Reelight RL770: Retro-fit Dynamo Lighting

Reelight RL770 Review

This is a review of the Reelight RL770 battery-less lighting system.

Introduction

First off, what is this system and how does it work?

Reelight is a Danish company which designs and sells battery-less bike lights. They work by having powerful magnets mounted to the spokes of the bicycle wheel and a coil mounted to some stationary part of the bike. As the magnet on the spoke passes the coil, a current is induced to power the lights.

Reelight have several models for various applications. The RL770 is their top-of-the-range system with the intention of a ‘see-by’ lighting system rather than a ‘to-be-seen-by’ lighting system.

Packaging

A lot of people I know think I’m a bit crazy for including packaging in a review, but I believe it to be an important part to any product. Fortunately, Reelight have done very well here. Packaging is compact, but fits well together, is informative of what the product is and made me want to open it as soon as I could!

First Impressions

Opening the box, we find:

• Instruction booklet,
• The dynamo and dynamo mounting system,
• 3 mountable magnets (each of these has 2 magnets, so 6 magnets in total)
• Front light,
• Rear light,
• A number of tie-wraps (cable-ties/zip-ties) for attaching the wires to the frame.

My first impression of the system was one of solid build quality. The magnets are really very strong and the dynamo feels solid when held. The lights themselves are housed in plastic which feels durable enough despite the odd creak when handled with force. There are no seals at the joints of the parts, nor where the wires enter the light housing so I doubt it would be waterproof. However, as my current system is even less waterproof and has stood up to the rigours of the British summer (and winter) for the past two years, I’m not too worried about the waterproofing of these lights. I wouldn’t trust them in a monsoon, but then again I wouldn’t be cycling in a monsoon either.

The light units have reflectors on them too, for added visibility. This is a great addition, in my opinion.

Setup - Positives

The instructions provided with the RL770 were very clear. It isn’t difficult to understand how they are set up, but the pictures provided helped a lot. I particularly liked that the parts being discussed are drawn in different colours and the fact that the instructions are printed in thirteen languages.

The hardest part for me was getting the magnets aligned correctly; they must be equally spaced around the wheel, pass within 1mm of the dynamo (not unlike setting up a speedometer) and be fixed between two spokes for safety and stability.

The dynamo itself is mounted onto a bracket and can be removed easily. The bracket mounts to the seat stay and uses metal ribbon to hold it in place. Importantly, the metal ribbon is surrounded by thick rubber to prevent any scratching of the frame. Once the bracket is in place and secure, the ribbon can be snipped off.

The front light mounts onto the brake block behind the caliper brakes. If you use cantilever, V- or disc brakes, then you can still use the light provided your fork has a place for a bolt. Installation of the front light was dead easy. The angle of the light is easy to set, too.

The rear light mounts to the back of a rear rack only. Again, installation is a simple matter.

Running wires to the dynamo is easy. Insulation tape is my method of preference, though tie-wraps are provided (9 in total, which should be enough). The wires provided are long enough for even a large touring frame. For my Audax bike, I trimmed them to a more manageable size, stripped the ends and set about wiring it into the dynamo. Connecting the wires is a little fiddly but not a massive challenge. Each light has two wire ends, which must be connected into the dynamo. I twisted the ends of the wire and wrapped them round the contacts with the wire long enough to let me do this, but short enough to prevent a short-circuit. If you know how to use a soldering iron, you can make it a more permanent fix by soldering the wires into the contacts.

Setup - Negatives

Reelight provide 3 sets of magnets which are to be mounted in an equilateral  triangle onto the spokes. That’s great if you have a wheel with a number of spokes divisible by three, but if you don’t then you won’t be able to get them equally spaced. My rear wheel has 32 spokes so to combat it, I had to mount them in more of an isosceles triangle arrangement. More on this arrangement later.

The cover for the wiring on the dynamo unit is easy to click into place but impossibly difficult to remove, should you want to. I tried to remove it and the plastic tabs keeping the cover in place snapped off. Not the end of the world as I had a roll of insulation tape to hand, but perhaps a slide mechanism would be better. (For the record, the tape has held the cover securely in place without any trouble at all).

The rear light can be attached only to a pannier rack. That’s fine if you have one, but if you are buying this system for, say, an Audax where you will be riding through the night but don’t want to use a pannier rack then unfortunately you’ll have to look elsewhere or use seatpost mounted bottle cage to mount the light. (The light can be mounted onto it, albeit at a strange angle)

The setup also requires readjustment every so often. It’s not the end of the world. The magnets used are so strong that they will, over time, pull the dynamo towards them. The next time you ride, you will be greeted with a loud noise of the magnet hitting the case. It only requires a simple twisting of the dynamo housing to bring it back to the correct place, so don’t let it put you off!

Performance - Positives

At the time of writing this, the lights have been on my bike for seven weeks and I have been using them on my 6 mile commute into and out of London every day. It’s summer, so cycling home in the dark is not as common than in winter but I have taken the bike out for a spin on as dark a lane as I could find (more on that later).

The lights start working at walking pace. However, there is noticeable flickering due to the pulsatile nature of the electric induction. At cycling pace, this disappears. The rear light does not have this problem as it has a small capacitor (battery, essentially) which stores energy and thus evens out the ‘surges’. The capacitor also allows it to remain lit for a while once you have come to a stop - essential for commuting at night.

