update on the great ypsi bike-powered movie thing

OK, it was super short notice, but some of us met last Friday evening to discuss the bike-powered movie project. About 8 people attended. Following are my rough notes on what was discussed. If it’s not clear from reading through them, the consensus of those present was that it’s not only a project worth doing, but one that might actually work.

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  1. Brackache
    Posted April 22, 2008 at 7:26 pm | Permalink

    If that $150 ballpark figure is correctish, point me in the direction of where to purchase one of them bike generators and I’ll buy one and let y’all use it. Also, I have a tandem bike we don’t use, say maybe if the generator is really rusty and requires the power of two people to crank it together dorkily.

  2. mark
    Posted April 22, 2008 at 8:26 pm | Permalink

    The $150 number may be way off base. We’ve got to look into it. I’ll keep you posted though.

    The first thing we have to do is figure out how much wattage we’ll require. That means we need to identify the VCR, projector, and sound system we’ll be using and get their specs. Once we have that, we’ll know exactly what we need. If we’re right about ten bikes, maybe we could get a volume discount somewhere.

    And thanks for the offer of the tandem. That’s very cool.

  3. Posted April 22, 2008 at 8:39 pm | Permalink

    – What if the bottom of the screen (if it was light fabric like a sheet) had weights stitched into it? I’m pretty sure something like this could be picked up at Joann Fabrics (some kind of weighted piping). Or it gets made so that the two sides of the fabric screen have casings/openings for inserting poles that then go into the ground. For fabric, there’s also heavier light-colored fabric for home decorating stuff that would work that wouldn’t flap around as much and also wouldn’t tear like a vinyl-type material might.

    – What about some kind of play on “drive-in movie” for a name?
    Or calling them “dirty movies” cuz they’re being powered all down and dirty style.

    – I’m going to be the owner of a used mini van beginning next week, so if you need stuff hauled around, let me know.

    – If you end up needing bikes really badly, get in touch with Back Alley Bikes– last time I was there they had bikes coming out of their eyeballs and were dying to get rid of them.

    Are you shooting to have this running this summer? What’s your timeline?

  4. mark
    Posted April 22, 2008 at 8:49 pm | Permalink

    Yup. We could try weights at the bottom. Or, we could stake the bottom into the ground somehow. I still think that it would be almost impossible to keep the wind from rippling though it. And, I suspect it would be almost impossible to get it completely straight to begin with. Personally, I’d be fine with it. Some folks, however, might find it too distracting.

    There’s also the question of what to make the screen out of. I’d been thinking about a plain white sheet. I’m told, however, that we might be able to get real screens from Property Disposition at UM. They’re apparently made with silver stuff that makes them more reflective. If we can get ahold of one, I figure that we should try it.

    I’ll add “Dirty Movies” to the list of titles being considered. I like it, especially given our City’s reputation for smut, but I think it could work against us PR-wise. We should still consider it, though.

    Cool on the mini van. Congratulations on that.

    And, yeah, assuming we can all get our shit together, it would be great to at least get a test screening in this year. If we bust our asses, I bet we might even be able to get in a few.

  5. Posted April 22, 2008 at 8:49 pm | Permalink

    I’m so out of shape, and I got so exhausted just reading that, I had to take a break ;)

    Now that I’m all rested, I’ll check into the lighting situation and see if the lights can be turned off.

  6. Posted April 22, 2008 at 8:57 pm | Permalink

    Mark, did you miss my remark here
    where I put this link to my offer of a DC-AC inverter?

    I wasn’t at the meeting, so I don’t understand why the idea of using an automobile alternator was rejected. At $150/generator I’d think the alternator route would be a lot less expensive.

    My DC-AC inverter was the largest available at Wal-mart. It was about $80 for 750 watts, quite a bit less than $1500 that you put in your post for only twice the power. The key would be to find a projector that runs on less than 750 watts.

    I don’t know why the radio idea wouldn’t work, re: “We have some concerns about how it might sound with dozens of radios playing”. Drive-in movie theaters use that technology all the time with great success.

    Also, Marlena offered her talent as a pre-event. She is quite serious about this offer.

  7. Deadhand Dan
    Posted April 22, 2008 at 8:58 pm | Permalink

    I really want this to work for you guys, even though I don’t live in Ypsi – I’ll even paypal you some money, but I’m wondering about the noise of 10 generators – will that interfere with people hearing the film?

