Cyclists: blinding tail lights make you less safe

You need to be visible – you don’t need to be obnoxious.

Why are we obsessed with the idea that brighter is better?

First, forgive me – put your driving hat on! Do you think the safety of your car could be improved if you drove around town at night with your high beam headlights?

Probably you’d agree that this would be counterproductive (and nobody does it).

So let’s think about the back of your car. Would you drive around town at night with your rear foglight on because you felt it made you safer? No (and again, nobody does this).

blind_3

What about traffic lights? Making them twice, five times or ten times brighter than they are? (Maybe we could recycle the bulbs from car foglights when they’re scrapped to make traffic lights really hard to miss?)

News flash, people who shoot red lights already know they’re red…

You’ve probably figured out that I’m asking why we don’t seem to apply the same logic to the back of our bikes. There, “the brighter the better” seems to be the rule of the day, and it’s interesting to wonder why.

Rise of the dynamo

From 80’s “never-readies” to the current age of laser death beams, I’d always gone with the flow and bought successively brighter and badder lights for my bikes.

That is until I decided to go for a dynamo when I got into audax a few years ago.

Instead of packing multiple 1W LEDs, in dynamo tail lights you have a design which burns a mere ~50mW (0.05W) and has some clever focusing or diffusing technology. I admit I was unsure – my commuter at the time had three separate Smart Superflash LEDs on the back.

But after countless thousands of miles in all weather and all conditions, from urban streets in rush hour and pub closing time to deserted glens, I’m more or less convinced that drivers can see dynamo tail lights.

In case this is starting to sound like a dynamo commercial… there are lots of great reasons not to use a dynamo!

It’s just that the visibility of the nice steady tail light simply isn’t one of them.

dscn08472
Official product shot of a 500 lumen tail light “in a country lane at 20 metres”. Good luck judging anything as you overtake…

Obnoxious tail-lights are counterproductive for safe cycling

Despite all the obvious counterexamples, people definitely seem to think that brighter tail lights are safer.

A quick Google and you’ll find such gems as “SAVE YOUR Life, Ride Ultra BRIGHT, DAY And night” … followed up by “If you can look directly at the light, it’s not even close to being brite (sic) enough”.

Not only do I disagree, I think that running an epic tail light is actively reducing your safety on the road.

I was driving through Edinburgh recently at dusk when a rider joined the road up ahead. I was some way off, so he was perfectly safe jumping on, and he proceeded at a reasonable pace. Maybe it’s just been a while since last winter, but I found his rear light to be ferociously bright – just painful to drive behind.

Rather than wait behind as we came up towards a pinch point for a railway bridge, I found myself dropping a gear and accelerating hard to get past. I didn’t cut it too fine, but since this is my commute I know that I’d have been shaking my head.

Inevitably, I had to queue to turn right at the T-junction ahead and after maybe twenty seconds the rider had filtered past and I was being blasted by the red howitzer once more. I’m not sure of the brand – it had a regular flash going on but also an off-tempo nuclear strobe effect.

What happened to this rider with the ultra brite light on the next bit of open road?

Let’s just say that neither of the drivers in front of me wasted any time in ripping past him as he climbed the shallow gradient, even though it was tight with oncoming traffic. Neither did I, and neither did any of the cars I caught passing him in the rear-view. I’m probably the only one who felt guilty about it, too.

If this guy bought his light on the basis that it would make him safer, then he really ought to ask for his money back!

blind_2
A headlight. It is not a tail-light. There are big differences!

There is an optimum brightness for safe riding.

A tail light just needs to be bright enough that motorists notice you (and can account for your course and speed). You blatantly don’t need an atomic tail light to achieve this – just look at the huge number of cyclists who have either no lights at all or the bare minimum.

While I’d never advocate it, casualties from the practice are astonishingly low. If you pop out in your car, you’ll quickly reassure yourself at how easy it is to spot riders with even pretty pathetic tail lights.

After that you’re relying on goodwill, and who ever thought that brighter lights create goodwill?

There’s a strong argument for brighter headlights in safety terms, but tail lights aren’t headlights and there is a vital difference between them.

When you increase the power of your front light, you are incentivising other road users in a way which promotes your own safety – motorists in oncoming vehicles (and those at side streets) have to actively decide that you aren’t as big as you look, and to actively decide to put themselves into your glare when waiting for a couple of seconds puts you out of the way.

Uber tail lights also incentivise other road users, but they do not do so in a way which is beneficial for you. Drivers who find your light unpleasant are rewarded the faster they get past you, and it’s no secret that other cyclists don’t like riding behind Joe Death Star.

Conversely, do you really think that taxi drivers who cut past you in the city’s bus lanes would decide to be more responsible if only you had more photons at your disposal? They’re actually deciding based on a layman’s knowledge of bike lighting that you do or don’t deserve a legal amount of space? Really?

No, it’s simply faulty thinking to imagine that a brighter tail light will get more attention and more consideration from other road users.

You need to be visible – you don’t need to be obnoxious.

Cateye TL-LD1100 rear light review

A big light with ten(!) LEDs, the Cateye LD1100 has great battery life and a variety of modes, some more gimmicky than others…

Bulky but long-running 10 LED lightfest

The Cateye TL-LD1100 is the brand’s top-of-range rear LED light. It makes use of a whopping ten LEDs (some rear, some side-facing) and takes full-fat AA batteries to give outstanding runtimes.

Currently Chain-Reaction are doing 14% off while Wiggle have it on a 10% discount.

I’ve been commuting using dynamo lights for some time now, but my better half has made do with a few different battery rear LEDs since we own so many rear lights of various ages!

As it’s quite a costly option, the TL-LD1100 has stayed on as a backup light for longer than you might expect, and before that served as primary light for a year on our shared 12 mile commute.

cateye_ld1100

Mounting

The Cateye TL-LD1100 is not a clip-on style light – you must use one of the Cateye mounts (although you can get hold of a belt clip adapter mount if you want to use it this way).

