>First of all it makes it very hard for others to estimate your speed

In my experience, the more harrowing near misses with cars have been where they don't seem to be aware that I'm there, rather than that I'm not moving at the speed they expect. If they know that they can't accurately assess my speed, they'll most likely be more cautious.

I've thought the same thing. Some bikers have lights which flash extremely brightly and aimed at eye-level, probably with the idea that brighter things are harder to miss, but whether I'm a driver or a biker, I hate to be behind them since they are painfully blinding.

I wonder whether the best light is two: one which is always on and one which is flashing. Flashing lights are to get drivers' attention even when it is in peripheral vision, and the steady light is for speed/position estimation.

Flashing doesn't need to be on-off. Many bike lights now pulse - e.g. constant light of 700lm with pulse of 1500lm. twice a second.

Patterns are also common e.g. strip of 5 LEDs with 2 on at a time, sequence changes a few times a second.

Anecdotal, but in my experience pulsing lights signfificantly reduce SMIDSYs over solid lights along. (I ride around 2hrs a day, in the dark in winter months)

Even more effective than pulsing lights is helmet lights. When you scan the road you're creating moving light and much more likely to be seen. A quick glance at a motorist waiting at a T-junction to pull out and you've maximised your chances of having been seen.

I second movement being the most effective. When motorcycling at night one of the biggest dangers is cars making left turns across your lane. It's really hard to judge how far away and how fast a motorcycle is moving because there's only one headlight, with cars you can extrapolate based on how far away the headlights are from one another and how much that distance is widening.

The most effective strategy I've found is to do a little waggle if you see a car ahead lining up to turn. The movement catches their attention and makes them realize you're not a car that's really far away

> The most effective strategy I've found is to do a little waggle if you see a car ahead lining up to turn. The movement catches their attention and makes them realize you're not a car that's really far away

My instructor called it the "SMIDSY weave", but cautioned that the car waiting to turn might see your light going in/out of their vision as you flashing your lights and giving them permission to turn across you.

He also talked about creating a triangle of lights (headlight + 2 aux lights either side) as it helped people judge your closing speed, vs. the standard headlight alone.

For those equally baffled over 'SMIDSY': "Sorry Mate, I Didn't See You"

As another thing to consider, my girlfriend gets really bad migraines from flashing lights, and literally has to pull over whenever when an oncoming bike has a strong flashing light.

As a driver no to the last part. Car lights have to light up the road so that we can see things, and at quite a distance too because cars moves fast.

Bicycle lights exists to be visible and draw attention so I don't kill you (last thing I want). That said, blinking lights means I can't guess your speed or whether there is more than one bike. Both matters.

If you wild-assedly guess the speed of a bike somewhere between 0-30 mph, you're probably right, unless it's a serious downhill situation.

Drivers don't need super accurate estimates of bicycle speed; the speed is generally "low, but perhaps faster than you might think, so pad your estimate".

As an extension of that thought, just for fun, the lights on boats follow the pattern for bikes of being seen, not improving your ability to see. If you go out onto a lake in a remote place without a good flashlight, this fact quickly becomes uncomfortable.

>"Bonus:If blinking lights would be a good idea wouldnt cars also have them?" //

Vehicles that need to be seen like police, fire, paramedic, road safety, all have flashing lights. Indeed cats have flashing lights to use when they're causing a hazard.

I suspect you're right WRT difficult to estimate distance/approach speed for vehicles with only a flashing light, but not sure about combinations of constant and intermittent lights.

Bonus: in UK cyclists may use flashing lights but only on clothing IIRC, at least they need separate constant lights on their bicycles.

Rules for cyclists in the UK:

At night your cycle MUST have white front and red rear lights lit. It MUST also be fitted with a red rear reflector (and amber pedal reflectors, if manufactured after 1/10/85). White front reflectors and spoke reflectors will also help you to be seen. Flashing lights are permitted but it is recommended that cyclists who are riding in areas without street lighting use a steady front lamp.

https://www.gov.uk/guidance/the-highway-code/rules-for-cycli...

Blinking lights are certainly getting your attention, but the more recent, electronically flashing variation makes it very difficult for me to locate the position of the flashing light. The flash catches my eye, but when I try to pinpoint it, it turned completely dark, and by the time it flashes again, I am already looking into some other direction. This applies both to bicycles as well as modern police lights.

In old times, police cars would have rotating lights, and I found those much easier to track. So if one uses flashing lights, there should also be some constant level of light to make positioning of the source easier.

> Indeed cats have flashing lights to use when they're causing a hazard

Just spent a minute imagining my cat with his eyes brightly blinking on and off just before he jumps onto my cluttered desk and knocks things over, or starts rubbing up against my feet trying to trip me up; then sadly realised you meant cars...

Slight tangent - some cars do actually have flashing (break/hazard) lights now that kick in when heavy breaking is detected. These definitely catch a drivers attention when they kick in.