  8. Posted April 22, 2008 at 9:04 pm | Permalink

    I could tow my sailboat down to the park, put up the mast, and hoist the sail if you want to use that as a movie screen.

    OK, bad idea. Still a wind problem and besides the sail is not flat.

  9. amanda
    Posted April 22, 2008 at 10:26 pm | Permalink

    we so very much need electricity at the downtown ypsi farmers market, and i wanted to do the bike-powered generator thing a few years ago to get it, though never made it happen… if we could make some of these bikes to use at the market (which i think would be a huge hit with visitors, and a *great* community physical activity promoter– and then also of course at the film fest, i could probably find funding for them… i’ve long dreamed of having one of these things we could take to garden sites for workdays– just to have enough electricity to charge cordless drill batteries and maybe a radio…

  10. mark
    Posted April 22, 2008 at 10:32 pm | Permalink

    John, I did see your earlier note about the inverter, and I believe I left a comment in reply in an earlier thread. My understanding is that we’ll need more than 750 watts, but I’ll let you know after we’ve identified all of the items we’ll be using and what their power needs are. And I’m not sure about price. Jim looked into inverters today too, and, like you, found that they were pretty inexpensive, at least those in the 750 watt range. I haven’t had a chance to talk with Dave yet, but I will. Maybe once they go over 750, there’s a big difference in the kind of technology that’s required.

    And I appreciate Marlena’s offer to do story telling prior to the film. Given the fact that the first film, Night of the Hunter, isn’t too kid-friendly, however, I was thinking that we probably shouldn’t encourage kids to come. If it works, though, and we have other films, then it’s absolutely something we’d consider.

    And thanks for checking on the lights, Trusty. I appreciate it.

    And, Dan, you’re right – it could be noisy. We’ll just have to wait and see. Hopefully we can put the bikes far enough away that all the spinning generators won’t interfere too much.

  11. mark
    Posted April 22, 2008 at 10:34 pm | Permalink

    And my original thought, John, was to put the screen on the other side of the river, and project across the water. I think, given the power of the projectors that we’re talking about, though, it’s just too far. I think it would be cool though.

  12. mark
    Posted April 22, 2008 at 10:35 pm | Permalink

    Or, here’s another idea. We could drop the screen from the bridge. Everyone would have to watch it at kind of an angle, but it might be cool.

  13. mark
    Posted April 22, 2008 at 10:42 pm | Permalink

    Actually, Amanda, I wanted to talk with you about it. I think there are grants we could go after, but, as we’re not a 501c3, we can’t. I was thinking that maybe we could join forces on this and run it, or at least some component of it, as a Growing Hope project. Anyway, it’s something to think about. Regardless, I think that’s a great idea about providing energy at the Farmer’s Market. Our hope was always that they’d be put to good use when not being used by us, and this would be perfect. I love it… The only problem would be getting them too and from the market each week… But maybe there’s space around there that someone would donate. If it was only a few blocks, we could put them on wheels and roll them over.

  14. amanda
    Posted April 22, 2008 at 11:01 pm | Permalink

    yeah let’s talk more. i don’t know about ten, but we could store a few at the GH Center…

  15. Andy C
    Posted April 23, 2008 at 12:25 am | Permalink

    A few things. The radios should work with the FM transmitter since I saw a lot of places advertising them for Drive-in theaters. We can cover 150 feet for pretty cheap right off the shelf. I have a electronics geek friend, here in Ypsi, who is looking into the cost of home building a larger one. We should still have some external sound back by the bikes but a stereo will do, no need for a PA. Lots of small radios will keep the noise down too.

    In the summer it doesn’t get dark until 10pm so kids staying up till midnight might not be the best idea. Can we even be in the park that long? Not to mention an hour break down and the mosquitoes!

    I have large sheets of white material we can use for a screen and to test for reflectiveness if needed. Could be spray them with a gloss paint to increase the light bounce? This is only a back up if the screens fall through.

    As for storage, maybe can split them up amongst us. I’d be happy to store one in by basement.

    I’m sure Ypsi Bike or Tree Fork Bikes would be happy to help out. Word on the street is there’s a lot of piping in the basement of Ypsi Bike on Michigan Ave. Seems someone was trying to make custom bike frames down there. Well it was there when Bikes in Town owned the spot less than a month ago.

