TT road record on an athletics track

Comments about this discussion:

Started 22 Apr 06:13

The guidelines state that a TT WR can be set on an athletics track. I wasn't familiar with the methods used to measure athletics tracks, but recently a number of things have come to my attention and I need to discuss them with you.

I've just read the following:
- the official distance of an approved athletics track is measured at 30 cm from the inside edge of the track for lane 1 (and 20 cm for the other lanes).
- the measurement of an athletics track is fixed, with no correction factor
- if the athletics track is not approved and has a special surface, then it is not possible to use the Jones counter method to measure it, because it's not possible to find a straight 300m calibration base that has the same type of surface

For athletics records, it's the official track measurement (30cm or 20cm from the inside edge depending on the lane) that's used for records, isn't it?

On lane 1, you can be 1m shorter than the approved distance for a 400m (riding 15cm from the edge). While this is of no importance for unicycle track records, as they are all achieved under the same conditions, it can raise questions for road records.
Personally, I think that the surface and the short distance of 400m are greater handicaps than courses on tarmac roads.

In any case, this is something that Samuel Coupey (who has done several road race measurements and who has just finished the athletics federation training course to obtain the diploma and continue with the measurements) is thinking about with regard to a forthcoming 100km record attempt on an approved athletics track by Aurélien Paulmier.

What is your opinion on the subject?

Comment 22 Apr 07:34

> For athletics records, it's the official track measurement (30cm or 20cm from the inside edge depending on the lane) that's used for records, isn't it?

For all atheltics records, the nominal distance is decisive - i.e. 400 m for one full lap. It does not matter whether the track is actually slightly longer than 400 m (which it may be according to the requirements of WorldAthletics). An officially measured track is always at least 400 m long and these 400 m are decisive.

> While this is of no importance for unicycle track records, as they are all achieved under the same conditions, it can raise questions for road records.

If a course is measured according to the requirements of WorldAthletics, this measurement is also made at a distance of 30 cm from the inside edge of the running surface. The measurement of WorldAthletics is therefore completely consistent between road and track races.

All in all, I would expect a lap length of 400 m for all time trail records set up on a track if the track is officially certified. If this is not the case, it must be proven that it is at least 400 m long and 400 m must be used as lap lenght. I would never use the actual length determined.
In my opinion, the Jones counter method has a completely different disadvantage: The method described by WordAthletics is designed to never measure too short. However, when measuring a short circuit that is ridden very often, this would result in the distance actually ridden being overestimated, as the distance of each individual lap would be set too high. The method - as described by WorldAthletics - is therefore not suitable for measuring a single lap in races with several laps.

Comment 22 Apr 08:11

> If a course is measured according to the requirements of WorldAthletics, this measurement is also made at a distance of 30 cm from the inside edge of the running surface. The measurement of WorldAthletics is therefore completely consistent between road and track races.

You're absolutely right. I should have checked the World Athletics reference text before comparing the "shortest possible route" and the trajectory "30 cm from the kerb". This 30 cm is also indicated in the road race measurement reference text.

Thanks for your quick reply, it's reassuring that there's consistency between the measurements for track and road races.

> However, when measuring a short circuit that is ridden very often, this would result in the distance actually ridden being overestimated, as the distance of each individual lap would be set too high. The method - as described by WorldAthletics - is therefore not suitable for measuring a single lap in races with several laps.

The correction factor of 1:1000 is used to guarantee the official fixed distance. It's like measuring 100.1km instead of 100km. In an 100km attempt, to set a fixed distance record on a loop, the distance of the loop will be underestimated in the calculation.
You need to use a correction factor, because you can't guarantee the measurement, as you could when building a track.

Comment 25 Apr 17:19

I always thought the measurement is taken as the inner perimeter of the track, for all time trial records. By definition every time trial record distance is greater than the actual distance measured by a factor of 2 π the distance from the measured inner perimeter.

Jones counter is for measuring courses that take place on roads, with twists and turns, rather than a track.

If indeed athletics don't use the inner perimeter for their measurement, then I don't agree with this. Do we need to follow athletics for every rule?

Comment 27 Apr 05:08

The Jones counter is a suitable measurement method for unicycle course, even on a closed circuit, provided that the track surface is the same as the calibration base (which is not possible for an athletics track). The measurement is made on the shortest possible real trajectory (or "30cm from the edge"), with a correction factor of 1.001.

The smaller the track, the more complicated it is to ride close to the inside edge. However, we can imagine that some athletes have covered less than the official distance if they were able to squeeze the inside edge, whether for unicycle time trial records or unicycle track records.

That said, if we abandon the rules for track and field measurements because the measurement is certified at 30cm and not 10cm from the inside edge. This would pose a problem for certifying track records.

Comment 27 Apr 06:47

> If indeed athletics don't use the inner perimeter for their measurement, then I don't agree with this. Do we need to follow athletics for every rule?

Of course we don't have to, but it seems logical to me to follow the rules of athletics: Our track races take place on athletics tracks, measuring them differently to athletics seems illogical and doesn't make sense to me; our road races should be measured with a Jones Counter according to the rules of athletics - so why should we use different measurements for the time trails? That would mean, for example, that a marathon road race could take place on a course, but not a marathon time trail. That seems extremely illogical to me.

