How much power do we really need in a tail light?

[Phil4000]

Bicycle light s have changed a fair bit, in the long break I've had. One thing I've noticed is that lights have got a lot brighter.

How many lumens are sufficient for a big city? I don't want to be one of those cyclists with blinding, irritating lights but as cars have got more powerful and people have become less aware, I wish to be safe.

Am considering the basic cateyes, the viz150 and viz300. Their constant ratings are 20 lumens and 30 lumens respectively.

 

[MontyVeda]

In city traffic your little rear lights are competing with lots of bigger rear lights. Your road sense will contribute more to your safety than your lights will in lots of nighttime traffic. Saying that, I'd always advise two rear lights. They needn't be super bright.

 

[figbat]

In city traffic your little rear lights are competing with lots of bigger rear lights. Your road sense will contribute more to your safety than your lights will in lots of nighttime traffic. Saying that, I'd always advise two rear lights. They needn't be super bright.

Agreed. Either one flashing and one static, or two flashing but with different patterns. If this annoys a following driver then at least they’ve seen and acknowledged you.

 

[oxoman]

I use a couple of usb Smart lunar r2s that knock out 30 to 50 lumens depending on settings. I tend to have them either side on my work bike and flashing alternately.

 

[Sharky]

It's contrast against the background that you need. On dark country roads, you don't need super bright rear lights, but in the city, you need to be visible.

Reflective, ankle slap bands or reflective pedals are very effective. Also tyres with reflective tyre walls.

When I was commuting to work, for a while I use a blue flashing light, in addition to the red ones. It may not have been strictly legal, but I never got challenged and a couple of motorists, actually stopped me, asking where they could get one from.

 

[fossyant]

I'm using a Magicshine Seemee 300, with a planet X COB strip light.

The Seemee is used in Smart mode - so, night it's 20LM constant with a fade upto 100LM, then back down, with a 60LM downlighter (this works well). It features a brake function. In daylight, it switches to a brighter pulse mode.

Despite is saying 300LM, that's the day mode, which is ideal for tree covered roads in bright sunshine. The night mode is perfectly acceptable brightness.

 

[nogoodnamesleft]

Would a suitable power depend on whether it's used in daytime or after dark?

 

[T4tomo]

It's contrast against the background that you need. On dark country roads, you don't need super bright rear lights, but in the city, you need to be visible.

Reflective, ankle slap bands or reflective pedals are very effective. Also tyres with reflective tyre walls.

When I was commuting to work, for a while I use a blue flashing light, in addition to the red ones. It may not have been strictly legal, but I never got challenged and a couple of motorists, actually stopped me, asking where they could get one from.

this^^

On my City bike, for commuting thru London, I had 3M reflective tape at strategic bits of the frame forks and cranks (reflective and moving ++) which creative more visibility that any lights do. Also used those tyre fly, illuminated valve caps. I also had a provis gilet in the cooler months - they light up like a Christmas tree in car headlights.

 

[Phil4000]

Thanks all.

Im going to use both for night time city; viz300 on the bike and viz150 on helmet or backpack.
Then swap them around depending on what I'm doing; eg if on a dark country lane or low lit area use the 150 alone. Got a couple of daylight options also, doubt I'd need more than the 150 for daytime but would be nice to have the option for more.

Good point that you are competing with a lot of other lights. Many more drivers have SUV's and are sitting higher. Also, as many cyclists are using brighter lights that's what drivers are perhaps used to, and may fail to notice lower powered lights as much.

 

[Phil4000]

Think I may use a couple of front lights also in the city, on bike and helmet.

 

[MontyVeda]

...
Good point that you are competing with a lot of other lights. Many more drivers have SUV's and are sitting higher. Also, as many cyclists are using brighter lights that's what drivers are perhaps used to, and may fail to notice lower powered lights as much.

Never underestimate a driver's ability to fail to notice anything, not matter how big or brightly lit it is.

 

[Binky]

I have the Cateye Viz 450 and on hyperflash I can signal distant planets.

 

[N0bodyOfTheGoat]

Using a low-moderate Lidl "shield" in static mode from 2020 and a retina burning Moon Nebula in flash mode from ~2018, on this summer's sunset rides.

 

[Dogtrousers]

+1 for running 2x rear lights for redundancy. It's hard to know if one of them has failed, or fallen off.

I use cateye omni 5s

 

[Sharky]

I'm not keen on helmet lights.

To me, they don't present a steady image of a cyclist. When the rider turns their head, the light to the car behind can momentarily disappear.

Off road is a different case, as the light points to where you look, which is a bonus.