As a ‘to-be-seen-by’ light system for commuting, the RL770 is great. The lights are bright and make the cyclist very visible on the road. The rear light, by being rack-mounted, cannot be obscured by panniers or a rack bag, unlike a seatpost-mounted light. Both lights also have reflectors for added visibility. Where the system really excels is in the ‘always there, always on’ nature. The lights are fixed to the bike, so you can’t leave home without having lights. There are no batteries, so you never run out of power mid-commute. This just removes a lot of thought from my commute. The amount of times I have left home either without my lights or with flat batteries before installing the RL770 is an absurdly high number. As well as that being illegal, it’s just plain dangerous to commute in London (or anywhere) during the hours of darkness without lights.

The front light has a good spread of light directed towards the road. This is often lacking on normal battery powered light systems where the light is spread in a normal circle. Half of that light is wasted...

Performance - Negatives

Remember how I mentioned that I had to mount the magnets in an isosceles arrangement? This turned out to be a bit of a problem when I took the lights on a longer distance test. In a London commute, you’re never travelling particularly fast. On a long country cycle, you can pick up speed on the country lanes. When I did this, the unequal weighting of the magnets on the wheel caused a loud (and annoying) hum. Initially I had no idea what the problem was but careful diagnostic investigation pointed to the magnet arrangement. The hum is there because the wheel is significantly unequally weighted and the centrifugal forces are thus unbalanced. I don’t know if this causes damage to components if left over time, but I wasn’t putting up with the hum enough to find out.

I subsequently removed one of the magnet pairs and arranged the remaining two opposite each other and this solved the problem. That’s all good and well, but it resulted in decreased current as not as many magnets are going past the coil per revolution. It’s important to note that this is NOT an issue if you have a rear wheel with a spoke count divisible by 3. Mine was a 32 spoke wheel, so it was a problem. If you have a 36, 24 etc then you won’t have this problem.

The arrangement of the magnets opposite each other and the associated decrease in power really affected the front light. Flicker was only eliminated at more than 15mph and the light was, in my opinion, a bit dimmer. The rear light was not affected, presumably because of its capacitor.

As a to-see-by system, I find the RL770 to be lacking. The flickering of the front light is really tiring on the eyes when cycling in the dark and if you encounter a moderate hill then it will only make matters worse. Though the spread of light is decent, it just isn’t bright enough for illuminating dark roads when cycling at night. When compared with cheaper battery powered lights, it cannot compare at the illumination competition. Furthermore, the front light remains only minimally illuminated when you stop.

Drag

Without a doubt, someone will be reading this to try find out how much extra drag this system gives and how much it slows the rider down, so I would like to address this. Firstly, you cannot get any light unless you put energy into the lighting system. This manifests as drag. If you could overcome that, you have essentially invented/discovered perpetual motion and broken the laws of physics. For anyone wondering about drag, let me state it plainly: there is an imperceptible amount of drag. You can feel a ‘cog-wheeling’ effect when you turn the wheel slowly. At walking pace, I do not notice this. Riding at 10mph, I notice nothing. Riding at 15mph, I still notice nothing. For the people who really think the drag is huge, there is a fantastic article in the CTC archives on dynamo resistance. This system was not tested, but I honestly have not noticed any difference. As an aside, Reelights markets this as a ‘friction-free’ system which I find misleading. There is always friction but in this case, it is a special type of friction called ‘magnetic damping’.

What I would like to see improved

I think the RL770 could be a much better system if the following improvements were made:

1. Another magnet was included in the kit. Why? Performance would be better for everyone who used it, but especially the people with 32 spoke wheels. 36 and 24 spoked wheels would still be able to use 3 or 4 magnets at their discretion.
2. The front light needs a capacitor and ideally a more powerful light, too. This is probably more important than including an extra magnet in the kit.
3. Perhaps replace the cover of the dynamo wire housing unit with a slide mechanism.
4. Possibly a frame/seatpost mount for the rear light to appeal to the people who want a system to see with but who don’t have/want a rack.

Overall Impression

One issue I have not yet addressed is the price. The RL770 costs around £75, which I will admit sounded steep to me at first. However, factor in that never will you ever need batteries for it, the bulbs will burn for a very long time before anything happens to them and the convenience of them always being there and ready before you make a decision about whether it’s too pricey for you or not. It’s also worth having a look at how much more expensive some of the well-known brand lights are.

After using the RL770 system quite extensively, I can draw two conclusions. If you’re reading this looking for information on whether to buy it or not, then I hope it helps you.

1. It’s great for commuting and as a to-be-seen-by system.
2. It is not good enough as a standalone system for cycling on unlit roads at night.

Much as it pains me to say it, the RL770 just isn’t powerful enough for cycling at night on unlit roads. The idea is great but the headlight lacks adequate brightness and the flickering I experienced will tire the eyes very quickly. If you want to cycle long periods of time in the dark without fear of running out of batteries, you’re better off spending some extra money on a hub dynamo lighting solution.

If you want a foolproof lighting solution for commuting which, once installed, requires no thinking and gets the job done AND have a 36 or 24 spoke wheel, then look no further; this is what you want (or you have a 32 spoke wheel and can deal with flickering lights, look no further).

In one sentence:

Good for commuting on streets with lighting, but don’t go on a long night cycle without a brighter headlight.

Pictures

Front light mounted

Rear light mounted

The dynamo. I kept the metal ribbon on so I could remove the system if I wanted to.

One of the magnets. The black ends are the magnets.

The front light in my (small) hallway

The front light outside at night. The ethereal wisp of light in the middle is the illumination you get on the road.

(The green dot towards the top of the frame is the LED on a battery light telling me it is getting power...)

This is a picture taken from the same spot as the one above, but with a battery powered light I picked up for £10

This video, if it works, shows me cycling towards the camera around the Outer Circle of Regent's Park at night. Halfway through, I switch on the battery light as a comparison so if you can't see where I am at the start, you will soon. You may have to replay the video a few times to see the stretch of road lit up by the RL770.