  16. meximese
    Posted April 23, 2008 at 6:27 am | Permalink

    I love the idea. It’s great.

    A couple of things: You’re going to want at least a 2000 ANSI lumen projector, to cut through ambient light and whatnot. You could get away with less, but then keep things dark.

    Apparently you can get by using a 600 watt inverter to power a 2500 ANSI lumen projector. And these things run around $80 – $100 dollars. So you might be over estimating the expense.

    Powering a stereo, vcr and other items shouldn’t take much. But you will want a decent receiver to make things audible. Ambient noise adds up. Also, the FM transmitter for audio can work, but only if there isn’t a nearby, dominant radio station to interfere. In ann arbor, WCBN proved too powerful for this idea.

    Finally, and I may be wrong here, but by registering with the city, getting 501c3 status, etc, it seems you’re going to need “permission” to screen movies outside the public domain. And that is costly.

    Just something to think about. I used to screen movies behind Michigan Theater in 04-05. But I stole my electricity from the

  17. Posted April 23, 2008 at 8:54 am | Permalink

    This is a very cool idea! Please add me to your mailing list – adavis,ubasics,com.

    Some thoughts and research:

    Inverters (Sam’s Club):
    3,000W – $338
    1,200W – $114
    800W – $ 57

    Projector (Sam’s Club):
    Sharp XR30X
    2300 lumens
    1024×768 DLP
    283W consumption

    Most projecters will consume between 200 and 300W max. DLP projectors are more efficient – they put out more light per input watt than LCD projectors.

    Sheets are cheap and available, but a 100″ projection screen is only $70 (again, Sam’s Club). If we wanted to expand later we could buy 4 and attach them to each other for under $300, giving a 200″ screen, although that wouldn’t be perfect, it would probably be brighter than a sheet.

    Coating a sheet could be troublesome without the right paint – it has to be flexible, adhere to the sheet, but once dry not adhere to anything else even in hot weather. Once coated it would always have to be rolled to avoid creases (same as a real screen).

    Other than ugly/visible seams, cheap 1/8″ fiberboard is only $10 for 4′ x 8′ so for $40 we could have a 214″ screen (17′). Lots more storage, but much less susceptible to wind, etc. Would still require a good coating of flat, reflective paint.

    Stretching the screen:
    Replacement tent poles (flexible fiberglass sections with shock cord through the middle) are inexpensive:
    If we sewed a loop or roll along each edge of the sheet in a bowed pattern, and had angled corner pieces to put the poles into we could have a rectangle or square with bowed edges to keep the sheet/screen taut. It would take a bit of fiddling, and probably be iterative until we got the technique down, but it would take up very little space in storage, and would result in a ripple-free surface.

    Alternately, set it up like a volleyball net: two poles with ropes along the top and bottom, and guy wires pulling the poles away from the screen.

    DVD player:
    A nice DVD player consumes about 40W. A portable DVD player will run off 12V, and can consume less, especially if the screen is turned off. $40-$150.

    FM transmitter:
    Even with a powerful station nearby, a good FM transmitter will do very well. Ramsey Electronics has a few synthesized FM transmitter kits for $140-$200. I do like the idea of using individual radios – that way we can optimize sound output individually, rather than having people who think it’s too quiet, people who think it’s too loud, and possibly annoying others that are in the area but not interested. I’m willing and able to build and test a kit if we want to avoid the expense of purchasing it assembled. These run off 12V, and consume maximum 8W.

    Power consumption:
    Projector <300W
    DVD/VCR <100W
    FM <10W

    The entire system could be lower than 500W, so an inexpensive inverter should be fine. In fact, given that these are max values (which usually include a significant operating margin) we should be able to run them off a $25 400W inverter and still have a 25% margin. But if flexibility and over-engineering is required (or you want to run a PA) then an 800W would be more than enough.

    With 10 bicycles, each cyclist could be cycling very lazily to provide the needed 500W. I’d recommend at least one small battery so we don’t have power dips when people slow down cycling for intense parts of the movie, and it will create a load that will help avoid over-voltages when they all speed up during other intense parts of the movie. Two trained cyclists, going fast but not sprinting (aerobic) could maintain 400-500W for 2 hours, so there’s a good upper limit if you need to know what people are capable of.

