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  1. #26
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    Quote Originally Posted by centurionomega
    Not only is this thread cracking me up, I think this is the right answer.
    Aye. The weight is on the hub. The hub is suspended by the spokes, from above.
    Other countries need to stop hatin' or we'll unfriend them. - Christine

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  2. #27
    More carbon fiber please!
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    Would a sky hook be okay?
    http://inlinethumb36.webshots.com/48...600x600Q85.jpg'05 Giant NRS C1 & '06 Giant TCR Advanced
    '68 Schwinn Typhoon

  3. #28
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    True, but irrelevant

    Quote Originally Posted by Pieter
    Skyliner, your hook is mounted in an unfavorable position.

    If you want minimum force on the rim, mount the hook from the ceiling so it hangs vertically.

    Your hook however is about 45 degrees from vertical. That way, the weight of the bike introduces a horizontal component of force tending to compress the tire agains the wall. You can draw a vector diagram to show this. Anyway, the upshot is that the force of the hook acting on the inside of the rim is greater than the weight of the bike alone (square root of 2 times greater when the angle of that hook is exactly 45 degrees).
    The forces are still far too small to worry about.

  4. #29
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    Quote Originally Posted by PlatyPius
    Aye. The weight is on the hub. The hub is suspended by the spokes, from above.
    This is interesting, but more on that later....

    To OP: as has been pointed out this is a common way of hanging bikes, and regardless of personal musings, it just doesn't damage a fim. But even if you don't accept that as persuasive, think about it: IF the bike is simply hung from the rim on a hook, the maximum pressure on that point is the weight of the bike. 20 lbs or less for a light weight bike w/ light weight rims. More than that for a heavier bike, which also probably also has heavier rims. Grip strength for an average adult male is on the magnitude of 60+ lbs, and if I'm not mistaken, pinch strength even exceeds that 20 lb. magic number. Do you think you could damage your rim by trying to crush it with your hand? IF the bike is hung at an angle that changes the force angles, the tire more than likely absorbs any crushing pressure that might exceed the bike's weight.... if it were significant anyway.

    But back to the hanging from the spokes vs. being supported by the spokes issue: I can picture this in my mind, but in my mind, it seems to be both, equally, at the same time. But it's been so long since I studied physics, and even then I doubt I could have figured it out. But it is interesting to me.

  5. #30
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    I hang my wife's bike like that. The only difference is the rear wheel rests on the grown. So it is supported by the ground as well.

  6. #31
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    Don't Start!

    The hanging vs.standing vs. whatever from the spokes debate. On certain forums this is debated and argued loudly and at length, with much confusion and argument about terminology.

    Google Jobst Brandt and the word "standing" and follow a few links. Your head will spin.

    Here are some basic facts, without interpretation. In a properly built bicycle wheel, all the spokes are under tension at all times -- i.e, they're pulling on the rim. When you load the wheel by pushing down on the hub while the ground pushes up on the bottom of the rim, tension on the spokes at the bottom decreases substantially (but is still a positive number -- i.e., they don't go slack), while tension on all the other spokes stays about the same. Tension on the spokes at the top does not increase significantly.

    Hanging? Standing? Something else? Discuss amongst yourselves.
    Last edited by JCavilia; 06-14-2010 at 11:37 AM.

  7. #32
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    my bike corral at the office stores bikes in a similar way. last winter after my lower headset race disintegrated, I realized that accumulated salty snowy crap was able to melt and run into the bearing when the bike was in this position.

    other than that, no prob, in fact if it was just wet from rain, a frame with drain holes near the rear dropouts is going to drain better hung this way.

  8. #33
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    Quote Originally Posted by viciouscycle
    Each time you hang up the bike, put the hook between a different set of spokes.

    so thats how they true wheels
    you cant say 3rd without turd.

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  9. #34
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    Quote Originally Posted by Camilo
    This is interesting, but more on that later....

    To OP: as has been pointed out this is a common way of hanging bikes, and regardless of personal musings, it just doesn't damage a fim. But even if you don't accept that as persuasive, think about it: IF the bike is simply hung from the rim on a hook, the maximum pressure on that point is the weight of the bike. 20 lbs or less for a light weight bike w/ light weight rims. More than that for a heavier bike, which also probably also has heavier rims. Grip strength for an average adult male is on the magnitude of 60+ lbs, and if I'm not mistaken, pinch strength even exceeds that 20 lb. magic number. Do you think you could damage your rim by trying to crush it with your hand? IF the bike is hung at an angle that changes the force angles, the tire more than likely absorbs any crushing pressure that might exceed the bike's weight.... if it were significant anyway.

    But back to the hanging from the spokes vs. being supported by the spokes issue: I can picture this in my mind, but in my mind, it seems to be both, equally, at the same time. But it's been so long since I studied physics, and even then I doubt I could have figured it out. But it is interesting to me.
    When you are riding your bike, your weight theoretically goes down the fork to the hub. From the hub, it pulls down on the spokes at the top of the wheel and pushes down on the spokes at the bottom of the wheel. Since all of the spokes are under tension, however, there is minimal change. The force is radiated out through 20/28/32/36/48 spokes; keeping the rim round.