The TL-LD1100 does not come with Cateye’s newer flex tight brackets – probably because it’s just too heavy. You will need to keep coming back to check your mount as there have been numerous reports of lights dropping off.

Ours uses the rack mount adapter, working around this problem.

The physical size of the TL-LD1100 may seem intimidating but in fairness it is fat in every dimension, so at least you avoid the difficulties presented by the TL-LD600 strip light.

Beam quality and strength

The Cateye TL-LD1100 has two buttons and a total of 24 modes – four modes per button, the buttons being independent in operation.

In much the same way that you don’t worry about how many modes your car lights have, I’m a bit “meh” about anything other than plain old “on then off”…

The side-facing LEDs are a nice touch. While there are limited situations in which a driver is likely to be targeted by them, it’s certainly reassuring to know that you’re spraying red light in every direction!

One of the biggest annoyances with this light is that if you just want all the LEDs to flash, each “half” of the TL-LD1100 operates at a slightly different speed, so it slowly changes from all flashing at the same time to perfect counterpoint (i.e. effectively non-flashing at half-strength) and then back again.

This will drive you mad if you’re riding behind!

The LEDs are not ‘power LEDs’ (as found on, say, the Smart Superflash and similar lights). However, there are so many of them that, combined with the use of full-size AA batteries, the Cateye TL-LD1100 remains a very bright light indeed.

Depending on the mode you use, the TL-LD1100 is a borderline mega dazzler. Making it unpleasant for people to drive behind can definitely encourage them into a rushed overtake. It’s not as bad as many of its competitors, however.

The TL-LD1100 does allow you to run only half the light at a time, reducing glare (although then, why aren’t you just running a cheaper light?).

It’s important to mount the light completely level, as designers depend on this when working out off-angle visibility and other factors. Do not point it at the ground by mounting vertically on the seatpost!

Because the Cateye TL-LD1100 hasn’t passed the relevant tests it isn’t road legal when used on its own (in any mode).

I’ll write more about this separately, but unless you go for a dynamo (all dynamo lights are genuinely road legal), it’s true of pretty much anything a bike shop will sell you.

Useability

The Cateye TL-LD1100 has two small rubber buttons to one side of the case.

You have to count many different presses to take the light from ‘off’ to your chosen modes, and a different number of presses to turn it off again. I actually found this surprisingly frustrating!

Battery life

Unlike a great many of its rivals, the Cateye TL-LD1100 runs on two full-size AA batteries.

This gives it fantastic battery life despite the large number of LEDs – 50 hours steady and 100 hours flashing. Remember that the temperature at which you use the light and the type of battery used both influence that figure.

A word on true brightness

Unlike many ‘power LED’ lights, the Cateye uses full-size AA batteries. It delivers 50 hours on solid from 2x2850mAh cells – (2 x 2850 / 50) = 114mA. The power is thus (0.114 x 1.25) = 0.143W

This is actually more than the real wattage of both the RSP Astrum and Smart Lunar R2 lights!

Durability / waterproofing

The Cateye TL-LD1100 has solid weather sealing (based on all weather mileage), but I have had repeated trouble with the little rubber buttons on the end being dislodged if brushed across the light (say in a pocket or bag, or just a badly-aimed finger).

Trying to get the rubber bit back in to re-seal the button is an exercise in exquisite frustration!

As with all lights, mounting under the seat (combined with a mudguard) virtually guarantees trouble-free operation.

Overall

The Cateye TL-LD1100 rear LED light is a comparative giant – both in size, weight, long runtime and cost.

It is not outrageously bright, especially if you moderate the modes – which is a great advantage if you are a social rider and especially if you don’t subscribe to the simplistic “more watts = more safety” bandwagon. It is reliable but operation can be frustrating due to the millions of different modes, and the fact that each half of the light seems to run to a different rhythm.

The apparent dodgyness of the seatpost mount is a worry. At twice the price of many rivals, this is not a light you would be happy to lose.

Again, Chain-Reaction are doing 14% off while Wiggle currently have it on a 10% discount.

Cateye TL-LD600 rear light review

An older design, the LD600 is reliable and easy to operate, while having the advantage of not being offensively bright.

Distinctive strip LEDs: cheap and effective, awkward to mount

The Cateye TL-LD600 is a distinctive rear light consisting of a single strip of five low power LEDs. An older design, they’re still a common sight all over the country.

Although Cateye have produced a replacement in the LD610, you can still buy the older version of the light for a song. Currently Wiggle have it on a 17% discount, while Chain-Reaction are doing 12% off.

I’ve been commuting using dynamo lights for some time now, but my LD600 is still doing sterling service as an extra rear LED on my Carry Freedom trailer. Since I’ve often lent the trailer out, I’ve been able to check its performance in different circumstances, and it’s still a very effective rear light.

cateye_ld600

Mounting

The Cateye TL-LD600 is not a clip-on style light – you must use one of the Cateye mounts (although you can get hold of a belt clip adapter mount if you want to use it this way).

Rather than a nice jubilee-clip style mount, the Cateye TL-LD600 has a more primitive fixed-size band, tightened by a small metal screw.

Say hello to packing out the mount with tape if it’s not just the right size, and don’t strip that screw head!

(Depending on packaging, you may find that the TL-LD600 comes with one of Cateye’s newer flex tight brackets – a step in the right direction).

Because the light is a long strip, it’s quite easy to use zip-ties or rubber o-rings in a figure of eight to clamp it onto any tube or flat surface (this is how I’ve fitted mine to the Carry Freedom – no risk of loss or theft).

The long strip format does work against the TL-LD600 however, in that you can’t really mount it on a seat stay (it goes into the spokes) or vertically (it’s too long and hits the seatpost or seat stay – forcing you to point it at a crazy angle).

Beam quality and strength

The Cateye TL-LD600 has four modes – three flashing patterns as well as solid mode. In much the same way that you don’t worry about how many modes your car lights have, I’m a bit “meh” about anything other than plain old “on then off”…

The “chasing” LED mode is particularly weak – why would you reduce your light to just 20% brightness *and* let it flash? Crikey!

