To Flash or Not to Flash?

To Flash or Not to Flash - Lights.

When it comes to bike lights I believe the back and the front do not require the same approach. Sure, this is my opinion and therefore does not make it the only way to use your lights. I hope that my opinion will help to enlighten cyclists to make a more informed decision of what would offer them the best use in different scenarios. I have considered this from various points of view and have tried to recall as many moments, that I have personally experienced, in order to reflect on situations others many not have considered. One of the reasons I felt the need to talk about this is that in the event of an incident or accident you may find that the law or regulations may be against you due to the small print.

Question: Should lights be used on flashing or steady beam mode?


Road Vehicles Lighting Regulation states that both front and back lights must be used between sunset and sunrise. The front must be a white light and the back a red light. Both beams should be steady beams unless the light only has an intermittent function, thereby suggesting that if your light has both functions, the steady beam should be used. However, there is a comment that suggests that flashing lights are acceptable too, as long as they conform to regulation BS6102/3.

Let's take a look at it from a cyclist's point of view: I want to see where I am going and have the best opportunity to avoid hazards so I might use the strongest front light I can buy. If I use it on steady beam I run the risk of dazzling oncoming traffic. Now on a public motorised road, my cycle light is not likely to cause as much of an issue as cars lights might, but should I be on an unlit public footpath at night, I am very likely to blind the oncoming cyclist or walker / runner. I may not see that as being a problem, but having been on the receiving end of bright lights I can say that it is not easy to navigate well. I have often felt threatened and become so disorientated due to the bright light, that I've unintentionally strayed into the path of the cyclist coming toward me. If I use it on flashing mode I run the risk of rapid pupil contractions and expansions to both cyclists and or footpath users. Apart from causing a possible collision hazard, I also don't afford my eyes the best opportunity to see other hazards in my path because of this constant adjustment to the changing light.

A back light used, whilst on a public footpath, is less of a concern in that it is unlikely that something will be coming up behind me so fast that I am in danger of a collision. Back lights are also less likely to cause blinding or dazzling.

When on a motorised public road, and in particular built up areas, my small back light, if it is burning as a steady beam, might get lost in the surrounding lights whereas a flashing light has more of a chance to attract attention.

Question: What to do?


Invest in 2 sets of lights. One set to be used in steady mode, allowing me a clear uninterrupted vision of the road/path ahead. This will satisfy any regulations and not allow that clever lawyer to have me on a technicality. The 2nd set is to be used on flashing mode to draw attention to myself. I don't often use a strong or bright flashing front light due to the reduced vision when looking into a strobe light that other road users may experience, but I do tend to use a strong flashing back lights when on a motorised public road. I often use my lights on flashing mode during the time of low ambient light. Although the light does not offer me any visibility advantage, it serves to attract attention to the fact that I am on the road. The flashing front light is not intended to only attract the attention of oncoming traffic, but also to make me more visible to traffic joining from a side road or driveway. In my experience, and I'm sure the experience of many others, many non-cyclists don't realise how fast a cyclist can travel, and what they see as sufficient space for them to pull out into, is in fact not safe. Or at times they look but don't see.

There are many other regulations relating to visibility and the use of lights on bicycles so have a read Here.


By Coach Trevor

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