Yes we are all confused about twilight – but set aside the vampire saga for a moment.

I’m about to take a new route to my new job and want to do some forward planning.

I will be off-road on unlit paths and trails – I have off-road lights. I’m looking at charts of sunrise/set times.

It seems to me that out of, from lightest to darkest, Civil, Nautical and Astronomical twilight, if my ride ventures into civil twilight I’ll need lights – maybe before if it’s cloudy, or I’m in the trees, unless it’s winter and the trees have no leaves.

Is there any rule of thumb I can use for planning – such as 30 mins before civil twilight I’ll need to bust out the big lights?

I could just observe the sky for a couple of days (not forward planning) – but wonder if anyone knows the answer.

😯

Legally do you need to use lights off road?

I’d use lights all the time, small ones at least.

why plan? why not just have the lights on your bike and turn them on when it’s dark?

A garmin or BBC weather page will tell you sunrise/set times.
I leave home @ 0640 for my 13 mile offroad commute & I used my lights for the first time yesterday since Easter.

but wonder if anyone knows the answer.

Just put the lights on your bike.

If worried about them getting nicked then either use quick release mounts or non-quick release mounts. If secure mounted, and have a seperate battery pack, take battery with you after locking bike, to make stealing light less worthwhile.

Having just completed a 24h race (5 man relay, I’m not that ‘ard 🙂 ) I am currently of the opinion that several lights are better than 1 :

– You can run them all on low power most of the time and the batteries will last way longer
– You have some resiliency if one goes pop
– You can get a combination of helmet mounted and handlebar mounted that is useful (and if something breaks, a helmet mounted is really good for fixing stuff on the trail because it lights up what you’re looking at – try sorting something out whilst holding the light with the other hand…)
– I’d have a least one light with me at all times. Think a quick drink after work, think an issue that means you leave later than planned, think horrific thunderstorm…

Screw all the nonsense about twilight, I got caught out on a 25 minute lap thinking I’d have loads of time; it was pitch black in the forest parts by the time I’d finished, but still light enough in the open. At the very least one on the helmet all the time that I’d turn on if needed in your situation.

I usually plan that it’s dark approx 25-30 mins after the time advertised as sunset.

^Ditto.

Sunset is 8:00 here. Need lights (off road) before 8:30.

Cheers guys,

I have QR lights (2 of, one bar mounted, one helmet mounted)

From what @snaps is suggesting there is some (Civil) twilight riding to be had without lights – unless I go in the trees (cheers @orangespyderman).

After looking at sunrise times – I’ll plan to fit lights from around mid-September – should see me right until late Feb

After looking at sunrise times – I’ll plan to fit lights from around mid-September – should see me right until late Feb

Fit them now, every chance of a dull, grey or cloudy/foggy/wet day where having some more light or being seen by other users will be great, not having them will be annoying, yep in the time it took to write the post and wait for an answer you could have fitted them already 😉

why plan? why not just have the lights on your bike and turn them on when it’s dark?

Woah there! That’s utter madness.

In addition to all the above, for bicycles lights (and reflectors) are required on a pedal cycle on the road between sunset and sunrise.

For motor vehicles, lighting-up time is defined as from one half-hour after sunset to one half-hour before sunrise.

Is there any rule of thumb I can use for planning

There is yes. Plan that if you can’t see owt, turn your lights on.
I keep re reading the op but can’t seem to work out how there is a problem with just turning lights on when it’s dark. What are you actually planning for? 😀

Could we include wood burners and artisnal trousers. Peak STW would then be achieved.

As others have said, not sure that you need to do much detailed planning on this one – take your lights and regarding when to use them, use your integral light sensors – you should hopefully find a couple of them somewhere near your nose.

You actually need to think about this?
Too many variables (cloud cover, sunset, woodland etc) to get an accurate time of when to light up.
If in ANY doubt take your lights.
Seriously, use your own judgement, twilight is irrelevant.

I had the same issues as the OP.

Erred on the side of caution and just put the lights on when I thought it was getting a bit dim.

Imagine my embarrassment when I realised it was only 11a.m. after I removed my sunglasses. 😳

For road riding I would tend to switch lights on about half hour to hour before sunset depending on how overcast it is.
Offroad depends on how overcast it is and also if I riding through somewhere with a thick tree canopy.
Basic lights (eg commutable and slow offroad) tend to get stuck on the bike when heading out soon as the nights draw in. Then add on the good lights as needed. So if heading out say hour or so before sunset or going for a long ride they go on. Then switch them on when i cant see well.

Overthinking something has just been taken to the next level 😆

I could just observe the sky for a couple of days

Do this. Lying on your back in a field. Plot your findings on a chart and post them here for our delectations.

Off road commuting tracks I consider it a challenge to keep the lights off as long as possible.

Civil, Nautical and Astronomical twilight

We use ‘ride leader chooses’ on group rides. It avoids everyone else arguing over when lights go on.

at this time of year the amount of cloud cover makes more difference to visibility under trees etc than a few minutes change in sunset times.

Probably need to check moon phase and moonrise and potential for cloud cover
I’d rule out planning for any events “brighter than a thousand suns” other than maybe staying at home for a final nice cup of tea

Just fit them when it’s at all gloomy. Don’t overthink it.

Having lights on when it’s not that dark is nothing. Not having lights on and risking someone hitting you – that’s serious.

Get a dynohub and forget about all this nonsense forever 😉

So these are lights to see with, not to be seen by (as you’re off road)

Then doesn’t it depend on if you’re on open moorland or tight twisty wooded singletrack

Personally, I’d always carry a light anyway. What if you need to stop (puncture, mechanical, shop) and then need to get home later than planned?

This makes my overthinking somewhat amateur 🙂

Perhaps we need an app that will be linked to lights that detects whether the rider is on or off road, and if it is dark or not, and turns them on and off accordingly.
Additional features could include altering brightness to suit conditions/length of ride, reminders to charge them…

Or you could stick to using a finger and grey matter.

What about full moon conditions? I’ve ridden for miles before in the middle of the night with my lights off.

Have you factored in light pollution levels where you will be riding?

Don’t think the OP has allowed for the reflectivity of different types of vegetation either.