The LEDs are not ‘power LEDs’ (as found on, say, the Smart Superflash and similar lights). Visibility is OK from behind but the light doesn’t excel at off-axis visibility – another area in which it shows its age a little.

One advantage of not being an insanely bright mega flasher is that it’s much less unpleasant to ride or drive behind someone using it. Making it unpleasant for people to drive behind can definitely encourage them into a rushed overtake. As a driver, I can vouch that sitting at light behind someone with a mega LED flasher definitely focuses my mind on getting past!

The TL-LD600 definitely doesn’t have that problem. Few will want to buck the trend and deliberately opt for a less dazzling light, but it’s certainly an option.

It’s important to mount the light completely level, as designers depend on this when working out off-angle visibility and other factors. Do not point it at the ground by mounting vertically on the seatpost!

Because the Cateye TL-LD600 hasn’t passed the relevant tests it isn’t road legal when used on its own (in any mode).

I’ll write more about this separately, but unless you go for a dynamo (all dynamo lights are genuinely road legal), it’s true of pretty much anything a bike shop will sell you.

Useability

The Cateye TL-LD600 has a small rear button to one side of the case.

One nice touch is that the light is switched on and off with a long press, so you can cycle through modes while riding without going dark. Unfortunately there’s only really one mode worth using..

Battery life

The Cateye TL-LD600 runs on two AAA batteries.

I seem to get much more than the stated battery life (15h steady, 30h flashing) but neither is much to write home about. Remember that the temperature at which you use the light and the type of battery used both influence that figure.

In this area the TL-LD600 does start to show its age compared with newer, high power LED lights that manage more than twice as much battery life (flashing mode) and 50% more on solid, despite being much brighter. See the Smart Lunar R2 or Smart Superflash amongst many others…

Durability / waterproofing

The Cateye TL-LD600 has solid weather sealing (based on all weather mileage on the back of my trailer, 6″ from the tarmac!).

As with all lights, mounting under the seat (combined with a mudguard) virtually guarantees trouble-free operation.

Overall

The Cateye TL-LD600 rear LED light is an older design that’s clearly long in the teeth in some respects, especially battery life vs output.

It is not offensively bright, which is a great advantage if you are a social rider and especially if you don’t subscribe to the simplistic “more watts = more safety” bandwagon. It is reliable and easy to operate.

The light is let down slightly by the awkwardness of mounting it, but at the same time the width of the TL-LD600 can make it more prominent than a single point source (and more useful for drivers trying to fix your position).

There are probably better options, but it’s certainly not one to avoid.

Again, Wiggle currently have it on a 17% discount, while Chain-Reaction are doing 12% off.

Smart Lunar R2 rear light review

Extremely bright and benefits from respectable runtime, the Lunar R2 is also fairly well built and not overly expensive. A good all-rounder.

Two 0.5W LEDs make this another blinder

The Smart Lunar R2 is a small (AAA) rear LED in the clip-on tradition. It benefits from superior construction quality relative to the infamous Smart Superflash 0.5W LED light, but at greater cost.

Currently Wiggle have it on a 10% discount, while Chain-Reaction are doing a respectable 20% off.

I’ve been commuting using dynamo lights for some time now, but my better half has made do with a few different battery rear LEDs since we own so many rear lights of various ages!

This has actually been pretty useful, since I’ve been able to check the performance of the Smart Lunar R2 in different circumstances while riding along behind, instead of so many bike light reviews which boil down to “it seems bright and nobody has run me over yet” 😉

smart_lunar_r2

Mounting

The Smart Lunar R2 has a clip on the rear which allows you to attach it to items of clothing, bags, and so on.

It is also supplied with a seatpost and seat stay mount that secures the light using the same clip. Rather than a nice jubilee-clip style mount, the Smart has a more primitive fixed-size band, tightened by a small metal screw.

Say hello to packing out the mount with tape if it’s not just the right size, and don’t strip that screw head!

It’s rare to see people riding with a light attached to bag or body that’s actually pointing in the right direction. I’ve tried this myself often… either the light points to the sky or ground or it waggles around spraying photons like a garden sprinkler!

The ability to mount on the seat stays means you should be able to find somewhere for the Smart Lunar R2, even if you have a short seatpost or use a seat bag. Don’t worry that the spokes will obscure the light from drivers on an inside lane – in reality they’ll have spent plenty of time being lasered getting into that position.

Beam quality and strength

The Smart Lunar R2 has five modes – a variety of flashing patterns as well as solid mode. In much the same way that you don’t worry about how many modes your car lights have, I’m a bit “meh” about anything other than plain old “on then off”…

Both LEDs have a plain lens (compare with the RSP Astrum’s diffuser lens). Visibility is still good from all angles and the Lunar R2 throws so much light downwind that you can be picked out minutes away on the open road…

The R2 is extremely bright – so bright that it’s unpleasant to ride or drive behind someone using it, especially in flash mode. While this may be great in some circumstances, making it unpleasant for people to drive behind you can definitely encourage them to overtake. As a driver, I can vouch that sitting at light behind someone with a mega LED flasher definitely focuses my mind on getting past!

It’s a difficult balance to strike. When driving I often find it quite difficult to work out the speed and course of a cyclist using a flashing light, so I recommend solid mode. (This is less of an issue under street lights.)

It’s important to mount the light completely level, as designers depend on this when working out off-angle visibility and other factors. Do not point it at the ground in lieu of just buying a less dazzling light!

That said, you can safely ignore anyone who says flashing lights aren’t road legal – this hasn’t been the case for about a decade.

Because the Smart Lunar R2 hasn’t passed the relevant tests it isn’t road legal when used on its own (in any mode).

I’ll write more about this separately, but unless you go for a dynamo (all dynamo lights are genuinely road legal), it’s true of pretty much anything a bike shop will sell you.

