Serious bike on bike crash. Head on.

[Bobsiii]

Why speed limits on MUPs? Try this.

This sounds like it would have been a lot less serious if the one biker were not going so fast. I ride here often, keep to 14-15 mph and get passed a ton. Hell, an idiot on scooter passed me the other day! I rode here the day after the crash and saw two radar setups, waving cyclists over.

And the point about the infrastructure is dead on.


https://www.denverpost.com/2019/06/...59U29vcE56_w9VmuksHnb6wqjVUyyTIYX9l2R3eY6heqw

 

[AlanDB]

Yikes! What a terrible crash! I hope both riders can fully recover. From the story and comments, it doesn't sound like e-bikes were involved, but still, this kind of story does not help the public perception of cyclists and cycling.

 

[christob]

I felt a pang of relief to read there WASN'T an ebike involved... just an old-fashioned collision of pedal-bikes, where the high speed of (at least one rider) was human-powered.
I don't mean at all for that to sound crass; I'm certainly glad both parties live, and can't imagine the pain and injuries you'd take away from a bad crash like that... but I can't deny the small relief reading the details that for once, it wasn't an "ebiker recklessly speeding" that was blamed for the cause, or even involved...

It is a scary reminder of just how fast 'athlete' cyclists can go, while ebikes are routinely focused on for the "speed problem" on trails; I routinely get passed by higher-speed pedal-bikes comfortably doing 20+ (on local MUT's as well as a popular 3 mile stretch of one-way road I ride, where I'm usually at about 15 or 16mph avg.) The commentary on the Denver MUT capacity and design is spot on -- our trails here, too, are frequently very popular with all manner of users, all ages, all modes of movement -- very much at capacity or beyond (not to mention, not wide enough, nor in places, maintained well enough) and yet, not all cyclists or scooter riders, hopefully knowing this as common sense, adjust their ride through the crowded areas accordingly and sensibly, nor seem to obey the posted (granted, not at all easy to spot) MUT speed limit of 15mph.

 

[Mr. Coffee]

We should all keep in mind even with a 15mph speed limit a head-on collision can do the damage that a 30mph collision into a stationary object would do -- which is easily enough damage to send you to the ER.

In addition to enforcement efforts and improving infra, it seems like this trail is a good candidate for adding traffic calming elements like bollards that would make a 15mph limit self-enforcing.

 

[Bobsiii]

\

In addition to enforcement efforts and improving infra, it seems like this trail is a good candidate for adding traffic calming elements like bollards that would make a 15mph limit self-enforcing.

I hate the speed racer crowd when they show up on MUTs but despite the role speed played in the severity this crash I don't think it had much to do with causing the accident; I think the extreme multi-modal nature of the traffic on this path and the crowding in the area of the accident - Downtown - have a lot more to do with the problem. I'm not a fan of bumps and bollards, I think the whole metro area needs to figure out how to deal with the changing transportation landscape, with an eye to safe accommodations for all. There is a Regional Council of Governments but I haven't heard anything from them in forever.

 

[AlanDB]

We have probably all seen videos of the masses of people in Asia and Europe riding bikes on very congested bikeways in a very organized, controlled and safe fashion. So we know it is possible. I think proper infrastructure has a lot to do with it, but also riding experience and a culture that promotes respect for everyone using the public facilities.

 

[Toomanycats]

Horrifying. I hope the gentleman makes a full recovery.
I’ve said it before and I’m sorry to be repetitive. It’s not just speed, although that contributes. I’d rather deal with a fast rider that keeps a straight line, has good control of the bike, and knows what they’re doing. It’s the oblivious rider that veers all over the bike lanes (or the little kid not being watched by their parent riding their bike all over the place) the worries me.
That being said, I don’t know why the lady on the beach cruiser went out of the lane. Maybe she was trying to avoid yet another rider, although it sounds like she was riding next to another rider or trying to pass, and they collided.

 

[Over50]

Horrific crash. I can see this happening on my local greenway. Common are the meandering, casual riders who stray around the lanes, have no mirrors, ride multiple abreast. Common as well are the roadies in pairs or groups approaching pedestrians and casual cyclists at speeds easily around 20 mph. Common are the dog walkers, walking in the bike lanes looking at their phones whilst the dogs are running to and fro on their long leashes or even unleashed. Common are the little kids, excited to be out on a summer's day, darting around their parents like squirrels. Common are the youth standing in the bike lanes in front of a mural staging a selfie ... Speed on the MUP in those conditions is not a wise choice.

