Revolights Keep You Safe While Riding At Night


Bicycling at night can be a potentially hazardous endeavor for several reasons, but primarily because well, it’s dark. Inattentive drivers, weather, and other factors aside, the most important thing you can do to keep yourself safe is to ensure that you can see and that you are seen by others.

Revolights, an invention put together by [Kent Frankovich, Adam Pettler, and Jim Houk], is an ingenious way of accomplishing both of those things. The ring-shaped system attaches to nearly any bike tire, and includes LEDs that shine like a car’s head and taillights. A magnet attached to the bike’s fork triggers the onboard microcontroller to light only 4 LEDs at a time, letting persistence of vision take care of the rest.

We think it’s a great idea, and clearly others do as well. With nearly a month left on their Kickstarter page, they have nearly doubled their initial funding goal.

Check out the video presentation on their Kickstarter page to get a better look at the Revolights project.

[Thanks, medix]

42 thoughts on “Revolights Keep You Safe While Riding At Night

  1. This has so many problems it’s not even funny.

    Side visibility hasn’t been an issue for decades since reflective sidewall tires were introduced. Most battery lights have a wide cone of visibility, many lights now specifically have side LEDs, and so on. If you want a safe light, buy one that meets Germany’s standards, like Busch and Mueller’s stuff.

    The project creators dug out an ancient (almost half a century old) study to make their claims that somehow bicyclists of the world are in mortal peril from people flying at them from the sides. About a dozen cyclists were involved and like the consumer safety product commission, they completely misunderstood how cyclists are vulnerable. Side collisions where a driver strikes a cyclist from the side are rare. Doorings, “right hooks”, and oncoming-left-turn-into-cyclist-in-other-lane are the principle ways drivers hit cyclists. All of those are solved with clear front lighting (your rear light isn’t very important – collisions from the rear are rare too.)

    It’s a lousy lighting solution, and a very expensive one at that. For the money involved, you can buy a generator hub ($50 for a Sanyo), LED front light bright enough to see 20-30 feet with ($50 or so for B&M’s cheapest LED models) and a bright, 330 degree rear taillight ($30 for B&M’s top-notch “Topline” unit). Spend a little more and you can get a top-of-the-light front light with auto daylight shutoff. That’s ~$130 plus the cost of re-lacing the wheel, which shouldn’t be much – you’ll still be WELL under $200, and you’ll never have to by batteries/charge anything/remember to take them with you, because they’re bolted to the bike. And no, generator hubs are nothing like those crappy sidewall generators you saw years ago- they drag is unnoticeable and put out about 6W of electricity, which is plenty for some really, really bright lighting. During the day, you can use the electricity to charge your phone and whatnot (several companies make adapters for regulating the voltage from the hub.)

    Lastly: revolight will negatively impact the handling and performance of the bike significantly. It places a huge amount of weight at the very edge of the wheel- the worst possible place for inertial mass, which is what you feel every time you try to accelerate your bike. Go do the math if you don’t believe me, and look at typical rim weights (not wheel weights) compare to what the revolights weigh.

    Did I mention that it’ll also place the lights right near the ground, where they will be subject to a lot of water/splashing and constantly need cleaning? I haven’t had to clean the front lens of my generator-hub-powered light in weeks because it’s up high at the top of the wheel, protected by a fender.

    1. Some good points – mainly the price
      One note though. . .if you took a look at the site, you’d see that these are visible from the front and back.

      Without diving into math, I’m not sure how much of a difference in acceleration there would be – certainly its no more weight than a slick mountain bike tire – this is thin aluminum

      My main concern about this would be durability over years of bicycle commuting abuse – where I can see it’s most usefulness.

      Another concern is the claim that it provides enough light to be used as a head light – you’re really going to be able to see well enough with 4 LED’s that have very little heat sinking while flying down the road at 30+ mph?

      On a positive note, it certainly can’t hurt to have nearly half of your entire wheel lit up – much more noticeable than a single lamp, partly due to the uniqueness of the shape.

      When it comes right down to it, HackJack may have had it right. . .”People put those on to mimic TRON.” Still, with $80k+ pledged funding, that’s a lot of people that want to mimic TRON!

      1. Visible from the front and back? So? That’s why people use a front and rear light. Front generator lights usually have a set of leads to power the rear light- and as I noted, the Topline rear light has a 330 degree arc of visibility.

        Rim weight is a huge factor in responsiveness to acceleration, trust me (or google it.) People spend a lot of money to lose 50 or 100 grams from just the rim, and these things weigh much more. If you live in an area where you have to slow or stop frequently, this is going to matter.

        I agree, durability is a major concern that low to the ground. Shock, water, dirt, you name it.

        30+mph? Bud, I’m in great shape, and my commute in the city is an average speed less than half that (my moving average is probably 16mph. The bike’s not built for speed, but durability, cargo-carrying, and reliability.) On my road bike, 20mph is a heck of a lot of work. Speeds over 30 generally require a pretty steep and/or very long hill.

    2. BD, I’m out in the country with a combination of mountains and cornfields – streets here have names like “trout rd.” and “hoof trot ln” RE: > 20mph being a lot of work – yep, you betcha! The 30+ mph is referencing a route that is literally down the side of a mountain and very densely wooded – running head on into a deer here is a very real problem and 30MPH is extremely easy to hit here. also, it’s extremely easy/common to hit 20mph on the flats around here – provided there isn’t a nasty head wind.

