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IM Boulder swim start procedure / drafting
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The swim start at IM Boulder was very spread out: first swimmer got in at 6:20, last around 7:15. About 1200 athletes in total.
This means 1 athlete every 3 seconds.
Result: very relaxed swim (which is probably a good thing in thin air at altitude), no congestion in T1 (and great help from the volunteers there to dress up for the cold) but more importantly no draft packs during the bike part.
Combined with the great tracking app for spectators, I think this is the way to move forward. After all, it is an individual sport!
Too bad this was the last edition of this race. It was really well organized and the course was very nice (bike part 3k short but run part 1.5k too long).
Sam
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Re: IM Boulder swim start procedure / drafting [sgy] [ In reply to ]
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I think it would be great, but wondering if race directors would be unhappy with how long it would take to start all the swimmers at races with 2500+ athletes.
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Re: IM Boulder swim start procedure / drafting [SBRcanuck] [ In reply to ]
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IM 70.3 Chattanooga RD stated since they had so many athletes this year they were going to spread swim entry over 80 minutes instead or the normal 30 minutes in an attempt to reduce congestion on the bike. I don't know if that actually happened as they had some delay due to having to move the buoys when they cancelled the upstream portion of the swim.
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Re: IM Boulder swim start procedure / drafting [SBRcanuck] [ In reply to ]
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SBRcanuck wrote:
I think it would be great, but wondering if race directors would be unhappy with how long it would take to start all the swimmers at races with 2500+ athletes.

2 People every 3 seconds :-)
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Re: IM Boulder swim start procedure / drafting [sgy] [ In reply to ]
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True, and Tremblant essentially started doing this a couple years ago I think.

If memory serves, I think in 2017 they let like 5 of us run in every 3 seconds, or something like that, and it was great. Or maybe that was the '18 70.3..

It looked like they intended to do the same for the full IM in 2018, but the start was delayed by an hour+ due to fog, and when they finally started I think they just had us stream in non stop through the narrow start gate to get things moving...... It was still way better than a mass start in terms of crowding.
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Re: IM Boulder swim start procedure / drafting [sgy] [ In reply to ]
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Memphis in May has been doing this for over 20 year years. It really breaks up drafting & I observed very little drafting while out spectating all over the course yesterday. It was a multidirection/swirling wind and constant yesterday. The swim data from several Garmin files showed the swim to be slightly long, but there were also white caps out there. It did not hit 60 F until much later in the race & was in the mid 50's well into later stages of the bike. Excellent conditions compared to the 98 F heat from last year. I felt sorry for so many people last year...much harder conditions then for sure.
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Re: IM Boulder swim start procedure / drafting [sgy] [ In reply to ]
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I did IM Boulder. I thought the rolling start was too slow. Certainly made the swim nice and spread out. But, I think they could have easily had maybe 2-3 go off instead of just 1 person. I've done IM Lou 5 times and they at least had two starting mats so there was more starting at once. And, IM Lou is also not congested.

Michael in Kansas
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Re: IM Boulder swim start procedure / drafting [jayhawk.] [ In reply to ]
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True, in South Africa they let 5 people in at once every 5 seconds I think and that spreads out things nicely as well.
In Texas in 2018 there was an uncontrolled rolling start and it was a disastrous draft fest.
Boulder was slow but very effective!
Sam
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Re: IM Boulder swim start procedure / drafting [sgy] [ In reply to ]
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It was 1 athlete every 2 seconds.

But I do agree that it made it very spread out, with nearly no congestion on the bike course and the run quite solitary in places.

However, the run course was only about 0.2 miles long - the weirdest thing was that if you ran the tangents right, the distance was exactly right until mile 24, but the mile 25 marker was way off and the mile 26 marker just did not exist :)

Next races on the schedule: none at the moment
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Re: IM Boulder swim start procedure / drafting [alex_korr] [ In reply to ]
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Not so sure about course distance being right. I have data from 3 different devices and all have a +43k marathon. Also, if I export the position data to any mapping service it shows around 43.3k. It is perfectly possible that these devices and mapping services are totally wrong though... Anyhow, it doesn't really matter. It was a nice race and I was happy to be a part of it, regardless the distances :-)
Sam
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Re: IM Boulder swim start procedure / drafting [sgy] [ In reply to ]
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IMFL 2018 had a metered rolling start... there were 4 or 5 lanes with gates and every time the gates beeped one person per lane was let out. I think it beeped once every five seconds.

sgy wrote:
The swim start at IM Boulder was very spread out: first swimmer got in at 6:20, last around 7:15. About 1200 athletes in total.
This means 1 athlete every 3 seconds.
Result: very relaxed swim (which is probably a good thing in thin air at altitude), no congestion in T1 (and great help from the volunteers there to dress up for the cold) but more importantly no draft packs during the bike part.
Combined with the great tracking app for spectators, I think this is the way to move forward. After all, it is an individual sport!
Too bad this was the last edition of this race. It was really well organized and the course was very nice (bike part 3k short but run part 1.5k too long).
Sam

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