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Personal transportation

  1. Jan 27, 2005 #1
    Would it be possible to make a vehicle that could transport an adult at, say, 10 mph yet fold up small enough to carry easily in one hand and weigh on the order of 10 pounds? Something like a miniature scooter with pedals instead of a board. It would need a handle that reached up to waist level or so. Its tires would have to be very small and its gear would have to be fairly high.

    The device would be useful for whenever you need to get somewhere quickly on foot, indoors or out. Instead of walking you'd just unfold the device and go twice as fast. The main problem in its design would probably be making it strong enough without making it too heavy.
  2. jcsd
  3. Jan 27, 2005 #2
    With small wheels, endoing is a problem. This is an endo:
    http://bloombikeshop.com/photogallery/levi/endo%2001.jpg [Broken]

    There are foldable bicycles with full-size wheels (many are exactly like ordinary bicycles except for having decoupler joints midway on the top and down tubes), but they weigh in the neighborhood of 20-30 pounds. However, if you towed the carrying case behind a folding bicycle, you might be able to carry your bike around with you without having to lock it up or worry about it being stolen or dismantled. Here is such a bike with towable carrying case:
    http://www.co-motion.com/espresso.html [Broken]
    http://www.co-motion.com/travmenu.html [Broken]

    The most efficient way to travel, though, might be to hop, instead of to roll. Artificial kangaroo legs might be your best bet if they could be made light and small enough.
    Last edited by a moderator: May 1, 2017
  4. Jan 27, 2005 #3
    Why would small wheels make endoing a problem? It doesn't seem to me like they'd affect anything, even when they're like 4 inch wheels. Short wheelbase would make that a slight problem, but this machine would be intended to be used on fairly flat surfaces--hallways, roads, etc. And it would be easy to jump off.

    I think that ordinary foldable bicycles commonly weigh 40 or 50+ pounds. Anyway even if you used titanium to make a 20 lb conventional folding bicycle, it would still weigh too much to be carried nonchalantly by most people.

    Carrying cases, etc. are not an option. This has to be convenient before it is anything else. I'm thinking that a rushed businessperson might use it to cut 5-10 minutes off his daily routine.

    I read somewhere that a bicycle and rider is the most efficient form of land transportation that exists. http://www.watchtower.org/library/g/2000/4/8/article_01.htm [Broken] says that a kangaroo can reach a speed of 38 mph; this is not an unfamiliar speed to a bike racer, who is human and has much less power, and there are one or two streamlined bicycles that can do 80 mph on a flat stretch.

    Of course, all this wouldn't be true when the bike is basically a skateboard with pedals, but I doubt a pair of pogo sticks ("kangaroo legs") would compete.

    I think roller skates are a practical option. They would have to attach to your ordinary shoes and/or shins quickly and easily without a lot of tying or untying knots (5 seconds would be a time to shoot for). How fast does an average person who isn't going too fast go on roller skates?
    Last edited by a moderator: May 1, 2017
  5. Jan 27, 2005 #4


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    I've seen skateboards with small motors attached to them. I don't know just how fast they go, however, and I'm not sure I would want to travel at 10 mph on one.

    Good point about the roller skates by the way. Those are a much safer way of reaching 10 mph and about the right weight.
  6. Jan 27, 2005 #5
    The only problem with roller skates is that they have a somewhat undignified stigma to them. If a businessman is going to use portable transportation, he's not going to want to look silly. A scooter with pedals is unusual enough to find its own market, but roller skates already have a stereotype. The unusual appearance you'd get from a skate designed to attach quickly to shoes would help to set them apart as "non-play" skates, but would it set them apart enough?

    I looked online, and those skateboards go 20 mph and weigh 50 pounds. There's no way any of them is going to go down to 10 pounds.
  7. Jan 28, 2005 #6
    Small wheels, road abnormalities, and crowded pedestrian thoroughfares

    The people who have cracked their heads open on Bike Fidays (20"-wheel folding bicycle built in Eugene, Oregon) report that the small front wheel seems to not clear road abnormalities very well.

    Anything other than walking does not work in hallways. Try running daily down crowded hallways. After you knock the books out of Macho-Man's girlfiend's arms, you might be sorry you put your theory to the test.

    Many folding bicycles are ordinary bicycles that have merely the addition of two of these:

    Two of these torque couplings together only weigh 8 oz. If a normal bike weighs 15-30 lbs., why would a folding bike weigh 40-50 lbs.?

    Bike Friday's small-wheel folding bikes weigh 16-26 lbs.

    Titanium does not make a bike significantly lighter.

    Most steel-frame folding road bikes weigh ~20 lbs.

    They might consider hiring taxicabs and pedicabs. That way they can talk on the phone and organize their files while en route.

