop helmet with Bluetooth and internal rear-view cameras, an airbag vest in a backpack, and a tailbox. Maybe a bug deflector?
Sounds right to me, with the bug deflector simply being your visor. Certain days and times of the year that can be a real PITA, but usually it's a bug here or there. One time it was a yellow jacket up through the chin gap, and stuck in my face. Another time it was a yellow jacket that found the 1/4" fold in my full race leather suit at the back of the neck at 80 MPH, and his response to surviving all that was to sting me in the center of the back. Well played, but I live on, and he does not.
__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!
  Reply With Quote
The Following User Says Thank You to redpoint5 For This Useful Post:
freebeard (03-21-2023)
Old 03-21-2023, 11:45 PM   #6 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,561
Thanks: 7,736
Thanked 8,554 Times in 7,041 Posts
Kevlar neck gaiter?
__________________
.
.
Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster

____________________
  Reply With Quote
Old 03-22-2023, 12:37 AM   #7 (permalink)
It's all about Diesel
 
cRiPpLe_rOoStEr's Avatar
 
Join Date: Oct 2012
Location: Porto Alegre, Rio Grande do Sul, Brazil
Posts: 12,548
Thanks: 0
Thanked 1,622 Times in 1,447 Posts
Quote:
Originally Posted by j-c-c View Post
At highway speeds regarding mpg, in a full upright ride posture and at what point is a windscreen too big for mpg improvement?
It will depend mostly on the shape and inclination of the windscreen, but it's still most often way more efficient than having no windscreen at all. Even if the windscreen is a little more upright, like you'll be more likely to see on a Harley, if it's quite curved, may deflect better the air than the rider's torso would when directly exposed to the air flow.
  Reply With Quote
The Following User Says Thank You to cRiPpLe_rOoStEr For This Useful Post:
j-c-c (03-22-2023)
Old 03-22-2023, 02:28 AM   #8 (permalink)
Human Environmentalist
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 12,392

Acura TSX - '06 Acura TSX
90 day: 24.19 mpg (US)

Lafawnda - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Prius Plug-in - '12 Toyota Prius Plug-in
90 day: 57.64 mpg (US)

Mazda CX-5 - '17 Mazda CX-5 Touring
90 day: 26.68 mpg (US)

Chevy ZR-2 - '03 Chevrolet S10 ZR2
90 day: 17.14 mpg (US)
Thanks: 4,189
Thanked 4,378 Times in 3,353 Posts
I just don't see how a windscreen is likely to increase efficiency, because to provide comfort to the rider it must necessarily increase frontal area beyond the exact dimensions of the rider.

A windscreen that doesn't increase frontal area by definition would have to be smaller than the rider. What's the point of a windscreen that doesn't prevent wind from hitting the rider?

I doubt I'd notice a difference in a tuck on my bike with the windscreen there or not. Maybe my chin would be spared the feeling of a strong man shoving my head backwards.

Only advice I have is to try the Julian method of throttle blocking to test the various top speeds at a given throttle opening on a given stretch of road. My guess is the bigger the windscreen, the slower you go, which is why sportbikes have windscreens that look like this.



If you rest your chin on the tank, your eyes will finally peer out through the windscreen, and the top of your head will still stick above it.



The problem isn't the bike, it's the rider.
__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!

Last edited by redpoint5; 03-22-2023 at 02:40 AM..
  Reply With Quote
The Following User Says Thank You to redpoint5 For This Useful Post:
j-c-c (03-22-2023)
Old 03-22-2023, 08:46 AM   #9 (permalink)
Master EcoModder
 
Join Date: Dec 2016
Location: Florida
Posts: 380
Thanks: 64
Thanked 160 Times in 135 Posts
Quote:
Originally Posted by cRiPpLe_rOoStEr View Post
It will depend mostly on the shape and inclination of the windscreen, but it's still most often way more efficient than having no windscreen at all. Even if the windscreen is a little more upright, like you'll be more likely to see on a Harley, if it's quite curved, may deflect better the air than the rider's torso would when directly exposed to the air flow.
My thinking was a rider has to be completely a high drag obstruction, and a small to medium windscreen might deflect enough air smoothly to lower the total overall drag, even by adding some drag of its own, ideally there would be a sweetspot, but I'm not reading that so far with these replies.
  Reply With Quote
Old 03-22-2023, 10:41 AM   #10 (permalink)
Somewhat crazed
 
Piotrsko's Avatar
 
Join Date: Sep 2013
Location: 1826 miles WSW of Normal
Posts: 4,043
Thanks: 462
Thanked 1,103 Times in 973 Posts
Im old enough to remember Craig Vetters early efficiency wrap around fairings for Honda 750's They were pretty good at increasing bike speed and bug deflection

__________________
casual notes from the underground:There are some "experts" out there that in reality don't have a clue as to what they are doing.
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com