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  1. #1
    Blissfully bent
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    Has any[bent]body used an elliptical chain-ring?

    Just wondering if it affected hill-climbing?
    [Sitting] DF riders "rock" while doing hills - I think "rocking" allows them to keep a more constant velocity between pedal-strokes - improving their efficiency during the climb. Going up hill, if we slow-down between strokes, we speed-up (accelerate) on the next, and energy is required - lost - just to accelerate, in addition to the work required to go a few feet up hill. Does an elliptical chain-ring help keep a constant velocity going up hills?

    "Rocking" example: http://www.youtube.com/watch?v=OzIxObE2A0U

  2. #2
    Senior Member gcottay's Avatar
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    I run Rotor cranks on a Trice Q and find them useful in climbing, but not enough that I have put them on my Rocket.

    In general, I think you will find that you want to increase your cadence while riding a bent and get used to applying power throughout the stroke. If my pedal stokes are not smooth, that's a sign to shift down and pay attention.

    The bent equivalent of rocking is, I think, bracing back hard against the seat. You can generate an amazing amount of pedal pressure that way, certainly enough that one's knees threaten to explode and create an embarrassing display of debris on the roadway.
    George
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    Blissfully bent
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    Hi gcottay,
    Belated "thanks!" for the reply.

    Higher-cadence, yes. While trying to drag peddle through bottom of stroke and keep average rpm around 85-90, it'll be a while before it's a habit. (will beware exploding knees too.)

    Still... is the [percieved] superiority of DF on hills simply a consequence of less-well-trained bent riders? If there's something about the physics/ergonomics of a bent, which puts it at a disadvantage (compared to DF) on hills, I'd really like to understand it - before purchasing the next bent. Like, if the orientation of the hips relative to the pedals affects the ease/efficiency of peddling, it would be good to know.

    Again, thanks

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    Senior Member gcottay's Avatar
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    Though it's often said that everything else being equal a bent does not climb as well as a DF. For me, the opposite is true. On a DF I flat avoid any serious hills but bent on two wheels or three turn into a mountain goat.

    Some bent riders with many years on various bike suggest that some are better climbers than others. My impression is that short wheel base machines with a relatively high BB tend to be among the better climbers.
    George
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    Quote Originally Posted by greybum View Post
    ...
    Going up hill, if we slow-down between strokes, we speed-up (accelerate) on the next, and energy is required - lost - just to accelerate, [I]in addition to the work required to go a few feet up hill.
    There's no real loss of energy in the constant variation in speed as you climb a hill. Sure you need to work harder to accelerate after slowing down, but you got a little free boost while decelerating since you were still climbing while putting out less work than needed to maintain your speed.

    The only loss would be from the slight bit of extra air resistance while going faster than your average speed - since air drag is non-linear you lose more from this than you gain by the reduced resistance while going slower.

    But typically while hill climbing the speeds involved are slow enough that air resistance isn't a dominant factor and the slight speed variations would only add an insignificant amount of added loss due to air drag.

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    Quote Originally Posted by greybum View Post

    Still... is the percieved superiority of DF on hills simply a consequence of less-well-trained bent riders? If there's something about the physics/ergonomics of a bent, which puts it at a disadvantage (compared to DF) on hills, I'd really like to understand it
    I was wondering why recumbents have such a hard time climbing hills.
    So, I did a little experiment.
    I used a digital scale to compare the force available to the pedals.
    When on a DF standing up pedaling, you obviously have your weight + any additional force from extending your leg.
    On a recumbent you only have the force from extending your leg.
    For me, standing on the scale I got 200 lbs static.
    When I extended my leg, I saw the scale jump to approximately 270 lbs.
    Then I positioned the scale so I could replicate my recumbent position.
    With my back against the wall and the scale securely mounted, the most force I could muster from my leg extension was 160 lbs.
    However, I really doubt that I could exert this force continuously while pedaling.
    I tried to exert what I thought was my normal uphill leg force.
    The scale reading was around 100 lbs.
    So, basically what we have is 200 - 270 lbs vs 100 -160 lbs force to the pedals.
    That's essentially a 2 to 1 advantage that DF riders have over recumbents.

