Battery-free Reelight bicycle light launches on Kickstarter

Looking at the RRP in the kickstarter campaign ($60) for one light?!

So when they come to production they're going to cost $120 for the set (£80)!

I don't think so!!!

Battery or hub dynamo light as Rim dynamo is no go. Just not as efficent

"Not going to work with my carbon rims though ;-)."

Graphite is conductive, and so is CF, although I don't know if there would be enough network connectivity between the fibres to get significant eddy currents building up. Would be interesting to try it with something like this.

These are a copy of the Magnic lights which have been around for a few years (the latest version is very good).  Be interesting to see how these new units compare and whether the patents already filed for this cause Reelight any problems - having seen the patent, I'm skeptical they can get around it but time wil tell.

Although contactless, there is drag from these systems - it's just so small as to not be noticeable.  I haven't been able to measure any slowdown of the wheel during coastdowns with and without the lights.  LEDs are so efficient now that running 1W lights only needs ~3W of power input.  I certainly can't tell the difference while riding.  The output is fine for being seen by (particularly at the back) and just about good enough to light the way on well lit roads but you need something beefier for unlit areas.

Biggest issue is mounting - they have to be VERY close to the rim to work (within a few mm), so unless the mounting system is very stiff, the average British road can cause them to bounce against the rim a lot over bumps.   Magnic had to redesign theirs to get them to work robustly (which they do).

Visibility from certain angles isn't brilliant because the wheels block some of the light - best solution for me is to use 2xfront and 2xrear which with the Magnics gives great all round visibility.  It also makes the bike look more like a moped from a distance - I've noticed a significant drop in the amount of tailgating & close passes on evening rides along country roads with them.

I thought I'd give a set a try for £30 inc delivery.  I do like a gadget/light. Not going to work with my carbon rims though ;-). I'll have these as emergency/supplementary lights on the commuting bike. 

I went for another Kickstarter light the DING as well earlier this year. 
https://www.kickstarter.com/projects/dingbikelight/ding-bike-lights

Looks like that one won't now turn up till December now but they have made some good improvements on the original design.

Quote:

Big physics red flag here: there may be no parts in contact with the wheel, but since the light is taking energy out of the system to charge itself, there is (and must be) drag.

Yes, raised my physics red flag too - but.. the loses in the system will not be from friction. This design sounds like it will be a very effecient transfer of power - so while energy will be taken out of the wheel (so you will need to pedal a tiny bit harder), the friction losses associated with a traditional dyno will not be present... so a more efficient system, and will be interesting to hear how noticable the extra pedelling effort is.
 

£18 isn't for a set of lights, it's for ONE light.

The way they're using kickstarter seems a little odd as well, the estimated shipping date is Decemeber 2015, when it's running until Dec 8th.  Clearly if they're shipping in December they've already made them and you're just buying a light rather than funding production.

"so there’s no speed-robbing friction."

Big physics red flag here: there may be no parts in contact with the wheel, but since the light is taking energy out of the system to charge itself, there is (and must be) drag. In this case, that will manifest as the eddy currents causing their own small magnetic fields which repel the magnet in the light, causing you to have to work a little harder to push the wheel around.

If there was no additional drag at all, this would be a free energy device, and in this house we obey  the laws of thermodynamics.

Can't help thinking these lights are not positioned in the best place, fork and seat stay?, they're going to get covered in road crap and are obscured by the wheels/ fork/seat stay from one side.  Bars and seatpost/rear rack/mudguard have got to be a more visable option.

Also, "To get your hands on a set of lights will cost just $18, with a choice of colours to choose from. That’s 70% of the estimated $60 RRP when the lights go into full production."?

70% of 60 is 42 by my reckoning, or is "70% of" supposed to be "70% off"?