    A typical small car battery is 45AH, which is about 500W for one hour. With a few batteries and 10 powerful cyclists you could cycle/sprint for 20 minutes and get enough energy to run the show for two hours with no cycling.

    Would be neat to have an energy meter display in front of the cyclists (individually and collectively) that shows exactly how much power is coming from them vs the battery and each other – see if they can work together to match the load exactly, or ‘work ahead’ and sprint for a bit, then rest for a bit, etc. Would add an additional game to the fun.

    Note that I’m not suggesting you use the components above, I’m merely giving examples of pricing and power consumption to use as ballpark figures.

    I hope this is helpful, please keep me updated.


  18. Posted April 23, 2008 at 9:04 am | Permalink

    Thank you, Mark, for addressing the kids’ program offer. I wasn’t thinking of a particular film, though, and of course, I agree with you . However, If experience serves, I bet some parents will cart kids along to even the bloodiest, zombie-filled movies anyway. Seriously-we’ve all seen it happen.

    I wanted to help, and it’s the only thing I had to offer. Got no money, no engineering skills, my bike is too stupid to use for anything.

    I can cartwheel for money at a future fundraising event for the freight-house, though. Some people might pay money to see a woman of my years cartwheel and end in the splits for a grand finish. (all proceeds to the freight house, of course. except for tips.)

    still thinking about a name? is “sweat equity movies” useful? “Biker films”? “Pedal powered park movies”?

    about noise and hearing the film-
    some movies are excellent without sound, I think. Provide a mood and a tone to a get together. Really old movies are fun that way. I do it in one room of our house when we have our annual halloween party.

  19. Posted April 23, 2008 at 9:29 am | Permalink

    This is awesome. I’ve wanted to play with a bike and generator to generator power for close to a year now. I’d like to try it just for charging my AA batteries and cell phone and things. I’ve wondered how long and how much it would take.

    I’m wondering what the typical efficiency of a store bought AC/DC inverter is. I’ve always seen them throw off a lot of heat, which makes me think that one could be built to be far more efficient. Maybe Dave knows?

    If you are interested in presenting your progress or a report after the fact, the Ann Arbor Computing Society would love to hear about this.

  20. ypsilanti cycle llc
    Posted April 23, 2008 at 10:48 am | Permalink

    Ypsilanti Cycle LLC is the new bicycle shop downtown Ypsilanti at 116-118 W.Michigan ave, since March 1st, 2008.
    734-482-7881 NEW NUMBER.
    We have a full e commerce website for all your cycling needs if you can’t stop into the shop right downtown Ypsilanti.
    We also have an ebay section.Click on the Ebay link on the Website and it will take you to our special auctioning ebay store center; where we offer deals on closeout items and other great specials.

    Ralph Ellis and Paul Neff have teamed up to bring a top notch bike shop to Downtown Ypsilanti again.
    We sell new bicycles all levels, and repair all makes and models. We also sell used bikes.
    Schwinn, GT, SE, FUJI, FELT, Diamondback bicycle lines and more being added are in stock and selling on a daily basis..

    The past month has been great as several lines of bikes have had to be reordered because of such great support from Ypsilanti customers. Thank you very much.
    Ralph and Paul appreciate the enormous support from the community, the day we opened up.

    Ralph Ellis owned Ypsilanti Cycle, and the buildings since 1982 and had the shop through 1997.
    Bicycles in Town owner moved to Canton in Feb 2008.
    He is gone from Ypsilanti.
    YPSILANTI CYCLE LLC. is here to stay and support the community in anyway possible.

    Ralph Ellis has been building frames since, 1982 and has a full frame building technology center downstairs at the shop.
    He can build any steel frame, fork set up you want.

    Please feel free to stop in anytime at Ypsilanti Cycle LLC

  21. Andy C
    Posted April 23, 2008 at 11:39 am | Permalink

    Even most of the large auditorium projectors, 4000-6000 Lumens, do not exceed 500W.

    VHS was decided on because it can start right back up at the same place in the film if power was lost.

    Adam-thanks for the Ramsey Electronics link.

    My apologies to Ypsilanti Cycle for calling them Ypsi Bike, it was late.

  22. Posted April 23, 2008 at 2:56 pm | Permalink

    $25 used VHS player – runs on 12V or 110V: http://losangeles.craigslist.org/sfv/ele/650890273.html

    Also might look at junkyards, they may have an older minivan with a built in VHS player. I’ve been happy with http://aachenauto.com for parts for my car.

