Glide distance on Bicycle 3

[ImnotfromMars]

Hello,
Is there any standard to determine the glide ratio of a bicycle? I was looking for a standard which would be like: a bike loaded with rated load allowed to glide down an angle slope of a certain surface roughness and measuring the distance the bike went.
Robert

 

[ACtrafficengr]

I think their are too many variables - you'd also need to specify a standard coefficient of drag and frontal area for the rider. Air drag is much more important than rolling resistance for a bicycle.

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[Heckler]

You would have to calculate that based on your specific needs. Their is no standard but you can figure that out by doing some experiements and calculations. Check

http://www.pasco.com

Some things to keep in mind.

Position of riders cg
Mass of rider
rolling resistance
Type of incline (dirt road or asphalt road)
Frontal area of rider and bike
Type of bike (disk wheels or spoked wheels)

You may need to spend some time in a wind tunnel to validate some of this data.


Heckler
Sr. Mechanical Engineer
SWx 2007 SP 4.0 & Pro/E 2001

o
_`\(,_
(_)/ (_)

"Avoid the base hypocrisy of condemning in one man what you pass over in silence when committed by another." -- Theodor

 

[ImnotfromMars]

Hello,

Thank you for your replies. I was hoping to get gliding distance of different types of bikes. In the town where I live there is a natural slope. On my 10 speed road bike I can glide all the way to the library, yet on my mountain bike I can only make it half way there.(without adding any energy - approx 5 km). Since the journey is really slow aerodynamics play a very small part.

I was hoping to get a comparative standard that lists glide ratio which I could see when I purchase my next bike.

Robert

 

[ACtrafficengr]

Does your mountain bike have knobbies? Get street tires, and you'll go farther!

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[Heckler]

Also, there is a big difference in the rolling characteristics of a 26" mtn bike wheel and a 700c road bike wheel. Even if they both have road slicks....In the mtn bike community their is a big movement called 29er which is a mtn bike with 700c wheels.

Heckler
Sr. Mechanical Engineer
SWx 2007 SP 4.0 & Pro/E 2001
o
_`\(,_
(_)/ (_)

"Avoid the base hypocrisy of condemning in one man what you pass over in silence when committed by another." -- Theodore Roosevelt

 

[bicycledisciple]

I'm not sure of what you mean by glide, but I believe its coasting action without pedaling that you're referring to,

I think its just a simple case of energy conservation physics. On top of a hill you have potential energy, as you come down, its converted to kinetic energy. Once you got all that figured out, use the newton's laws of motion to figure out how much how much distance you travel, and how thats affected by aerodynamics and other parameters. The role of aerodynamics is much more here.

If you have simple bike computer, you can figure all this out by just a few minutes of experimentation (you may change weight on the bike, try out radical - more aero positions, change the wheels etc).

I can point you to this :

http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=6394&start=45

In that page, scroll down to Mark MCM's equations for a bicycle. Alternatively, you can use the handy calculators on analytic cycling as well (

http://www.analyticcycling.com).

Hope this helps.

 

[bicycledisciple]

I'm not sure of what you mean by glide, but I believe its coasting action without pedaling that you're referring to,

I think its just a simple case of energy conservation physics. On top of a hill you have potential energy, as you come down, its converted to kinetic energy. Once you got all that figured out, use the newton's laws of motion to figure out how much how much distance you travel, and how thats affected by aerodynamics and other parameters. The role of aerodynamics is much more here.

If you have simple bike computer, you can figure all this out by just a few minutes of experimentation (you may change weight on the bike, try out radical - more aero positions, change the wheels etc).

I can point you to this :

http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=6394&start=45

In that page, scroll down to Mark MCM's equations for a bicycle. Alternatively, you can use the handy calculators on analytic cycling as well (

http://www.analyticcycling.com).

Hope this helps.

Ron
-------------------------------

http://cozybeehive.blogspot.com

 

[ImnotfromMars]

bicycledisciple,

Thank you for your post. The web sites are very interesting and helpful.

Robert