Cyclists with a "Running" Problem

[Fred van Vlaanderen]

5 hours ago, shaper said:

I recorded 88.7 and 5 other athletes I coached recorded 88.6, 89.0, 88.0, 88.5 and 88.7.  Discrepancies likely depending on where your 2nds were stationed and whether you were taking the shortest line.  All recorded longer than official distance given.

And how far in the bushes you walk to do a number 1… haha

[TheoG]

11 hours ago, Fred van Vlaanderen said:

And how far in the bushes you walk to do a number 1… haha

I was lucky enough to never need to go for a No 1 in the 5 times I did Comrades.  Pee a lot though ... 🤪

[NotSoBigBen]

5 minutes ago, TheoG said:

I was lucky enough to never need to go for a No 1 in the 5 times I did Comrades.  Pee a lot though ... 🤪

No 1 not a pee? Het my kinders dan verkeerd geleer 🤪

[TheoG]

15 minutes ago, NotSoBigBen said:

No 1 not a pee? Het my kinders dan verkeerd geleer 🤪

Nee jy is reg, I messed it up

[Shebeen]

1 hour ago, NotSoBigBen said:

No 1 not a pee? Het my kinders dan verkeerd geleer 🤪

JZ's codename when president was Number1. There's a Zapiro (or other) cartoon that I can't find now that has the punchline, "No.1 is a No.2"

[NotSoBigBen]

1 minute ago, Shebeen said:

JZ's codename when president was Number1. There's a Zapiro (or other) cartoon that I can't find now that has the punchline, "No.1 is a No.2"

I guess the same can be said of our current #1 and his cronies 

[Shebeen]

22 hours ago, dave303e said:

For me I think the itch was too much this year, coach was very very happy yesterday when I said put Comrades 2024 on the calendar, I guess this also means I need to finally run a road marathon...

I have threatened to do this before too. I think 2023 ARWC + 2024 Comrades is a dance I could do. 

at least I have a road marathon under the belt. and a knysna forest jeanpant 42.2 from a previous life too!  

[saggy]

19 hours ago, shaper said:

I recorded 88.7 and 5 other athletes I coached recorded 88.6, 89.0, 88.0, 88.5 and 88.7.  Discrepancies likely depending on where your 2nds were stationed and whether you were taking the shortest line.  All recorded longer than official distance given.

GPS allways over read by a bit .... usually a couple of metres per kilometre, but over a 90km race that adds up.

The route is measured with a jones counter which is about as accurate as you can get

 

 

 

[Pieter-za]

10 minutes ago, saggy said:

GPS allways over read by a bit

Indeed - 1-2%.  Also one does not necessarily follow the 'racing line'.   Eg a couple of meters wider each turn does add up.

(When following a GPS track on a race I compensate for this by adjusting my est times a bit) 

Edited June 14, 2023 by Pieter-za

[dave303e]

Honestly, what a load of click bait. Must we all run around with wheels so we know how far we have gone? They also don't mention was it gps, gps with glonass, gps with glonass and galileo? etc etc etc, there are factors in your setting that can affect it as well. Is your watch recording every second or did you need to scrimp on battery and it is recording every 3 or 5 seconds?

The horizontal error in a gps is so small it will not affect your pacing strategy to a point where it will affect your performance, you have also spent month training with that same error so you really can't feel the difference between what a gps measures and a jones counter measures. If your gps over read for all your training runs and over reads for a race, the ratio of distance in training to racing is still similar.

Please also remember a jones counter is accurate for the exact route that the wheel follows. Now when the road is 8-16m wide like for comrades, just going back and forth across the road and to the sides for water, to throw away rubbish, high 5 a friend etc will add more distance so a jones counter is great, if you know the exact route it took and follow it exactly. Again not needed- the error margin is so minimal it makes no difference to your race. Like I said before you should not be cutting it fine for goals and cutoffs, you need to leave some error margin. Want to run a 40min 10km, aim for a 38min 10km. If you are planning to cross the comrades finish line in the last 5 mins you actually shouldn't even bother starting, if you going to do something, do it properly.

