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Old 03-21-13, 11:52 AM   #1
tcasselm
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Interested in helping an MIT student design a rear bike light???

Hi Everyone,

I'm a graduate student at MIT taking an entrepreneurship class. I'm working with a local Cambridge start-up and we're working on a new rear bike light.

I would love to hear what your frustrations are with the current lights on the market and if there are anything you wished a rear bike light would do that it currently doesn't.

I appreciate any feedback that I can get.

Regards,
Thomas
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Old 03-21-13, 12:16 PM   #2
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Welcome to the Forums, Thomas.

If you are thinking of posting a link to a survey, allow me to point you to the proper area for that- http://www.bikeforums.net/forumdispl...sumer-Feedback and the requirements can be found in the second sticky.
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Old 03-21-13, 01:46 PM   #3
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You need to tell us what market you plan to cater to. Do you plan to create a light that is small and with a limited output or do you intend to to create a light that is super bright with external battery? Assuming you want something that will sell to a wide range of people I would suggest creating a light almost exactly like the Cygolite Hotshot. The mode selection and UI on the Hotshot is almost perfect. The LED lens is a little narrow though. If you took the lens from the Moon Shield and used it on the Hotshot it would be even better. Other improvements to consider would be to make the lamp a little more visible from the side by extending the outer red lens which would allow some of the spill light to exit from the sides. Other areas for improvement might be better mounting options which should include a very durable, adjustable quick release mount. This lamp should have the maximum output at least in the 100+ lumen range. The run time on high should be as near five hours as you can get and still maintain 100+ lumen. Not sure that's possible but hey, I'm not from MIT...;-)
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Old 03-21-13, 03:14 PM   #4
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My DREAM rear light would include:

Built in li-ion battery
5+ hours runtime on high
Wireless charging
Extremely waterproof
Wide viewing angle
Ability to have some LEDs flash while others stay lit constantly
200+ Lumens
multiple mounting options (clip to clothing / mount to seatpost / mount to rear rack)
Under $200 US
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Old 03-21-13, 03:34 PM   #5
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You could start by searching for all the other times design students have come up here asking for ideas, there are dozens, and some asked about lights.

I'd agree that there are many different needs, there's no one perfect bike light. The Cygolite HotShot is good. Personally I just bought a Knog Blinder 4V and it's my new favorite light. It does have a few quirks.

Pros for a "perfect" light:
USB rechargable - ideally just plugs right into the computer or a supply, like the Blinder does - but the blinder plug is a little tough to impossible to plug into some computers so a redesign couldn't hurt.

Multiple blink settings. Again, the Blinder has a good variety.

Wide angle - the Blinder gets this right - nearly even distribution of light. The Hotshot fails in this category, even 10 degrees off center the light falls off a lot.

Good mounting options - this is where the Blinder really fails - it has one option - clip around a seat post. Period. Now, if that's what you want, the Blinder's mounting is superb; simple and effective. but I'd like to buy one that could clip onto clothing/bag, or go onto a rack or seat stay.
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Old 03-22-13, 09:41 AM   #6
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We're looking to cater to urban cyclists and are working to design a theft proof rear light.
Obviously, range of visibility and battery life are also key features. We're looking at using some highly efficient LEDs combined with unique flashing batteries that optimize light output and battery life.
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Old 03-22-13, 11:55 AM   #7
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We're looking to cater to urban cyclists and are working to design a theft proof rear light.
Obviously, range of visibility and battery life are also key features. We're looking at using some highly efficient LEDs combined with unique flashing batteries that optimize light output and battery life.
I think you'll find that most people aren't too concerned about theft. That might be because there is no such thing as a thief proof light unless it is actually built right into the frame of the bike. Best way to prevent theft is to take the lamp with you and that means making something quick-release so there are less hassles for the buyer.

As for the flashing patterns the Hotshot does a really good job at giving the buyer a nice array of different patterns.
These patterns are also "adjustable" via a secondary UI. This is why I gave the Hotshot as an example of a good UI.

Since I've been assuming you might create another ( battery) self-contained USB type light you might consider building a hybrid system; something self-contained but with the option for additional plug-in external battery. A system like that could do real well especially if it contained a two-tier driver, one for the self-contained battery ( lower-powered ) and one for the external battery ( high output ...200+ lumen ). The buyer could then decide which driver menu he wanted to use and which battery....this creates a win/win for the buyer...less output for longer rides or more output for needed safety with use of additional battery.

