Time Gaps

[Dogtrousers]

When the TV shows a time gap in the race, what does it mean?

For simplicity lets assume there are only two riders in the race, A and B. A is in the lead and has a time gap of 2 minutes. I guess that means that A passed the point where B is now 2 minutes ago.

This means that anything that happened to A since passing that point isn't factored in to da calculation as Kelly would say. Is this right?

So imagine there is a red house and some way down the road a blue house. A and B are travelling at the same speed. A passes the red house, then 2 minutes later B passes it. So A has a 2 minute lead. But on arriving at the blue house A gets a gets cramp or something and slows to a crawl, or even stops.

This means that time gap between A and B will remain at 2 minutes until B arrives at the blue house, whereupon it will drop rapidly until B passes A.

This seems fairly straightforward but it does my nut in.

 

[ColinJ]

You must get really confused when the stretched out peloton takes 45 seconds to cross the line but they are all given the same time!

 

[rich p]

When the TV shows a time gap in the race, what does it mean?

For simplicity lets assume there are only two riders in the race, A and B. A is in the lead and has a time gap of 2 minutes. I guess that means that A passed the point where B is now 2 minutes ago.

This means that anything that happened to A since passing that point isn't factored in to da calculation as Kelly would say. Is this right?

So imagine there is a red house and some way down the road a blue house. A and B are travelling at the same speed. A passes the red house, then 2 minutes later B passes it. So A has a 2 minute lead. But on arriving at the blue house A gets a gets cramp or something and slows to a crawl, or even stops.

This means that time gap between A and B will remain at 2 minutes until B arrives at the blue house, whereupon it will drop rapidly until B passes A.

This seems fairly straightforward but it does my nut in.

I think it's a bit more scientific than that which was explained once on TV but don't ask me WTF it was!
Tweet Carlton Kirby - he'll make something up if he doesn't actually know (similar to his commentary style)

 

[si_c]

Essentially they do use reference points to determine the time gaps, but how this is done depends on the race and the race organisers. For example on the Tour currently showing you will notice that there are transponders on the back of a lot of the riders seat posts - these broadcast the current GPS position of each rider on the road, this means that the Tour can use continuous reference points to calculate the time gaps. This provides more timely information than other methods, but the general process is the same.

If you want the TT races live you will see that they often have time checks at intervals along the course, and will comment that X is 20seconds faster at the first time check for example.

 

[Dogtrousers]

I only brought up the idea of reference points (red house, blue house) to try to build a mental picture. I'm not so concerned about how they do it - For simpilicity I'm assuming they know everything about all riders' positions instantaneously.

I'm still concerned about what the time gap actually means. Does it mean "the elapsed time since the leader passed the pursuer's current location"?

Because if it does, it will have strange results. If the leader bonks and slows down or stops this won't have any effect on the gap until the pursuer reaches the point where the leader bonked/stopped, whereupon it will plummet.

 

[matticus]

Yes - I'd describe the "blue house" technique as an "Actual" time gap. As DogTrousers says, it doesn't tell you EVERYTHING, so if 1 riders is riding erratically you have to deal with that info yourself.

If you start calculating rider's speeds and extrapolating from that, you might get a "better" picture, but it is prone to error.

If you want the TT races live you will see that they often have time checks at intervals along the course, and will comment that X is 20seconds faster at the first time check for example.

I actually find it really poor how little comparative data you get during a TT. They could use the same techniques from the road stages to give us gaps every few minutes. They are boring enough anyway, without having to wait 20km for updates!

 

[rich p]

Here's an explanation

https://cyclingtips.com/2012/06/how-time-gaps-are-calculated/

 

[Dogtrousers]

Here's an explanation

https://cyclingtips.com/2012/06/how-time-gaps-are-calculated/

Fantastic. Thanks.

The more we thought about it, we came to the realisation that we had no clue of how this is done

So I'm not alone.

 

[mjr]

When the TV shows a time gap in the race, what does it mean?

Easy answer: it means nothing except the TV production is trying to guess the result. Only the time across the finish line is meaningful for the race.