    One thing that is often brought up in these debates is that the rim is designed for the spokes to pull on it; not for a hook to do so. Theory aside, I have never seen or heard of a rim being damaged by hanging.
    Last edited by PlatyPius; 06-14-2010 at 05:38 PM.
    Other countries need to stop hatin' or we'll unfriend them. - Christine

    Apparently I left my reading comprehension glasses in my ass. - DrRoebuck

    Still, it felt great and I felt like I was sitting on some kind of vibrator -Touch0Gray

  10. #35
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    Quote Originally Posted by PlatyPius
    When you are riding your bike, your weight theoretically goes down the fork to the hub. From the hub, it pulls down on the spokes at the top of the wheel and pushes down on the spokes at the bottom of the wheel. Since all of the spokes are under tension, however, there is minimal change. The force is radiated out through 20/28/32/36/48 spokes; keeping the rim round.

    On thing that is often brought up in these debates is that the rim is designed for the spokes to pull on it; not for a hook to do so. Theory aside, I have never seen or heard of a rim being damaged by hanging.
    The other thing not mentioned thus far is that each spoke, if properly tensioned, has around 80-100kgf or more of tension on it. It varies with lacing mind you, but there is LOTS of tension on that rim keeping it round under the rider's weight. The weight of the bike is nothing compared to the tension even on one spoke.
    "Refreshingly Unconcerned With The Vulgar Exigencies Of Veracity "

  11. #36
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    shouldn't cause any problems unless you have some strange rims. I hang all my bikes like this that have some form of aluminum rim and there haven't been any issues. I've never tried hanging a bike with a carbon rim, trispoke or front disc but even then it probably wouldn't hurt them.

  12. #37
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    Quote Originally Posted by JCavilia
    The forces are still far too small to worry about.

    Yes. They are.

    But the geometry is still something to consider.

    It is possible to inadvertently mount that hook in a way which will result in still greater forces.

  13. #38
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    Quote Originally Posted by Pieter

    It is possible to inadvertently mount that hook in a way which will result in still greater forces.
    Go on...

    "Refreshingly Unconcerned With The Vulgar Exigencies Of Veracity "

  14. #39
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    Quote Originally Posted by kbg
    Only time it's bad is for an MTB with hydraulic disks.
    Air can float from the reservoir into the line or the caliper, which is definitely a bad thing.
    Then again, stopping is overrated ...
    If you've got air in your hydro lines there's something wrong with them. Hanging bikes with hydros that function properly will not allow air into the lines.
    "Those who can make you believe absurdities can make you commit atrocities." Voltaire

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  15. #40
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    Think i'm going to get this instead:


  16. #41
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    Quote Originally Posted by skyliner1004
    Think i'm going to get this instead:
    If you have room for it, that works. If it's going to be in a permanent location, consider something that attaches to the wall. Leaves floor unobstructed. I built myself some wood brackets years ago and they're still working. For cheap, you could get some closet pole brackets like this, and pad the the hooks with some stick-on felt.


  17. #42
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    Quote Originally Posted by JCavilia
    ...Here are some basic facts, without interpretation. In a properly built bicycle wheel, all the spokes are under tension at all times -- i.e, they're pulling on the rim. When you load the wheel by pushing down on the hub while the ground pushes up on the bottom of the rim, tension on the spokes at the bottom decreases substantially (but is still a positive number -- i.e., they don't go slack), while tension on all the other spokes stays about the same. Tension on the spokes at the top does not increase significantly.

    Hanging? Standing? Something else? Discuss amongst yourselves.
    Thanks, that makes sense and even I can understand it!

  18. #43
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    Quote Originally Posted by Kerry Irons
    Believe it or not, you're the first person to ever ask this question and as a result you win the RBR Grand Prize of a brand new ..... Oh, wait. This gets asked about every other month. The answer is always the same question. How could the weight of a 20 lb bike cause more stress on the wheel than a 200 lb rider?
    ..

    I've been reading this forum pretty faithfully for six months, and haven't seen it from what I recall. Sure, a search may turn up one. But the search feature sucks, as it does on most message boards. I'd probably have better, more refined search results via a straight-up search on google.

    I don't mind if questions are repeated once in awhile. It's good to get fresh insight, and you don't have to respond or even view the thread if you don't want, right? I don't read every post that comes up here.

    And often, it's the questions that are worth repeating that actually have substance, b/c they are something that everyone has either asked or will ask/need to know.

  19. #44
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    Quote Originally Posted by Marc
    Go on...

    OK.

    You have hook available which is on the short side. You screw it horizontally into the wall.

    It is short enough so that when you hang the bike, the wheel 'rolls' only to the point where the level of the hook is 10mm above the wheel's axle.

    You now have a cantilever with one arm about 350mm, the other 10mm. The fulcrum is the contact point of tire with wall. The mechanical advantage is a factor of 35.