Comment 30 Apr 05:54

"Of course we don't have to, but it seems logical to me to follow the rules of athletics: Our track races take place on athletics tracks, measuring them differently to athletics seems illogical and doesn't make sense to me; our road races should be measured with a Jones Counter according to the rules of athletics - so why should we use different measurements for the time trails? That would mean, for example, that a marathon road race could take place on a course, but not a marathon time trail. That seems extremely illogical to me"

That's because our 'time-trial records' should more accurately be called 'track records', as they are with bicycling. You have to use a circuit, which means measuring an inner perimeter line, rather than the shortest possible route.

In track bicycling, there is a black measurement line in a velodrome, which denotes the length of the track. They don't add an extra 30cm radius to this because riders don't ride exactly on the line.

If we go with athletics rules, then all the Guinness track records measured by the inner perimeter need to be corrected by a minimum 2 x pi x 0.3m. It adds another 2.2km to my 24hr world record, and probably about the same to Sam Wakeling's 24hr record.

Comment 04 May 06:15

> In track bicycling, there is a black measurement line in a velodrome, which denotes the length of the track. They don't add an extra 30cm radius to this because riders don't ride exactly on the line.

The measuring line in a velodrome is 20cm from the inside edge of the track. In any case, the velodromes have too steep an angle for it to be realistic to achieve unicycle records on this type of infrastructure.

One solution would be to abandon the 30 cm for road race measurements and just talk about the shortest possible distance.

For the information, 9 days ago I went to a velodrome where I planned a 100km record attempt in 2 weeks' time. I wasn't involved in the measurement, but there were 2 measurers: 1/ Samuel Coupey (president of my unicycle club who has already done several measurements and has just validated the road measurement judge training with the athletics federation) and 2/ An international measurer who has measured courses for the Olympic Games.
Samuel measured the course 30 cm from the edge, ran 2 laps and obtained exactly the same number of counter laps on each lap. The international measurer told Samuel that his trajectory was correct and he took his measurement. The international measurer found the trajectory to be 2m shorter (over 910m, corresponding to the 30 cm margin in the bends). It seemed clear to us that he hadn't kept a 30 cm margin from the edge.
In fact, he was proud to have found less, since it's his measurement that's used as the official distance. Samuel got the impression that there was already a competition going on during the measurement, with the measurer who found the least winning...

Comment 07 May 05:35

"One solution would be to abandon the 30 cm for road race measurements and just talk about the shortest possible distance."

Or use the inner perimeter as the measurement, as stated in Section 5.1.1 in the 2011 IUF WR guidelines as well as Guinness.

Comment 07 May 06:33

> One solution would be to abandon the 30 cm for road race measurements and just talk about the shortest possible distance.

In my opinion, this is not an option, because if we refer to the athletics procedure for road races, then the 30 cm distance is again included in the measurement. To avoid confusion, the measurement procedure must be clearly defined and I think this is the case with the procedure described by athletics.

Comment 08 May 05:01

Ok fair enough. Just have to be aware that there will be a discrepency between world records done in an official 400m IAAF athletics track, and those done under Guinness and IUF 2011 guidelines, where the inner perimeter is used.

Comment 08 May 07:17

I hadn't understood that the WRG 2011 sentence referred to a specific method of measuring the inside edge of a track. I thought it was a general phrase meaning that the track should be measured as short as possible with good accuracy.

It seems important to me that measurement methods should be relatively homogeneous between disciplines and that the methods validated by World Athletics should be valid for unicycle records, whether for track, road or timed records.

The difference in circle perimeter depending on whether the radius varies by 30cm is constant and is 2*π*0.30 or 1.885m.

The shorter the circuit, the greater the penalty. It's a double penalty, because short circuits are already penalizing because of the steep angle of the bends.

I think it's important to specify the measurement methods in section 5.1.1. And for the methods to be consistent, if the circuit is measured by a surveyor using a cm-accurate method, then the measurement should be taken 30cm from the inside edge of the track.

I talked about dropping the 30cm margin in my previous post, that was clumsy. I meant that when measuring with the Jones meter, when several measurements are taken, the shortest is always taken (it's not possible to check that the 30cm margin has been respected by the measurer). I wasn't trying to change the rules, but rather to encourage you to measure a little closer to the edge rather than a little further out...

If a surveyor can make a precise measurement 30 cm from the edge, that might seem a much better solution.

Comment 08 May 11:04

> It seems important to me that measurement methods should be relatively homogeneous between disciplines and that the methods validated by World Athletics should be valid for unicycle records, whether for track, road or timed records.

I definitely agree with that.
I think it makes little sense to demand a different measurement for a time trail record on an officially recognized athletics track, which would mean that the 400 m track is no longer 400 m long.

> I think it's important to specify the measurement methods in section 5.1.1. And for the methods to be consistent, if the circuit is measured by a surveyor using a cm-accurate method, then the measurement should be taken 30cm from the inside edge of the track.

Currently, the rule that we voted on and that was accepted for the Time Trials, the following about measurement of the course:

1. The course must be a circuit, with distance taken from the inner perimeter of the track, accurate to 0.01m. A measurement report from a registered surveyor must be submitted as evidence of circuit size. If the track is a bicycle velodrome any certification by a national bicycle federation or higher is permitted. If the track is a 400 m athletics track evidence of the track size should be submitted according to Section 3.2 paragraph 1. For fixed distance Time Trail Records, the start and finish are usually not at the same place. The position of the start and finish must be measured accordingly and stated in the measurement protocol.

