Measuring Breakaway Gaps

[Ildabaoth]

I can't understand the logic in this thread. Gaps are measured in time, but not such as in time equal distance over speed. Actually, if that was the case it would be because distance is being equally measured in real time, which isn't possible very accurately. As others have stated, they simply measure the time between 2 motorbikes. That's is the reason a lot of times the gaps aren't correctly shown: one motorbike is moving from one peloton to another one.

Consider this: we do see time gaps in formula 1 too and they don't change dramatically. If this was done using speeds and distances, we would see the time gaps would increase drastically as soon as the chasing driver is entering a curve because of his reduced speed and so on.

The most accurate possible time measure system would require a real time speed predictor (as in it needs to predict future peloton speeds, not just estimate current ones) algorithm so it would almost perfectly estimate the time required for the chasing peloton to get to the current lead peloton position. Obviously, such an algorithm is very very difficult to create, even in simple conditions. Besides, current method is good enough.

 

[Master50]

The real time gap cannot fall from 9 minutes to 6 minutes inside 30 seconds. That is a practical error in measuring it and displaying it on our screens, not a theoretical deficiency. Perhaps it is a lazy guy in the control room, not making sure that the moto he is using the signal from is the moto with the group. Perhaps they switched from a vehicle in behind the peloton to a vehicle in front of it. Maybe they haven't got a signal from them in a while - it is, after all, mountains. Whatever it is, it is not a fundamental error in the concept of time gaps.

People only claimed that it would stay the same until you released the rather perplexing scenario in which they both speed up at the same time .You seem to be the only one who thinks in this situation that the time gap shouldn't decrease. The chasing group has raced a given section faster, so the time gap decreases. That's really not particularly revolutionary.

Read my post a couple of frames up it explains how a group can loose 2 minutes in 30 seconds. The gps units are on vehicles not the riders and cars can close a gap like that over a bike rider.

 

[onetofifteen]

The problem with the GPS system in the giro seems to be a concept problem for measuring time gaps.

From what I heard the commentators say, they are taking the position of the race leaders and the chasers, compute the distance and estimate how much time will take the chasers to get to the current position of the race leaders. This way of estimating time gaps is very sensitive to the instantaneous velocity of the chasers (read crap).

It would be much simpler to just measure how much time ago the race leaders were at the point the chasers are now. GPS engineering can't be any simpler and more accurate than that.

This is different from what most people have been saying in this thread.

There are two possible ways of calculating time: this one and the one where you measure the time it takes the peloton to reach the point where the break were.

This entire conversation makes no sense until we know which one they actually use in cycling races. Which one are they using in this Giro?

Does anybody know for sure.

 

[Buffalo Soldier]

I didn't know the measured it like that. It seems overly complicated, and rather stupid.
It's only in the Giro they use this system?

 

[Ildabaoth]

This is different from what most people have been saying in this thread.

There are two possible ways of calculating time: this one and the one where you measure the time it takes the peloton to reach the point where the break were.

This entire conversation makes no sense until we know which one they actually use in cycling races. Which one are they using in this Giro?

Does anybody know for sure.

Normally, measuring time between motorbikes, as in lead moto pass through point A while chasing moto is in point B, then time passed until chasing moto reach point A. Simple and accurate. To try to estimate the time using current speeds is non sense. To be fair, and I don't want to be aggressive, I find it odd so many forum members think speeds are used in some sort of t=speed/distance equation which is useless unless we can predict the exact instant speed of the chasing group from point B to point A or even useless if the speed used for the calculation is the instant speed of the chasing group when passing through point B.

 

[Bavarianrider]

I think there should be a quotient of distance and current speed

Gap= km/km/H
The bigger this number is the bigger the real gap is. I think this would be a good system once everybody is used to it.

 

[Caruut]

I think there should be a quotient of distance and current speed

Gap= km/km/H
The bigger this number is the bigger the real gap is. I think this would be a good system once everybody is used to it.

What does that offer that simple time gaps don't?

It is dependent on parcours, which is just stupid.