    The point about VHS tape restarting where it was stopped is very good. Alternately use a portable DVD player with its own battery (keeps playing if power stops) or a portable media player (zune, ipod, etc) both of which use significantly less power than VHS or DVD, but may require some conversion time.


  23. ypsilanti cycle llc
    Posted April 23, 2008 at 7:07 pm | Permalink

    No problem,
    we just want to make sure, people know we are here right downtown.

  24. Posted April 23, 2008 at 9:13 pm | Permalink

    I am not sure if it will work out in time, but I have been looking at the model projector mentioned above at Sam’s for my cafe. I thought it would be a nice thing to have for meetings and in the winter we could do a student film night or a you tube night or something like that. If I come up with the finances in time, I would be more than willing to share it for this project.

  25. Posted April 23, 2008 at 11:25 pm | Permalink

    mark, I could launch my sailboat into the river and we could project onto the sails there as I navigate up and down the river.

    Wait, I already said that was a bad idea.

    Has anyone heard of those inflatable movie screens? We’d probably need 3000 watts just to run the fan for one of those though. That’s a lot of bikers.

  26. Posted April 24, 2008 at 9:24 am | Permalink

    At the Bluish Barn, we used a wide white roller shade and flipped it sideways to fit an even wider aspect ratio. Those things are a pretty strong kind of vinyl I think and can be reinforced at points where they tie to supports. Then they can be simply untied and rolled up for storage.

    Most projectors now are bright enough to make a projection that’s easily viewable even with some light pollution. I wouldn’t worry too much about that, unless you plan to have a gigantic screen.

    Give me a month and I can get some bikes from my job. Also a VHS player, no problem.

    I definitely think getting the radio transmitter thing to work would be awesome. Like meximese said, they tried this once at Twitch but had too much interference from WCBN at all frequencies for some reason.

    From the sound of it, I think a logical thing to do is to actually go to the site and figure out the exact location before more decisions get made. How big does the screen need to be? Where/how will people sit? What would the traffic flow in/out be like? Could people come and go as they please? Would noise be an issue for any neighbors? These are just some of the questions that a good site scouting should answer.

    Another thought: what about self-powering electric exercise bikes? Does anyone know if these could be somehow rewired to draw power?

  27. eric
    Posted April 24, 2008 at 10:18 am | Permalink

    I don’t know if it would save anything, but most of the power you’d be using would be converted to DC for the electronics anyway, so why not skip the whole inverter part and just open up the devices, find out what their internal DC requirements are, bypass their AC power supplies and connect regulated DC directly to their internal DC power inputs?

    As for screens, one idea would be to construct a basic wooden frame over which to stretch a large sheet. You can make the frame using loose-pin hinges to hold it together, and you could gesso the sheet to make it more rigid and reflective. It could then be stored by simply removing the pins and folding it up, and would be more resistant to wrinkling than if it were painted.

    A source for generators could be old motors from vacuum cleaners, fans, or washers/dryers.

  28. frenchfries
    Posted April 24, 2008 at 11:28 am | Permalink

    There are plans on the web for adapting a bike trainer to fit a generator instead of the usual magnetic or fluid resistance thing. Here is a link


    Also, I put a link to this post on the Bike Ypsi forum. It would be sick if this could be the evening activity following the May 4 spring ride and festival–but probably that’s not likely.

    Anyway, I should be able to kick in about 100 W if I can put together one of these generators. Too bad it means less beer.

  29. Posted April 24, 2008 at 3:05 pm | Permalink

    How about “Cycle Cinema”? or “Reels on Wheels”?
    The Cs could be artistically joined to look like both a bicyle and film reels.

  30. Posted April 24, 2008 at 11:22 pm | Permalink

    East Quad Bicycle Coop did a bike fixup recently – details at


    as you think of building bike generators this might be a good approach to parts (or people too).

  31. Posted July 8, 2008 at 10:10 pm | Permalink

    Did this project die??

  32. egpenet
    Posted July 8, 2008 at 10:38 pm | Permalink

    As the Lord said as he brought Lazarus back from the dead: “Yam feteth!” (You stink, cousin!)

    Requiescat in pace. Amen.

  33. Andy C
    Posted July 9, 2008 at 1:52 am | Permalink

    It can’t die until it’s born.

    Consider it going through birth pangs.

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