I think the first sentence is based on the assumption that the measurement of such a course is not done with the Jones counter method - here an accuracy of 0.01m would be absolutely unrealistic - but with an electronic surveying system, where certain reference points are measured and the length is calculated based on these reference points. It is quite easy to do this on the inner perimeter. To use the Jones counter method on the other hand will probably not work on the inner perimeter.
For me, it would be perfectly okay to move the reference line 30 cm inwards, regardless of the method actually used. This would of course give us a standardized procedure for all our measurements - although, as Ken has already mentioned, we would then use a different measurement method than Guinness. Of course, the Guinness method would still be okay for our records, as the measured distance would be shorter compared to our method. Nevertheless, this can of course result in differences between IUF and Guinness World Records.

Comment 08 May 11:50

> The difference in circle perimeter depending on whether the radius varies by 30cm is constant and is 2*π*0.30 or 1.885m.
If the curvature of the circuit goes both ways, i.e. left and right bends, then the difference in circuit length is generally more than just 2*π*0.30.

Comment 09 May 15:13

The shortest possible route is also not 30cm from the inside edge. That is an assumption based on where someone running on an athletic track is likely to be positioned.

On a unicycle or bike, you can right against the line, so the shortest possible route is a the tyre against the inner perimeter. This is not where people ride in reality because of speed, fatigue or track surface (eg I had a staircase structure in my way in my 2005 track). Nevertheless, it's still the shortest possible if you measuring by Jones counter.

Comment 09 May 15:41

What we are referring to is better described as the measuring line, rather than shortest possible route. The faster you go, generally the further out from the inner perimeter you ride. I was riding a meter out from inner perimeter on average for my latest 24hr record, and probably slightly more in 2005. On the other hand, in 2009 for my hour record I would have ridden about 30cm from inner perimeter because it was a very smooth track. Measuring would be most accurately done by a surveyor on the inner perimeter, and then adding 2 x pi x r, rather than a Jones counter. We can also add this 'measuring line' distance to existing records measured on the inner perimeter.

Comment 09 May 16:20

It would raise questions if all historical records set with the SPR method, would be adjusted to a new rule. Assuming that we are indeed changing the nominal distance to 30 cm from the edge as opposed to on the edge, then to me it would be better to note that such older records have been verified against an older set of rules.

A further complication that would also be avoided by this, is that the correction for "zig-zag" circuits is more than 2 x pi x r per lap. I had this in my Dutch 24 hr record, and the guy who broke it last year had that also. Lap length for both of these was measured on the edge as per the (still) current rules. I'm pretty sure there are more of these cases.

Comment 09 May 16:29

Another issue is that Guinness allows certified athletic tracks to be used without needing a survey plan, and they probably assume that an inner perimeter measurement is the measuring line.

This brings up another issue. Will we allow resubmission of old Guinness/IUF records with survey plans, and add 2x pi x 30 cm distance?

Apologies for typos and short messages, I'm away from home and typing on phone.

Comment 09 May 16:50

"If the curvature of the circuit goes both ways, i.e. left and right bends, then the difference in circuit length is generally more than just 2*π*0.30."

I'm not quite clear what you mean. It's still a circuit, so having bends just means it's harder to ride at 30cm from inner perimeter. If it was a very steep bend, you can take shortcut across the bend which effectively shortens the circuit.

Comment 09 May 16:56

The 2x pi x 30cm is also a constant, if are fixing 30cm from inner perimeter as the measurement line. So for all world records, we still specify inner perimeter measurement, but adjust by 1.88m per lap.

You have a fixed line to survey, rather than an imaginary one using the SPR method, which introduces wheel wobble error.

Comment 10 May 03:48

> The shortest possible route is also not 30cm from the inside edge. That is an assumption based on where someone running on an athletic track is likely to be positioned.

I don't know exactly what you mean by that. According to the definition of Worldathletics, a course should be measured on the shortest possible route (SPR) - the measuring line and SPR are therefore identical here. Quote from the specifications of Worldathletics: "Measuring the SPR means hugging the inside edges of bends. The path you should attempt to measure officially lies 30 cm from the kerb or other solid boundaries to the running surface."
Of course, the 30 cm distance between the SPR/measuring line and the inner kerb is related to the fact that in reallity nobody is able to run exactly on the inner kerb. However, this assumption is also valid for unicycling, because in reallity nobody is able to ride constantly on the inner kerb. So I see no difference here to the considerations from athletics.

> Measuring would be most accurately done by a surveyor on the inner perimeter, and then adding 2 x pi x r, rather than a Jones counter.

But what is the difference if the measuring line is on the SPR described by Worldathletics or on the inner radius and a value is subsequently calculated that corresponds to the SPR? In that case, can you also measure directly 30 cm from the inside kerb?

> It would raise questions if all historical records set with the SPR method, would be adjusted to a new rule. Assuming that we are indeed changing the nominal distance to 30 cm from the edge as opposed to on the edge, then to me it would be better to note that such older records have been verified against an older set of rules.

I absolutely agree with Klaas here.

> Another issue is that Guinness allows certified athletic tracks to be used without needing a survey plan, and they probably assume that an inner perimeter measurement is the measuring line.

