Don't drink and ride.

We a friend do this, they didn't hurt anyone but themselves, and not too badly. And they did hit their head when they fell off , but were wearing a helmet (thus becoming a advocate for helmets..). Still pretty scraped up.

I am on board with this. You can do someone a serious injury while cycling.

Also, you might kill yourself by drunk cycling. And that is likely to have a huge effect on lots of people you care about.

It's just a bad idea all round...

It's a bad idea, but orders of magnitude less of a bad idea than drunk driving. People ditching cars means less drunk driving (even if it means more drunk cycling), as well as less road deaths in general. That can only be a good thing.

If you kill yourself while cycling then you were almost certainly hit by a car, which is probably more likely if you are drunk cycling. But this is also the fault of bad cycling infrastructure and arguably the driver who cannot avoid another road user.

> It's just a bad idea all round...

Drinking alone is a bad idea all around.

Yes, better not to drink alone if at all possible.

Don't most of you points also apply to drunk walking?

The damage is a function of mass and speed. Obviously walking < e-bike << car

To quickly do the calculations:

Walking: 5 km/h * 70kg = 97 kgm/s

e-bike: 20 km/h * 90 kg = 500 kgm/s

car: 50 km/h * 2000kg = 28,000 kgm/s

Wouldn’t joules be more indicative of damage caused?

Just as there is the law of conservation of energy, there is also the law of conservation of momentum. Both explain it equally well IMO.

How can mv and mv² explain the damage "equally well", when one is linear and the other is quadratic with respect to velocity?

The point is the extreme magnitude of difference between a car and a bike/person. This shows it just fine.

Momentum is always conserved. Energy is partially conserved. If it squishes, it will be more like MV, if it bounces, it's more like 1/2 mv^2.

No. The kinetic energy of the car/bike/… doesn't tell you anything because you don't know how much energy gets transferred to the victim until you have applied momentum conservation to the elastic/inelastic problem. So, the right approach would be (in this order): Calculate momenta, calculate how much momentum gets transferred to the victim via momentum conservation, deduce the resulting change (increase) in kinetic energy of the victim. This kinetic energy will be converted into heat (= damage/injuries) in one way or another, so it's the relevant physical quantity for our considerations.

Finally, in case of an inelastic problem (likely with cars, not so likely with bikes or people), you also need to consider the energy loss during momentum transfer. Once again, this energy will become heat (= do damage), so it adds to the aforementioned increase in kinetic energy when we're interested in how much damage will be done.

Energy is proportionate to the square of velocity. So it's:

Walking: 5 km/h * 70kg => 875 (although this is a very slow estimate for a walker) (please ignore the non-canonical units)

e-bike: 20 km/h * 90 kg => 18,000 (I think your estimate for ebike mass might be on the low side at 20kg, but whatever)

car: 50 km/h * 2000kg => 2,500,000 (and that's a fairly low speed for cars! Drunk drivers often drive faster than is wise.)

Everything else is a rounding error compared to the energy of a car.

Initial kinetic energy is not the right physical quantity to look at. Most of that kinetic energy will remain in the car/bike/…, i.e. it doesn't tell you much about how much energy will get transferred to the victim – it merely gives you a bound from above.

More details: https://news.ycombinator.com/item?id=35233887

Realistic estimates:

Walking: 6kph, 70kg => 100J (0.02% of car)

Analog bike: 18kph, 80kg => 2kJ (0.36% of car)

E-bike: 25kph, 100kg => 4.6kJ (0.82% of car)

Car: 50kph, 2000kg => 560kJ (100% of car)

Thanks. Just for the sake of fleshing out the speeding angle:

Car, 64 kph => 164% of car at 50 kph

Car, 110 kph => 480% of car at 50 kph

* * *

it's worth noting that most collisions don't happen at full speed (and combination of velocity matters a lot).

This is awesome, thank you (and ditto for this whole chain of replies).

I cannot believe this is getting downvoted. The reasons cars are inherently dangerous is 99% because they are heavy and fast. Everything we build around that (traffic rules, dedicated lanes, buffer spaces, ...) is purely to deal with this fundamental physical reality.

With great power comes great responsibility. Whether you take that perspective in Joules, Watts, Newtons, kg.m/s, the conclusions are roughly the same. Drivers needs to be hundreds of times more responsible than cyclists or walkers.

The argument above was that you can still hurt a bus driver psychologically by having them kill you. So it doesn't really matter that an ebike is heavier.

The argument above was that you can still hurt a bus driver psychologically by having them kill you. So it doesn't really matter that an ebike is heavier than walking.

Literally just being drunk enough can end up in you being dead or maimed.

