Why You Should Use Bike Lights Day and Night
Most cyclists think bike lights are for riding after dark. Switch them on at dusk, off at dawn — job done. But if that’s your approach, you’re invisible for some of the most dangerous moments of your entire ride.
Here’s why smart cyclists keep their lights on all day long.
The Danger Nobody Talks About — Dappled Light
Picture a typical UK country road or tree-lined cycle path on a sunny morning. You’re riding through patches of bright sunshine broken up by the shadows of trees and hedges. To you, visibility feels fine.
But to the driver pulling out of a junction ahead of you, the picture is very different.
As their eyes adjust between bright sunlight and deep shadow, a cyclist dressed in dark clothing can effectively disappear. One moment you’re in light, the next you’re in shade — and for a split second, you simply aren’t there. That split second is all it takes.
This dappled light effect is one of the most underappreciated hazards in cycling safety. It happens on sunny days, on rural roads, in autumn when low sun cuts between bare branches, and on urban streets lined with buildings that create sharp light and shadow contrasts.
A bright, flashing bike light cuts straight through it.
Why Daytime Running Lights Work
Car manufacturers figured this out decades ago. Daytime running lights (DRLs) are now mandatory on all new cars in the UK — not because drivers can’t see the road, but because other road users need to see them.
The same logic applies to cyclists. A flashing front and rear light in daylight doesn’t help you see — it helps everyone else see you.
Studies consistently show that cyclists using daytime running lights are significantly more visible to drivers, particularly at junctions where most serious cycling accidents occur.
Topside Bike helmet light
When Are Cyclists Most at Risk in Daylight?
The times when daytime lights make the biggest difference:
- Early morning and late afternoon — low sun creates long shadows and poor contrast
- Tree-lined roads and country lanes — dappled light causes rapid changes in visibility
- Overcast winter days — flat grey light makes dark clothing almost invisible against tarmac
- Wet roads — spray and reflections reduce contrast and make cyclists harder to spot
- Urban junctions — drivers emerging from side streets are often looking for cars, not cyclists
What About Being Seen From the Sides?
Front and rear lights are essential — but they only make you visible to traffic ahead and behind. What about the driver pulling out of a side road to your left?
Side visibility is one of the most overlooked aspects of cycling safety. The majority of serious cycling accidents happen at junctions, where drivers simply don’t see a cyclist approaching from the side.
Brightside’s dedicated side lights are designed specifically for this — bright amber LEDs that make you visible from both sides, not just front and back. Combined with front and rear lights, you’re visible from every angle, in every condition.
Do I Need Different Lights for Day and Night?
Not necessarily — but it’s worth thinking about modes. A light that’s perfect for being seen in daylight (high-intensity flash mode) may be too bright for night riding on unlit roads, where a steady beam is more courteous to other road users.
The best approach:
- Daytime: high-intensity flash mode front and rear, plus side lights
- Night riding on lit roads: flash or pulse mode is fine
- Night riding on unlit roads: steady beam at the front for road illumination, flash at the rear to be seen
Brightside’s lights offer multiple modes so you can adapt to conditions quickly — no fumbling with complicated settings mid-ride.
The Simple Rule
If you’re on your bike, your lights are on. Rain or shine, dawn or dusk, summer or winter.
It takes two seconds to switch them on, and the battery life on Brightside lights means you won’t be caught out — up to 43 hours on a single charge on the Topside helmet light, and up to 34 hours on the Brightside side light.
There’s no excuse not to be seen.
Be Visible. Every Ride.
Brightside lights are designed for exactly this — riders who take their safety seriously, whether they’re commuting through city streets or tackling country lanes at dawn.
Explore the full Brightside range and find the lights that keep you visible all day, every day.
Brightside Bike Light & Bell Set
Brightside Bike Lights — be seen front, back, sides and top. Day and night.
Frequently Asked Questions
Are bike lights required by law in the UK during the day? No — UK law only requires lights between sunset and sunrise. However, using lights during the day significantly increases your visibility to other road users and is strongly recommended, particularly in poor weather or low-contrast light conditions.
What is the best bike light for daytime use? A high-intensity flashing light is most effective in daylight, as the pulsing effect catches the attention of drivers more effectively than a steady beam. Front, rear and side lights together give maximum all-round visibility.
Do bike lights help in the shade? Yes — this is one of the most important reasons to use lights during the day. When cyclists move between bright sunlight and shaded areas (under trees, hedges or buildings), drivers’ eyes struggle to adjust quickly enough to spot an unlit cyclist. A flashing light remains visible regardless of background light conditions.
How long do Brightside bike lights last on a charge? The Topside helmet light lasts up to 43 hours on flashing mode. The Brightside side light lasts up to 34 hours. Both are USB rechargeable, so a quick top-up before your ride is all you need.
Should I use front and rear lights or side lights? Ideally both. Front and rear lights make you visible to traffic ahead and behind, while side lights make you visible to drivers at junctions approaching from the side — where many serious cycling accidents occur. The complete Brightside system covers all four directions.