So do I understand correctly that Guinness also counts a 400 m athletics track as 400 m long and that there is no measurement on the inner perimeter? That makes even less sense, as the distances with Guinness are also not measured consistently.

> The 2x pi x 30cm is also a constant, if are fixing 30cm from inner perimeter as the measurement line. So for all world records, we still specify inner perimeter measurement, but adjust by 1.88m per lap.

As Klaas has already pointed out, this is only the case for tracks on which a total “angle” of 360° is traveled, if the angle traveled is increased by curves in different directions, the distance that each lap is longer will of course also increase. Each course will therefore be at least 1.88 m longer if it is measured 30 cm from the inside kerb - but it can also be significantly longer.

All in all, I see two options:
Option 1: A standardized measurement method for all our disciplines - and therefore different lengths for the Time Trails compared to Guinness.
Option 2: The same lengths as Guinness - and therefore different measurement methods for Time Trails.
In particular, it would not be possible to measure the distance for a Time Trail record using the Jones counter method as described by Worldathletics.

Personally, I would clearly prefer option 1, as we would be consistent in our disciplines, measurement with the Jones counter method would be possible and at the same time all courses measured according to Guinness specifications would still be valid for our records, as the distance would be underestimated and not overestimated compared to our measurement line.

Comment 10 May 10:12

"If the curvature of the circuit goes both ways, i.e. left and right bends, then the difference in circuit length is generally more than just 2*π*0.30."

> I'm not quite clear what you mean.

Say you ride your circuit anticlockwise, as an example. On a circuit of which the curvature goes only one way (such as an athletics track), then one is assumed to ride (or at least, measure the nonimal distance) 30 cm from the lefthand edge of the track.
BUT if the curvature goes both ways so that in addition to left turns, there are also one or more right turns in the circuit, then in those curves one would ride 30 cm from the RIGHTHAND edge of the track. That means that in those turns, you have to ride also more distance compared to riding ON the righthand edge. In total, the additional distance resulting from riding 30 cm from the edge is more than 2 x pi x 0.30 meters.

A picture would make it clearer, but this doesn't seem to be possible here. I hope I made myself clear now.

Comment 10 May 10:22

I have always understood "shortest possible route" (SPR) as the theoretically shortest possible route, and thus 0 cm from the edge (if that is the shortest - not always true depending on the circuit). If this is not how we must interpret SPR because it is not actually possible to ride there, AND we continue to use SPR, it would be good to add an unambiguous definition.

Comment 10 May 10:37

> I have always understood "shortest possible route" (SPR) as the theoretically shortest possible route, and thus 0 cm from the edge (if that is the shortest - not always true depending on the circuit). If this is not how we must interpret SPR because it is not actually possible to ride there, AND we continue to use SPR, it would be good to add an unambiguous definition.

I can understand that this assumption is made - in the new rules that we voted on here in the committee, however, the SPR is no longer mentioned at all (this was previously only the case for road races) and instead reference is only made to the procedure approved by World Athletics for measuring the course. And here, in my opinion, it is very clear that the measuring line for the SPR is 30 cm from the inside kerb. So I don't really see a place in our WRG where we need to define the term SPR in more detail. (Unless we want to use it again somewhere)

Comment 10 May 11:04

> the SPR is no longer mentioned at all (this was previously only the case for road races)

That's right. In the old rules, for time trials, the statement is
"The course must be a circuit, with distance taken from the inner perimeter of the track". So that means 0 cm from the edge. To me, this seemed the same as SPR and I even thought that the term "SPR" was used for time trials, but indeed it is not.

BTW, in the old rules also an athletics track may be used for time trials. Since these are nominally 400 m as measured 30 cm from the edge (generally, and for track 1), they are about 398.12 m (400 - (2 x pi x 0.30)) on the edge, but in the distance calculation they are counted as 400m. So there is a discrepancy with non-athletics-track-circuits, which was also noted by someone else in this discussion.

Comment 10 May 12:22

> Another issue is that Guinness allows certified athletic tracks to be used without needing a survey plan, and they probably assume that an inner perimeter measurement is the measuring line.

Are you saying that GWR doesn't take into account the fact that the measurement of an certified athletics track is taken 30 cm from the edge on lane 1? Besides, for approval, the track is measured over all 8 lanes, but for approval, there is no measurement at the inner edge of the track.

> On a unicycle or bike, you can right against the line, so the shortest possible route is a the tyre against the inner perimeter.

I agree that unicycling or cycling, you can put your center of gravity further inside than running. But when running, you can have your center of gravity closer than 30 cm from the edge. For me, this choice of 30 cm margin is arbitrary. Probably on a unicycle you can ride 10 cm closer to the edge than when running, but I think that for reasons of simplicity and because we use running structures, it is better to keep 30 cm.

> If the curvature of the circuit goes both ways, i.e. left and right bends, then the difference in circuit length is generally more than just 2*π*0.30.

Yes, this distance is the minimum difference that can be found between a measurement of the inner edge and a measurement at 30cm, in the case where the track forms a perfect circle. Indeed, the question of revaluing old records at a rate of 1.88m per lap should be discussed.

Comment 11 May 05:27

"I don't know exactly what you mean by that. According to the definition of Worldathletics, a course should be measured on the shortest possible route (SPR) - the measuring line and SPR are therefore identical here. Quote from the specifications of Worldathletics: "Measuring the SPR means hugging the inside edges of bends. The path you should attempt to measure officially lies 30 cm from the kerb or other solid boundaries to the running surface."