  7. #7
    Senior Member gcottay's Avatar
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    Quote Originally Posted by iconoclast View Post
    I was wondering . . . .
    So, basically what we have is 200 - 270 lbs vs 100 -160 lbs force to the pedals.
    That's essentially a 2 to 1 advantage that DF riders have over recumbents.
    This would not be true for me and other bent riders who can hang with me or pass on hills. Though my knees are decidedly unappreciative in the long run, I can apply greater force from a bent position than from simply using weight on pedals.

    The notion that bents cannot climb has been around for a while. Many, for example, expected the RANS team riding RAAM to lose ground in mountain stages and were surprised by the results as the bent riders scored an overall first place.
    Last edited by gcottay; 07-19-09 at 11:48 AM.
    George
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    Quote Originally Posted by gcottay View Post

    I can apply greater force from a bent position than from simply using weight on pedals.
    Oh, I'm sure there are riders with strong legs who can exert more force.
    I consider myself to be in pretty good shape from riding hills on a daily basis.
    But, I found that I couldn't come close to the pedal force available when in a standing position.
    It would be interesting if you could prop up a bathroom scale at an angle and measure the force you can exert with one leg while sitting down in your usual recumbent position.
    You might be surprised at the result.

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    Raptobike Rider djwid's Avatar
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    I use elliptical q-rings on all of my recumbents. it really helps me smooth out my pedal stoke and keep spinning while climbing.
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    Quote Originally Posted by iconoclast View Post
    Oh, I'm sure there are riders with strong legs who can exert more force.
    I consider myself to be in pretty good shape from riding hills on a daily basis.
    But, I found that I couldn't come close to the pedal force available when in a standing position.
    It would be interesting if you could prop up a bathroom scale at an angle and measure the force you can exert with one leg while sitting down in your usual recumbent position.
    You might be surprised at the result.
    OK, I tried the experiment. Put the scale up against a wall and sat down and pushed with one foot. Easily reached a force of 275 lbs for brief periods. Best I could do while standing on the scale was 145 lbs unless I jumped up and down - and then the results were rather inconsistent.

    But I think this is irrelevant from the standpoint of climbing while cycling. Our efforts aren't limited by the maximum force we can exert, but by the power we can put out over a period of time. Anything over about 200 Watts and I quickly become fatigued - and that's true whether I'm generating that power sitting upright or reclined. If I use that 200 W to carry a heavier bike up the hill then I'll be slower than with a lighter bike - and most recumbents weigh more than equivalent quality uprights.

    I think the belief that recumbents can't climb as well is partly based on the physical weight difference, but mainly because the recumbent rider has a significant air drag advantage that is evident when on flat ground or when descending, but is no longer significant when going up any substantial hill. Therefore the recumbent rider who kept up with stronger upright riders on the rest of the ride is suddenly seen dropping back once the grade gets steeper.

  11. #11
    Senior Member gcottay's Avatar
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    Quote Originally Posted by iconoclast View Post
    You might be surprised at the result.
    Fifty percent surprise factor:
    • I look stupid sitting there on the bathroom floor
    • Our scale tops out at 300 lbs.


    prathmann has explained bent climbing well, I think.
    George
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  12. #12
    Recumbent Ninja
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    q-rings are the bomb-diggety!

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    Quote Originally Posted by greybum View Post
    Just wondering if it affected hill-climbing?
    [Sitting] DF riders "rock" while doing hills - I think "rocking" allows them to keep a more constant velocity between pedal-strokes - improving their efficiency during the climb. Going up hill, if we slow-down between strokes, we speed-up (accelerate) on the next, and energy is required - lost - just to accelerate, in addition to the work required to go a few feet up hill. Does an elliptical chain-ring help keep a constant velocity going up hills?

    "Rocking" example: http://www.youtube.com/watch?v=OzIxObE2A0U

    The "rocking" of any sort or direction on a DF is to try to use more gravity and less leg muscle. The more tired the rider's legs are, the more creative ways you're going to see of them trying to keep the pedals going around.

    Elliptical rings increase the chainring size when you have the most power, and decrease it when you have the least. That's their purpose. The most important part of this effect is that the ellipticals make it easier to get through the dead spot. There is no quantitative data for this, but I believe the biggest gear you can turn over is what you can get through the dead spot. When the dead spot gear inches are reduced, you can turn a higher than normal gear through the power spot.

