|Does anyone know why pedals that put your foot closer to||Bruce J.|
Feb 6, 2002 9:16 AM
|the pedal axles are deemed more efficient??|
|re: Does anyone know why pedals that put your foot closer to||LC|
Feb 6, 2002 10:15 AM
|I read some sort of marketing hype about it at Shimano or Time or somewhere like that. It had something to do with the leverage advantage at the top or bottom of the pedal stroke. Theoretically I could maybe see it, but when you are only talking about 1 to 2 mm difference between any pedal brand it has to be B.S.|
|re: Does anyone know why pedals that put your foot closer to||DINOSAUR|
Feb 6, 2002 11:14 AM
|That's the same thinking I have. Closer to the pedal spindle is supposed to create more leverage, which also allows you to lower your saddle a couple of MM. Probably has something to do about your pedaling style and this might suit riders who ride flat footed...I guess it all comes down to what feels right for you...|
|Sort of , if I squint my eyes and think real hard...||cory|
Feb 6, 2002 10:39 AM
|That's the Q Factor, named (I think) because when your feet are farther apart, you pedal like a duck (quack-quack, get it?). Grant Petersen has an explanation of it in the Rivendell Reader, and it may be still on the website, too (www.rivendellbicycles.com). The basis of the theory is that you're pushing straight down rather than out at an angle, and that's the way your hips-thighs-knees-ankles work best. I can't tell much difference, if any, but I'm a Clydesdale and the small variation among my bikes might not be enough to matter relative to my body size. My wife (5'1") says she can feel it between her big-Q mountain bike and her narrow-Q roadie.|
|Sorry, I think the Q factor is important too, but thats not the||Bruce J.|
Feb 6, 2002 10:44 AM
|topic here. Its the distance from the ball of the foot to the pedal axle.|
|No, that is a different thing||LC|
Feb 6, 2002 10:47 AM
|Q factor is basically how far your feet are appart. He asked about the distance between the ball of your foot and the pedal spindle.|
Feb 6, 2002 12:56 PM
|Well, isn't there a limit to how close you can get your foot to the crank arm without rubbing it? Seems like the bigger and wider your foot is, the furthur away from the crank the pedal platform has to be.
Q is really determined by BB spindle width and how far the crank arms have to be fluted out to clear the chainstays. That might have to be wider on a short chainstay racing bike than on a longer chainstay mountain bike. Grant Petersen's gripe is that as builders widen the rear dropouts to accomodate ever more gears, they have to widen the crank to clear the chainstays, and riders can't push straight down on the pedals anymore. So Litespeed and others make the chainstays narrow in front, then fluted out in the rear, to keep the Q as narrow as possible. Interesting, huh? How many gears do you really need on a bike?
|Clearing the stays is one thing, but...||Ray|
Feb 7, 2002 6:07 AM
|you also have to take chainline into account. On a touring or mtb with 135 mm rear dropout spacing, the cogs are out there pretty far and the chainrings have to be out there pretty far in order to line up properly. So crimped chainstays only solve part of the problem.
I used to think "Q" factor was too silly to even think about, but then I rode on a bike with a low "Q" crank. Jeez, what a difference! Now I don't have any bikes with dropouts more than 130 mm apart and no setups with a "Q" of more than 150.
Feb 6, 2002 1:12 PM
|It may be because the foot rotation around the axle is more symmetric. At the top of the stroke, the foot is above the crank centerline by the crankarm length plus the pedal offset. At the bottom of the stroke, the foot is under the centerline by the crankarm length minus the pedal offset. This gives a slightly non-circular rotation of the foot, kind of a micro biopace effect. This may be be less efficient than a circular rotation. The closer the foot is to the pedal axle, the more circular the foot rotation.
|lessens the dead zone||Dog|
Feb 6, 2002 1:23 PM
|Think about a pedal with an exaggerated stack height between the spindle and foot, say 24 inches. When the foot passes over 12 o'clock it will spend a lot of time moving over the pedal instead of moving the pedal, unless the foot stays in a perfectly fixed position in relation to the pedal. Same at the bottom. The same thing happens on a micro scale in reality, but multiply that by thousands or millions of revolutions, and it adds up. Less stack height makes the dead zone smaller.
|shortens your shim||cyclopathic|
Feb 6, 2002 2:30 PM
|if interested there's a "scientific" explanation on www.analyticcycling.com take a look. I remember reading somewhere young Ulrich was selected for bicycling because he had exceptionally short shim and it creates additional leverage advantage.
Basically it is all BS the diff would be less then 0.5%
|shortens your shim||Dourbadaky|
Feb 7, 2002 5:09 AM
|In theory what Dog said was correct. However, that notion ignores one critical part of the whole equation. The biemechanical effects on the riders body himself/herself of having their feet effectively closer together. No one has really done a meaningful study as to whether you may in fact be stressing your legs more the closer you move the balls of your feet to the pedal spindle. You may in fact be causing excess strain on your legs in such a situation and perhaps not, but whithout knowing there is no real scientific proof that what is asserted on the rivendell site actually works out to superior performance in a real life situation.|
|Here's your explanation, and my take...||ohio|
Feb 7, 2002 8:27 AM
|The further away your foot is the more likely you are to exert a force that does not pass directly through the spindle, which would cause your foot and ankle to rock forward or back, which you then have to expend energy to correct if you want to keep your foot in the optimum position for pedaling. If the ball of your foot is axle at the pivot point of the pedal, then ANY force you exert goes directly to the crank arm.
In my opinion it won't noticeably increase your efficiency, BUT it is the reason Time pedals feel so stable to people. Like they can just stomp away on them... try to stomp away on doug's 24in platforms.
Note that this is a different situation than the Speedplay float issue that's been brought up, because in this case it's muscles that control the alignment, whereas with float, it's ligaments.
|How can you say slippery float doesnt effect the muscles?||DR dave|
Feb 7, 2002 11:18 AM
|and that it only effects teh ligaments? So, youre saying ligaments will move your ankle back into position as the ankles pivot 4 o'clock to 8 o'clock?|| |