flangehead

First off, thank you for the discussion and I have changed my behavior as a result.

I have examined the lights I use for DRL. Before COVID, when I was commuting, I only used some low-powered Cateye lights for DRL. With COVID, I rehabilitated some non-utility bikes and I only had mounts for higher-powered Cygolite lights. I have had one case where a pedestrian appeared to shield her eyes from the blinking Cygolite. I see her often and I have been covering the light when I’m near her.

The Cygolites have a mode where the light is on continuously with a bright pulse emitted about once a second. Based on the discussions here, I’m going to start using that mode for my Cygolite DRL. (I could look at the Cateyes all day long; they’re pretty low power.)

More and more, the lights I buy have these modulating modes like the Cygolite. I bought a Planet Bike rear red LED and it has 4 modes, from full on to only pulsing. In one of the intermediate modes there is a portion that ramps up and down on about a 6 second period. I think that is good variability for a driver that is coming up behind me as they have much more exposure than an impatient driver who is only going to glance before making a turn to/from a side street. Anyhow, the manufacturers appear to be adding flexibility in how their lights present and that helps.

I have read through this article and have several observations.

First of all, the article is addressing flashing lights at night. I agree that flashing lights at night should not be used.

There are two mentions of usage on roads. The need for a continuous light to judge distance is only a night issue. Then, there is where Eric discusses the “moth effect” which I suspect is also much stronger at niight. It seems unlikely to me that an oncoming motorist either in the opposite lane or making a left turn in front of me is going to be drawn to my DRL, either in solid or flashing mode. It seems much more likely that opposing traffic will continue. The primary benefit of a DRL, flashing or not, is increased visibility to turning vehicles, reducing the chance they will pull out because of SIDSY (sorry I didn’t see you).

Regarding seizures, the first mention is that some people felt "ill and disoriented" but the reference goes to dead links so I don't know the situation. They didn't say it caused a seizure. The mention in the article that blinking red taillights up close can cause a seizure is on full reference not as alarming as the sound bite:
Furthermore, I’m not finding any indication that the “non-flashing” regulations are due to seizures. The current German rules allow blinking lights that are not affixed to the bicycle. https://www.pd-f.de/2017/09/27/ein-l...euchtung_11822 using Google translation.

Unless I see something more convincing, I think the risk of me inducing seizures in bystanders with my DRL during the day is Powerball odds.

This did lead me to an interesting article, which again primarily addresses the clearly demonstrable problems with flashing lights at night. https://bikeshed.johnhoogstrate.nl/b...ight/blinking/ This is an article that uncategorically rejects flashing lights on the basis that there is no proof they help but are annoying. No distinction is made between daylight and night operation. The article contains an extensive excerpt from a 2008 TNO (Netherlands research institute) study that concluded “in most cases flicker [blinking] raises the conspicuity of front lights” but then later recommends they not be used. Unfortunately, the link to the study was broken for me. Based on the summary, it sounds like it was a careful and considered study and often the “sound bites” don’t represent the real results. It would be very interesting to see what that study showed for daylight operation. Anyone have this study? I couldn’t find it anywhere.

I looked at the law and it applies to highways. Does it apply to MUPs?

I found this website interesting: https://swhs.home.xs4all.nl/fiets/te.../index_en.html My (quick read) interpretation is that Germany’s regulations are very prescriptive. Sounds like the CPSC helmet regulations here in the US, where the rules tend to preserve in amber the technology in place at the time of adoption. This can have the unfortunate effect of increasing cost and/or making better technology unavailable. I have two early-generation Phillips Safelite headlights that they dumped on the US market for $80/each; the normal price I believe was $140. They have a great light pattern and I’m doing all I can to preserve them .. I really like them .. but .. a lot of our utility cyclists are poor; they are on a bicycle at night out of necessity, not choice. It’s very easy to get regulation wrong and end up putting more people at risk.

Interesting. UK cyclist fatality rate is very comparable to Germany’s. Both are about half that of the US. Pretty unlikely that flashing LEDs have much explanatory power for any of that. Though the Europeans may be doing better, they are not necessarily infallible.
So where I’m at now is that that I don’t see the epileptic seizure as a valid reason for not using blinking DRL, both front and back. I keep seeing people cite this and it is a canard wrt DRL.

I know from my own experience that a flashing light shows up in my peripheral vision better. Much of my commute is on 40-45 mph posted roads, which is unavoidable, and my objective is that no one gets hurt on my trip. The specific target for my front flashing DRL is motor vehicles turning across or into my lane. (And the DRL is just one slice of my swiss cheese.. I'm watching for eyeballs and ready to make an emergency stop.. and I've got on a helmet.. more slices means less chance the holes line up...)

I’m not seeing that annoyance of some people as sufficient reason for a blanket condemnation of blinking DRL.

I appreciate the discussion and remain open to new information.