    Full-fairing recumbents have practicality problems. One problem is that the engine of the vehicle loses all of its cooling potential when the fairing is on. If you read the human land-speed record pages carefully, you will see that some of the hazards of those record attempts include overheating.

    The ones that have been made and linked-to on Slashdot are referred to IIRC as spring-loaded exoskeletal devices. The ones I saw on the inventors web page were pretty big and heavy, so some design and materials advances might be in order before they could be marketed to the downtown crowd.

    They have small wheels, and so they have the tripping problem. They might also need hand-controlled brakes (remote brake levers in the hands). Wheel abrasion might be excessive, requiring frequent wheel replacement.

    I would assume lollygagging skaters go a bit slower than lollygagging bicyclists -- so, say, around 8 to 15 MPH.
    Last edited by a moderator: Apr 21, 2017
  8. Jan 28, 2005 #7
    These exist. They are better described as skates with a removable wheel frame as regular shoes don't have enough ankle support to allow comfortable skating. This version is yet sufficiently flexible to allow walking when the wheels are off, and they look like hiking/work boots.

    I have experienced going to school on both skateboards and skates, and one problem is that sidewalks are rather rough for a comfortable ride (endos are only problematic at very low speed - slower than walking). Another is carrying your books. You need your hands for balance/safety. Wearing a backpack would wrinkle a business man's suit, and can cause sweating.

    As for motorization, the weight of batteries needed to tow 180 lbs human is much of the problem in achieving a 10-lbs device. At this weight, you need to look at human-powered devices.

    I believe the lightest race bicycles are carbon fiber and titanium, weigh about 20 lbs and cost between 5-10k$. A bicycle motor+battery kit I saw recently could be added for about 2k$, adding about 10 lbs.
  9. Jan 28, 2005 #8


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    Since we're solidly based in reality here....NOT!

    People are fat enough as it is. Get off your butts and walk!

    How about this as an idea (see attachment when available).
    Last edited: Nov 7, 2005
  10. Jan 28, 2005 #9


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    I'm buying one of those. :approve:

    Dang. I should have bought one for each foot. :frown:
  11. Jan 28, 2005 #10
    "Titanium is not as strong as steel and it is not as light as aluminum. The result is a frame that has a better ride than aluminum, but weighs more."
    http://www.torelli.com/home.html?http://www.torelli.com/tech/material.shtml&1 [Broken]

    "My personal favorite bike is a 55-centimeter all Columbus Foco Steel Torelli bike with a steel fork, generously chromed, built up with a Campagnolo Record 10-speed group. It weighs about 19 pounds.....

    UCI regulations limit a racing bike to about 15 pounds. What we are discussing, from a normal all-steel bike to a super-light, barely legal bike is about 4 pounds. This is what we're going crazy about, 4 pounds....

    But, most weight conscious people aren't bringing their bikes down to 15 pounds because down at that weight, the handling gets very sketchy. 17 - 17.5 pounds is the normal range. The real discussion is about 1.5 to 2 pounds."
    http://www.torelli.com/home.html?http://www.torelli.com/tech/material.shtml&1 [Broken]
    Last edited by a moderator: May 1, 2017
  12. Jan 28, 2005 #11
    Last edited by a moderator: Apr 21, 2017
  13. Jan 28, 2005 #12
    Meh on the weight of folding bikes--I was getting my information from a 1970s book :P. Still, folding to put the bike in a trunk or suitcase is not the same as folding to carry the bike around with you.

    Perhaps the bike could fold into a straightish configuration, with one wheel at the end you don't hold so you could roll it like a rolling suitcase, only without the suitcase.

    I agree that in general skates are not as good as bikes, but you can't beat them for portability. The problems are steering, braking, and awkwardness getting into and out of them.

    Skate shoes would not be acceptable, even if you can detach the rollers; if you need stiffness (and these wouldn't really need to be high-performance skates anyway) you could have rods that come up from the skate and strap to your calf. The idea here is something you can use, and in general not really think about; if you have to wear special shoes every day, it's not going to be worth the effort.

    The situation I'm really thinking about here is getting around my college. There are a few hundred feet between buildings, linked by concrete pathways, and longitudinal hallways that go on for quite a while and are usually empty except right when various classes end. For those who live in dorms, there's maybe a quarter mile to walk. Many people use bikes to get in, but once you're there a conventional bike is somewhat unwieldy. I noticed a tremendous improvement in transportation time the few times I've brought a bike to campus, but it did get annoying when the time spent locking and unlocking the bike was almost as much time as was spent actually riding it, and of course I couldn't ride it indoors. I could walk with it indoors and avoid having to lock it, but that felt kind of strange.

    Apparently, in the human speed record, weight is not too important. One guy was putting a water-cooling system on his bike seat.

