Niles H.

It was found that in a 60km/h speed limit area, the risk of involvement in a casualty crash doubles with each 5km/h increase in travelling speed above 60km/h.



from: https://casr.adelaide.edu.au/speed/

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Does anyone know of any studies of how injury rates and fatality rates increase with increased cycling speeds?

Also, how do injuries and fatalities increase (for cyclists) in relation to increases in motor vehicle speed? Is it significantly more dangerous to be riding on a road when the traffic is moving faster? Is it significantly more likely to result in serious injuries, or fatal injuries?

How steep are the changes? Do the risks double with each 5km/h increase (as in the casr. adelaide.edu study)?

The Human Car

These are good questions but unfortunately good cycling statistics that the experienced rider can use and learn something from are very hard to come by. Currently the young and inexperienced riders overwhelm the stats so it looks like riding on 25mph roads are the most dangerous while riding on faster roads is the safest option. The safety experts explain this as because there are just a lot more cyclists on slower roads but from looking at crash locations in my city, even if I isolate just the major bike commuter routes on fast busy roads they have a lower then expected bike crashes on them but the adjacent roads leading to these routes can have a high density of crash locations.

There have been studies that show that bike club members (and I assume a number of these are faster bike riders) put more miles on their bikes and have fewer accidents then other groups studied. This gives us a hint that it is not the speed of the cyclist that contributes in any significant way to their general safety.

I will also note that most speed limits are set because the way the road is engineered. If you exceed the speed limit you exceed the safety limits of that road. Cyclists on the other hand generally do not exceed the speed limit.

genec

Are not speeds set initially by road engineers with the road metered some time later after a traffic pattern is established?

Aren't roads designed with a certain speed window in mind?

CaptainTandem

Your cycling speed has to be such that you can react to any emergency situation in time to save yourself. Blasting through an intersection at 20 mph is not safe (ignoring the stop sign isn't either). Same thing on a MUP. Blasting along at 20 mph will get you in trouble. I think a lot of bicycle accidents result from too much speed on the bike and not enuf handling skill.

yes

^depends on how you define safe.

The Human Car

Just because you can safely exceed the speed limit under certain conditions does not imply you can always safely exceed the speed limit. To make such an assertion would also be equally ridiculous. It is also ludicrous for a non road engineer to state that they have full knowledge of a given roads restrictive features or other factors that govern the setting of speed limits.

https://www.youtube.com/watch?v=-izycNgKsyA

The Human Car

You sought to qualify my statement and I sought to qualify your statement. It is not putting words in your mouth but only pointing out detail that you failed to cover as you pointed out detail that I failed to cover.

There is a principle in general conversation that you keep points simple unless asked for details. For example, most people will say that they always stop for red lights but that is a false statement because if there was a police officer waving them though an intersection with a red light most people will proceed without stopping. To always provide the full list of exceptions for every point we make in a conversation would make for very tediously long conversations and not to mention boring.

So I am saying that my first statement was an oversimplification and since there is an interest in the details we are merely sharing the details that are of interest to us.

The Human Car

Ahh so you are saying you are being argumentative just to be argumentative without offering any real points at all. Are you advocating for always breaking the speed limit? No, then what’s your point? I honestly don’t get it.

Just because one can safely exceed the speed limit under certain circumstances and one can also go under the speed limit and be unsafe for current conditions does not make my statement erroneous. If you feel differently then that’s fine.

This whole conversation is a waste of time, it is a statistical fact that motorists speeding are causing an increase in accidents.

Oh, I'm sorry, just one moment. Is this a five minute argument or the full half hour?
https://www.mindspring.com/~mfpatton/sketch.htm

MrCjolsen

I'll settle this argument. Cars go too fast. Bikes go too slow.

It is extremely rare that I am going down any road on my bike and feel the need to slow down. After all, the slowest roads have speed limits of 25 mph, which is almost my top speed on my bike. IMHO, if I can't go the speed limit, I need to go faster.

closetbiker

I'm no physicist, but I have read "It's No Accident" by Lisa Lewis recently and in it (if I remember right) she says, the impact of a crash doubles with each 10 mph increase in speed.

Also, she mentions that seatbelts are tested in impacts of 30 mph with a vehicle of the same size (did I remember that right too?). Point is, if a car hits either above 30 mph, or into a larger vehicle, the limits of the belt are exceeded.

I also know that a motor vehicle is involved in almost every death (about 95%) of a cyclist. However, that doesn't mean every collision with a motor vehicle will result in a death for a cyclist. In my province, each year there are about 2,000 (reported) collisions between motor vehcles and bicycles (1,000 of those being claim related crashes) and only about 5 deaths to cyclists. The most common injury category used by The Insurance Corporation of British Columbia in a car/bike collision is - no injury.

I'm not sure if cycling speed has much to do with fatalities as do the impacts with motor vehicles. A slow cyclist can die just as easily as a fast cyclist, and my guess would be that poor knowledge, skill, and lack of observation to avoid collisions with motor vehicles contributes to cycling deaths the most.

Niles H.

Interesting point. Two cars of equal size colliding head-on at 35mph are sometimes said to have a combined speed of 70mph.

But the severity of the impact is about the same as hitting a solid wall at 35mph.

Yet if a cyclist is going 35mph and collides head-on with a car (or an SUV, van or truck) going 35mph, the cyclist can end up (depending on the exact nature of the impact) experiencing something more like the 'combined speed'.

(A close friend actually did this. She was blasting down a hill, went wide on a curve, and collided head-on with a car. She had some serious injuries and a live-in nurse for a couple of months.)

closetbiker

...and consider when people feel nonchalant about driving "just" 10 or 15 mph over the speed limit of 30mph and feeling "safe" because they have their seat belt on.

Speed definitely has an effect, but often a speed where one feels safe is not safe and a device that mitigates injuries are not nearly as effective in routine situations as many people think.

I'm old enough to remember the catch-phrases to get people to buckle up. One was (from a police officer or an ambulance attendant), "I've never had to unbuckle a dead man". Now we know that was BS. Plenty of dead men are wearing seat belts.

The best way, by far, to reduce injuries stemming from collisions, is to avoid collisions in the first place, not to think about what they can get away with in a collision (slow speed, seat belts).