Useability

The Smart Lunar R2 has a small end-on button that isn’t the easiest to operate. It works more like “press in part of the body” than the distinct, super-positive rubber button you’ll find on many Cateye and Raleigh RSP lights.

That said, it’s not rocket science to turn it on at the start of your ride and off at the end – just a bit of hassle if you want to change modes on the way, especially gloved up.

It has a simple “press for next mode” (including the “off mode”) which makes it straightforward to change on the fly whilst riding. The large number of modes makes it slightly more tricky to switch off as you need to count just the right number of clicks.

I bought two Lunar R2 lights from my LBS around two and a half years ago. One of them failed (bounced off on a pothole and run over) but the other is going strong.

Battery life

The Smart Lunar R2 runs on two AAA batteries.

We get around the stated battery life (50 hours flashing, 25 hours solid). Remember that the temperature at which you use the light and the type of battery used both influence that figure.

With rear LED lights it’s important to bear in mind that brightness and battery life are a direct trade-off. Almost all are manufactured using essentially the same mature technology and LEDs which are broadly equal in efficiency.

All you need to decide is whether you’d like twice as many photons for half as much battery life, or vice-versa.

The Smart Lunar R2 produces quite a lot of light and so is fairly battery-hungry.

A word on those 2×0.5W LEDs…

If you know battery life, you can work out the true power draw of your light using simple mathematics.

Two AAA batteries max out at around 1200mAh each, and so the 25 hour runtime of the Smart Lunar R2 points to a current draw of (1200 x 2 / 25) = 96mA. At 1.25V this is (0.096 x 1.25) = 0.12W

A genuine 0.5W LED current draw would give a battery life of just six hours on AAA. Two 0.5W LEDs would last just three hours!

Durability / waterproofing

The Smart Lunar R2 is reasonably sealed, given that it’s lasted three winters.

The internet is less sure, with quite a few reports of water ingress. While I agree that the sealing could be better, we’ve never had a problem with our lights in pretty foul weather (although we do use mudguards).

Overall

The Smart Lunar R2 2×0.5W rear LED light is a solid effort – it’s much better built than the cheaper Smart Superflash 0.5W LED, although perhaps not as well built as some competitors (especially the mount, which is competent but not outstanding).

It is extremely bright and benefits from respectable runtime for its power – 25% more than the RSP Astrum in solid mode (although less in flashing mode)

Again, Wiggle currently have it on a 10% discount, while Chain-Reaction are doing a respectable 20% off.

Smart Lunar R1 rear light review

Whatever its weaknesses, at the end of the day it’s useable, effective and economical… one of the best all-round battery tail lights.

Solo power LED tail light – the gold standard?

The Smart Lunar R1 is a small (AAA) rear LED in the clip-on tradition. It’s the direct descendant of the infamous Smart Superflash 0.5W LED light, but with a better quality of construction (and at greater cost).

Currently Chain-Reaction are doing a cracking 35% off.

Although more than half of our bikes are now dynamo equipped, I don’t actually own enough sets of dynamo head/tail lamps (!). The Lunar R1 is probably my go-to recommendation for a battery powered rear light, taking all things into consideration.

smart_lunar_r1

Mounting

The Smart Lunar R1 has a clip on the rear which allows you to attach it to items of clothing, bags, and so on.

It is also supplied with a seatpost and seat stay mount that secures the light using the same clip. Rather than a nice jubilee-clip style mount, the Smart has a more primitive fixed-size band, tightened by a small metal screw.

Say hello to packing out the mount with tape if it’s not just the right size, and don’t strip that screw head!

It’s rare to see people riding with a light attached to bag or body that’s actually pointing in the right direction. I’ve tried this myself often… either the light points to the sky or ground or it waggles around spraying photons like a garden sprinkler!

The ability to mount on the seat stays means you should be able to find somewhere for the Smart Lunar R1, even if you have a short seatpost or use a seat bag. Don’t worry that the spokes will obscure the light from drivers on an inside lane – in reality they’ll have spent plenty of time being lasered getting into that position.

Beam quality and strength

The Smart Lunar R1 has a low mode in addition to steady and flashing – when a light is as excessively bright as this one is, that’s a big advantage in terms of extra runtime for no loss of safety.

The main LED has a plain lens – there are also mini-LEDs to light up the housing itself, giving the light a slightly larger profile. Visibility is good from all angles – and plenty of light is flung out of the back for any situation…

The R1 may only have half as many power LEDs as the R2 (or RSP Astrum) but it’s still very bright – ten years ago it would have been revolutionary. Because it’s slightly less dazzling, there’s less of an issue of making it so unpleasant for people to drive behind that encourage them to rush an overtake.

As a driver, I can vouch that sitting at light behind someone with a mega LED flasher definitely focuses my mind on getting past!

It’s important to mount the light completely level, as designers depend on this when working out off-angle visibility and other factors. Do not point it at the ground (especially when you can just use low mode when riding socially)!

You can safely ignore anyone who says flashing lights aren’t road legal – this hasn’t been the case for about a decade.

Because the Smart Lunar R1 hasn’t passed the relevant tests it isn’t road legal when used on its own (in any mode).

I’ll write more about this separately, but unless you go for a dynamo (all dynamo lights are genuinely road legal), it’s true of pretty much anything a bike shop will sell you.

Useability

The Smart Lunar R1, like other Smart tail lights, has a small end-on button that isn’t the easiest to operate. It works more like “press in part of the body” than the distinct, super-positive rubber button you’ll find on many Cateye and Raleigh RSP lights.

That said, it’s not rocket science to turn it on at the start of your ride and off at the end – just a bit of hassle if you want to change modes on the way, especially gloved up.

Battery life

The Smart Lunar R1 runs on two AAA batteries.

We get around the stated battery life (100 hours low mode, 30 hours steady). Remember that the temperature at which you use the light and the type of battery used both influence that figure.

