Rear lights—when are they too bright?

[Salted_Peanut]

among others, Lezyne offers several rear lights with 400 lumens. Are they dazzling and, therefore, counterproductive for road riding? How bright is too bright for the road?

[Smitters]

Based on some of the moronic drivers and also moronic cyclists who dress in black, never.

[BoRED S2upid]

Aren’t the real bright ones measured in 1000’s now.

Whatever you get make sure you are using 2x front and rear.

[FMOB]

A lot depends upon the alignment, if you dazzle the driver following you then don't be surprised at what happens next.

[Stewss4]

When you are sat at traffic lights with your foot on the brake. 👍

[Master Bean]

The 400 lumen mode is for daytime. Night modes are usually between 50 and 100 lumens. Obviously nothing stopping you using the day mode at night.

[Xenoous]

I have one of these: https://www.knog.com/products/blinder-rear-bike-li...

It's insanely bright, like can't physically look at it bright. States it's 100 lumens, I can't imagine needing anything brighter for a rear light. Maybe the difference between real and fake lumens? My front light is also a Knog branded 700 lumen light, and again, it's fantastically bright. Lights up the road brilliantly.

[cobra kid]

Smitters said:

Based on some of the moronic drivers and also moronic cyclists who dress in black, never.

The young "roadman" on his dodgy e-bike this morning. Dressed head to toe in black. Weaving through traffic on Penistone Road in Sheffield in the dark.

The knobhead was pretty much invisible. He was at a rate of knots and just swerving everywhere.

[BunkMoreland]

Seems to me that we have Schrodinger's bike lights

Too bright is a problem and no lights is a problem

Of course, not like cars don't have LED rear lights and LED matrix or Laser headlamps is it. And lets not even get into the stty "HID" conversions from ebay that have ZERO pattern and are an MoT fail

FMOB said:

A lot depends upon the alignment, if you dazzle the driver following you then don't be surprised at what happens next.

So the answer when dazzled by a bike light (or a low sun. Or fog) is to not slow down or anything. But to just keep steadfastly on the same path and fk everyone else? I do wonder if that's what the Highway code suggests...

Salted_Peanut said:

among others, Lezyne offers several rear lights with 400 lumens. Are they dazzling and, therefore, counterproductive for road riding? How bright is too bright for the road?

I have that very light. And I have it on the Day flash when riding in the dark. Obviously the flashing draws the eye. But it doesn't constantly blind others as there's a very definite "off" part of the sequence. Mines just above the rear brake on the frame which angles it slightly downwards.

https://www.youtube.com/shorts/Vb8m8kjDCvs

[Daveyraveygravey]

Rear bike lights are rarely a problem. Front ones however...can I ask my fellow mountain bikers in the South Downs area to dip their 10 billion candle power front lights when they see another light approaching them? Or maybe aim them at the ground in front of them?

[outnumbered]

Daveyraveygravey said:

Rear bike lights are rarely a problem. Front ones however...can I ask my fellow mountain bikers in the South Downs area to dip their 10 billion candle power front lights when they see another light approaching them? Or maybe aim them at the ground in front of them?

I find bright rear lights a real problem on group rides, especially if they're flashing. I have a clubmate who insists on riding with a very bright rear flashing light that when you go into a darker area feels a bit like you're being continually punched in the face. At least he turns it down when asked. The overall problem is only getting worse as new cyclists seem to think they need bright lights at all times, rather than just when it's dark - fine if you're riding solo, but not in a group.

[OutInTheShed]

BunkMoreland said:

I have that very light. And I have it on the Day flash when riding in the dark. Obviously the flashing draws the eye. But it doesn't constantly blind others as there's a very definite "off" part of the sequence. Mines just above the rear brake on the frame which angles it slightly downwards.

https://www.youtube.com/shorts/Vb8m8kjDCvs

Flashing lights are pretty good at buggering up people's judgement of distance.

[Salted_Peanut]

BunkMoreland said:

https://www.youtube.com/shorts/Vb8m8kjDCvs

That’s a helpful video, thanks.

[BunkMoreland]

OutInTheShed said:

Flashing lights are pretty good at buggering up people's judgement of distance.

True. But the flash I use is not a regular on/off pattern. Its a bit more random 1 small 1 big, 1 small 2 big. Which I guess is designed to help with that.

By contrast I usually run 2 front lights. And have 1 flashing to draw the eye and the other on constant to assist others to judge where I am. Especially when passing side turnings.


Of course, there's the argument that it doesn't matter what lights you have, it only takes one person being a dick and its a problem for everyone.

[irc]

I would suggest that at night it is the flash that draws the eye. It doesn't need to be megabright. Especially when running two rear lights which is advisable. Too bright won't increase safety and is not showing consideration to other road users.

I use Cateye LD610s and Cateye Rapid 3s which are around 15 or 20 lumens which I think is perfectly adequate.

[mie1972]

On our club rides its sometimes a problem - some riders have very bright rear lights.
Been mentioned they should turn them down/swap to a lesser powered one.

But this is only cos we are following wheels at close distance in chaingang - ie after a few minutes it burns the retina's a bit.

If mainly riding solo I wouldnt worry - if a car is behind you for a few seconds its not as big a deal as they will pass you soon enough.