[Pieter-za]

Why your GPS will show 89 km plus at the end of Comrades!!!! by Norrie Williamson 

Edited June 14, 2023 by Pieter-za

[TheoG]

12 minutes ago, dave303e said:

Honestly, what a load of click bait. Must we all run around with wheels so we know how far we have gone? They also don't mention was it gps, gps with glonass, gps with glonass and galileo? etc etc etc, there are factors in your setting that can affect it as well. Is your watch recording every second or did you need to scrimp on battery and it is recording every 3 or 5 seconds?

The horizontal error in a gps is so small it will not affect your pacing strategy to a point where it will affect your performance, you have also spent month training with that same error so you really can't feel the difference between what a gps measures and a jones counter measures. If your gps over read for all your training runs and over reads for a race, the ratio of distance in training to racing is still similar.

Please also remember a jones counter is accurate for the exact route that the wheel follows. Now when the road is 8-16m wide like for comrades, just going back and forth across the road and to the sides for water, to throw away rubbish, high 5 a friend etc will add more distance so a jones counter is great, if you know the exact route it took and follow it exactly. Again not needed- the error margin is so minimal it makes no difference to your race. Like I said before you should not be cutting it fine for goals and cutoffs, you need to leave some error margin. Want to run a 40min 10km, aim for a 38min 10km. If you are planning to cross the comrades finish line in the last 5 mins you actually shouldn't even bother starting, if you going to do something, do it properly.

Agree with you 100%.  I tried using a Polar foot pod and calibrating it as good as possible only to find out it require slightly different calibration for different running speeds hence I went back to GPS.  For the vast majority of us it is for sure accurate enough.

Maybe if you a top athlete and chasing records it can fall short in accuracy.

[saggy]

28 minutes ago, dave303e said:

Honestly, what a load of click bait. Must we all run around with wheels so we know how far we have gone? They also don't mention was it gps, gps with glonass, gps with glonass and galileo? etc etc etc, there are factors in your setting that can affect it as well. Is your watch recording every second or did you need to scrimp on battery and it is recording every 3 or 5 seconds?

The horizontal error in a gps is so small it will not affect your pacing strategy to a point where it will affect your performance, you have also spent month training with that same error so you really can't feel the difference between what a gps measures and a jones counter measures. If your gps over read for all your training runs and over reads for a race, the ratio of distance in training to racing is still similar.

Please also remember a jones counter is accurate for the exact route that the wheel follows. Now when the road is 8-16m wide like for comrades, just going back and forth across the road and to the sides for water, to throw away rubbish, high 5 a friend etc will add more distance so a jones counter is great, if you know the exact route it took and follow it exactly. Again not needed- the error margin is so minimal it makes no difference to your race. Like I said before you should not be cutting it fine for goals and cutoffs, you need to leave some error margin. Want to run a 40min 10km, aim for a 38min 10km. If you are planning to cross the comrades finish line in the last 5 mins you actually shouldn't even bother starting, if you going to do something, do it properly.

I agree with everything you say.

The only point I was trying to make with my post is that, just because your gps reads 88.5km it does not mean the route was long. More likely your watch over reading or a number of other factors.

[dave303e]

2 minutes ago, saggy said:

I agree with everything you say.

The only point I was trying to make with my post is that, just because your gps reads 88.5km it does not mean the route was long. More likely your watch over reading or a number of other factors.

Sorry I just get over hyped at click bait and title to get views.

It did spark me looking into official measuring a bit. Turns out a jones wheel on a bicycle is the go to method. Which made me laugh as well because the nature of balancing a bicycle is small corrections left and right to balance. So their official method also over measures. You just need to stand on a dirt road after a bicycle rides past to see that bicycles don't go in straight lines...

[Pieter-za]

14 minutes ago, dave303e said:

Which made me laugh as well because the nature of balancing a bicycle is small corrections left and right to balance. So their official method also over measures.

Actually this is the procedure:

Quote

The basis of the method of measurement is to compare the number of revolutions of the bicycle wheel (recorded in ‘counts’) needed to cover the race course with the number of revolutions needed to cover a standard ‘calibration course’ of known length. The method is simple and direct, but there are many important details to follow in order to obtain an acceptable measurement.

 

Road-Race-Course-measuring.pdf

[tjommies3]

I can't find Tete Dijana's stats but according to Strava, Piet Wiersma (GARMIN FR955) covered 86.23km whilst Gerda Steyn (COROS PACE 2) covered 88.48km. These individuals had the best available lines to pick, yet the distances don't match anything official.