With rear LED lights it’s important to bear in mind that brightness and battery life are a direct trade-off. Almost all are manufactured using essentially the same mature technology and LEDs which are broadly equal in efficiency.

All you need to decide is whether you’d like twice as many photons for half as much battery life, or vice-versa.

The Smart Lunar R1 produces quite a lot of light and so is fairly battery-hungry.

A word on that 1W LED…

If you know battery life, you can work out the true power draw of your light using simple mathematics.

Two AAA batteries max out at around 1200mAh each, and so the 30 hour runtime of the Smart Lunar R2 points to a current draw of (1200 x 2 / 30) = 80mA. At 1.25V this is (0.096 x 1.25) = 0.1W

A genuine 1W LED current draw would give a battery life of just three hours on AAA. That’s the physics…

Durability / waterproofing

The Smart Lunar R1 doesn’t have the greatest weather sealing, but it is respectable enough, especially if you take care with the seals when you open and close the light. (Also: making sure you close it properly is a good way to avoid getting home to discover you’re just carrying the rear half of the light, the actual electronics part having bounced off!)

As with the Lunar R2 light, there are plenty of reports of water ingress online. I have on occasion had one of these lights short circuit (jam in flashing mode) but they’ve always been fine after drying out.

I’ve never had one fail to the off mode.

Overall

Over the years we’ve had a fair number of this type of light (from the original Smart 0.5W Superflash through to the present day). Whatever its weaknesses, at the end of the day it’s useable, effective and economical… one I just keep coming back to!

The Smart Lunar R1 0.5W rear LED light is probably my best recommendation for an all-round tail light, taking all factors into consideration.

Again, Chain-Reaction are doing a 35% discount at the time of writing.

Raleigh RSP Astrum rear light review

The RSP Astrum is a budget priced but well constructed rear LED in the clip-on tradition. This excellent twin-lens design is a step above many other lights.

Two 0.5W LEDs make this a dazzling contender

The RSP Astrum is a budget priced but well constructed rear LED in the clip-on tradition. Amazon are selling it for £15 delivered (25% off) at the time of writing (it’s not stocked by the usual mail-order companies).

I’ve been commuting using dynamo lights for some time now, but my better half has made do with a few different battery rear LEDs since we own so many rear lights of various ages!

This has actually been pretty useful, since I’ve been able to check the performance of the Astrum in different circumstances while riding along behind, instead of so many bike light reviews which boil down to “it seems bright and nobody has run me over yet” 😉

astrum

Mounting

The RSP Astrum has a clip on the rear which allows you to attach it to items of clothing, bags, and so on.

It is also supplied with a sturdy seatpost mount that secures the light using the same clip. Unlike many rear light mounts, the Astrum has a big thumb-friendly screw-drive affair which makes it a dream to fit and adjust. Giant thumbs up from me!

It’s rare to see people riding with a light attached to bag or body that’s actually pointing in the right direction. I’ve tried this myself often… either the light points to the sky or ground or it waggles around spraying photons like a garden sprinkler!

Fortunately the Astrum’s seatpost mount is sturdy and easy to fit. I recommend this approach over the alternative, even if you want the Astrum as a backup light.

Beam quality and strength

The Astrum has two flashing modes (one on, one off and both flash together) and offers a solid mode too.

One LED has a plain lens while the other is fitted with a diffuser. This casts light out at a much wider angle – improving the light cast to the sides at point blank range.

The Astrum is extremely bright – so bright that it’s unpleasant to ride or drive behind someone using it, especially in flash mode. While this may be great in some circumstances, making it unpleasant for people to drive behind you can definitely encourage them to overtake. As a driver, I can vouch that sitting at night behind someone with a mega LED flasher definitely makes a quick pass more tempting.

It’s a difficult balance to strike. When driving I often find it quite difficult to work out the speed and course of a cyclist using a flashing light, so I recommend solid mode. (This is less of an issue under street lights.)

It’s important to mount the light completely level, as designers depend on this when working out off-angle visibility and other factors. Do not point it at the ground in lieu of just buying a less dazzling light!

That said, you can safely ignore anyone who says flashing lights aren’t road legal – this hasn’t been the case for about a decade.

Because the RSP Astrum hasn’t passed the relevant tests it isn’t road legal when used on its own (in any mode).

I’ll write more about this separately, but unless you go for a dynamo (all dynamo lights are genuinely road legal), it’s true of pretty much anything a bike shop will sell you.

Useability

The Astrum has a central and large rubber button which is a breeze to use, even with gloves. This is a much better solution than the end-on ‘soft body’ style buttons you can find on other lights (like the Smart Lunar R2).

It has a simple “press for next mode” (including the “off mode”) which makes it straightforward to change on the fly whilst riding. You don’t need to count half a dozen clicks as is often the case (Cateye! I’m looking at you…)

So far my Astrum is still going strong after two and a half years. A big part of this is the quality of construction of the ‘interface’.

Battery life

The Astrum runs on two AAA batteries.

We get around the stated battery life (80 hours flashing, 20 hours solid). Remember that the temperature at which you use the light and the type of battery used both influence that figure.

With rear LED lights it’s important to bear in mind that brightness and battery life are a direct trade-off. Almost all are manufactured using essentially the same mature technology and LEDs which are broadly equal in efficiency.

All you need to decide is whether you’d like twice as many photons for half as much battery life, or vice-versa.

The RSP Astrum produces quite a lot of light and so is fairly battery-hungry.

A word on those 2×0.5W LEDs…

If you know battery life, you can work out the true power draw of your light using simple mathematics.

Two AAA batteries max out at around 1200mAh each, and so the 20 hour runtime of the RSP Astrum points to a current draw of (1200 x 2 / 20) = 120mA. At 1.25V this is (0.12 x 1.25) = 0.15W

A genuine 0.5W LED current draw would give a battery life of just six hours on AAA, so 2×0.5W would give just three!

Durability / waterproofing

The Astrum is well sealed, as it would have to be to survive three winters unscathed.

The quality button construction (see above) plays a large part in this.