...Oh, almost forgot. If it uses a self-contained rechargeable battery make sure that battery is easy to replace...so far no one's done that yet either.
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Old 03-22-13, 05:15 PM   #8
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I can't imagine anything much more beneficial than my cheap $10 bicycle tail light. It's bright, can be seen from far, and one battery lasts forever.
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Old 03-23-13, 03:34 AM   #9
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I can't imagine anything much more beneficial than my cheap $10 bicycle tail light. It's bright, can be seen from far, and one battery lasts forever.
I'm glad you like your $10 light. While you might think it is bright ( and "can be seen from afar"... ) that would be your personal perception. As such, it might not be as visible to others as you might think. Just remember there are a lot of distracted motorist out there that are likely not to even see your light until they are right on your butt. The brighter the light the more likely you are to be seen sooner ( all other factors taken into consideration ).

You need to plan for the unexpected when riding at night. That will require some "Imagination" on your part mixed with a light dose of paranoia. When it comes to rear lamps having something that is more "attention getting" is the way to go. It may cost a little more for a brighter light but having a good rear lamp is worth it if just for the extra peace of mind. If I went out with just a $10 blinkie on my seat post I really don't think I would be able to relax while cars are zooming by me at 50mph. Paranoia is kind of a drag but the trade-off is that it helps keep you alive. Besides, better to have more light and not need it than to need more light and not have it.
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Old 03-23-13, 03:40 AM   #10
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I like my solar powered 2 led tail light. Its weakness is battery life (4-5 hours run time) and it could be brighter. A 4 LED version with a larger battery and an option for external power via usb would be ideal for me.
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Old 03-23-13, 08:22 AM   #11
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I can't imagine anything much more beneficial than my cheap $10 bicycle tail light. It's bright, can be seen from far, and one battery lasts forever.
Replace your battery...today.
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Old 03-23-13, 01:37 PM   #12
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I'd like it to be easy to use, with MANY mounting options. I would use it more if it met these requirements.
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Old 03-23-13, 02:11 PM   #13
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Replace your battery...today.
...this made me laugh. I can't tell you how many times I see people riding with the cheap blinkie's and with batteries that must be half dead. This is likely because either the people who own them really don't care how visible they are or don't realize that when you turn a light on with half dead batteries that the initial output will still look pretty good ( which can be misleading ). Ten minutes later when riding down the road the voltage sag on the half-dead batteries will kick in and the led's will barely be lit. Cold weather will cause this to happen sooner. If you use a cheap blinkie best to use rechargeable batteries and recharge them every couple weeks or so ( if you are a frequent night rider ).
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Old 03-23-13, 06:54 PM   #14
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My request...
Cleanly integrated into the seatpost, which is stuffed with 18650s for a full winters runtime. Maybe control less like the motion/light activated cateye lights.
Use those invisible laser drilled led holes apple is fond of. Most hipsters are filthy rich so outrageous production costs shouldn't be an issue.
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Old 03-23-13, 07:30 PM   #15
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Here's an automatic rear light typical of those included on new city bike for sale in the Netherlands. It bolts to the back edge of the rear rack, and therfore sits about 80cm from the ground. It uses AAs powering LEDs which turn on when the bike begins to move and stay on for a couple of minutes after the movement stops. They're rarely stolen due to the finicky nature of the attachment bolts.
This seems to be the gold standard in that type of light. Reviews suggest it's very visible. No personal experience with this one.

My comments: They're designed to be mounted low, and could therefore be missed.
On smooth road surfaces, the movement sensor sometimes decides that the trip is over and turns off prematurely.
Most people on this side of the Atlantic don't ride with a Dutch type rear rack, so a better positioning might be in order, preferably not tucked deep under the seat.
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Old 03-26-13, 06:56 AM   #16
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Quote:
Originally Posted by tcasselm View Post
Hi Everyone,

I'm a graduate student at MIT taking an entrepreneurship class. I'm working with a local Cambridge start-up and we're working on a new rear bike light.

I would love to hear what your frustrations are with the current lights on the market and if there are anything you wished a rear bike light would do that it currently doesn't.

I appreciate any feedback that I can get.

Regards,
Thomas
Skip the light thing. Try designing a system that measures cadence and is wireless and doesn't need attachments to the chainstays or spokes.
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Old 03-26-13, 07:33 AM   #17
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Skip the light thing. Try designing a system that measures cadence and is wireless and doesn't need attachments to the chainstays or spokes.
Already invented! Count the number of times your right foot goes down in 15 seconds. Multiply X 4 to get RPM.
You're welcome.
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Old 03-26-13, 07:31 PM   #18
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THE most common type of battery in the U.S.A. is the AA size battery in 1.5V alkaline chemistry.
THE most common rechargeable type of consumer battery in the U.S.A. is the AA size battery in 1.2V NiMH chemistry.