    Ellipticals don't smooth out the stroke, in fact, they do the exact opposite. For the same ground speed, when the elliptical approaches the large diameter of the ring, the crank speed slows down. As the ring then passes the large diameter and rotates toward the smallest diameter, the crank speed increases. For the entire pedal rotation, the foot speed is constantly slowing and speeding up. It's noticeable at first, but you quickly get used to it. The more exaggerated the ellipse, the more of the change in pedal speed. Some people have knee problems if the pedal speed change is too much because as the pedalsslow for the high spot, the loading also increases, which can be too much for some knees. The ellipticals are most noticeable for people with bad technique who grind because the acceleration and easing through the dead spot is most noticeable. Ellipticals can help anyone though and the benefits are not diminished with proper pedal technique. While the power output using round rings during a complete pedal rotation would produce something like a sine wave with the actual pedal speed looking like a relatively flat/straight line, using elliptical rings would still produce a power sine wave but the peaks would be longer while the valleys would be shorter. At the same time, it would change the pedal speed line from pretty much flat, to a sine wave also.
    Last edited by 25hz; 07-26-09 at 12:30 PM.

  14. #14
    Blissfully bent
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    Quote Originally Posted by 25hz View Post
    Ellipticals don't smooth out the stroke, in fact, they do the exact opposite. For the same ground speed, when the elliptical approaches the large diameter of the ring, the crank speed slows down. As the ring then passes the large diameter and rotates toward the smallest diameter, the crank speed increases. For the entire pedal rotation, the foot speed is constantly slowing and speeding up. It's noticeable at first, but you quickly get used to it. The more exaggerated the ellipse, the more of the change in pedal speed. Some people have knee problems if the pedal speed change is too much because as the pedalsslow for the high spot, the loading also increases, which can be too much for some knees. The ellipticals are most noticeable for people with bad technique who grind because the acceleration and easing through the dead spot is most noticeable. Ellipticals can help anyone though and the benefits are not diminished with proper pedal technique. While the power output using round rings during a complete pedal rotation would produce something like a sine wave with the actual pedal speed looking like a relatively flat/straight line, using elliptical rings would still produce a power sine wave but the peaks would be longer while the valleys would be shorter. At the same time, it would change the pedal speed line from pretty much flat, to a sine wave also.
    Thanks 25Hz, this confirms what I proposed in the original post. Ellipticals, by producing a more linear force-profile where the rubber-meets the road, will facillitate less accellerating/decellerating. I think it's a matter of physics [perhaps a bit of calculus too] to show that a given amount of energy will get us farther/faster if we travel at a constant velocity (after an initial accelleration.)

    I appreciate that being able to stand on [df] bicycle peddles is a comfortable action and makes it easier to [apply force to] turn them, but the rider is doing work to step-up on the peddle. Assuming for sake of argument that we're comparing two riders and bikes of the same weight, and doing the same climb, then, whether riding DF or 'bent', we're moving the same weight up the same elevation - which should take the same amount of energy. Unless there's something inherently inefficient about the ergonomics of the bent, shouldn't they be just as fast [up hills]?

    I'm beginning to suspect that my Haluzak isn't especially aerodynamic (especially after a df rider coasted past me going down-hill) and would like my next bent to be low-slung. Also suspect that with every change in body/hip/peddle orientation, some leg-muscle re-conditioning may be required.

    Re: ellipticals and bents, found these links interesting:
    http://www.cruzbike.com/content/worl...-record-holder
    http://www.cruzbike.com/Fitting_Elli...ainwheels.html
    Last edited by greybum; 07-27-09 at 01:22 AM.

  15. #15
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    For hills and bents, there's always heated commentary about the topic. Ellipticals are a separate matter and while they will make hill climbing on a bent a little easier, they'll also make hill climbing on a DF a little easier too. You need to watch when you talk about "energy use", because no one has quantified that for any style of bike, or at least not anything published. An upright uses pretty much every muscle group the body has, while a bent predominantly uses only the legs. While a power meter on a bent and a df might read the same power output at the wheel because they are going up the hill at the same speed, the upright is going to be burning a lot more energy to produce the same wheel power because they are using considerably more muscle groups. That's why calorie outputs for bike computers are way overstated when they are used with bents.

