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Reelight SL 120

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1 Review

Manufacturer: Reelight / Reelight SL120 Power Backup lights flash while your bike is in motion, and continue to flash for 2 minutes after you have stopped.

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    1 Review
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      19.11.2007 18:25
      Very helpful
      1 Comment



      Flashing LED bike lighting powered by magnets fitted to the spokes. Almost friction and effort free

      You know how you read about something for the very first time, and then, suddenly you’re confronted with the same thing in real life, as if it’s been there all along, implying that you’ve been walking around with your eyes wide shut all this time?

      I’ve had two such revelations in the past few weeks, both occurring in the same 24 hour period. One was to see the picture of a headteacher’s husband on the wall of her office (I was borrowing her office to talk to year 6 kids), only to come home to watch the programme about the Great Storm of 1987 to see his face on TV, as one of the Kew Gardens tree experts interviewed.

      The other, whilst at the same school, was to read the ads on my CTC (Cycle Touring Club) magazine to espy the Reelight SL 120 lighting system on the back cover. The next day, outside the same school, blow me there’s a bike with the damned things fitted, and yet I’d never seen them before in my life.

      Generally bike lighting falls into two categories, battery-powered and dynamo-powered.

      They both have their pros and cons. Battery lights stay on when you’ve stopped, but cost you money to run. OK, the modern breed of Light Emitting Diode (LED) lights doesn’t cost a King’s Ransom, but every now and then buying batteries comes into the equation.

      Dynamo lights go out normally when you stop*, but only require a little extra effort on your part to keep them running indefinitely – well maybe until a bulb blows anyway.

      *Dearer dynamo systems have an energy store to keep the back light running for a while.

      Those bottle-shaped dynamos can also put a little extra sidewall wear on your tyres, but as normally the tread would go first, it’s not really a factor. You can however feel the drag once they are in use. The other main dynamo type is fitted inside the front wheel hub and has minimal drag, but the drag is there 24/7 irrespective of whether the lights are on or not.

      Now just suppose someone could come up with a dynamo light that stays on when you’re not moving, and hardly has any perceptible effect on your effort to get home against the wind.

      Well Reelight have! (See www.2pure.co.uk)

      Someone’s obviously put a lot of thought into this classically ‘simple’ idea; the simple idea being that if you pass a permanent magnet over an electrical coil, it induces a current into that coil. Do it often enough with a strong enough magnet and you’ve just reinvented the bike dynamo for the 21st century, only this time, thanks to LED lighting, the power needs are tiny, and therefore the drag on your poor legs infinitesimally small.


      Never a truer word, Chris. Not only do these lights have no on-off switch, being intended just as much as daylight running lights as they are for night use, but they can only flash (i.e. once every time magnets start going past them to generate the current).


      When fitted what you get is one rear light trailing backwards on a bracket fitted to the offside rear wheel nut, and the front lamp, thrusting forwards from the corresponding offside front wheel nut.

      I’ll freely admit that axle level is an odd height for a cycle light, and the smaller your wheels, the closer to the ground they get. I’m thinking that my Brompton folding bike is NOT a candidate as I don’t fancy chancing 15 quid’s worth of front light to being 8 inches off the ground. Anyhow, the spokes need to be longer than the length of the arm on which the light sits. Any truly adolescent- or adult-sized bike wouldn’t be a problem though.

      The brackets to which the lamps are fitted have slotted holes to allow for around 3-4 mm of sideways movement, to allow for the light to be clamped within the optimum distance from the passing magnets. Reelight’s packaging tells you that the intended clearance is 1-3 mm. If your spokes are at all flexible, I’d advise the larger clearance.

      There is only one tiny bit more of installation to do before the Reelights are ready to roll, and that’s to clamp the magnets to the right spot on your spokes to come close enough to the light without fouling it.

      To be honest, I found the latter operation, i.e. getting the magnets in place, the trickiest part – they are very strong and capable of pulling the light against the strength of the bracket, so you must check that your wheels spin freely before taking the bike out onto the road otherwise you run the risk of contact between light and magnet with dire consequences for the plastic casing of the lights.

      You get two sets of magnets for each wheel so purists who like their wheels balanced can relax. This also ensures that the power reserve gets charged to capacity quicker.

      IN USE

      You’d have to get used to a few barrackings of “Oi mate, yer lights are on” when out in the day, in the same way that Volvo drivers must get fed up with being taunted about their daytime running lights. However, the way I see it is that at least someone has noticed them. Since the SL120 versions stay lit for up to two minutes before fading completely, get used to this also as you walk away from your locked (hopefully) bike, e.g. “Oi mate, you’ve LEFT yer lights on!”

      Now that the law allows for a flashing LED light on bikes, which was to my mind one of the more sensible outpourings to become cycling law, these really are all you need for use in lit streets. However, do not expect the front light to light your way – after all it flashes for one thing. For another thing, it’s only a Light Emitting Diode, not the Bell Rock Lighthouse.

      If you need to see where you’re going in the dark, you should make extra arrangements.

      However the Reelights are still a useful back-up for those off-roaders who’ve drained their 12v halogens forcing them to creep home on ‘sissy’ lit roads.


      There are four UK versions, whilst I’d imagine that continental versions will be limited to two. It’s hard to think of a bike as ‘right hand drive’ but since we adhere to the left-hand side of the road here, the light needs mounting to the ‘chain-side’ which is also the off-side of the bike. This then means that depending on the type of gears you have (or even if you have any at all), you will need a different shape of rear wheel bracket. Derailleur gears of the type fitted to racing and mountain bikes, with their wide ‘cone’ of several cogs mean that the rear light’s bracket needs to be curved inwards to get it anywhere near the magnet on the spokes, whereas bikes with hub (or no) gears need a flatter bracket.

      On top of this option you then consider whether you want the pricier version (SL 120) with an up-to-two-minute power reserve or not (SL100), hence the four permutations. This slightly more expensive option was my choice. I stop at lots of traffic lights in the dark, so having a constant tail light matters to me quite a lot. However, I got mine for a pleasing £29.99 including P&P from www.timani-ltd.co.uk which is cheaper than the list price of the cheapest version


      As these lights are designed to be seen in daylight, it’s a safe assumption that they are more than bright enough for night time use, at least to be seen. They still can’t show you where you’re going. The off-side axle-height placement is a problem for me but I see where Reelight are coming from – anything else, like a two-part sensor and separate light placed higher up would spoil the elegant simplicity of the design. The Reelights really are entirely self contained which bodes well for their weather resistance.

      I’ve also got my reservations as to whether pedestrians can see the front light. For one thing, how many look at all before assuming that the lack of engine noise means there’s nothing coming and step out with their back to you? For another thing, even if they are looking, are they looking down? Even then, the off-side position of the light will mean that for a brief moment, the light will be hidden from them by your own tyre and rim.

      Parking in a crowded cycle rack needs some forethought if you want to avoid some clumsy so-and-so bending them as they extract their steed with a good yank although the brackets seem pretty stout to me.

      What also concerns me is that they’re just that bit too inconvenient to remove yourself to prevent theft (whilst shopping for example) but equally a mite too easy to find stolen when your back is turned, especially if you have quick-release wheel spindles instead of wheel nuts needing a spanner. What’s “quick-release” to you is “quick-release” to a bike thief.

      Time will tell how long I’m able to hang on to them.

      In the mean time, Reelight’s advertising tells me that “Studies have shown that the use of bicycle safety lights reduces the number of accidents by 40%”.

      I’ll drink to that, but not while I’m cycling.


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    • Product Details

      Reelight does not use batteries, permanently mounts to your bike, and has no on/off switch.

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