Velodrome banking helps how?

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

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

On 23 Jan 2006 11:39:48 -0800, "Rik O'Shea"
wrote:

Its true that the CG of the rider travels a bit less than the wheels of
the bike BUT the wheels of the bike always travel more than the
distance of the track because it is impossible for the rider to travel
exactly along the "line" that prescribes the exact measurement of the
track

It is also impossible to ride a single track vehicle in a precisely
straight line, even more so one with huge out of balance loads
providing the motive force. I expect that pro track riders travel as
close to the measured distance on the track as they could in a
straight line, and further that if there is any deviation between the
distances ridden on the track vs. on the putative straight course it
is an order of magnitude smaller than the amount by which riding in
circles reduces the distance traveled by the heavy draggy rider vs.
the tyre path.

Kinky Cowboy*

*Batteries not included
May contain traces of nuts
Your milage may vary

Zog The Undeniable wrote:
wrote:

Hi all,

Yet another pointless, non-answerable math question!

Out on the speed-skating track the other day I got to discussing
velodrome records vs speed skating records with some of the other
skaters who also ride.

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. The transmission
losses of a bicycle, as well as the rolling resistance and wind
resistance of the bike are greater than the frictional losses of skates
on ice. The wind resistance of a skater vs a cyclist (just body) I
think is essentially the same.

But the bikes have lower times for the same distance. I belive this is
due to the banking of the velodrome making it such that a track bike
doesn't have additional losses from drag on the front wheel from
turning as a bike on a velodrome is essentially going straight the
whole time, while a skater has to exert quite a bit of energy to
counter centripetal forces in a turn.

pedantic Centripetal force acts INTO a turn and is provided by the
skates against the ice. It's the force needed so the skater doesn't
travel in a straight line, which is what he would do otherwise.
Centrifugal force, as all physicists know, is a myth ;-)

I think the difference is basically that the cyclist can get more power
down due to gearing. The speed skater is effectively riding a bike with
the same size chainwheel and sprocket.

A skater has actually almost an infinitely adjustable "gearing" by
adjusting the angle of the skates relative to straight ahead, and
cadence can be adjusted too. The range of the quasi-gearing may have a
limited effective top end, but they are certainly out of the box
quicker than over-geared track bikes. Lots of short wide-angle strides
to get up to speed. But as you say riders may be able to get more power
down at the top end.

Joseph

In article
. com,
wrote:

Hi all,

Yet another pointless, non-answerable math question!

Out on the speed-skating track the other day I got to discussing
velodrome records vs speed skating records with some of the other
skaters who also ride.

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. The transmission
losses of a bicycle, as well as the rolling resistance and wind
resistance of the bike are greater than the frictional losses of skates
on ice. The wind resistance of a skater vs a cyclist (just body) I
think is essentially the same.

But the bikes have lower times for the same distance. I belive this is
due to the banking of the velodrome making it such that a track bike
doesn't have additional losses from drag on the front wheel from
turning as a bike on a velodrome is essentially going straight the
whole time, while a skater has to exert quite a bit of energy to
counter centripetal forces in a turn.

So the question is, how much energy or power does a banked turn save
over turns on flat ground with tire scrub? Let's ignore the pedal
clearance issue.

What is the straight line maximum sustainable speed for an
ice skater?

For a bicyclist?

Over
500 m

1000 m

1500 m

1 hour

How fast does an ice skater travel in a turn?

How fast does an ice skater travel on the straight?

--
Michael Press

wrote in message
...
Joseph Santaniello writes:

So the question is, how much energy or power does a banked turn save
over turns on flat ground with tire scrub? Let's ignore the pedal
clearance issue.

None at all because there are no additional losses from the curve.
That is why it is banked to match the speeds attainable on a bicycle.
The banking is there to make the track essentially a straight course
with bicycle and tires normal to the surface, that conveniently ends
where it starts and is observable from a fixed position.

The only argument arises from purists who note that the rider does not
travel the prescribed distance because they travel at a smaller radius
than the surface of the track where the tires roll over the distance.

The purists also note the increase in rolling resistance of tires due to
centripetal acceleration (higher contact force) and the height change of
center of mass going in and out of the turn (which balances out). There
is a tendency to speed up going into the turn and slow down coming out.

Phil H

"Robert Chung" wrote in message
...
wrote:

The only argument arises from purists who note that the rider does
not
travel the prescribed distance because they travel at a smaller
radius
than the surface of the track where the tires roll over the distance.

That's a couple hundred watts difference between the straights and the
turns.

Troll

Phil H

writes:

Hi all,

Yet another pointless, non-answerable math question!

Out on the speed-skating track the other day I got to discussing
velodrome records vs speed skating records with some of the other
skaters who also ride.

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. The
transmission losses of a bicycle, as well as the rolling resistance
and wind resistance of the bike are greater than the frictional
losses of skates on ice. The wind resistance of a skater vs a
cyclist (just body) I think is essentially the same.

I think (but don't know) that bikes can go faster longer, but that
skaters accelerate much more quickly from a standing start to full
speed. If you were able to compare at 2000, 4000, 10000 meters you'd
find the time gaps larger. That's a guess, anyway. Could be all wet.

A skater has practically no frictional losses, just wind resistance to
overcome. Cyclists have rolling resistance, frictional losses in
bearings and wind resistance to overcome. But a cyclist's "gait" is
much faster than a skater (150-200 steps per minutes for a cyclist)

A 48 x 14 gear results in a developpement of 7.2 meters, the
equivalent of 3.6 meters per stride (one "step" with each foot). I
don't know how far a speed skater goes with one step, but I'd guess
farther than that at top speed (but much shorter at the start, in
effect giving the skater the benefit of variable gearing, while the
track cyclist is stuck with one gear). So effectively, I'm guessing
that a speed skater at full flight is in a "higher gear" than a track
cyclist. But a skater can't take 200 steps a minute for the entire
event, I wouldn't think, but a track cyclist can spin 200 rpm without
too much trouble. Of course for longer events like pursuits, the
cyclist will be using a larger gear than a 48 x 14.

Eric Hayden, Art Longsjo, and some others made the transition back and
forth between skating and riding with great success. There are some
definite similarities between the two sports.

"Robert Chung" writes:

wrote:

The only argument arises from purists who note that the rider does
not travel the prescribed distance because they travel at a smaller
radius than the surface of the track where the tires roll over the
distance.

That's a couple hundred watts difference between the straights and
the turns.

A couple *hundred* watts? Huh. Can you show us your math?

wrote:
...
I contend that speed skaters are faster than cyclist....

Faster than 81.00 mph/130.36 kph on skates?

See http://www.ihpva.org/hpva/hpvarec7.html#nom01.

--
Tom Sherman - Fox River Valley (For a bit)

Johnny Sunset wrote:
wrote:
...
I contend that speed skaters are faster than cyclist....

Faster than 81.00 mph/130.36 kph on skates?

See http://www.ihpva.org/hpva/hpvarec7.html#nom01.

--
Tom Sherman - Fox River Valley (For a bit)

ok, cyclists was too broad a term...

Joseph