 

[Toomanycats]

sorry but that's not how physics work, there's no difference if you hit a stationary object at 15mph, or if you hit a 15mph cyclist head on while riding at 15mph.

Also, there was a recently settled lawsuit by the City of Tacoma after an older man hit a bollard (White, so it was tough to see) and became a quadriplegic
https://www.thenewstribune.com/news/local/crime/article180086061.html

 

[harryS]

The story is sad. I hope both recover.

Not to cheapen the thread, but there's a diff between hitting a wall at 15 mph and you and another cyclist hitting each other at 15 mph. Just calculate the energy. You hit that wall, you dissipate all your energy. Two of you hit each other, kaboom, twice as much energy.

 

[Deafcat]

sorry but that's not how physics work, there's no difference if you hit a stationary object at 15mph, or if you hit a 15mph cyclist head on while riding at 15mph.

Go back to school bud, you skipped the last few years of junior physics.

 

[christob]

It will probably diverge the thread, but two objects of same mass, colliding with each other head-on while traveling at the same speed towards each other, does not "double the energy of the collision" in that way, as intuitive as it feels to think it would work like that. Two ideal cyclists (ie, of same mass) hitting each other head-on while traveling at 15mph each, will each experience a similar impact as if they'd each hit an ideal, solid cliff-face of stone, while traveling towards it at 15mph.

 

[dAz63]

It will probably diverge the thread, but two objects of same mass, colliding with each other head-on while traveling at the same speed towards each other, does not "double the energy of the collision" in that way, as intuitive as it feels to think it would work like that. Two ideal cyclists (ie, of same mass) hitting each other head-on while traveling at 15mph each, will each experience a similar impact as if they'd each hit an ideal, solid cliff-face of stone, while traveling towards it at 15mph.

MythBusters episode where they ran two cars into a wall, one at 50mph and the other 100mph, then they ran two cars head on at 50mph and the damage was equal to the car that hit the wall @ 50mph.

 

[Deafcat]

Try it with bicycles some time, not an arbitrary test with advanced vehicles engineered around crash protection. While it may be true that two opposing moments may result in effects similar to hitting a stationary and fixed obstacle, it is NOT the same as say, hitting another stationary cyclist. the damage is much worse when they are both colliding head on at matching speeds, compared to one moving cyclist colliding with a stationary cyclist.

 

[6zfshdb]

Not good news for the cycling community. My prayers go out to the riders involved.

The thing that upsets me the most about the article is the comment about cycling groups protesting enforcement of the speed limit?? These folks are breaking the law and have the gall to protest when they get caught??

 

[Deafcat]

However, we're talking about head collision when somebody else come towards you at the same velocity.
The argument here was a 15mph + 15mph = equivalent of hitting a wall at 30mph. Which is not true.

What I'm saying is that from a physics perspective, the collision energy of two head on cyclists is similar to a moving cyclist of the combined velocity hitting a stationary cyclist in the same orientation. You're correct that it's not the same as hitting a fixed wall at that speed, though.

You may certainly disregard my original comment about high school physics though! Cheers

 

[GregGritton]

Not to cheapen the thread, but there's a diff between hitting a wall at 15 mph and you and another cyclist hitting each other at 15 mph. Just calculate the energy. You hit that wall, you dissipate all your energy. Two of you hit each other, kaboom, twice as much energy.

There is twice as much energy, but that energy is absorbed by 2 cyclists instead of 1. The wall, if it is truly inflexible, doesn't absorb any energy. (Real walls have at least a bit of give, but not necessarily very much.)

 

[6zfshdb]

Not a pleasant thought but there is also the factor of being pierced by broken pieces of bike.

 

[tomjasz]

Not good news for the cycling community. My prayers go out to the riders involved.

Exactly. But when one of the most viewed forums for kit builders and the sponsoring company insists high-speed eBikes are what the cool kids ride... well here we go... down the road to regulations.

 

[tomjasz]

15mph isn't hard to break, ebike or not.
people can run faster than 15mph and get ticketed for it.

Oh for crying in the beer. 15MPH is fast enough on ANY multiple use path. I swear if I read one more 30MPH kit builder using a Walmart bike... I'll implode. There IS NO bike frame on the market designed to kit and run 30-35MPH. I do get that I've veered off the topic at hand, but having ridden a dozen bikes with kits, not even the disc brake models offered a level of braking one should have. I have written this before... NO ONE rides and tests braking distance or practices panic stops or avoidance swerves. Basic stuff when riding a scooter or MC. And now that eBikes are running at 50cc speeds it's even more important.