Assuming you run mudguards, you can improve the reliability of any rear light by mounting it under the saddle (fairly sheltered) instead of on your body or bag.

Overall

The RSP Astrum 2×0.5W rear LED light is a great little number – well built, easy to operate, extremely bright and with a mount that’s head and shoulders above some competitors.

Again, Amazon are selling it for £15 delivered (25% off) at the time of writing (it doesn’t seem to be stocked by the usual mail-order companies).

Hub Dynamo Friction

What exactly is the cost in friction / drag of running a hub dynamo system? Perhaps not as much as you expect…

I’ve already written a little about the weight implications of choosing a dynamo hub (in short: there needn’t really be a significant weight penalty).

However, there is still another objection to dynamo use – the friction which must constantly be overcome as you ride along. I hope to demonstrate that dynamo hub drag is not much of an issue for the majority of riders, and more of you should be giving serious thought to investing in one (especially as you can now enjoy a discount from our favourite mail order stores).

Power loss versus a regular hub

Let’s start by putting some hard numbers on friction losses in ordinary hubs, before moving onto dynamo hub losses.

Manufacturers of ceramic bearings have helpfully quantified this (because you can’t sell a fancy bearing without demonstrating how ‘bad’ ordinary ones are) and it seems that losses in an ordinary hub are around 1W at 25mph [1].

So at a more reasonable 12.5mph, a ‘typical’ front hub will lose roughly 0.5W.

Screen shot 2013-03-05 at 21.26.09

With the lights switched off,  dynamo hub friction means a loss of 1-2W at the same speed, for a penalty of 0.5-1.5W over the ordinary hub. With the lights on, 7W is a good estimate. “Mini” dynamos like the SON 20R / SONDelux or Shutter Precision SV8 save around 1W on “full fat” ones like Shimano’s Deore, 3n72, or 3n80 series [2] [5].

Calculating a per-day power loss

The ratio of darkness:sunlight during the summer months most favoured by long audax rides is not far off 1:5 (civil twilight in mid-June gives 19.5h of light and 4.5h of ‘dark’).

This gives an overall hub dynamo drag of under 2.5W (averaged across all the hours of a day), so let’s use that as the basis of comparison.

What’s the impact of 2.5W?

A rider on a long distance ride might be producing as little as 100-150W, in which case the drag of a dynamo is ~1.5-2% of the rider’s output. Let’s take that at face value and imagine the impact of a 2% speed penalty:

1% of an hour is 36 seconds, so double that means you will fall back 1 minute 12 seconds per hour compared with your battery powered self: twelve minutes over a ten hour event.

Screen shot 2013-03-05 at 21.35.13

A robust 200W effort reduces the impact to 0.75% (27 seconds per hour) or 4.5 minutes over a ten hour event – should you be one of the few who can put in that kind of effort for a whole event!

Another way this is popularly expressed is in terms of synthetic gradient, with the hub dynamo friction made equivalent to an extra X feet per mile of ascent. It turns out this is not such a difficult calculation, and comes to around 28cm per mile for a dynamo during daylight and 2m per mile for a dynamo at night. Scroll to the end if you want to see the maths!

Comparing with other sources of friction

So far you are perhaps thinking “OK, so 5-10 minutes over a ten hour event isn’t such a big deal, but it’s still something I’d rather avoid”. Fair enough.

This makes it a good point to contrast hub dynamo drag with some of the other things that can hold you back. For instance, it was recently reported that some types of chain lube can add as much as 10W over the factory lube [3] while, at only 12.5mph, the difference between a Continental GP3000 racing tyre and Vittoria Open Corsa racing tyre is already 20W [4].
Screen shot 2013-03-05 at 21.32.26

Remember in the graph and example above we’re just comparing two racing tyres – the effect of changing from something like a Gatorskin or many other types of puncture-protected tyre will be significantly larger. Finally, I’ve already written about the tremendous efficiency advantage of the recumbent riding position: my own drop-bar racer is left for dead at roughly a 100W deficit to a midracer. 100W is a lot more than 2W yet many riders seem just about as loath to try a dynamo as they might be to try the dark side…

Conclusion

When the difference between ‘good’ and ‘bad’ chain lube and two superficially similar tyres is around 30x more than the difference between an ordinary hub and a dynamo (daylight hours) and 4x more than the difference between an ordinary hub and a dynamo (at night), you’d better start asking hard questions about your chain cleaning products/routine and whether or not you should be splashing out on new tyres!

Most people, of course, can’t tell the difference between different brands of chain lube and perhaps not even between comparable models of tyre. Certainly it’s a popular comment by dynamo users that they can’t tell whether their lights are on or off (in daylight!)

Even sample variation between production runs of any particular tyre probably exceeds the drag of a hub dynamo with the lights on… but how many of us spend as much effort making sure to buy just the right examples of a particular model of tyre as we do avoiding dynamos?

For no-holds-barred maximum efficiency, obviously you want to bring your power with you in the form of batteries; but for 99.9% of us, there’s little real reason to avoid all the goodness of a fully self-powered bike…

After holding out for years, I bought one nervously (and now have three…)

As I mentioned up-page, even Wiggle are in on the action: get yours here.

Disagree with the maths or had an experience (either way!) that you’d like to share? Please drop me a comment below!

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The maths…

We can take advantage of straightforward formula here, with the following parameters:

  • It takes 288 seconds to ride a mile at 12.5mph
  • The power lost to the dynamo (lights off) is just 1W
  • The weight of rider plus bike (all in) is 100kg

Then it follows simply that the equivalent height gain per mile is 28.8cm, so:

Power (W) * Time (s) / Force (N) = height (m)
(1 * 288) / 1000 = 0.288m

Run the same sum for a dynamo which is on (at 7W) and you get

Power (W) * Time (s) / Force (N) = height (m)
(7 * 288) / 1000 = 2.01m

Note these are roughly the 1 foot / 6 feet measure you will see referenced in popular articles! It’s easy to subsidise different values; for instance swapping chain lube on your bike (10W, if you’re unlucky):

Power (W) * Time (s) / Force (N) = height (m)
(10 * 288) / 1000 = 2.9m

From the driving seat: bike lights and reflectors

When it comes to cyclist safety, what’s more effective – a light or a reflector? It’s not as easy as you might assume…

Countless British motorists have badly inflated or worn out tyres, faulty lights or dodgy brakes – a massive 40% of vehicles fail their annual MOT inspection at the first attempt.