      I can see your point about acceleration from a city riding point of view – i guess i was under the impression that a lot of city commuters were more interested in heavier duty rims that could take the pot holes than saving weight. i know when i was commuting daily in college, i was definitely more interested in anything that could hold up to the curbs and general abuse – i can’t remember how many cheap axles i went through. acceleration isn’t too much of an issue for me now – i only have one stop light on my 9 mile route. sometimes i’ve run more aggressive tread (the tire and tubes are noticeably heavy), the most difference i’ve noticed (during my riding) was the extra rolling resistance – again, it’s not stop and go.

      the two times i got hit were both on a college campus. one was by a car filled with pledges going to a frat house – i was passing a slowing car on it’s left side (no turn signal from the car), suddenly the car veers left – apparently they didn’t realize where the party was until the last second! the second time involved a busy intersection, a pick up truck and a bus i think – can’t really remember the details – neither were serious though (luckily) have had much worse mountain biking.

      if i were to have another run-in with a car on the routes i ride currently i probably wouldn’t be talking about it; most speed limits are 40 with most cars traveling over 50.

  2. Fun, but over-engineered. Why not just use normal head and tail lights with a spoke light without timing? A spoke light is easier to remove, cutting down on the wheel rotational mass when riding in daylight. It does look really cool though.

  3. This is absurdly overengineered for the effect it produces. All you need is a lightweight reflective hoop for each wheel and a spotlight mounted to each fork. Bam, single-quadrant wheel lighting with stationary active components. If you’re using LEDs, you can even blink them in sequence while the bike is stopped to mimic that sweeping pattern.

  4. I agree with the comments about over-engineering, at least for most commuter-rider budgets.

    I achieved the same visibility with an LED glow stick I found after going clubbing. Tape it to a spoke, push a button to turn it on when you need visibility. Could be made easily detachable with reusable zip ties.

    These glow sticks can be purchased for $6.25 a piece w/ free shipping on amazon.

    That being said, I’m glad Hack a Day posted this, so we can show how it can be “hacked” on the cheap.

  5. This is a fantastic idea. For future iterations, is there any way to make it less ufo-like? Seeing two glowing arcs zooming down the street does not tell me I’m looking at a bike, but looking at two glowing circles might do a better job of that.

  6. Cool but silly expensive.

    You would need a bunch of power LEDs, a reed contact, a small microcontroller (ATMega8 would do fine) and a battery.

    That doesn’t add up to $200. I know R&D costs money. But this smells like a 100% markup.

    Still, VERY cool effect. As I’m not under US patent laws I guess I can build my own. As I ride my bike a lot, and my lights always break down. And I wonder what the cops would say about this :-)

  7. I think its a pretty neat idea. I think its way to pricey. But Id really like to see someone from hackaday make a almost identical project for a fraction of what there selling it for.

  8. As stated above, to expensive for the project…

    Hell, one could buy the LED strips that wal-mart sells for cars and just 3m adhesive tape it so the wheel on each side and a simple flip switch to light the whole wheel, why stop at just the rear? I want to LIGHT my whole tire and make it like a red hot brake rotor at night that way someone will stop and ponder rather than just say: “o thats a bike ill continue to go the same speed.”

    Anyhow, cool but if it doesn’t meet a budget of $20 for rear and maybe $25 for front with brighter LEDs, I myself would not purchase.

  9. Are they really trying for a patent? Great idea for something that looks cool. Not that great for use as a headlight. I might have to build my own version for 1/4 of the price.

  10. This also looks like it has a great potential in making motorcycles/scooters more visible at night. Living in a city brimming with both, I could see this having great potential. Hmmmm, Ideas….

  11. Wow, none of you even read or looked at it, did you?

    The lights shine forward and back, not from the sides. Strip lights wouldn’t do the trick because you’d still have to mount them the same way as the Revolight…. Every ‘alternative’ mentioned will take just as much engineering time as these guys put in to their project and if it does cost significantly less, then it will probably look very unprofessional/unfinished in comparison.

    While I agree, this is not the ideal solution for lighting, it does look cool. Sure, a head and tail lamp are cheaper and a generator hub can power them, but you won’t get the “My bike looks like a futuristic motorcycle!” feeling.

  12. I love the design, and it’s very well put together. He’s gone through a lot of prototypes, and the evolution of the project really shows.

    However, as an avid cyclist, he lost me 10 seconds in when he said he wished bicycle lights were “Lower to the ground”. Doesn’t really make much sense to me functionally (although aesthetically it looks awesome). To be seen is to have lights higher, and a lot of cyclists I’ve seen actually put lights on their helmet as well (both rear and forward facing) to solve this problem. I’ve never seen a cyclist voluntarily mount a light “as low as possible” for added visibility.

    Well executed though, the final product looks awesome!

  13. I wonder if the bulk of the cost goes into the manufacture of the thin aluminum band to which the lights are mounted. From the prototype, it looks as though it’s been machined (which would be awfully silly), though I don’t know how you’d go about bending the aluminum in this shape without breakage from work hardening.

  14. It’s a nice idea cosmetically, but branding this as a safety device would be a disaster. Also the fact that the electronics is being mounted in the wheel hub means that in all likelihood it’ll get shaken to bits by the motion of the bike over the road.

    Would it be possible to put the electronics on the frame somewhere (under the seat maybe?) and have some sort of inductive power transfer between the forks and the wheel rim?

    I do like how the light pattern changes when you stop the bike, that’s a funky feature.

  15. I would really like one but not for $200. Though it doesn’t have the “wow” effect, I think regular bike headlamps are more economical. The other question I have is whether LEDs can be seen the legal distance without a reflector. The other question is how easy it will be to maintain and how it will be effected by rain and elements.

    I’m still waiting to see what the police would think about this because I can just imagine them pulling me over and asking to see my bike.

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