From a harm reduction perspective, Drunk Driving -> Drunk Bicycling feels like it reduces the capacity for damage roughly proportionally to Drunk Bicycling -> Drunk Walking. At a critical level, the speeds you can comfortably achieve are reduced at each step, thereby increasing the amount of reaction time available to avoid an incident, reducing the ramifications of an error, and reducing the amount of damage your body has the capacity to do (by nature of the amount of kinetic energy you are attempting to control).

one major difference is that someone who is incredibly drunk can still drive a car at 100kmph, but they can't balance well enough to ride their bike.

Not sure if this is an example of anti-fragility, but it made me think of that. there's def something diff about bikes for this. Get too drunk as a cyclist and you remove yourself from the situation in relatively safe way, just by not being able to stay in control :)

You have to be really plastered to not ride a bike any more. Like a lot, a lot.

That's true, but most fatal car crashes happen for people who are very drunk https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/... reports that in the US, of the 2019 crashes of drivers who had a BAC above .01, 68% had BACs of .15 or higher (and about half were .20 or higher). That's a group that would have a pretty hard time riding a bike at high enough speed to do much damage. None of this is to say that biking while drunk is a good idea. It probably at least triples your likelyhood of being hit and killed by a car. Defensive riding is one of the things I would expect to be significantly impaired by relatively little alcohol, and it's probably dark out which makes everything more dangerous.

That's true, but most fatal car crashes happen for people who are very drunk https://crashstats.nhtsa.dot.gov/Api/Public/ViewPublication/... reports that in the US, of the 2019 crashes of drivers who had a BAC above .01, 68% had BACs of .15 or higher (and about half were .20 or higher). That's a group that would have a pretty hard time riding a bike at high enough speed to do much damage. None of this is to say that biking while drunk is a good idea. It probably at least triples your likelyhood of being hit and killed by a car. Defensive riding is one of the things I would expect to be significantly impaired by relatively little alcohol, and it's probably dark out which makes everything riskier.

The risks you're concerned about are not statistically relevant.

Cool thanks for letting me know. Time to down a 40 and start doing wheelies through high traffic crosswalks.

Safer than doing the same with burnouts in a parking lot.

It's also very illegal to bike when drunk where I live in Germany

Not in Sweden and we have less accidents than Germany.

You are not allowed to be driving anything while drunk in Sweden.

> Not in Sweden and we have less accidents than Germany.

I don't think you got the memo where everyone seems to think getting blind drunk and then getting on an electric scooter is totally ok "in Sweden".

I've had a few near-misses myself with crazy drunk riders on pedestrian streets in central Stockholm; I once interviewed a job-candidate with a cut-up face who laughingly told us he'd crashed a scooter with two(!) friends on the back after a drink night; a friend of mine smashed their hip after a night drinking and then jumping on a scooter.

The rules may be there. The actual reality is different.

You can not be convicted for drunk cycling, but you can still be stopped for recklesness in traffic. Same goes for e-scooters. As long as you do not cause problems there is no legal or social taboo.

Correction: it's illegal to bike when very drunk. In the moderately drunk range, German law is surprisingly reasonable in acknowledging that drunk driving would have been much worse.

Where I live the amount of alcohol allowed in the blood is less than is allowed for driving in the UK

Germany has a BAC threshold where acting stupid while being slightly tipsy is considered worse than acting stupid while being perfectly sober and that is indeed quite low (0.3). This entry level threshold does not distinguish between car and bike at all (pedestrians are fine). That level basically means "go for it, but at your own risk, and if someone else fucks up, you are partially responsible because might very well have have saved them if you had not been drinking".

But the "folk wisdom" of drivers completely ignores that threshold and only considers the next stage relevant (BAC 0.5+, used to be 0.8) and this only applies to motor vehicles. For cyclists, the next threshold does not happen before BAC 1.6. I suppose that wouldn't exactly be allowed in the UK either?

In the UK there are not these thresholds. If you have too much BAC, it's immediately really bad.

You can hit a pedestrian

However, there's a good incentive to not hit pedestrians. In collisions with pedestrians, cyclists often get more injured and surprisingly, pedestrians are more likely to be to blame for the collision (e.g. stepping into a road or cycle lane without looking).

Nice suggestion, but drunk-cycling is self-limiting in a way that drunk-cycling is not. Drunk-driving you are seated, and only need to be barely conscious. for drunk-cycling, you still must be sufficiently functional to balance on a bike, which puts a bit of a floor on the level of perceptual and cognitive function available, in addition to the far lower bike vs car ceiling on available momentum to do damage.

Not recommended, but cycling is a very substantially less-worse choice, absent getting another ride.

True, I remember watching a guy "cycling" drunk, and he was just walking with a bike between his legs.

> which puts a bit of a floor on the level of perceptual and cognitive function available

Absolutely. I cannot believe people are actually equivocating on this. A drunk driver is hundreds of times more dangerous than a drunk cyclist, it's a categorical difference.

