Alex has posted yet another gem:
http://alex-cycle.blogspot.com/2013/02/pour-me-draft.html
The results were a little surprising and he makes some good observations about how it is problematic to eliminate drafting in Tiathlon.
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One thing that cracks me up at Ironman events is that if you have 2000 participants, with a minimum distance of 12m, and each bike being about 2m, that is a train almost 18 miles long.
One thing that cracks me up at Ironman events is that if you have 2000 participants, with a minimum distance of 12m, and each bike being about 2m, that is a train almost 18 miles long.
and sometimes the courses are loop courses!
field size is incompatible with the rules.
One thing that cracks me up at Ironman events is that if you have 2000 participants, with a minimum distance of 12m, and each bike being about 2m, that is a train almost 18 miles long.
You assume that nobody is passing.
You assume that nobody is passing.
No, I assumed that nobody is drafting.
Well for age groupers the rule is 7m, so that changes things… both in drafting benefit, and crowding. I think we have to look at it as we have a set of rules in place that minimize (not eliminate) drafting benefit. You can follow the rules and get a significant benefit over riding the course completely solo. In fact, it is basically impossible not to get a benefit of some sort.
This of course should NOT be an excuse to exceed the rules and spend too much time in the “draft zone” while passing.
Though I must say that a 20-30W benefit of drafing at 12m is significantly more than I suspected!
It may be a bit less outside, since you aren’t going in circles stirring up the air in the velodrome
Well for age groupers the rule is 7m, so that changes things… both in drafting benefit, and crowding. I think we have to look at it as we have a set of rules in place that minimize (not eliminate) drafting benefit. You can follow the rules and get a significant benefit over riding the course completely solo. In fact, it is basically impossible not to get a benefit of some sort.
This of course should NOT be an excuse to exceed the rules and spend too much time in the “draft zone” while passing.
Though I must say that a 20-30W benefit of drafing at 12m is significantly more than I suspected!
I wish Alex would come back here. Thanks for posting a link to that!
http://triathlon.competitor.com/2012/10/news/konas-secret-rule_63439
These guys did some similar testing at the old distance of 10m and measured about a 12watt savings.
They also point out the problems of passing legally when the legal draft distance is increased. It was that article that made me wonder why there aren’t more “teams” in triathlon in which a group would draft in the, then ride in a pack (at the legal distance), and then run however fast they want. A person trying to qualify for Kona would do well to get a couple of buddies to sign up and help him on the bike course. We already saw that pro do it in Florida with her boyfriend.
That is a very good point. Outdoors a crosswind can move the disturbed air out of the way at legal drafting distances. I wonder what crosswind component it would take to completely move the draft effect out of the way? The speed at which it is shifted is obvious (simply the side component of the wind), but I am not sure how wide the draft off of a bike is at various distances. I also don’t know how quickly the disturbed air moves. I would expect at about the speed of the bike right behind the bike, but expect it to slow down as distance increases.
It would be fairly simple math if you had the width of the “vortex” and its deceleration rate.
It may be a bit less outside, since you aren’t going in circles stirring up the air in the velodrome
Well for age groupers the rule is 7m, so that changes things… both in drafting benefit, and crowding. I think we have to look at it as we have a set of rules in place that minimize (not eliminate) drafting benefit. You can follow the rules and get a significant benefit over riding the course completely solo. In fact, it is basically impossible not to get a benefit of some sort.
This of course should NOT be an excuse to exceed the rules and spend too much time in the “draft zone” while passing.
Though I must say that a 20-30W benefit of drafing at 12m is significantly more than I suspected!
It may be a bit less outside, since you aren’t going in circles stirring up the air in the velodrome.
Makes sense for a closed indoor velodrome, but can that really be happening that much at an outdoor velodrome in light winds?
It may be a bit less outside, since you aren’t going in circles stirring up the air in the velodrome.
Makes sense for a closed indoor velodrome, but can that really be happening that much at an outdoor velodrome in light winds?
I don’t know for sure but I wouldn’t be surprised, even outdoors it is still a big ‘bowl’
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This would be an interesting CFD project. Simulate 1, 2, 5, 10, and 100 cyclists (highly simplified… don’t want it to take a week to crunch the numbers) all in a line 7m apart along a straight road with a slight crosswind. See how much the drafting benefit increases as the number of cyclists increase.