    For me, I am anywhere from 2 to 3 times faster on a hill on an upright than I am on a bent. Why? It's simple. On both bikes, I'm using my leg muscles to turn the cranks over. On an upright, I can use my entire body's power and weight, with the help of gravity, to push the pedals around and I can also twist the bike from side to side to further increase the force against the pedals. On bents, you just can't do this as effectively (or at all) on a bent. Add to this the effect of having to pump blood uphill to the legs (on most bents) and then you further have the reduction in power due to blood flow issues (test reports list these concerns in a "black art" area because the effect is not well understood). So why do I still ride bents then when the hills are harder or a lot harder? Simple. Because hills are never more than a fraction of my rides, and even if they are half of a ride, the small amuont of time lost on an up-hill is more than made up for by the increased speed in every other aspect of the road terrain. One of the primary benefits of bentdom IS the fact that you only have to use your legs, but that is the same thing that makes hills tough.

    If you do tilt your seat back, a couple bent manufacturers with strong racing pedigrees found that with seat back angles lower than 25, the power loss (due to minimized use of the glutes) was greater than the aerodynamic gain.

  16. #16
    Senior Member gcottay's Avatar
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    Quote Originally Posted by 25hz View Post
    . . . .

    For me, I am anywhere from 2 to 3 times faster on a hill on an upright than I am on a bent . . . .
    Unless he is talking about a particular hill, this is either a typo or 25hz is a singularly unusual rider.
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  17. #17
    Blissfully bent
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    Quote Originally Posted by 25hz View Post
    If you do tilt your seat back, a couple bent manufacturers with strong racing pedigrees found that with seat back angles lower than 25, the power loss (due to minimized use of the glutes) was greater than the aerodynamic gain.
    Thanks - this is very interesting! Will follow-up on this.

    Gotta say I agree with gcottay: it sounds a bit extreme to go from, say, 7 mph on a bent, to between 14 and 20mph on a df - assuming the same level of effort (V02) on each. But DF riders do seem to have an advantage on hills and this is exactly the point, do df riders go faster because, for the same VO2 burned, they transfer more energy to the peddles? Are gluts/pushing, more efficient than hams/pulling?

    (I know you said that df riders are burning more energy (more muscle groups). But if energy burned is roughly proportional to V02, then df riders are, simply, breathing harder???)

    I don't know if there's another (better) pic floating around this forum, but I ran across this on my travels:
    Copied from (http://www.me.utexas.edu/~neptune/Papers/job41(7).pdf)
    Fig. 1. Right leg of the bipedal bicycle-rider musculoskeletal model. The
    10 muscle groups included in the model are SAR (sartorius), PSOAS
    (iliacus, psoas), RF (rectus femoris), VAS (three component vastus), TA
    (tibialis anterior), SOL (soleus), GAS (gastrocnemius), BFsh (biceps
    femoris short head), HAMS (medial hamstrings, biceps femoris long
    head), and GMAX (gluteus maximus, adductor magnus).
    Attached Images Attached Images

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    Quote Originally Posted by gcottay View Post
    Unless he is talking about a particular hill, this is either a typo or 25hz is a singularly unusual rider.
    Why would this be unusual? I would think this is standard. On the bent, I work nothing but my legs (and possibly a little glute depending on seat back angle) and doing that for 6 years. On an upright, not only do I get to use those strong leg muscles I've built up, but I can also use gravity, plus pull down on the bars, plus crank the bike over and lever the crank arm too. With all that extra opportunity to put down power, how could I not be faster? On one of the commute hills, it's fairly steep and I averaged about about 6kph on it. On a DF or MTB, I was close to 20. All the hill times were faster, but I was slower on the flats and downhills and overall, my upright commute times were slower than the bent times. 3 friends I commuted with, who also had bents and rode uprights more than I, reported similar experiences.

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    Quote Originally Posted by iconoclast View Post
    I was wondering why recumbents have such a hard time climbing hills.
    So, I did a little experiment.
    I used a digital scale to compare the force available to the pedals.
    When on a DF standing up pedaling, you obviously have your weight + any additional force from extending your leg.
    On a recumbent you only have the force from extending your leg.
    For me, standing on the scale I got 200 lbs static.
    When I extended my leg, I saw the scale jump to approximately 270 lbs.
    Then I positioned the scale so I could replicate my recumbent position.
    With my back against the wall and the scale securely mounted, the most force I could muster from my leg extension was 160 lbs.
    However, I really doubt that I could exert this force continuously while pedaling.
    I tried to exert what I thought was my normal uphill leg force.
    The scale reading was around 100 lbs.
    So, basically what we have is 200 - 270 lbs vs 100 -160 lbs force to the pedals.
    That's essentially a 2 to 1 advantage that DF riders have over recumbents.
    I'm not a physicist, but I can't get my mind around this analysis. When you saw the scale jump to 270 pounds, (presumably by starting from a squatting position, then suddenly standing up?) you must have noticed that the effect lasted only a second or two. To reproduce it you would first have to squat down again, causing the scale to momentarily move in the other direction. Moving your body up and down in this way would seem to be just a back-and-forth transfer of energy with no net gain.

