A while back someone posted a link to an article suggesting that reflectors on bikes are basically useless, as a car has to be directly behind the reflector in order to see the light reflected from it. I believe it was in a thread talking about removing wheel reflectors.

Last night I was driving home after dark and as I came to the outskirts of a town up ahead I noticed the familiar loop-de-loop of a pair of wheel reflectors. The cyclist was crossing the highway and going down the street I was going to turn on. I think he was roughly 100 yards ahead of me when I noticed the wheel reflectors. Knowing that he was going the same direction I was headed, I was a bit more cautious after I turned, keeping my eye out for him. I saw his red rear reflector and the up/down motion of the pedal reflectors. He had no lights on his bike whatsoever.

The point is, had he not had the wheel reflectors I wouldn't have known there was a cyclist up ahead and going down the same street I was going to turn on. Had he not had the rear and pedal reflectors, chances are I wouldn't have seen him until I was very, very close, and with the headlights of oncoming cars, it could have been a very dangerous situation.

True, it probably would have been better had he had lights on his bike, but there's no mistaking the familiar pattern the wheel reflectors make.

The reflectors reflected light. Thanks for letting us know.

This is in response to the claims in the article that reflectors don't work, implying that you might as well remove them from your bike.

https://www.sheldonbrown.com/reflectors.html

if you're going to ride at night, get a light.

reflectors aren't the right tool.

It's not EITHER lights OR reflectors, it's BOTH lights AND reflectors, together.

I've had this same experience. And the guy was wearing dark clothes.

You can argue the point here al you want, but guys like that (and they are legion) don't hang here. They buy the bike and take it as it comes, with (thank Heaven) reflectors.

yes they reflect light but theyre also pretty much useless, you can sticker that reflective stuff on your bike at it will be more useful

This. I run two front and two rear lights, but I've gotten more comments on how visible my reflective sidewalls and Scotchlite tape on the rims are than any of the lights except the Radbot.

Here's why reflectors are useless in the situation you described.

You were 100 yards (300 feet) from the intersection, when you spotted a bicycle crossing directly in front of you. Suppose you were traveling at 60 mph (90 ft/sec). It would have taken you 3.3 seconds to reach that intersection. In the meantime, the bicycle may have been traveling at 10 mph (15 ft/sec). The bicycle would have traveled 50 ft before you reached the intersection.

Let's further assume it would have taken you an additional 5 seconds to turn onto the street on which the bicycle was headed. The bicycle would have traveled an additional 75 feet. Thus, the bicycle would have been a 125 feet ahead of you at the time you actually turned onto the street.

Wheel reflectors would not be seen by you, once you and the bicycle were on the same road and going in the same direction. Something else would be required for the cyclist to be seen by you, e.g. taillights.

What did the wheel reflectors contribute? You saw the bicycle from a distance, in which the bicyclist was never in any danger. The bicyclist was long gone by the time you reached the impact point.

Better words were never spoken.

They work for cars too. A couple weeks ago, I was driving () on a freeway at 3:30 AM. While I rarely overtake anyone when driving, I came upon a car going slower than I was. I commented to my wife that this guy had the dimmest tail lights I have ever seen, also had some weird white light pointing back at me and if he had headlights they also appeared to be dim. When I caught up to him, I noted that his tail lights were actually just the reflector units, his headlights were just the daylight running lights that automatically come on and that weird white light was from his phone screen (appeared to be Facebook, from the view I had).

Anyway, this moron who was playing with his electronic vibrator while driving in the dark without turning on his headlights was at least reasonably visible because of the reflectors on the rear of his car (inside the tail lights).

But that was a new car. This morning at about 3:15 AM I was passed by an old VW bug that also didn't have its lights on. Those tail light reflectors were a lot more difficult to see, but maybe this is due to the difference between a bike light and car head lights.

And yes, driving at night without using headlights is apparently a "thing" here. No wonder we have so many head-ons and driving off the road fatalities.

Way to be dense; try reading the post next time for some context.


OP, you've touched upon a very good reason why Sheldon is not the venerated saint he is often touted to have been. Half of the article in question hinges on assuming that reflected light is a specular reflection off of a flat CPS surface...the problem here is quite easily and obviously solvable by using a CPS-surfaced reflector which has multiple surfaces at different angles relative to each other. E.g., I wear a reflective belt which provides 360 degrees of coverage with respect to angle of entrance, the buckle notwithstanding of course.


The second half of Sheldon's argument - angle of observation - gives no merit to the high R values of modern retroreflectors. The angle of observation argument is also nearly moot because, like my reflective belt, cyclist's tend to wear/place their reflectors at angles very acute to a car driver's eyes (lifted trucks notwithstanding of course).


I've been wearing said reflective belt in lieu of my rear 3w light for months now, and have noticed no change in how driver's approach me from whatever angle.

Will not help when you encounter a salmon cyclist coming at you at night who also has no light.

