2-second rule (DRAFTING)

Triathlon Forum
1

When I was learning how to drive a car, I was told to follow the car ahead at least 2-seconds back for safety and to avoid a “following too close” citation. On the highway/interstate I would start counting 1 mississippi…2 mississippi when a car went past a mile marker post. If I came up on that same post before I got done counting, then I had to back off on the speed to follow at the recommended distance.

As for the bike leg of a triathlon, the rules state that a cyclist must stay back at least 3 bike lengths or 7 meters. Is there a way to gauge this distance using the automotive example? Does this stay at 2-seconds or increase/decrease due to the speed of a bike (18-26 mph) versus a car (55-75 mph).

To take the guesswork out of the drafting zone, I could simply count the “X” number of seconds from the time the rider ahead passes over an expansion seam in the road, then take appropriate action.

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2

No such rule, here’s why: For cars the idea is to leave enough distance that you have time to react/brake. This distance changes depending on your speed. In triathlon, the draft zone is not speed-dependent (you need to be 7m back slogging up a climb at 8mph or screaming down it at 50).

3

If you take your speed in kph and divide by 3.6 you get m/s (meters per second)
So, for example:
36 k/h / 3.6 = 10 m/s or just under a second to get 7 meters back.

For mph divide by 2.25 to get m/s.

4

I’m not sure how you came to this conclusion, but I’m pretty sure it’s wrong. The faster an object is traveling, the longer it’s slipstream (all other things being equal). That slipstream is the major reason why the trailing rider has to do less work and thus the distance would not be the same to get a drafting effect at 8mph as it is a 50mph.

5

I think you should re-read his post…
The rules don’t care how fast you are going. Traveling slow or fast, you still need to stay a minimum distance away from the rider ahead of you (unless you are over taking them).
…That’s all that was stated

6

You’re right, I mistook what he meant by draft zone. Thanks.

7

Just memorize this chart or print it out and tape it to your handlebars:

mph Seconds/7m 1 15.66 2 7.83 3 5.22 4 3.91 5 3.13 6 2.61 7 2.24 8 1.96 9 1.74 10 1.57 11 1.42 12 1.30 13 1.20 14 1.12 15 1.04 16 0.98 17 0.92 18 0.87 19 0.82 20 0.78 21 0.75 22 0.71 23 0.68 24 0.65 25 0.63 26 0.60 27 0.58 28 0.56 29 0.54 30 0.52 31 0.51 32 0.49 33 0.47 34 0.46 35 0.45 36 0.43 37 0.42 38 0.41 39 0.40 40 0.39
.

8

You see, this is the problem with rules, most do not know what they even are…It is 3 seconds you have to stay back in your car, 4 seconds if following a motorcycle or in bad weather…And I’m probably even wrong too!!!

It is not so much about the rule itself, but the will and enforcement to obey and enforce them…The rules are fine as they are, changing them will not change what is going on out there on the bike course…

9

Looks like you would be safe with 1-mississippi for the entire race.