The SPR is for a road course like a Marathon. There are curves, turns and generally one large circuit. There are many lines one can take when riding around corners, which is why they use the SPR.

A standardised track like a 400m athletic track is built to be a specific size, so the shortest possible route is the inner perimeter. The measuring line will be 30cm from the shortest possible route.

Of course, the 30 cm distance between the SPR/measuring line and the inner kerb is related to the fact that in reallity nobody is able to run exactly on the inner kerb. However, this assumption is also valid for unicycling, because in reallity nobody is able to ride constantly on the inner kerb. So I see no difference here to the considerations from athletics."

On a track, the shortest possible route may not be the fastest or most practical, but it's still the shortest possible route.

The 30cm measuring line is an arbitrary distance from the inner perimeter/shortest possible route.

An SPR is calculated with a bike riding the shortest possible route around corners on a road course, which has bends that could go in either direction. If it's a fixed circular track, then you have an inner perimeter line to measure/survey. You would not try to ride a bike with Jones counter on an imaginary 30cm line out from the inner perimeter, as it introduces unnecessary error.

The assumption that we ride 30cm out from the inner perimeter is completely arbitrary. It would depend on the wheelsize, the quality of the track, the steepness of the bend, and speed.

"So do I understand correctly that Guinness also counts a 400 m athletics track as 400 m long and that there is no measurement on the inner perimeter? That makes even less sense, as the distances with Guinness are also not measured consistently."

Guinness are not experts in unicycling or athletics. They probably assumed (as I did), that a 400m track is measured along the inner perimeter.

I've gone back through my previous Guinness record attempts. It looks like Guinness have changed the wording since my 2005 attempt, even though I interpreted their latest rules in the same way I did in 2005:

This is the rule in 2005 for the 24hr and 100mile records:

"The record attempt should take place on a closed circuit such as an athletics track. The exact length of the track must be measured by a qualified surveyor prior to the record attempt starting. The surveyor’s report must be submitted along with the record claim. Note that the measurements should be made on the inside edge of the track (i.e. the shortest portion of the track)."

This is the rule in 2025 for the 12hr and 24hr records:

"The track length must be submitted. If the track is not a recognized racetrack, then track length must be accurately measured beforehand by a qualified professional surveyor. The surveyor’s report confirming the length of the circuit must be submitted with the record claim."

It looks like Guinness' latest track measurement rule is open to interpretation, but would allow someone to use an IAAF 400m track under IAAF rules (ie 30cm measuring line from inner perimeter.

Comment 11 May 05:40

"Say you ride your circuit anticlockwise, as an example. On a circuit of which the curvature goes only one way (such as an athletics track), then one is assumed to ride (or at least, measure the nonimal distance) 30 cm from the lefthand edge of the track.
BUT if the curvature goes both ways so that in addition to left turns, there are also one or more right turns in the circuit, then in those curves one would ride 30 cm from the RIGHTHAND edge of the track. That means that in those turns, you have to ride also more distance compared to riding ON the righthand edge. In total, the additional distance resulting from riding 30 cm from the edge is more than 2 x pi x 0.30 meters.

A picture would make it clearer, but this doesn't seem to be possible here. I hope I made myself clear now."

I might have to message you privately, because I still don't get it. If it's a circuit, then there is an inner perimeter. You can have turns in the circuit, but it's still 30cm from the inner perimeter.

Imagine a giant "E". If you do a circuit around the 'E', you can still measure 30cm out from the inner perimeter even with left and right turns.

Comment 11 May 05:55

Sorry, just thought this through and I understand what Klaas is saying regarding the measured distance being more than 2x pi x 0.3 when there are left and right turns.

It's probably worth the participant avoiding courses that bend both ways. However, the measurement line can still be calculated by the surveyor without the SPR/Jones counter method. The fixed inner perimeter is surveyed, then add an electronic line 30cm from the perimeter for measurement. You don't need to ride a bike with Jones counter 30cm from the inner perimeter.

Comment 11 May 07:52

> Since these are nominally 400 m as measured 30 cm from the edge (generally, and for track 1), they are about 398.12 m (400 - (2 x pi x 0.30)) on the edge, but in the distance calculation they are counted as 400m. So there is a discrepancy with non-athletics-track-circuits, which was also noted by someone else in this discussion.

Yes, exactly - that's why it would be more logical for me to measure at a distance of 30 cm for other tracks as well. Then the measurement would be consistent between 400 m athletics tracks and other tracks, as well as the distance measurement for road races.

> A standardised track like a 400m athletic track is built to be a specific size, so the shortest possible route is the inner perimeter. The measuring line will be 30cm from the shortest possible route.

For measuring methods other than the Jones counter method, the term SPR is not defined at all and is not used anywhere that does not concern this method. Therefore, defining the SPR as the inner radius inevitably leads to confusion and, in my opinion, makes absolutely no sense.

> The 30cm measuring line is an arbitrary distance from the inner perimeter/shortest possible route.

The SPR is set at a distance of 30 cm from the inside kerb for the same reasons as the measuring line on a 400 m athletics track is. And if you watch track races on a unicycle, you will see that the 30 cm is also very suitable for unicycles and that they are not regularly ridden further inside. In my opinion, the 30 cm is therefore also very suitable for unicycling.

