# Thread: Anyone for physics? (article on banking...)

1. ## Anyone for physics? (article on banking...)

2. This means that a cyclist can only go at about 45.5 km/h around a [flat] corner without losing grip

3. That calculation only works when:

The radius of a turn on a Olympic velodrome is around 20 meters,

Now Short Track Ice Speedskaters with lots more traction on flat ice can corner way faster!

4. Originally Posted by Speedskater
That calculation only works when:

The radius of a turn on a Olympic velodrome is around 20 meters,

Now Short Track Ice Speedskaters with lots more traction on flat ice can corner way faster!
Speedskates have long sharp edges that dig into the ice in one axis and slide nicely across it on the other.

The article leaves out a lot of interesting physics about why the turns generally aren't semicircles, as well as some interesting angular momentum effects.

5. Originally Posted by bitingduck
The article leaves out a lot of interesting physics about why the turns generally aren't semicircles, as well as some interesting angular momentum effects.
So, what are the other interesting bits of physics, and why are velodrome turns not a constant radius?

6. Originally Posted by carleton
Note too, that this is only on a wood surface, not concrete.

7. Originally Posted by chas58
So, what are the other interesting bits of physics, and why are velodrome turns not a constant radius?
If you go from the straightaway into a constant radius turn you go instantly from no centripetal acceleration to V^2/R, and it would be instant changes from no "compression" to max compression and then suddenly back. Instead they're a cycloid (or close to it) so the centripetal acceleration comes on slow, hits a max at the middle of the turn, and decreases slowly as you exit.

Another thing that's fun is conservation of angular momentum-- it helps in the paceline transitions in the corners (in addition to the elevation change effects).

8. Originally Posted by carleton
But you are going to strike a pedal way before 45 kph.

9. It is a good start to the basics. The coefficient of friction is a variable on a bicycle. The author's first equation assumes that turning a bicycle is flat. Turning a bicycle on flat ground requires a lean which changes force vectors and friction. He/She doesn't come back to this until the end of the article where a correction is added.

I think there should have been material on the basics of superelevation.

10. Originally Posted by bitingduck
If you go from the straightaway into a constant radius turn you go instantly from no centripetal acceleration to V^2/R, and it would be instant changes from no "compression" to max compression and then suddenly back. Instead they're a cycloid (or close to it) so the centripetal acceleration comes on slow, hits a max at the middle of the turn, and decreases slowly as you exit.

Another thing that's fun is conservation of angular momentum-- it helps in the paceline transitions in the corners (in addition to the elevation change effects).
Is it a cycloid? I always thought it was some form of Euler curve. I've never thought if a cycloid in being used for a banking. They both make sense to me in some respects, but not being a rocket surgeon, I wouldn't know which is best.

11. Also found this if anyone is interested

http://en.wikipedia.org/wiki/Track_transition_curve

12. I'm a simplistic kind of guy. The kind who rides bikes in a circle. Fast.

Somebody want to explain to us ordinary mortals what's going on?

13. Originally Posted by David Broon
I'm a simplistic kind of guy. The kind who rides bikes in a circle. Fast.

Somebody want to explain to us ordinary mortals what's going on?
To turn fast, you must lean. To go (X) amount of speed, you must lean (C) amount of degrees. (C) amount of degrees is already farther than a bike can lean (A). So to get to the (C) degree angle needed, the track must me leaned as well (B). Therefore (A)+(B) = (C) and we can turn while going (X) amount of speed.

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•