    I think that if the amount of force you can generate by a leg extension is 160 pounds, that's about what you're going to get on any kind of bike. On a DF bike the effective pedaling force is ultimately limited by your weight (since anything greater would lift you into the air rather than pressing the pedal down), but since that's a higher number in your case it's basically irrelevant. On a recumbent the external limitation is the strength of the seat frame you're pushing back against.

    At least these are my rambling thoughts. It's an interesting subject, and I've never seen what seemed to me to be a competent analysis of it.

    Lee

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    You can't use "VO2". Most people don't understand what "VO2" actually refers to. It's a nice number that people like to bat around, especially trainers, but it has very little application to anyone or anything outside yourself unless that person is doing exactly the same exercise as you. The more muscles you are using, the higher your VO2. You can't compare bents to uprights unless they are both using all the same muscle groups, which they can't, and aren't. You could have an unfit rower with a much higher VO2 score than an extremely fit bent rider only using his legs. You have to compare apples to apples, and by apples, I mean the muscle groups. Your VO2 is going to change depending on what activity you are doing.

    For muscle group usage, the glutes are the strongest muscle group for opening up the hip, and they are also the biggest (on most people). The more closed open the hip angle, the loss they are employed. The problem with bents, is you want to lay back for better aerodynamics, which compromises your ability to use one of the strongest muscle groups. So you try to optimize the angle, for most aero gain and least power loss. As aerodynamics is an exponential effect at higher speeds, it gets the most attention.

    Another thing about angles. Not only do different angles recruit or stop using different muscle groups, but the angle changes also change the efficiency and function of muscle groups that are being used because their leverage changes across the joint. In a few studies on angles, it was found that the most effective hip angles (defined by shoulder-hip-BB) were 105 and 130. They weren't sure why these two angles were nearly identical in power output, it just seemed to work out that way. Too many variables for them to identify to figure out why they worked the way they did.

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    Quote Originally Posted by V-rex View Post
    I'm not a physicist, but I can't get my mind around this analysis. When you saw the scale jump to 270 pounds, (presumably by starting from a squatting position, then suddenly standing up?) you must have noticed that the effect lasted only a second or two. To reproduce it you would first have to squat down again, causing the scale to momentarily move in the other direction. Moving your body up and down in this way would seem to be just a back-and-forth transfer of energy with no net gain.

    I think that if the amount of force you can generate by a leg extension is 160 pounds, that's about what you're going to get on any kind of bike. On a DF bike the effective pedaling force is ultimately limited by your weight (since anything greater would lift you into the air rather than pressing the pedal down), but since that's a higher number in your case it's basically irrelevant. On a recumbent the external limitation is the strength of the seat frame you're pushing back against.

    At least these are my rambling thoughts. It's an interesting subject, and I've never seen what seemed to me to be a competent analysis of it.

    Lee
    It's not just limited by weight, it's limited by speed, total weight, rolling resistance and aero drag - the exact same things that power meters use. If the front wheel of a bike is parked against a wall, or you grab the front brake, in theory you could put considerably more force than just body weight on a pedal. In reality though, as soon as you start pushing, the bike starts rolling. In test results, elite riders in full out sprints/accelerations aren't applying more than 100 pounds of force on the pedal because the more force you apply, the more the pedal moves and the more the bike moves. The average rider might be applying 30 lbs or so, with a strong amateur maybe in the 50 lb range.

    People can only put out a finite amount of power. You have max force and zero velocity, up to max velocity and zero force. The faster your pedal moves, the less force is on it. Anyone who thinks they are applying even 150 lbs to a pedal, all you have to do is 60, one legged, half squats (same range of knee motion as on a bike or bent) and you'll find it's next to impossible except for those with massively strong legs. And even then, regardless of leg strength, the harder you push down, the faster the bike moves and the pedal force is reduced.