 

[Libertine Seguros]

I think there should be a quotient of distance and current speed

Gap= km/km/H
The bigger this number is the bigger the real gap is. I think this would be a good system once everybody is used to it.

So then the viewers at home, the commentators and the guys in the team cars (not to mention the ones drawing up the chalkboards) have to get their calculators out to work out what people WANT to know, which is the time gap.

We don't want to know what the distance between the break and the péloton is, because that's irrelevant. We don't need to know how fast each group is going, although at times it may be interesting. The time gap, however is wholly, completely and utterly relevant, because that's what the competition is judged on - who completed the course in the fastest time.

We, as the viewers, want to know:
- where the riders are on the course (so need to know distance travelled, or distance remaining, because the course is a set distance provided. The only exception is timed crits)
- where the contestants are relative to each other according to the criteria upon which they will be judged so that we can tell who is winning at any given time (so need to know time between groups, because time taken to complete the course is the judging criteria in cycling).

 

[Master50]

Normally, measuring time between motorbikes, as in lead moto pass through point A while chasing moto is in point B, then time passed until chasing moto reach point A. Simple and accurate. To try to estimate the time using current speeds is non sense. To be fair, and I don't want to be aggressive, I find it odd so many forum members think speeds are used in some sort of t=speed/distance equation which is useless unless we can predict the exact instant speed of the chasing group from point B to point A or even useless if the speed used for the calculation is the instant speed of the chasing group when passing through point B.

Perhaps I tell too long a story but this is as simple an explanation offered. What method does the giro use? For tv they use GPS as it is computer fast but as I explained earlier it is measuring the position of a vehicle following or leading a group. Vehicles can obviously confuse things because the can easily change position in a race much faster.
The officials and the time board use a stopwatch only. This is how it has been done for a hundred years. All the debate about speed and distance is not the tool that is usefull. Has anyone ever seen a distance gap at the finish? Ever read a result that says greipel is down 1.5 meters? In the end everyone covers the whole distance or we would just freeze the event as soon as the first rider crosses the line. What does distance mean? On a climb a kilometer is anywhere from two to five minutes and on a sprint stage it might be one minute. Time to cover the distance is the only meaningful measurement that works for fast and slow races. Sure we can compare times over distance to get other information but why do a bunch of complicated math when the watch works best?

 

[Libertine Seguros]

What does distance mean? On a climb a kilometer is anywhere from two to five minutes and on a sprint stage it might be one minute. Time to cover the distance is the only meaningful measurement that works for fast and slow races.

Not strictly true of course; you still get timed races (mostly crits).

Racing of all stripes has two criteria:

1) Race for a set DISTANCE.
2) Race for a set TIME.

Category 1) is by far the most common. Since everybody covers the same distance, we must score them based on the time taken to complete that distance.

Category 2) applies to timed races, such as sportscar events. Since everybody has to race for a set time to be classified, then we must score them on distance covered in the allotted time.

Of course, even sportscar racing and timed crits use time as a secondary element. If two cars have each covered the same number of complete laps, then they will be scored on whichever was first to complete that lap.

 

[Buffalo Soldier]

I think there should be a quotient of distance and current speed

Gap= km/km/H
The bigger this number is the bigger the real gap is. I think this would be a good system once everybody is used to it.

This is getting too ridiculous...

(btw: km/km/h=h??)

edit: that's wrong, I think it's 1/h

edit again: math people, help me. I'm getting lost.

 

[Waterloo Sunrise]

so then the viewers at home, the commentators and the guys in the team cars (not to mention the ones drawing up the chalkboards) have to get their calculators out to work out what people want to know, which is the time gap.

We don't want to know what the distance between the break and the péloton is, because that's irrelevant. We don't need to know how fast each group is going, although at times it may be interesting. The time gap, however is wholly, completely and utterly relevant, because that's what the competition is judged on - who completed the course in the fastest time.

We, as the viewers, want to know:
- where the riders are on the course (so need to know distance travelled, or distance remaining, because the course is a set distance provided. The only exception is timed crits)
- where the contestants are relative to each other according to the criteria upon which they will be judged so that we can tell who is winning at any given time (so need to know time between groups, because time taken to complete the course is the judging criteria in cycling).

km/km/h = h

What he has suggested is functionally identical to what you are describing - the only difference is it reacts quicker when the bunch change pace.