> The assumption that we ride 30cm out from the inner perimeter is completely arbitrary. It would depend on the wheelsize, the quality of the track, the steepness of the bend, and speed.

Even if it is arbitrary - we need a definition of where to measure. And if we set it at 30cm from the inside kerb, the measurement of an official 400m athletics track, a road race (where the Jones counter method is mostly likely to be used) and the measurement of courses for time trails would be consistent.
And this is exactly what I asked above: should we keep these measurements consistent or should we go with the (inconsistent) Guinness measurement?

> You don't need to ride a bike with Jones counter 30cm from the inner perimeter.

Of course not - if a different measurement method is used, that is perfectly okay and in no way contradicts the rules. The question, which is the only issue here, is how we define our measuring line: On the inner perimeter or at a distance of 30 cm vom the inside kerb. Of course, an official measurer can measure any other track, just as he measures an official athletics track, and the measurement would be perfectly fine for a record. Nobody wants to make the Jones counter method the only acceptable method. But consistency for the measurement lines between the different methods would be preferable in my opinion.

Comment 12 May 03:58

"For measuring methods other than the Jones counter method, the term SPR is not defined at all and is not used anywhere that does not concern this method. Therefore, defining the SPR as the inner radius inevitably leads to confusion and, in my opinion, makes absolutely no sense."

It doesn't need to be defined for a track, because it is really only useful when measuring road courses using a Jones-counter/bike. For a track, the SPR will always be the inner perimeter.

"Even if it is arbitrary - we need a definition of where to measure. And if we set it at 30cm from the inside kerb, the measurement of an official 400m athletics track, a road race (where the Jones counter method is mostly likely to be used) and the measurement of courses for time trails would be consistent."

I have no issue with this, as long as we are consistent. If we change our definition, we have to adjust records done under IUF 2011 guidelines.

And this is exactly what I asked above: should we keep these measurements consistent or should we go with the (inconsistent) Guinness measurement?

Guinness (which changed their definition from inner perimeter, to not defining it at all, as described in my earlier post).

"Of course not - if a different measurement method is used, that is perfectly okay and in no way contradicts the rules. The question, which is the only issue here, is how we define our measuring line: On the inner perimeter or at a distance of 30 cm vom the inside kerb. Of course, an official measurer can measure any other track, just as he measures an official athletics track, and the measurement would be perfectly fine for a record. Nobody wants to make the Jones counter method the only acceptable method. But consistency for the measurement lines between the different methods would be preferable in my opinion."

As long as we call this the 'measurement line' and not the 'shortest possible route', and we use a consistent distance like 30cm, then I have no problem with it.

A track should be surveyed using survey equipment, rather than the Jones counter method, because it would be too difficult to maintain a consistent line 30cm from the inner perimeter while riding a bike.

Comment 12 May 04:42

I know this discussion is mainly about athletics tracks and it has already been mentioned that for velodromes are certificated at a 20cm off set distance from the inside edge.

I think we should keep this in consideration of the wording for this rule as not all velodromes are inappropriate for unicycle records, some are very good for them as older velodromes have shallower banking and are actually ideal TT records as they are often 500m or bigger and often super smooth. How do we deal with the situation where we want to use these venues? do we accept the measured line? do we re-calculate them for 30cm? or do SPF? or keep the wording in the existing rule that allows the measured line?

Comment 12 May 06:37

> For a track, the SPR will always be the inner perimeter.

Only if the term SPR were defined at all for this case - otherwise SPR simply does not exist. Your statement therefore assumes that SPR is defined somewhere for an track and its measurement method, which is not the case. The use of SPR is therefore only meaningful in connection with the Jones counter method - everywhere else the definition is missing and every assumption you make is a completely personal assumption.

> If we change our definition, we have to adjust records done under IUF 2011 guidelines.

If the measurement allows it, that would be a possibility - but that's not the point here in the first place. Before we can think about how to deal with old records (which applies to all old records every time the Record Guidelines are changed), we first have to agree on which measurement we want to prescribe.

> Guinness (which changed their definition from inner perimeter, to not defining it at all, as described in my earlier post).

But would that mean that every circuit for a Guinness record can also be measured at a distance of 30 cm from the inside kerb? The requirement from 2025 quoted by you is indeed not very specific. If that were the case, I see no reason to place the measuring line on the inner perimeter. Because then a measurement 30 cm from the inside kerb would also be Guinness-compliant and consistent between a 400 m track and a road course.

> A track should be surveyed using survey equipment, rather than the Jones counter method, because it would be too difficult to maintain a consistent line 30cm from the inner perimeter while riding a bike.

Our current rules do not foresee the measurement of a 400 m track with the Jones counter method.

> I know this discussion is mainly about athletics tracks and it has already been mentioned that for velodromes are certificated at a 20cm off set distance from the inside edge.

I don't know what these tracks actually look like. Is it like an athletics track where the inside kerb is actually a physical kerb? Or is it just a line on an otherwise continuous surface? In the second case, I think the 20 cm is entirely justified, as without a physical kerb you will be more likely riding closer to the line than with a physical kerb (which is why the distance on an athletics tracks other than lane 1 is also measured at a distance of 20 cm from the line).