    Analogous to the situation where you use a claw hammer to draw a nail.

    With a bike of 10kg, the resultant force on the rim is thus about 350kg. If this doesn't tear the hook from the wall, it can surely dent the riim - or worse.
    Last edited by Pieter; 06-17-2010 at 01:28 AM.

  20. #45
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    Quote Originally Posted by Pieter
    OK.

    You have hook available which is on the short side. You screw it horizontally into the wall.

    It is short enough so that when you hang the bike, the wheel 'rolls' only to the point where the level of the hook is 10mm above the wheel's axle.

    You now have a cantilever with one arm about 350mm, the other 10mm. The fulcrum is the contact point of tire with wall. The mechanical advantage is a factor of 35.

    Analogous to the situation where you use a claw hammer to draw a nail.

    With a bike of 10kg, the resultant force on the rim is thus about 350kg. If this doesn't tear the hook from the wall, it can surely dent the riim - or worse.
    For your scenario to hold the available movement in the direction perpendicular to the wall would be given by 350( 1 -cos (arcsin 10/350)) which is 143 micrometres (that's about 6 thou or two hair's breadths, not sure how many bee's dicks but not many)

    Of course the force on the tire will cause it to compress much further than this - a tire compression of around 4mm (which is typical for a road tyre with a load around 500N) would cause the wheel to roll a further 52 mm down the wall, reducing your force multiplier to a factor of about 5 to 1 so the force on the rim would be around 500N

    (No, that's not a coincidence)

  21. #46
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    Quote Originally Posted by Mark Kelly
    For your scenario to hold the available movement in the direction perpendicular to the wall would be given by 350( 1 -cos (arcsin 10/350)) which is 143 micrometres (that's about 6 thou or two hair's breadths, not sure how many bee's dicks but not many)

    Of course the force on the tire will cause it to compress much further than this - a tire compression of around 4mm (which is typical for a road tyre with a load around 500N) would cause the wheel to roll a further 52 mm down the wall, reducing your force multiplier to a factor of about 5 to 1 so the force on the rim would be around 500N

    (No, that's not a coincidence)

    Nice math but at these small angles you may assume sin(x) approaches (x) when x is in radians. So no trig.

    A factor of 5 is bad enough - 50kg on the inner wall of the rim, a line load. I for one would not be happy to subject my wheels to that. Dents are likely, but in my house the plaster would give way first.

    I will take your word for the 4mm and 52mm- no convenient calculator here. Now if anyone is dumb enough to design a hook which fits snugly when the tire is deflated...

  22. #47
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    Quote Originally Posted by Pieter
    Nice math but at these small angles you may assume sin(x) approaches (x) when x is in radians. So no trig.

    A factor of 5 is bad enough - 50kg on the inner wall of the rim, a line load. I for one would not be happy to subject my wheels to that. Dents are likely, but in my house the plaster would give way first.

    I will take your word for the 4mm and 52mm- no convenient calculator here. Now if anyone is dumb enough to design a hook which fits snugly when the tire is deflated...
    All great math, I'm sure. Don't understand much of it since my last geometry (trig?) class was 40 years ago and I don't use it to this extent on a regular (ever?) basis. What I do know is this; I've hung my bikes from hooks in the ceiling and on the wall for the last 30 years. So does every bike shop I've ever had the pleasure of visiting. I have never seen a dented rim from hanging a bike on a hook at any angle. Old steel rims to new carbon rims. Double wall, single wall, tubular, aero, you name it. I know, it's a small sample but I think it's an observation that will stand up to scrutiny.
    "Those who can make you believe absurdities can make you commit atrocities." Voltaire

    There are your fog people & your sun people, he said. I said I wasn't sure which kind I was. He nodded. Fog'll do that to you, he said.

    "We are all ignorant about most things."
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  23. #48
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    Quote Originally Posted by Pieter
    OK.

    You have hook available which is on the short side. You screw it horizontally into the wall.

    It is short enough so that when you hang the bike, the wheel 'rolls' only to the point where the level of the hook is 10mm above the wheel's axle.

    You now have a cantilever with one arm about 350mm, the other 10mm. The fulcrum is the contact point of tire with wall. The mechanical advantage is a factor of 35.

    Analogous to the situation where you use a claw hammer to draw a nail.

    With a bike of 10kg, the resultant force on the rim is thus about 350kg. If this doesn't tear the hook from the wall, it can surely dent the riim - or worse.
    "Refreshingly Unconcerned With The Vulgar Exigencies Of Veracity "

  24. #49
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    Quote Originally Posted by tommyrhodes
    Remember. Your not pushing down on the spokes when you ride. Your hanging from them.
    Ba Da Bing!! Thank you, folks! I'll be here all week. Try the veal!
    Anyone who believes there are no stupid questions never worked in a bike shop.

  25. #50
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    Quote Originally Posted by Marc
    is that really all you do? post pictures? is that what all your 12k posts are about?

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