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    Quote Originally Posted by 25hz View Post
    If the front wheel of a bike is parked against a wall, or you grab the front brake, in theory you could put considerably more force than just body weight on a pedal.
    Touche. You could do this if you were pulling up on the handlebar, in effect using it for leverage the same way you use the seatback on a recumbent. This is probably what racers are basically doing when they "rock" the bike from side to side -- the rocking motion, itself a waste of energy, is a side effect of leveraging each side of the handlebar in sync with the pedal stroke.

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    Follow-up:
    I'm not a Physics-major either, and should have checked with one before my original post(s)
    I erroneously proposed some mechanical inefficiency due to sinusoidal nature of force supplied by rider. My physics-major friend said to remember conservation of energy. I think prathman hinted as much. Anyway, ignoring friction losses;
    After one peddle cycle, increase in Potential and Kinetic energy of system (bike and rider) must equal energy input. If force-supplied is a sine wave, and it's plotted as force vs distance, then the area under the curve will be energy - say Newton-meters. This would be the same area (same energy) if force was constant (avg.) over the same distance. Since one peddle-cycle implies a specific time and distance travelled, whether supplying a constant or sinusoidal force, the rider moves the same distance in the same time expending the same energy.

    This is NOT to say elliptical chainrings aren't of benefit to the rider.

    It seems that, mostly, rider fitness explains the (mis)perception that bents are slower.
    Still...
    Perhaps riders must train ON A BENT, to train the right muscles.
    Possibly, different shoulder-hip-BB angles help or hinder different bent riders, partly explaining the different experiences of riders - even fit riders.
    Uprights allow the rider more flexibility in use of muscles, this can't be a disadvantage!

    Sincere thanks to everybody who's contributed so far.

  24. #24
    OldFart
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    Quote Originally Posted by djwid View Post
    I use elliptical q-rings on all of my recumbents. it really helps me smooth out my pedal stoke and keep spinning while climbing.
    Can you please explain or show an example of "q-rings" to the unwashed? ;-)

  25. #25
    Senior Member
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    Quote Originally Posted by greybum View Post
    Follow-up:
    I'm not a Physics-major either, and should have checked with one before my original post(s)
    I erroneously proposed some mechanical inefficiency due to sinusoidal nature of force supplied by rider. My physics-major friend said to remember conservation of energy. I think prathman hinted as much. Anyway, ignoring friction losses;
    After one peddle cycle, increase in Potential and Kinetic energy of system (bike and rider) must equal energy input. If force-supplied is a sine wave, and it's plotted as force vs distance, then the area under the curve will be energy - say Newton-meters. This would be the same area (same energy) if force was constant (avg.) over the same distance. Since one peddle-cycle implies a specific time and distance travelled, whether supplying a constant or sinusoidal force, the rider moves the same distance in the same time expending the same energy.
    I'm not sure what you were trying to say in that paragraph. Not only is the force supplied producing a sine wave, but so is the power produced at the cranks, and with elliptical rings, foot speed is a sine wave too. The difference as well with this power production sine wave, is that there is no negative value, so I don't know what you're talking about by "area under the curve will be energy".

    This is NOT to say elliptical chainrings aren't of benefit to the rider.

    It seems that, mostly, rider fitness explains the (mis)perception that bents are slower.
    Who is mis-perceiving that bents are slower? If you're talking about hills, there's nothing to think about, they generally ARE slower for the same engine. If you're talking about on the flat or downhills, they're definitely faster. Nothing to guess about there either. If it's a purely mental exercise to try to figure out why they are slower, seriously, what's the point? You can't change the laws of physics. If you change a bent design so it eliminates a disadvantage, you've just created another disadvantage elsewhere in the design. If no one actually takes the time to understand what is going on with a bike, let alone a bent, what's the point of theorizing, especially theorizing wrong?

    Still...
    Perhaps riders must train ON A BENT, to train the right muscles.
    Again, no such thing as "the right muscles". "Bent muscles" are a complete BS myth propagated by people with approximately zero understanding of what is going on when they ride a bike. The difference between an upright and a bent? You have to use the leg muscles MORE, not differently. You can't use gravity and all the other muscles groups like on a DF.

    Possibly, different shoulder-hip-BB angles help or hinder different bent riders, partly explaining the different experiences of riders - even fit riders.
    Not at all. It's been proven, shown and tested multiple times that in all but the most extreme bent designs, shoulder-hip-BB angles are identical to those on a DF.

    Uprights allow the rider more flexibility in use of muscles, this can't be a disadvantage!
    This is, finally, actually applicable.

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