Comment 12 May 08:41

Velodrome black measuring line is measured from the inside edge of the track. The measurement is to the inside edge of a black marked line which is 5cm wide. There is not a hard edge to the velodrome (there are exceptions, but as general rule this is a correct comment), below the 0cm is the blue Cote D'azur which riders are not allowed to race on. The Cote D'azur is for safety (you have see it as it is sometimes used as a running track).

Comment 12 May 08:42

> The use of SPR is therefore only meaningful in connection with the Jones counter method

I agree

> we first have to agree on which measurement we want to prescribe.

I agree

> Our current rules do not foresee the measurement of a 400 m track with the Jones counter method.

If there were the possibility of having a calibration base with the same surface as the track, it would be technically feasible. But if you're going to use an athletics track, you might as well use one that's certified. I assume Ken is talking about measuring a non certified track. Besides, what do we call a track? In any case, taking a measurement 30cm from the edge doesn't present any technical difficulties, no matter what you're measuring. It is possible to place markers 30 cm from the edge, and deviations of a few cm inward or outward will not make a big difference to the final result, especially since this method is associated with a correction factor of 1.001.

> I don't know what these tracks actually look like. Is it like an athletics track where the inside kerb is actually a physical kerb?

The measurement line is the black line

I did some research, and I have the impression that there are very few older velodromes (longer with less banked turns) suitable for unicycles in the world (maybe Preston Park Velodrome, Palmer Park Stadium, Maindy Centre (Cardiff) in UK...

Comment 12 May 08:50

There are more gentle velodromes than you may think as the gradient on the older tracks is not consistent. They used to increase it gradually. In addition to those you listed, I have ridden on Herne Hill, Camarthan and Forest Town Welfare that I think work for unicycles. I do agree, modern velodromes do not work for us, but as I say, some of these older ones may.

Comment 12 May 12:04

> There is not a hard edge to the velodrome (there are exceptions, but as general rule this is a correct comment), below the 0cm is the blue Cote D'azur which riders are not allowed to race on.

Than a velodrome differs from lane 1 of an athletics track where there is actually a physical kerb at the inner perimeter and they are more similar to the other lanes of an athletics track, where the measuring line is also 20 cm from the edge of the permitted “running surface”.

All in all, when measuring tracks where there is a defined measuring line (such as velodromes or 400 m athletics tracks), I completely agree with using this for the measurement. In my opinion, it becomes difficult when there is no measurement line - as is the case with many time trail or road race courses. Of course, we could stick to the current measurement on the inner perimeter, but in my opinion this has two disadvantages:
1. A measurement using the Jones counter method as described by Worldathletics would not be possible.
2. The official track lengths of velodromes or 400 m athletics tracks could not be used because these official lengths would overestimate the distance compared to the prescribed measurement on the inner perimeter.
If, on the other hand, we were to require a measurement at a maximum distance of 30 cm from the inner perimeter, then the official track lengths could be used, as these would at most underestimate the length (if the official measuring line of a track is closer than 30 cm to the inner perimeter) and it would be possible to measure courses using the Jones counter method.

Comment 12 May 23:14

"Only if the term SPR were defined at all for this case - otherwise SPR simply does not exist. Your statement therefore assumes that SPR is defined somewhere for an track and its measurement method, which is not the case. The use of SPR is therefore only meaningful in connection with the Jones counter method - everywhere else the definition is missing and every assumption you make is a completely personal assumption."

Exactly- the Jones counter method is to find the shortest possible route through a road course, which has twists and turns. It is not necessary for a track, but if you had to ride the 'shortest possible route' on a track, it would be the inner perimeter, NOT the measurement line (whether we define this at 30cm or 20cm).

1. A measurement using the Jones counter method as described by Worldathletics would not be possible.

A track would not need measuring with the Jones counter. It should be surveyed on the inner perimeter, then 30cm (or whatever measurement line we choose) added to this.

Comment 12 May 23:22

I know this discussion is mainly about athletics tracks and it has already been mentioned that for velodromes are certificated at a 20cm off set distance from the inside edge.

I considered the 333m Saxton Velodrome in Nelson, NZ for my 24hr- the plan was to survey the inner perimeter of the Cote D'azur, and use this as my track. It is much faster than the track I used, but too far away for my support crew.

My 2009 Guinness Hour record was done in Victoria Park, Dubbo, NSW. It's not a velodrome as such, but is used by the local track cycling club for racing. It's perfect for unicycling- minimal banking, very large and smooth. I had the track surveyed and used the inner perimeter rule rather than the measurement lines.

There are images of both venues online.

Comment 13 May 06:16

> Exactly- the Jones counter method is to find the shortest possible route through a road course, which has twists and turns. It is not necessary for a track, but if you had to ride the 'shortest possible route' on a track, it would be the inner perimeter, NOT the measurement line (whether we define this at 30cm or 20cm).

The shortest possible route is officially defined by World Athletics as the shortest route that maintains a 30 cm margin from the inner edge, regardless of whether there are left and right turns or only one-sided turns.