    I think that the idea of the scooter-type bike, weighing around 30 lbs, having both a platform and pedals and folding so it rolls like a suitcase, could satisfy all the requirements. I wish I had one.

    Edit: By the way, this site http://www.airborne.net/eready/janette/store/titanium.asp [Broken] says titanium used in bicycles typically has 75% more strength for its weight than steel used in bicycles.
    Last edited by a moderator: May 1, 2017
  14. Jan 28, 2005 #13
    Wearing your bike key on your upper arm comes in handy for this. You can find coiled elastic key holders for this. You can also try an elastic lanyard to wear around your neck.
    http://shop.store.yahoo.com/jeffrasof/1neub.html [Broken]

    A frame-mounted holder for your lock also helps speed up bike parking.

    If I don't have a bike when I am on campus, I run between buildings. (This can be hard on your knees, though. If you have not destroyed your knees yet, you might want to take some precautions by following a low-inflammation regimen and wearing healthy shoes.) To run with a backpack, I find I have to take it off and carry it one-handed so it doesn't bounce around.

    Titanium also has to be welded, which weakens it. Steel has the advantage that it can be brazed, a process which can result in virtually no reduction in strength.
    http://www.henryjames.com/faq.html [Broken]

    "Silver or brass brazing completes the structure with minimal metallurgical damage (unlike welding which must melt the metal under essentially uncontrolled conditions). The hype put out by aluminum and titanium makers is that welding is stronger, lighter, the latest technology, and magically better. In fact, they can't use lugs and have no choice but to weld, and so they turn to hype... "
    Last edited by a moderator: May 1, 2017
  15. Jan 29, 2005 #14
    Normally I just hold the lock, with key still inside, in one hand while I pedal.
    The lock is either used to lock the bike, or I'm _riding_ the bike. Anyway, you can just wrap the lock around the seat post if you have the right type of lock (I used to do this though on my current bike I have a useful handlebar bag instead).

    I'm not generally so desperate for time that I'm going to run anywhere. For one thing you can't look cool and measured while dashing between buildings with your backpack in your hand.

    http://www.vanguardtitanium.com/titanium.htm [Broken] refutes the horrors of welding. The "strength-to-weight ratio is higher than steel, both before and after welding."
    Last edited by a moderator: May 1, 2017
  16. Jan 29, 2005 #15
  17. Jan 29, 2005 #16


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    Am I so old that people have never even heard of those skates I had as a kid? That's exactly how they worked. They were metal (even the wheels, but I'm sure nowadays could be fitted with polyurethane wheels or some other material that will get faster speeds, better traction on smooth floors, and won't scratch up/mark up hallways if used indoors...that's a bigger hindrance to indoor use, building owners prohibiting them because they destroy the flooring), and fit over your shoes. You used your skate key to adjust the length and the width of the front part around your toes so they'd stay on your feet. You could probably incorporate a different release/catch mechanism for tightening them than the old keys that easily got lost, which would make them quick to adjust and put on/take off. Use newer alloys, give it a slightly sleeker look, and offer some high gloss metallic paint finishes (like car paint), and have something the young professional would embrace.
  18. Jan 29, 2005 #17
    Perhaps, but there's still the steering/braking/putting on/taking off problem. They might have a marketing advantage if they're "retro" though.

    hitssquad, the eunicycle sounds like it is perfect for the purposes I described. Only thing is, how fast does it go? Does it go 10 mph (the desired speed)? I read that there's a video of it on the main site but that site is down due to exceeded bandwidth.

    However, if you can fit a motor that propells in a human AND a balancing system in a sub-30-pound vehicle, why not skip the balancing system and just have a low-weight motorized skateboard? Cheaper, and probably significantly lighter.
  19. Jan 29, 2005 #18
    The Trikke is 18 lbs., human-powered, has brakes, folds up, and cruises at 12 MPH:

    Ordinary folding kick scooters might fit the bill as well:
    http://www.wheelalternatives.com/catalog/item/1672582/1107300.htm [Broken]
    Last edited by a moderator: May 1, 2017
  20. Jan 29, 2005 #19
    Hmm, I thought kick scooters would necessarily be too slow, but a site here (http://www.electric-bikes.com/kickers.htm [Broken]) says they go up to 10 mph. Any idea how much effort that takes?

    I don't know about the Trikke--for one thing it looks too wide, for another thing you apparently have to "snake" it back and forth somewhat. It just would take up too much space.
    Last edited by a moderator: May 1, 2017
  21. Jan 29, 2005 #20
    Yes, the Trikke does not seem to fit well in people-crowded areas. I think I would opt for an ordinary foldable kick-scooter. The problem with the kick scooter for downtown business districts, though, is the only thing legal on the sidewalk is walking (and riding a kick-scooter in the street would be dangerous as well as possibly illegal).
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