HPVS March 2022

hpvs@lists.lysator.liu.se

1 participants
3 discussions

Re: [hpvs] LED
by B D 27 Oct '24

27 Oct '24

--- Den mån 2008-10-06 skrev Joakim @ BBB <joakim.barkstrom(a)bredband.net>: > Jag googlade lite och hittade en länk till en som har > startat en liten > databas för led-lights. > Vet inte om det hjälper men det kan vara intressant som > jämförelse. > USA-baserat naturligtvis men allt går ju att beställa > över nätet. > Ljusstyrkan på varje enhet är givetvis med liksom priset > i $. > > http://www.candlepowerforums.com/vb/showthread.php?t=176131 … [View More]

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None
by None 08 Mar '22

08 Mar '22

pedals are both pulled and pushed. It is just a lot easier to climb a hill that way. I can also say that that my feet tends to last longer if I try not to press on the pedals all the time. By lifting the feet att the return stroke, I can avoid the aching feet I will otherwise have after some time pedalling. This, btw, seems to be a recumbent problem. For mechanical reasons I assume the force pressing the foot to the pedal is actually higher on a recumbent (with a near horizontal leg) than on … [View More]

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by None 08 Mar '22

08 Mar '22

- My first impression of the Powercranks was a bit flawed. Their main principle is preventing "resting" (pushing if you like) on the pedal in the up-stroke. Learning to use muscles to lift the foot will increase effective power (theoretically). If the power contribution in the up-stroke remains small (but not negative) it will do nothing to smooth the power curve. This might work, but I'm sceptical. By the way: will this work at all on a recumbent? For me they are worthless anyway since I only … [View More]ride Mountainbikes. - My own reasoning around the possible benefits of Bikedrive has made my so curious that I just might have to try it. I have my power reading Tacx to check with. Too bad about the extra 400g's. Maybe I can give first hand reports this spring ;). Loooong message. Sorry about that ;) /Dick ----- Original Message ----- From: "Frederik Van De Walle" <frederixie(a)hotmail.com> To: <hpvs(a)lists.lysator.liu.se> Sent: Tuesday, October 22, 2002 5:18 PM Subject: [hpvs] Re: Vevarmar -->pedalling technique > > Richard Vizins wrote: > > >My main objection is that there is (as far as I know) very little evidence > >that even the most skilled proffesional cyclists use more than a small part > >of the down-stroke to produce power. > > I disagree :-) I am pretty much convinced that if that was really the case, > it would be a very bouncy ride!* ;-) Also I know of a clear example where > two brothers were doing the final sprint for a race (on lowracers) The one > that had the better technique won very easily from his brother, although > they had been racing together the whole race. The catch is, he won using ONE > leg!! And the next year, when the other brother improved his technique, he > couldn't even beat him anymore using both.... (I'm sure there are some other > factors in play here, but still...) > > >It was this knowledge(from experiments) that initiated Shimanos ill-fated > >BioPace project. > >BikeDrive for instance is just another try at the same thing but with a > different approach. Powercranks are very different visually, but really > >also adress the same problem. By preventing the cyclist from lifting > >his up-stroke foot with his down-stroke foot it prevents forces in the > >wrong direction, thus smoothing the power over the pedal cycle. > >BikeDrive does the same thing but by storing energy. > > I agree and I disagree. The explenation of powercranks is right, but I think > Bikedrive and Powercranks are completely different issues. Bikedrive in no > way punishes wrong pedalling technique as powercranks do! Maybe even to the > contrary.... > > >Powercranks develops new muscles, > I think that you can actually learn to pull pretty hard on pedals too. > During continuous riding, I can keep up the same power only pulling the > pedals and relaxing during the push, for quite some time. Sprinting and > climbing capacity improve a lot when I have clipless pedals so I can really > pull.... > > >Bikedrive doesn't require a lot of training and adaptation - which is best? > > Well, as I said before, I don't think very highly of bikedrive and I would > like to try out a powercrank, but I wouldn't actually buy it. Yet. I would > need to try it first, it's the law of stubborness ;-) > > >Do any of them make a difference? > > Even if there is scinetific 'proof', for me it does not guarantee it works > for you, as I believe there is room for a lot of different pedalling > techniques for different people. So I say, try it!!! > If you buy it, you can always sell it... maybe to see how many people want > to get rid of theirs is a better indication if it works ;-) > > Cheerio, frederik > > > *a bouncy ride: a simple calculation: > > Let's say we assume 'one-hour record' power: 500W @ 110 rpm equals a torque > of (500 * 9,54 / 110)= 43Nm average. For one leg this means 21,5 Nm. If only > during one fourth of the pedal stroke there is effective torque > (downstroke), then the torque should be 21,5 Nm x 4 = 86Nm. With a crank > length of 0,17m this means an upwardds force of (86Nm/0,17m)=506N or for > normal gravity 51,56 kg! So if the assumptions made here were true, the > rider has to withstand blows of 50 kg, 220 times per minute!! To me it is > clear no such forces exist, because in any aerodynamic position and > certainly Boardman's 'superman' position, these forces would be unbearable. > Of course very simplistic calc, but there should be some truth in it. > > _________________________________________________________________ > Unlimited Internet access for only $21.95/month. Try MSN! > http://resourcecenter.msn.com/access/plans/2monthsfree.asp > > _______________________________________________ > HPVS mailing list > HPVS(a)lists.lysator.liu.se > http://lists.lysator.liu.se/mailman/listinfo/hpvs [View Less]

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HPVS March 2022