That's correct. Drunk drivers are frequently completely unconscious by the time they crash a car, and can have been for quite a distance down the road. Can't happen on a bike.

One could envision that last beer or shot not having taken full hold when the cyclist gets on the bike. One could also envision balance being sufficient but reaction time not.

Have I crashed my bike at the bottom of a hill while drunk? Yes, yes I have.

The important part, for public safety, is “How many people did you kill/maim?”

Injuring yourself due to alcohol is bad. Hurting others is inexcusable.

I think "self-limiting" is a key point here. People who are moderately drunk are not very dangerous, and people who are very drunk are just not capable of cycling - it requires a certain degree of coordination.

Pretty sure it’s illegal to operate any kind of vehicle on a public street while over the limit in the US. No different than a car. Except, if you get in a wreck you’re almost surely dead.

I once had an office in an only somewhat renovated area of mill buildings in an old mill town in New England. One building always had a number of down at the heels looking bicycles parked outside. Eventually I found out it was an addiction rehab.

There was no public transport in the area. I'd rather have them getting to rehab on a bike than not going at all.

I see lots of folks in the comments assuming what would happen when you bike drunk, seemingly not ever having done so themselves or seen it.

I live in a student city in the Netherlands (Groningen), where most students go out on the town by bike. It's really not much more dangerous than walking drunk. And it's very much preferable to driving drunk.

Thousands of students park their bikes in the city's central underground bike parking spots every weekend. I have never heard of someone dying because biking drunk. The biggest danger for any bike, drunk or not, remains the car. This is also reflected in the enforcement of laws by the police. Although driving drunk, and being drunk in public is not allowed, fining cyclists for this is rarely enforced. Partially because the consequences are not too bad, and partially to make sure people don't drive home drunk instead to avoid a fine.

According to the Dutch central bureau of statistics in 2021, out of all deaths of cyclists 34% are due to losing consciousness, getting a foot stuck in the wheels, making a wrong movement, or due to bad road conditions and slipperiness. Out of this 34%, 72 % is over the age of 70. https://www.cbs.nl/nl-nl/nieuws/2022/37/meer-fietsdoden-na-e...

I once heard somebody describe cycling after a few drinks as the closest thing humans can get to flying.

A friend of mine in college drove down a (very) long flight of stairs with his bike while being (very) drunk. He was severely injured and I very much doubt based on his recollection of what happened that he would a) have injured himself at all if he was on foot and b) even if he had fell on those stairs, he would have had much less serious injuries.

Sure, but you are comparing statistics for an entire country to a specific incident. Of course there's a non-0 risk, but when it's about traffic and safety it's about acceptable, not complete elimination of risk.

It's still illegal in the Netherlands to bike drunk. I'm sure this would be aggressively enforced in cities like Groningen if statistically there were major safety issues Thursdays and Friday nights with drunk cyclists, but this is not the case.

Not to say that your friend shouldn't have walked instead though. Drunkness is also a sliding scale. Luckily with cyclists the chances are way lower of murdering others.

Hitting a pedestrian when riding a bike at 25 km/h has life threatening consequences for the pedestrian. Pedestrians do die when hit by bikers. Especially elderly which have worse awareness around them and are more fragile.

Not even being snarky but if hitting a pedestrian at 25kmh with a bicycle is so bad, how much worse would it be with a car/truck/bus?

I'm sure flying a plane with 300 people on board while being drunk is worse than driving a car drunk. But that doesn't mean it's now OK to drive under influence, because there is something even worse out there you could do while being drunk.

cool. that was not even my intent by asking the question. i was wondering how lethal it is being hit by a car at 25kmh.

It depends on how you get hit and how do you land. Cars builders have pedestrian safety in mind as they get NCAP ratings for it. If you are lucky, maybe not that much damage. On the other hand full frontal collision with a bus is probably not good for you as there is nowhere for you slide or bounce off to lose some of the energy. Bike is similar to bus as there is no way for you to 'gently' (no 'soft' metal to bend or curves to steer you off it) lose some of the energy.

Where do you think cyclists are going 25 km/h while interacting with pedestrians? If it's on a shared pathway they should be going more slowly, if someone fails to do that that's as much their failure as if they hit someone with a car. And if they're on a road/cycle lane and they fail to respect a ped crossing, that's again the same.

If everybody would do everything by the book we wouldn't have this discussion about drunken cyclist.

People here (northern Europe) don’t bike at 25 km/h while drunk, if at all (unless racing/exercising), so it’s not really an issue.

Then I hope you'll never get hit or worse, you hitting somebody else while intoxicated on a bicycle, even if you think is of no consequence.

> but don’t ride a bike.

I'm drunk biking and thought about if I should stop.

But I have never hear about anyone having an accident related to drunk biking. In theory I could run head first into oncoming biker. But I never felt being that drunk in a way that would lose control. That would also make it illegal where I live.