What happens when friends let friends ride drunk?

The most common fatal crash for a sober rider occurs during daylight hours at low speeds and involves another vehicle. The crash that kills a rider who’s been drinking is a solo affair that involves a higher median speed.

Vodka was chosen for the experiment. The first drink was a double (2.5 ounces) and the blood-alcohol concentration (BAC) ranged from .032 to a .043 (for the lighter weight female in the group). The interesting results from the course run after this first drink was all the riders started to become competitive and rode the track faster than they had sober. Everyone’s braking distances were also improved. The experts attribute this to the perception that you perform “better” after a couple of drinks. In reality it is because your inhibitions are down and you feel more confident and are acting with less caution. The problem with false confidence and motorcycle riding is that you probably lack the skill to back up that up. Riders who get profoundly better (smoother/faster) are at the greatest risk for disaster at low BAC levels.  

The next round of drinks was a single (a 1.25 ounce mixed drink). Because an hour had passed since the first round and BAC burn off is .015-percent per hour, the men riders remained in the .03 range but the female test subject’s BAC skipped from .043 to .063 due in part to her lower body weight and in part to the way the female body absorbs alcohol. On the track the same behaviors from before were observed only exaggerated. Some riders felt more aggressive, some were jerkier, and some felt more confident. The control subject, riding completely sober, by now was turning in much faster times and greater efficiency than the test subjects. 

A paper from the University of Washington found while investigating motorcycle accidents where head injuries were involved, “The protective affect of helmet use was lost on the intoxicated group, who sustained head injuries twice as frequently. The mortality following the critical head injury was twice as high among intoxicated patients (80% versus 43%)”. Another study investigated 900 motorcycle accidents in the Los Angeles area and found you are much more likely to die from your injuries when you’ve been drinking, helmet or not. Four percent of the non-drinking riders were killed as opposed to 21% of those who had been drinking.

For the next round of drinks, the test subjects were no longer measuring the alcohol and were pouring their own drinks; some were even drinking straight from the vodka bottle. Drinking negates caution including how much you drink. BAC levels for all but one of the men were above .10; the woman skipped this round of drinks but was still quite drunk. The course runs ranged from stalling, not finding neutral, crossing the lines, and riding too slowly. One subject’s BAC rose from a .033 to .10. He was all over the course lines (simulated head-on collisions, curbs, or ditches). Everyone was more aggressive and competition was fierce. On the course, one rider thought the officials were “out to get me” by adjusting his time for mistakes to make him look bad. When you’re sober it’s easier to separate emotions from actions. When you’re out there on the bike emotions like anger show up in your riding as aggression. By now all the riders fell into the second stage of alcohol intoxication which includes mild euphoria, increased self-confidence, sociability, and talkativeness, but also includes diminished attention, impaired judgment, and loss of control. After three rounds, the female’s BAC was .123.