When the owners of these cars take to the road on two wheels, it should come as small surprise that they don’t all conform to the letter (or spirit!) of the law.

In this post I present four very short videos to use as discussion points. I’ll take each one in turn before attempting to persuade you to draw the conclusion that I always arrive at following a rush hour drive on a dark winter’s night…

Incidentally, if you’re interested in getting a camera yourself, I’m using (and can highly recommend) this compact HD video camera by Contour.

Light or reflectors?

This video features two riders, one of whom has a rear light (but is still not road legal due to a missing mandatory reflector). The other has no rear light at all. All the same, he is in little danger of going over my bonnet, as you’ll see:

While the video doesn’t completely replicate the driving experience, what I hope to get across here is how visible the unlit rider is – his reflective ankle bands were competing with the second rider’s (perfectly bright) flashing light from hundreds of yards away.

  • Not only is the motion of the leg quite compelling, unlike the second rider’s barely visible pedal reflectors you can see ankle bands all the time, even from side-on.
  • As an added bonus versus lights, the pedals are off-centre (closer to traffic) increasing the perceived width of the bike.
  • We all know that reflectors don’t work when headlights aren’t pointing at them. All the same, between 00:17 – 00:21 you can easily see the rider’s ankle bands despite him being over 45 degrees off-axis. Aren’t modern retro-reflectives efficient?

Like many people, I find it difficult to estimate the distance of a flashing light. This isn’t much of a problem in town, where you can see everything in plenty of time regardless, but it should be thought-provoking that the nominally ‘unsafe’ cyclist might even be easier to place – especially if you’re in the habit of riding outside urban areas or off the beaten track.

The human touch

Contrast the riders above with this one (encountered a few seconds further on). He has sparingly fitted just one reflective band, but on the business side where it will best compliment his light:

Compared to an abstract light -flashing or otherwise- the human motion of the rotating ankle certainly discourages a braindead pass (dehumanising the cyclist to a narrow box-like object to be passed with as little care as you’d pass a traffic cone – if that).

Where does it all go wrong?

The real point of this post was not so much to contrast lights and reflectives (interesting though that subject may be).

Let’s look at our next example, a rider who is, at face value, doing everything right. Yet he’s doing something badly wrong… can you tell what it is?

I imagine experienced riders might have been a little uncomfortable there, especially if you imagine I’m just another white van…

The issue? The rider’s road position was completely indefensive. What’s the point being lit up like a Christmas tree if you’re just going to expose yourself to injury by riding in daft places?

You can see this quite acutely at 00:05-00:10 where the cyclist is actually riding on the double yellow lines – so passive (and so almost “not-there-ish”) that I nearly overtook regardless of the junction coming up.

Spend any time on the roads with an open mind and I think it’s easy to argue that a large proportion of collisions (and possibly the explanation of the great gender disparity in injury rates) comes down to the messages that riders give out – voluntarily or otherwise – and the opportunities for error that they present to the drivers they interact with.

Don’t go taking off your lights, but even if you have them on, please don’t assume that they are particularly important. The rider with only a reflective band, riding a sensible distance from the kerb, would have been a safe bet over the “legal” rider in the third video if I was running an insurance company…

Battery powered dynamo lighting

Did you know that many dynamo bike lights can be powered quite happily by ordinary DC batteries?

It’s only recently that manufacturers have finally started producing battery-powered lights with asymmetric reflectors, so you aren’t riding along spraying half your photons up towards the International Space Station.

The Busch & Müller Ixon IQ (£70) was the first decent effort that I’m aware of, and more recently the catchily-named Philips LED Bike Light (RRP £110) and the Supernova Airstream (an eye-watering £170).

Cycling off
Cycling off by Phil and Pam, on Flickr

If you already own a decent dynamo headlight, however, or are too just cheap to pay a lot of extra money for a proprietary holder with re-manufactured lithium rechargeables inside, there is a third way.

Continue reading “Battery powered dynamo lighting”

Long distance bike lights

Almost anything will do if all you need is to get ten minutes down the road to work! As your rides get longer the question of illumination gets a whole lot more interesting…

Almost anything will do to light up your bike at night if all you need to do is get ten minutes down the road to work! As your rides get longer, however, the question of illumination gets a whole lot more interesting…

This article was prompted when long-term reader Nick F asked me about lighting for this summer’s 1400km London-Edinburgh-London audax; pretty much the ultimate lighting challenge and one with a large number of competing considerations.

Lighting options

We can break down the general approach to one of three:

Hub dynamo

The ‘fit-and-forget’ option; I’ve had a dynamo hub and lights in daily use since Autumn 2011 (without any maintenance at all). It’s been so successful that my wife and I now have three hub dynamos between us.

Initially, it’s undoubtedly more expensive to buy and build a dynamo wheel and the counterpart light. There’s no question it’s cheaper in the long run (I’m looking at nearly £100 to replace the Li-Poly rechargeable batteries for our MTB lights, where a dynamo has no real recurring costs) – but in fairness, if you’re speccing a lighting system for one event like LEL you might not get enough use out of the dynamo system to benefit from such long-term savings.

randokit

With the lights off, the extra drag of a modern dynamo hub is said to be equivalent to climbing an extra gradient of one foot per mile (19cm per km). Over the course of 1400km that’s 265m extra to be climbed, but we should strive to see this in a proper context: using a tyre of moderate rolling resistance compared with a top quality one can add many times this much extra effort, while wearing a jersey or jacket that’s a little too big and flappy? All bets are off!

