Pros and cons of spoke count
#51
Originally Posted by shokhead
Dont think rotating weight means as much once your going. Acceleration from a start,yes but after that, not that important
The angulur momentum of the turning bicycle wheels makes them act like gyroscopes to help stabilize the bicycle. This gyroscopic action also helps to turn the bicycle.
Having pointed to the gyroscopic nature of the bicycle wheel, it should be pointed out that experiments indicate that the gyroscopic stability arising from the wheels is not a significant part of the stability of a bicycle. The moments of inertia and the speeds are not large enough. The experiments and review of Lowell and McKell indicate that the stability of the bicycle can be described in terms of centrifugal force. A rider who feels an unbalance to the left will turn the handlebars left, producing a segment of a circular path with resulting centrifugal force which pushes the top of the bicycle back toward vertical and a balanced condition.
A bicycle held straight up will tend to go straight. It is tempting to say that it stabilized by the gyroscopic action of the bicycle wheels, but the gyroscopic action is quite small.
If the rider leans left, a torque will be produced which causes a counterclockwise precession of the bicycle wheel, tending to turn the bicycle to the left.
So now you know.
#52
Senior Member

Joined: Dec 2002
Posts: 4,665
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From: So Cal
Bikes: 2012 Trek Madone 6.2
Interesting bike {not balls or anything else}science
How much does rotating weight matter
www.diablocyclists.com/bicyclescience.htm
How much does rotating weight matter
www.diablocyclists.com/bicyclescience.htm
Last edited by shokhead; 11-21-04 at 09:51 AM.
#53
Ok. Can't write it all down. I've spend a good amount of time to learn all this, and spend a few $$ in literature.
Here is a GREAT LINK though. Where you can find a lot of good articles and really good links like Princeton.edu, and what they say about aerodynamics
Here is a GREAT LINK though. Where you can find a lot of good articles and really good links like Princeton.edu, and what they say about aerodynamics
#54
Banned.
Joined: Jun 2004
Posts: 4,020
Likes: 1
From: Towson, MD
Bikes: 2001 Look KG 241, 1989 Specialized Stump Jumper Comp, 1986 Gatane Performanc
Originally Posted by Maj.Taylor
I must disagree with you on that one. Rotating weight is a far greater factor than simply the static weight of the entire bike. I understand that removing only 1 gram from a wheel is the equivalent of removing 2 grams from the frame. You want light wheels.
This is why light tires are nice! And, why carbon fiber rims have become so popular.
#55
Senior, Senior Member

Joined: Jan 2004
Posts: 681
Likes: 12
From: Nashville, TN
Bikes: Canyon Ultimate
Originally Posted by JavaMan
These arguments are academic. Bikes don't really go at a constant speed. Every pedal stroke is an acceleration. Your bike (and especially your wheels) should therefore be as light as practical.
Tom with a BS in Physics from Kansas State University, 1977.
Tom with a BS in Physics from Kansas State University, 1977.
Disagree 98% with the "academic" label
Indeed, bicycles themselves were in part a *product* of textbook, academic science! Today, cycling lends itself to a great deal of scientific analysis, at least by people who know what they're doing (ie, not me
). Most aspects of cycling can be approached quantitatively (mechanics, mass, speed, aerodynamics, enegy input of rider) and then can be (and are) addressed with creative scientific solutions (materials science, engineering, nutrition).
Last edited by ExMachina; 11-21-04 at 05:38 PM.
#56
Senior, Senior Member

Joined: Jan 2004
Posts: 681
Likes: 12
From: Nashville, TN
Bikes: Canyon Ultimate
Originally Posted by otoman
BTW, acceleration seems to have been misused a little in this thread. Not only is it a change in the rate, but it is also a change in the direction of movement. Therefore, the rim is always accelerating because of the change in direction of movement of any given location on the rim.
Acceleration when applied to rotational systems is called angular acceleration and is the rate of change of angular velocity. Angular velocity is expressed in terms of angle/unit time (usually radians/sec). Therefore a (theoretical) wheel moving at a constant speed is *not* accelerating, at least according to Newton's Second Law of for Rotation.
But enough of this, why arent we all out on our bikes!