 

[Waterloo Sunrise]

This is getting too ridiculous...

(btw: km/km/h=h??)

edit: that's wrong, I think it's 1/h

edit again: math people, help me. I'm getting lost.

You were right first time.

 

[Buffalo Soldier]

You were right first time.

Depends.
a
---
a =b
-
b

but

a
-
a = 1/b
---
b

 

[Waterloo Sunrise]

Depends.
a
---
a =b
-
b

but

a
-
a = 1/b
---
b

It really does not depend.

Distance divided by speed is time.

KM/KM/H = H

You can add brackets if it makes you feel more comfortable

 

[Libertine Seguros]

km/km/h = h

What he has suggested is functionally identical to what you are describing - the only difference is it reacts quicker when the bunch change pace.

And that if you want to work out the time gap you have to have a calculator on standby. Which, considering most people watch to be entertained, not to do mathematics, would be a bit contrived.

Nevertheless, if it's possible to have the km and the km/h up on the screen, it's easy enough to create an algorithm that converts that into a nice convenient time figure. You say that having the distance and velocity up there will be able to react more quickly than a time gap, but if you set up that calculation to automatically convert those two figures into a time gap, it will be just as quick to react AND more relevant.

 

[Buffalo Soldier]

It really does not depend.

Distance divided by speed is time.

KM/KM/H = H

You can add brackets if it makes you feel more comfortable

Come on.
Yes, let's add brackets
(km/km)/h = (1)/h
km/(km/h) = h

 

[Waterloo Sunrise]

And that if you want to work out the time gap you have to have a calculator on standby. Which, considering most people watch to be entertained, not to do mathematics, would be a bit contrived.

Nevertheless, if it's possible to have the km and the km/h up on the screen, it's easy enough to create an algorithm that converts that into a nice convenient time figure. You say that having the distance and velocity up there will be able to react more quickly than a time gap, but if you set up that calculation to automatically convert those two figures into a time gap, it will be just as quick to react AND more relevant.

Why do you need a calculator.

He suggested using distance/speed

If they provide you with that 'quotient', they've provided you with a time gap.

Really have no idea how a calculator will help you work back to the slower adjusting time gap measure, without you simply counting it yourself on your watch. If the speed isn't changing it will be identical. If the speed does change then your method will take a bit more time to catch up, but after the period of time indicated as the gap by Bavaria's method has elapsed, they will then be equal again.


No one is suggesting displaying distance and velocity. He suggested displaying a quotient of the two, so the calculation is already done for you and expressed as a time gap.

I keep reading your post and spotting new things to respond to.

Rather amusingly your final sentence agrees with Bavaria, and will greatly offend Caruut who has a serious complaint with comparing this instantly updating metric with the stop watch method.

 

[Waterloo Sunrise]

Come on.
Yes, let's add brackets
(km/km)/h = (1)/h
km/(km/h) = h

Which one of those describes the situation of dividing distance by speed?

Originally Posted by Bavarianrider
I think there should be a quotient of distance and current speed

 

[roundabout]

I think there should be a quotient of distance and current speed

Gap= km/km/H
The bigger this number is the bigger the real gap is. I think this would be a good system once everybody is used to it.

I don't understand.

Looks like the gap in the method you proposed is a function of the current speed which is what the OP was against.

 

[Libertine Seguros]

Why do you need a calculator.

He suggested using distance/speed

If they provide you with that 'quotient', they've provided you with a time gap.

Really have no idea how a calculator will help you work back to the slower adjusting time gap measure, without you simply counting it yourself on your watch. If the speed isn't changing it will be identical. If the speed does change then your method will take a bit more time to catch up, but after the period of time indicated as the gap by Bavaria's method has elapsed, they will then be equal again.

So you're sat on the couch, watching the race.

In the corner of the screen you have the following display.

G1 47km - 40,326km/h
G2 48,24km - 40,657km/h
G3 50,04km - 39,959km/h

A guy in G1 sits at 1'21" on the GC, the leader is in G2.