When the lights go on, the friction from the hub will rise to the equivalent of around 5-6 feet per mile (a little over 1m per km) or around 1/10th of a percent. This is still far too small to be detected while riding and still significantly smaller than the differences between tyres – for comparison, if you change from an Open Corsa with latex inner tube to a Gatorskin the extra friction will be 2.5x higher than the hub dynamo on full blast.

There are a couple of other things to consider with hub dynamo systems, such as making sure the wire can’t get damaged (not rocket science) but also noting that you can’t easily perform maintenance on your own bike using a dynamo light. Get a flat tyre in the middle of nowhere and you’ll wish for at least a keychain AAA micro torch to make a repair…

Of course, it also offers you the ability to charge accessories via USB (whether that’s a phone or a GPS unit) rather than carrying a dedicated USB battery pack. More drag again, but keeping things relatively simple and removing that worry over remaining charge.

When it comes to the actual lights I have meaningful experience of only three: the Philips Saferide and the B&M IQ Cyo and Lyt. The latter would struggle at speed on open roads, in my opinion, but both the Cyo and Saferide put out lots of light.

The Saferide, with two LEDs, is considerably brighter than the Cyo but on the flipside it seems to stop the wheel more quickly when spun by hand; I still have to do a detailed report on this light but wouldn’t be surprised to learn it’s drawing more power from the hub (in which case, you can choose how much friction and how much light you want buying one over the other).

On balance if I had to choose just one for a brevet bike, I’d probably settle on the Saferide, although it’s hella ugly.

Rechargeable batteries

At the other end of the scale you have rechargeable battery lights, which range from things like my Ay-Ups (with an external Li-Pol battery pack) to Fenix-style torches mounted with velcro or rubber bands.

ayup

The obvious disadvantage is that you have to match your battery life to the amount of light you need, either by carrying sufficient spares to last the whole ride, finding time to recharge your batteries, or running your lights on a dim setting (or a combination of all three).

On an event like LEL, it’s unwise to rely on charge points anywhere on the route (unless you provision them yourself!). Having said that, the efficiency of LEDs is now such that many riders do manage to get through even the longest events like PBP and LEL without too much difficulty using battery lights.

If you’re lucky enough to spend time in a group, for instance, all but the first pair of riders can take advantage by running almost in the dark (this also makes life easier for the front-runners, as they won’t have to deal with riding into their own shadows if their lights are outclassed by those behind). That might not always be appropriate, but at least it is an option.

Battery lights inevitably have symmetrical beams which waste much of the light output compared with a dynamo light’s shaped beam, but don’t worry about this too much (except insofar as it means you have to carry that much more spare battery!)

AA (lithium primary)

For dedicated eventing there is another option, in the form of AA lithium primary (non-rechargeable) batteries. These batteries aren’t cheap or environmentally friendly, but they do have the benefit of being extremely light and long lasting.

With the aid of a battery holder pack from Maplin you can make up a 4, 5, or 6 cell (6-10V) DIY battery pack and wire on a connector as appropriate.

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I did Paris-Brest-Paris with my Lumotec IQ Cyo wired into a 5AA battery pack (yes, it works off DC too!), and one of my Ay-Ups wired in parallel on a separate switch (providing a ‘high beam’ mode).

I managed to ride almost right through three nights (and half of a fourth) on just ten AA cells, a total weight of 150g. See the separate article for more detail on my Paris-Brest-Paris kitlist.

If you were to start this approach from scratch there’s also the option of the B&M IQ Ixon, which runs off 4AA batteries and is still perfectly respectable (if a little long in the teeth), rather than repurposing a dynamo light – although it must be said that the venerable IQ Cyo may actually be found cheaper, at street prices.

If you really want to blend options you can charge the Ixon using a hub dynamo while you ride (not with primary cells!), although this begs the question of why you wouldn’t just have a cheap and straightforward dynamo light in the first place 🙂

One thing that has to be said about the AA approach is that you will need to wire up at least part of it yourself. You may consider this a bonus (you’ve carefully put something together and know exactly how it works) or a downside (your cack-handed soldering gives way at 3am in the middle of moorland half way through the ride).

The advantage over stock LED lights really comes down to the low power consumption and high bang-for-the-buck you get with a dynamo lamp like the Cyo, so you can get away with much less in the way of spare batteries.

On PBP I also had lithium AA (4x) in a USB battery pack to keep my Garmin Edge topped up, and that did give some leeway in terms of common battery spares early in the ride. However, because I didn’t want to carry enough batteries to power the Edge for all 90 hours, I turned it off at controls and thus lost some definitive data – not a problem if I’d had a dynamo to charge it constantly.

Summary

Each type of lighting has its pros and cons and it’s not possible to say with any authority that you should choose one over the other.

For starters, if cost is a major issue and you’re preparing for an event as a one-off, you will probably want to find a way to use your existing lights, appropriate or no (carrying spare batteries for a light which can use AA or li-ion 18650 cells).

Alternatively, you might justify the purchase of a hub dynamo on the basis that it will see use on a commuter too (the wonder of always-on lights that need no thought – not leaving work to find you’re out of charge – can hardly be overstated).

That being so, I can recommend Shimano’s newer dynamo hubs as a good cost-effective option (or for a little more, the Shutter Precision which is as efficient as it gets).

For my part, I’ve just built a set of brevet wheels around the Shutter Precision SP8. I don’t struggle for time on events, so for me the drag (which you can’t feel) is an irrelevance; I’d rather know that I’m always going to have light, as well as enjoying the ability to charge my phone (which I hope to do via the new B&M Luxos light).

As an unexpected bonus, the hub dynamo system actually saves weight over my original Ay-Up battery setup.

shutterprecision-wheels2

I still have my Maplin battery pack for Lithium AA’s should I need to obsess over ultimate efficiency, in combination with my reliable old Cyo and Ay-Up LEDs. I’m not sure I will bother though, even for the next PBP.