I explored what other sports federations are doing:

World Athletics: Track races are measured 30 cm from the inner edge of the lane (or 20 cm if there is a raised curb). Road races (e.g. marathons) are measured using a calibrated bicycle (Jones Counter), following the shortest possible route 30 cm from the curb in curves, with an additional 0.1% margin to ensure the course is not short.
UCI (Union Cycliste Internationale): Velodrome races are measured 20 cm above the inner edge of the track surface, along the black line, which represents the shortest legal trajectory.
ISU (International Skating Union): For track speed skating, the track length is measured 50 cm from the inner edge of the lane.
World Skate: Both on the track and on the road, the race course is measured on the inner edge. ("On road courses with both left and right bends, measuring is to be taken along an imaginary line from the extreme ends of the bends themselves").

Although measurement methods vary from one federation to another, the federations concerned with competitions on closed tracks and on open roads have homogeneous measurement methods between their disciplines.

I think it's important to choose consistent method measurements. A "track" can be a standardized athletics track or any closed circuit on asphalt with or without banked turns. For an asphalt closed circuit of 1, 2, 5, or 10 km, I don't see how a measurement with a Jones counter would be inappropriate.

Comment 13 May 10:37

> The shortest possible route is officially defined by World Athletics as the shortest route that maintains a 30 cm margin from the inner edge, regardless of whether there are left and right turns or only one-sided turns.

That's it - World Athletics descibes how to measure a curse with the Jones counter method and is using the term SPR for this. But the descibed method is not depending on how the curse looks. If you would use this method to measure a big circle the measuremnt would still be done with 30 cm distance to the inner perimeter of the circle.
And by doing so the measurements descibed by World Athletics are consistent between how a 400 m track is measured (wich is a big "circle" with only one-side turns) and a road race that might have what ever curse (and especially can also have only one-side turns, even if it's unlikely).

> Although measurement methods vary from one federation to another, the federations concerned with competitions on closed tracks and on open roads have homogeneous measurement methods between their disciplines.

I think it is precisely this consistency between the different disciplines that is the reason why we should have this discussion at all. In my opinion, it would be extremely illogical, for example, to determine the distance of a 10 km road race on a closed circuit (as it was the case at the 2017 European Championships in the Netherlands, for example) differently to a 10 km time trial competition on the same track. Why should there be two different distances for two different competitions over the nominally same distance? This is inconsistent and, in my view, not desirable.

Comment 15 May 05:30

"The shortest possible route is officially defined by World Athletics as the shortest route that maintains a 30 cm margin from the inner edge, regardless of whether there are left and right turns or only one-sided turns."

Needs to be interpreted in this context:

World Athletics: Track races are measured 30 cm from the inner edge of the lane (or 20 cm if there is a raised curb). Road races (e.g. marathons) are measured using a calibrated bicycle (Jones Counter), following the shortest possible route 30 cm from the curb in curves, with an additional 0.1% margin to ensure the course is not short.

World athletics have standardised athletic tracks, where they use a measurement defined as 30cm from the inner edge of the lane. They do not refer to this measurement line as the shortest possible route. They use the shortest possible route to define road courses, with a 30cm measurement from the curb in the curves.

We should not be referring to the measurement line used in a track racing on an athletic track as the 'shortest possible route', because it isn't. You can always ride up against the inner perimeter.

"I think it is precisely this consistency between the different disciplines that is the reason why we should have this discussion at all. In my opinion, it would be extremely illogical, for example, to determine the distance of a 10 km road race on a closed circuit (as it was the case at the 2017 European Championships in the Netherlands, for example) differently to a 10 km time trial competition on the same track. Why should there be two different distances for two different competitions over the nominally same distance? This is inconsistent and, in my view, not desirable."

That's not the point I'm making. In athletics, there are standardised tracks, and non-standardised road courses. The SPR implies a Jones-counter bicycle method of measurement. It is designed for road courses. If you have a small circular track, it makes no sense to try to measure it with the Jones counter method, or to call it the shortest possible route.

In your 10km example- in a multiple lap race or time trial, it could easily be surveyed so that you can determine a measurement line 30cm out from the inner perimeter. If you were to ride the 30cm out from the curb with a Jones counter- it would be much less accurate because it would be hard to keep that distance consistent on a bicycle.

The distance definition will be the same.

Comment 15 May 05:47

AFAIK, 20 and 30 cm are the other way around for athletics tracks: 20 cm for lanes 2 and up, 30 cm for lane 1 with a raised kerb.

Comment 15 May 07:19

> We should not be referring to the measurement line used in a track racing on an athletic track as the 'shortest possible route', because it isn't. You can always ride up against the inner perimeter.

Nobody has done that - but it would be just as wrong to call the inner radius the “shortest possible route”, because that is not how the SPR is defined.
You could also theoretically follow something I'll call a “physically shorter route” in a road race, namely always on the inner kerb/perimeter, but this does not correspond to the definition of the SPR. Nor does the inner radius of an athletics track correspond to the definition of the SPR.

> That's not the point I'm making.

But that's exactly the point here - if we keep the current definition of distance measurement for Time Trails (i.e. on the inner perimeter), then a 10 km road race and a 10 km Time Trial on the same circuit will have different start/finish points. And this inconsistency should not exist in my opinion.

> In your 10km example- in a multiple lap race or time trial, it could easily be surveyed so that you can determine a measurement line 30cm out from the inner perimeter.

The distance definition will be the same.

But our current definition for Time Trials does not say that the course should be measured on a measuring line 30 cm from the inner perimeter, but that it must be measured on the inner perimeter. This means that the resulting courses for a time trail and a road race would not be identical.