It is very hard to find a decent quality but not overly expensive rear tail light that uses the AA size battery. Almost all of them use either AAA size batteries or have built in Li-Po rechargeable cells. Long story short there is an unfulfilled market nitch sitting right there just begging for someone to take full advantage of it.
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Old 03-27-13, 06:58 AM   #19
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AA is common, but as for me, I'm trying to phase them out of my life. Whenever possible I buy stuff that has built in LiPo batteries. Cylindrical batteries waste space versus flat batteries, the door for removable batteries wastes space and introduces both a place for water to get in and a place for the connection to the battery to fail. LiPo battery controller chips have gotten extremely good, and if the manufacturer uses good quality cells, they should last for a LONG time.
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Old 03-27-13, 08:09 AM   #20
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Regarding just the tail light thing, in general: make it brighter, more convenient, more stylish, add features.

For convenience design it to turn on automatically when I start and off when I'm done, but stay on during stops of course. That may require some MIT engineering ingenuity. Also a decent rechargeable battery charged off a hub dynamo, which needs to disengage when it's charged. No more drag than necessary you know.

Features, I'd really like a brake signal. Even if it only starts flashing or flashes yellow that would be enough to clue a driver or cyclist in that I'm doing something, and would be better than nothing. The same goes for turn signals - although we can't have good turn signals without separation a flashing arrow could work.

It needs to look good, not just a box hanging off the seat post or fender. I like the idea of making it look integrated on the post or an aero under-seat attachment similar to a seat wedge.
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Old 03-27-13, 08:15 AM   #21
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My big issues with rear bike lights are:
(1) They're not bright enough or don't give enough coverage
(2) They don't have enough run time
(3) They usually don't have user replacable batteries
(4) The ones with external batteries use flimsy wiring
(5) Totally waterproof units are hard to come by
(6) Most don't use shaped beams or claim they do but don't really

No chance anything currently on the market except for generator run lights is suitable for touring or all day cycling unless using the most feeble settings - which pretty much defeats the whole point. Finding a light that addresses ALL of those has been a real challenge.

The closest I've come so far is adapting some automotive 12V LED lights to mount on a bicycle and run off 11.1V RC Lipo batteries. About 15 or 16 hours of run time for dual lights on solid with a good combined 500 lumen shaped ouput that doesn't dazzle following traffic but paints the whole road red behind the bike - clearly visible from 2000+ feet
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Old 03-27-13, 08:18 AM   #22
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battery life and waterproofing are the areas i feel need to be improved upon
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Old 03-27-13, 12:30 PM   #23
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Start with the cygo lite hot shot, go from there. GET a better clip/ mount, one that won't fall off. Find a better way to attach to the back of the helmet, seatpost/ rack.
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Old 03-27-13, 12:35 PM   #24
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Quote:
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We're looking to cater to urban cyclists and are working to design a theft proof rear light.
Obviously, range of visibility and battery life are also key features. We're looking at using some highly efficient LEDs combined with unique flashing batteries that optimize light output and battery life.
Theft proof is easy, make it something you can take with you if you leave the bike.

My preferences would include having a battery I could replace, simply because if I did find the battery had run out (due to forgetting to charge it or a long night ride or whatever) I'd want to be able to plug another one in rather than having to have a spare light as a backup.

Having some lights on steady and others flashing sounds like a good idea.

It would also be good if there were some reliable way of the light automatically coming on in the dark - if it's on the back of a rear rack I can't reach it from the saddle so can't turn it on and off without stopping. It's nice to know the rear light will come on automatically if I ride through a tunnel, for example. It would obviously need a facility to manually turn it off completely so it didn't sit flashing away overnight when not being ridden, but also not suddenly turn itself off just because the rider had stopped at a junction or some such.
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Old 03-27-13, 01:37 PM   #25
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THE most common type of battery in the U.S.A. is the AA size battery in 1.5V alkaline chemistry.
THE most common rechargeable type of consumer battery in the U.S.A. is the AA size battery in 1.2V NiMH chemistry.
I agree with you about the ubiquity of the AA alkaline, but have a minor nit about the voltages.

Alkalines start at 1.5v and go down from there.
NiMH and NiCds start at 1.4v and go down from there.

The NiMH 1.2v figure is a "nominal' figure, below which the battery is nearly dead. The alkaline 1.5v is an initial figure, at which the battery is brand new.

Basically, it's an apples to oranges comparison, though yes, I do realize that everybody does it for some reason.

You're exactly right bout AA vs AAA, however. I'd pay a little extra for a tail light that took one AA rather than two AAAs, if for no other reason than AAs cost about the same as AAAs yet hold about 3x the energy.

I'm also not a fan of lights that take three cells -- two or four cells is better than three cells, because batteries tend to come in packs of four and the cheap rechargeable chargers generally do two or four at a time -- but not three.

But all of these are bigger issues for headlights rather than taillights, as tail lights tend to not hit the batteries anywhere near as hard.
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