Bike Drafting Penalties

The idiot behind is responsable for dropping off your wheel if you over take him.  If he wants to pass you, he must do so in a set amount of time.

Here are the rules from the USAT website.

5.10 Position Fouls.

In accordance with the Rules as set forth in this Section, a participant is not permitted to position his bicycle in the proximity of another moving vehicle so as to benefit from reduced air resistance. While on the cycling course, participants shall not work together to improve performance, efficiency, or position by teamwork or other joint conduct. A variable time penalty shall be imposed for any violation of this Section.

(a) Illegal Positioning. Except as otherwise provided in these Rules, while on the cycling course, no participant shall permit his drafting zone to intersect with or remain intersected with the drafting zone of another participant or that of a motor vehicle. With respect to a motor vehicle (including authorized race vehicles), it is the athlete's responsibility to move out of the vehicle's drafting zone or to continually communicate to the vehicle to move away.

(b) Definition of Drafting Zone. The term "drafting zone" shall refer to a rectangular area seven (7) meters long and two (2) meters wide surrounding each bicycle. The longer sides of the zone begin at the leading edge of the front wheel and run backward parallel to the bicycle; the front wheel divides the short side of the zone into two equal parts. With respect to a moving motor vehicle, the "drafting zone" is a rectangular area extending 15 meters to each side of the vehicle and 30 meters behind the vehicle.

(c) Right-of-Way. A participant is generally entitled to assume any otherwise proper location on the cycling course provided that the participant arrives in the position first without contacting another participant. When taking a position near another participant, however, a cyclist shall not crowd the other participant and shall allow reasonable space for the other participant to make normal movement without making contact.

(d) Blocking. Cyclists who have established the right of way must not block or obstruct the progress of another participant.

(e) Passing. A participant who approaches another cyclist from the rear or from another unfavorable position bears primary responsibility for avoiding a position foul even if the cyclist being approached decreases speed. A participant must not attempt to pass another cyclist unless adequate space is available and the athlete is confident of his/her ability to pass the other cyclist. All passing is to be done to the left of the cyclist being overtaken unless otherwise specified.

(f) Position. Except for reasons of safety and when no advantage is gained, all cyclists shall keep to the right of the prescribed course unless passing.

(g) Being Overtaken. When the leading edge of the front wheel of one cyclist passes beyond the front wheel of another cyclist, the second cyclist has been "overtaken" within the meaning of these Rules. A cyclist who has been overtaken bears primary responsibility for avoiding a position foul and must immediately move to the rear and out of the drafting zone of the passing cyclist. The overtaken cyclist shall first move completely out of the drafting zone of the other cyclist before attempting to re-pass the other cyclist. In no case, however, shall a participant move into the path of another participant possessing the right of way.

(h) Exceptions. A participant may enter the drafting zone without penalty only under the following conditions:

(1) When entering the drafting zone from the rear, closing the gap, and overtaking all within no more than 15 seconds.

(2) When cyclist reduce speed for safety reasons, for course blockage, for an aid station, for an emergency, when entering or exiting a transition area, or when making a turn of 90 degrees or more; or

(3) When USA Triathlon or the Head Referee expressly excludes a section of the bicycle course from the position foul Rules because of overly narrow lanes, construction, detours, or a similar reason.

If you look at point (e) you'll see that it's up to the cyclist behind you to make sure he is legal.  As long as you're not blocking him from passing you, you won't have problems.  The best thing you can do is stay right, move to the left when you pass, and then get back to the right.  When you are coming up on a lsower cyclist you can be in their draft zone momentarily while overtaking them.  You just have to make the pass within 15 seconds I believe.

If there is a pre-race briefing with the Head Referee I recommend attending it.  I have found that various head referees have different ways of describing enforcement of the rules.  Even though I've been in this sport for many years I've learned new things regarding the interpretation of the drafting rules.

The Saint A's course can be congested but you have to keep your wits about you.