Who's winning?

Furthermore, according to your statement above, doing it on time even by automatically converting these figures into time will be delayed. Why can't a system designed to automatically convert those distances and velocities into time react just as quickly as the updates to the distance and velocity? Shouldn't it do it instantaneously?

I fail miserably to see why the relative inaccuracies of time measurement make it worth sacrificing giving the information that is relevant to how the race is judged to take on a system that is still flawed, and more irrelevant?

 

[Waterloo Sunrise]

I don't understand.

Looks like the gap in the method you proposed is a function of the current speed which is what the OP was against.

We've moved on a long way from my whims by now.

What he's suggesting will just give a time figure that at constant speeds will be identical, and with chaning speed will update more quickly.

Agree it shares the same faults I have complained at. I would, on a contrarian basis, argue that it a more honest measure in that it makes the variable factor of peloton speed much more obvious, where in the stopwatch method the link is hidden by the muting factor of the slower updating.

 

[Waterloo Sunrise]

So you're sat on the couch, watching the race.

In the corner of the screen you have the following display.

G1 47km - 40,326km/h
G2 48,24km - 40,657km/h
G3 50,04km - 39,959km/h

A guy in G1 sits at 1'21" on the GC, the leader is in G2.

Who's winning?

Furthermore, according to your statement above, doing it on time even by automatically converting these figures into time will be delayed. Why can't a system designed to automatically convert those distances and velocities into time react just as quickly as the updates to the distance and velocity? Shouldn't it do it instantaneously?

I fail miserably to see why the relative inaccuracies of time measurement make it worth sacrificing giving the information that is relevant to how the race is judged to take on a system that is still flawed, and more irrelevant?

I think you've missed the point.

No one is suggesting displaying distance and speed.

He suggested a quotient, so the nice men in the TV studio will convert it in to a time figure for you.

This is different from the commonly understood current situation, in that it would update instantly to a change in peloton speed, whereas the stopwatch method would take the amount of time equal to the new gap on Bavaria's method to catch up and would then be equal.

 

[Libertine Seguros]

If they provide you with that 'quotient', they've provided you with a time gap.

Really have no idea how a calculator will help you work back to the slower adjusting time gap measure, without you simply counting it yourself on your watch. If the speed isn't changing it will be identical. If the speed does change then your method will take a bit more time to catch up, but after the period of time indicated as the gap by Bavaria's method has elapsed, they will then be equal again.


No one is suggesting displaying distance and velocity. He suggested displaying a quotient of the two, so the calculation is already done for you and expressed as a time gap.

Since this thread started with you suggesting displaying distance, then Bavarianrider started going on about distance and velocity, I was under the impression that we were still suggesting displaying something OTHER THAN time to divide up the groups.

I am thoroughly against that, as time is the ONLY truly relevant factor in defining the gap between groups, since that is what the race will be judged on.

Now, if BR is just suggesting using that as a means of getting a more accurate time figure, then I can't be against that. I'm not sure at what point conversation shifted from "other displays can be as accurate as time gaps" to "ways of making the time gaps more accurate", but that's fine.

What confused me was Bavarian saying it would take time to get used to. After all, it wouldn't take any getting used to at all for the viewer - they're still getting the figure they want - the time gap - on the screen. How it's calculated doesn't bother them, as long as they've got them.

 

[Waterloo Sunrise]

To try and make it clear, there are 2 alternates being suggested, which are in practice very similar.

A) - the current situation, stopwatch method.

Breakaway passes point A, stopwatch starts, and stops when peloton pass point A.

B) Bavaria's quotient.
A time gap is calculated and updated constantly based on the gap between the 2 groups and the speed of the 2nd group.

------

If the 2nd group is travelling with constant speed, these will give the same result.

If the chasing group changes speed, method B will instantly adjust the gap propotional to the speed change.

Method A will also adjust, but the adjustment will take the amount of time equal to the new gap under method B.

If the chasing group constantly changes speed, both measures will change, but A will smooth these changes and B will be more abrupt.