ZeroPlay Posted December 10, 2008 Share I've read the claim that when a downward force is applied to a hub in a spoked wheel (e.g. when you're sitting on your bike), the tension of the spokes above the hub is not increased, but the tension of the spokes below the hub is decreased. The hub is "standing on the lower spokes". It is not "hanging on the upper spokes" or equally distributing the downward force by both "hanging" and "standing". Have I presented the claim correctly? This claim seems very counter-intuitive to me. Can anyone point me to a website or other source that explains this in a simple way? Or maybe explain it to me in this thread? By analogy: Consider a bow (as in "bow and arrow") with a completely rigid frame and a bowstring under tension, orientated as you would hold it when shooting. If one pinches the string at some point along its length and pulls the string down (while the frame is held in place), is there only a decrease in tension of the bowstring below the point where you are pinching and no corresponding increase in tension above the point where you are pinching? Link to comment Share on other sites More sharing options...
controlc Posted December 10, 2008 Share This is going to be a long one... Link to comment Share on other sites More sharing options...
Thug Posted December 10, 2008 Share I'm going to fetch some popcorn........ Link to comment Share on other sites More sharing options...
AndreZA Posted December 10, 2008 Share I'll melt the butter Link to comment Share on other sites More sharing options...
cyclenut Posted December 10, 2008 Share Do you want to know or do you need to know? and the next question is ... why ? Link to comment Share on other sites More sharing options...
Gary Greer Posted December 10, 2008 Share I'll call JB. Link to comment Share on other sites More sharing options...
ZeroPlay Posted December 10, 2008 Share Do you want to know or do you need to know? and the next question is ... why ? I just want to know. Why? Curiosity. It's been bugging me since I saw the claim a long time ago. So has quantum physics, but this is probably easier to put to rest. Or is it? (pass the popcorn, please) Link to comment Share on other sites More sharing options...
cyclenut Posted December 10, 2008 Share what can go up a drainpipe down but can't go down a drainpipe up? Link to comment Share on other sites More sharing options...
Johan Bornman Posted December 10, 2008 Share I'll call JB. He's not here, went for a ride apparently. Link to comment Share on other sites More sharing options...
Minion Posted December 10, 2008 Share It is true. At first glance it does seem counter-intuitive. Upon proper, deeper, analysis the stress/force calculations show it to be true. It's been discussed in the past on the Hub with much associated wailing and gnashing of teeth. Link to comment Share on other sites More sharing options...
Ox_Wagon Posted December 10, 2008 Share O no not again..... The short off it is that if you do not own a Mavic R-SYS wheelset it is imposable for spokes to be in compression and therefore there is no "standing" involved. <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> Link to comment Share on other sites More sharing options...
Willehond Posted December 10, 2008 Share It's not hanging, but it's definitely pulling... If a spoke is tensioned how the heck can it 'push' a hub? Try pushing a spoke on it's own and see if it deforms. Now try pulling it and see if it deforms. You don't need quantum physics. Ag toe JB, moenie so skaam wees nie. Link to comment Share on other sites More sharing options...
Johan Bornman Posted December 10, 2008 Share O no not again..... The short off it is that if you do not own a Mavic R-SYS wheelset it is imposable for spokes to be in compression and therefore there is no "standing" involved. <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> Hey Ox, welcome to the club of the converted. But.....how do the Frenchies prevent a tiny little tube like an R-Sys spoke from buckling under compression? Answer, it never goes into compression. Link to comment Share on other sites More sharing options...
javadude Posted December 10, 2008 Share Man, didn't you okes watch that 80's Afrikaans program with the science teacher proving all sorts of science problems. He had a bicycle wheel with string spokes to "prove" that it was pulling and not hanging(or whatever). I think JB should approach the SABC to start a more modern series, kind of like an SA mythbusters. velo2008-12-10 08:45:46 Link to comment Share on other sites More sharing options...
Johan Bornman Posted December 10, 2008 Share It's not hanging' date=' but it's definitely pulling... If a spoke is tensioned how the heck can it 'push' a hub? Try pushing a spoke on it's own and see if it deforms. Now try pulling it and see if it deforms. You don't need quantum physics. Ag toe JB, moenie so skaam wees nie. [/quote'] Ek's nie skaam nie, ek's moeg vir die topic. Als is al gese en hulle moet net 'n bietjie gaan search. Keywords for searching here would include "standing on bottom spokes" and tension and compression - all with the word spoke in the search. Or as Edman says, go after the wailing and gnashing of teeth. Link to comment Share on other sites More sharing options...
Ox_Wagon Posted December 10, 2008 Share The R-sys spoke is only designed for compression on side loading but I agree with you that it is most probably a marketing gimmick as the drive side spokes are still normal spokes. Link to comment Share on other sites More sharing options...
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