Multiple lights for me + reflective clothing(more coverage):
TEMP, 22F or -5C by 1nterceptor, on Flickr

Lights on my Brompton by 1nterceptor, on Flickr

See this thread for more information about changes to "Sheldon's site" and Sheldon's alleged argument.
The Ongoing Destruction of the Sheldon Brown Repository and these specific posts in that thread:

https://www.bikeforums.net/18931796-post1.html
https://www.bikeforums.net/18933864-post15.html

What light were you using? you bike looks like on fire.

But he wasn't going 60 mph... it sounded like a dark residential neighborhood... and in fact the reflectors served their need, perfectly.

Bottom line, they worked... stop trying to set up some screwed up scenerio that the OP did not describe.

Reflectors work... lights work better, reflective tape adds to that and bright blinkies add more...

Frankly I light up like a UFO... and I also have reflectors. Big ones... from the trailer store... where they sell reflectors for vehicles... cause... they work.

But really, reflectors do work. Lights are just better.

I chose 60 mph because that's a worst case scenario to prove my point and the OP noted his location as KS. Had the driver been in a residential neighborhood and the driver's speed been 30 mph (45 ft/sec), reflectors would have been less even useful.

As noted, the reflectors were spotted when the car was 300 feet from the potential point of impact. That translates to 6.7 seconds. The bicycle would have traveled 100 feet (@ 10 mph) during those 6.7 seconds at 30 mph. The cyclist would have traveled even further had he been going 12 or 15 mph.

Missing a cyclist by 100 feet or even 50 feet (had the driver been going 60 mph) isn't a near miss. It's a non-issue. The wheel reflectors provided no information that would be vital to collision avoidance. It was only a false alarm.

This would be the end of the story, had the driver gone straight. The OP stated he turned onto the same street. That turn would take an additional 5 seconds. by which time the cyclist would have been an additional 75 feet up the road. That's a total of 175 or 125 feet in front of the turning car, depending on whether the car were traveling at 30 or 60 mph.

The point is that in a T-Bone situation, the cyclist has to travel 10 to 14 feet for a lane width plus 7 feet for the bicycle length to avoid a collision. That's a total of 17 to 21 feet. The time to traverse that distance is 1.1 to 1.4 seconds @ 10 mph and proportionately less at higher cycling speeds.

Any warning to the driver more than 1.4 seconds from the point of collision is superfluous. The cyclist at his normal, slow travel speed would have passed through the collision zone by the time the driver reached it.

Collision avoidance requires that a warning be given, if there is a danger of collision. The cyclist is in the collision zone for 1.1 to 1.4 seconds. Therefore, the warning should be given when both the cyclist and driver are 1.1 to 1.4 seconds from the collision point. This would place the cyclist 10 to 14 feet to the left (assuming the cyclist is traveling left to right) of the roadway's left edge. It would place the driver 50 to 125 feet behind the collision point, depending on the driver's speed (30 or 60 mph). The tangent of the angle between driver and cyclist at this point is between 0.08 and 0.28 or incidence angles of 4.6 and 15.6 degrees. The wheel reflectors are responsive to incidence angles up to 0.2 degrees.

The wheel reflectors will not reflect back to the driver, when he is within 1.1 to 1.4 seconds of a potential collision because the incidence angle between driver and wheel reflector is too great.

Wheel reflectors perform as follows as a collision warning. The will give a warning, when there is no danger of a collision. They will not give a warning, when there is a danger of a collision. As a collision warning system, what's the definition of "useless."

I put a number of strips of SOLAS material on my bike, especially the wheels, crank arms and pedals, and Glo Gloves on my hands, to compliment my high lumen lighting system.


As a passenger in a motor vehicle at night, the repetitive movement of wheel and pedal reflectors garnered my attention, especially in incidents of a cyclist having a low lumen lighting system, partial lighting system failure, or having no lights at all.

Never understood how one can advocate for lights as a safety device, while removing another safety device for aesthetics sake because they can rationalize a situation where it won't work. It is about as silly as me saying that lights don't help in a side impact, so obviously they are worthless.

Fatuous, pedantic and obtuse "safety promotion" arguments such as that offered by the Vehicular Cycling gurus and yourself on the practicality of bicycle reflectors, that fly in the face of common sense, fit my definition of "useless", as well as counterproductive.

Handlebars: Lezyne Mega Drive
Seatpost: Cygolite Hotshot Pro + Cygolite Hotshot Micro
Helmet: Niterider Lumina Flare(front + rear light combo)

Long Island City, NYC by 1nterceptor, on Flickr

I am not a fan of reflectors. That being said, you can't be TOO SEEN! (Except running 500 watts of flashing headlights on the bike path after dark).

Ok.

On today's city roads it is just not safe to ride day or night without active and passive lighting. Meaning reflectors and lights front and rear. There are more ways for drivers to get distracted today than there were even just 10 years ago. No, reflectors and lights are not a silver bullet but they do increase your odds of being seen. That just may save your life some day.

Your best defense is still your brain with the aid of a rear view mirror on your riding glasses. Your brain should be telling you reflectors and lights......