Velodrome banking helps how?

Dan Connelly wrote:
wrote:


Nice. 3.7 saved from wind, but how much more RR?

Joseph


Wow -- I canceled that one immediately after sending it. My revised
posting corrects the erorr: 37 watts.

There may be some rolling resistance loss from the turn transitions -- I'm
not sure. But if the track is properly banked, as Jobst points out, the
obvious source of RR is the centrifugal force itself. v^2/R @ R = 150m/2 pi
and v = 13.9 mps is 8.09 m/s^2. Wow. This increases rolling resistance
83%. For example, if total mass is 75 kg, and Crr = 0.2%, this increases
power required in the corners by 12 watts. So it takes a decent chunk from the
aerodynamic gains.


Dan

I wonder what the RR would be on a turn of similar radius that was not
banked? The banking doesn't change the angle of lean, it just chnages
the location and orientation of the contact patch, and allows for pedal
clearance, right? I imagine that if such a sharp turn at those speeds
on flat ground were even possible without wiping out, the rr would be a
lot more.

But there must also be some scrub losses since it is apparently
difficult to keep low by the line which means one needs to steer into
the turn to keep low.

Joseph

wrote in message
ups.com...
World records comparison:

Women 500m ice: 37 sec
Women 500m bike: 34 sec

Men 1000m ice: 1:07
Men 1000m bike: 58 sec

I contend that speed skaters are faster than cyclist.

They may well be. It occurs to me that skaters do not travel in a straight
line, they weave back & forth due to their method of propulsion. This is
obvious watching them from the front or back.

So, they may have already travelled well over the prescribed distance when
they finally get to the finish line. Make the track cyclist weave back &
forth a few meters either way and see what the times look like.

In article ,
Kinky Cowboy wrote:

On Mon, 23 Jan 2006 18:25:36 GMT, Dan Connelly
wrote:

Kinky Cowboy wrote:
On 23 Jan 2006 08:57:19 -0800, wrote:


I agree with your assumption that a straight 1km TT on a velodrome type
surface would be at least as fast as a normal velodrome.


Why? On a velodrome, the tyre contact has to travel 1km, but the CG of
the rider travels a bit less due to taking a tighter radius through
the turns. This amounts to several metres per kilometre, and applies
to the centre of pressure as well. Although the rolling resistance on
the velodrome is higher, due to the increased normal load on the
contact patches through the turns plus some camber drag/scrub as the
bike is rarely exactly normal to the track surface, it is far from
certain that a flat boarded straight track would be "at least as fast
as a normal velodrome"

The lean angle depends only on speed and turn radius, not on banking.

Dan

We're not comparing a banked oval with an unbanked one, we're
comparing any oval with a straight line. The banking, aside from
issues of side grip and pedal clearance, has the effect of reducing
the camber thrust in the tytrack interface, ideally to zero for a
well designed track ridden at precisely its design speed, but I
suspect that this effect is trivial (in the comparison between banked
and unbanked turns) compared with the effect of the CG and centre of
pressure taking a short cut round the turns (regardless of banking) in
the comparison between riding in circles and riding in a straight line

No, Dan is effectively correct: the reason the oval has to be banked is
because if you tried to ride that fast through the corners without
banking, you would fall down (pedal contact, loss of traction due to
extreme lean angle...pick your poison). Otherwise, you would still get
all of those magical "short path" advantages for your body. You know, on
some theoretical unbanked track with tires grippy enough to hold you up
in some GP1-motorcycle grade leans.

--
Ryan Cousineau http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos