SPD's power advantage....Myth?

1…5791011

Comments

  • Bikerbaboon
    Bikerbaboon Posts: 1,017
    meesterbond wrote:
    Ok, two questions...

    Why, with a decent set of flats and shoes, can you not apply any force at this 'dead spot'?

    Secondly, it seems to have been assumed that 'pulling up' on the up stroke is even possible when from memory there have been studies which concluded that the best that can realistically be achieve is an 'unweighting' of the back foot. Again something that can be done just as easiely with flats.

    with flats off road can you afford to unweight a foot if you did then you would have no grip and could well lose your footing. Grip comeing from friction thats is a function of the downward force on a surface.

    But all of this is a bit silly.... I can put more power down than some one on flats.. How many MTB'ers head out with a power tap on for a general blat round hte local woods ?

    If you are in a race every second counts, so getting maximum effichancy is needed so Racers use SPDs in XC, Down hill if there is long streaches to put power down again some pros use SPD's then again is its more twitchy and with lose corners they will stick with flats to beable to dab on the corners to support a slide as needed. All based off whats teh quickest.

    NON of that matters for a ride about in the local woods. So try SPD, try flats pick one you like to ride with and ride get muddy and end up witha smile on your face.
    Nothing in life can not be improved with either monkeys, pirates or ninjas
    456
  • Northwind
    Northwind Posts: 14,675
    meanredspider wrote:
    Gravity is interesting in the debate but a bit of a red herring - else recumbant (sp?) bikes wouldn't work - and I'm sure they do...

    Bit of a silly argument, recumbent riders push against the seat, regular cyclists obviously can't do that. A recumbent would work without gravity but a regular bike wouldn't, the only "opposite" force you could have would be from your arms, unless you developed a new SPD for your saddle/arris interface... And the arms along obviously wouldn't work.
    Uncompromising extremist
  • kangaroo
    kangaroo Posts: 1,199
    Northwind wrote:
    [unless you developed a new SPD for your saddle/arris interface... .

    think this might be one for dragons day
    what are brakes for again
  • Anonymous
    Anonymous Posts: 79,667
    supersonic wrote:
    yeehaamcgee wrote:
    I'd be intrigued to know how.

    I was thinking (lets say the ropes are purely vertical to remove any horizontal forces) the maximum rope tension would equal his body weight ie he would lift himself off the see saw. But what if he nailed his feet to the seesaw?
    If his feet were nailed to it, then still nothing happens. His feet would have to be nailed to the floor, not to the see-saw.
  • Anonymous
    Anonymous Posts: 79,667
    meesterbond wrote:
    Ok, two questions...

    Why, with a decent set of flats and shoes, can you not apply any force at this 'dead spot'?

    Secondly, it seems to have been assumed that 'pulling up' on the up stroke is even possible when from memory there have been studies which concluded that the best that can realistically be achieve is an 'unweighting' of the back foot. Again something that can be done just as easiely with flats.
    Personally, I'm not saying you categorically "can't" turn the pedals through the deadspot with flats. It's easier to do with SPDs, since you don't have to maintain downward pressure to keep your feet attached, meaning you're not fighting yourself with them if you see what I mean.

    You're right though, you CAN unweight your foot on flats on the upstroke. Unweighting doesn't mean completely removing your foot from the pedal.

    I wonder how many of these people who believe you have to be clipped in to do such things have ever skateboarded, or even thought about how skaters perform their tricks?
  • Northwind
    Northwind Posts: 14,675
    yeehaamcgee wrote:
    I wonder how many of these people who believe you have to be clipped in to do such things have ever skateboarded, or even thought about how skaters perform their tricks?

    Or for that matter done a bunny hop.
    Uncompromising extremist
  • meanredspider
    meanredspider Posts: 12,337
    Northwind wrote:
    Bit of a silly argument, recumbent riders push against the seat, regular cyclists obviously can't do that. A recumbent would work without gravity but a regular bike wouldn't, the only "opposite" force you could have would be from your arms, unless you developed a new SPD for your saddle/arris interface... And the arms along obviously wouldn't work.

    A couple of points:

    - If gravity were the only force (as some posters have suggested) power on the flat would be limited by the weight of the cyclist. Does anyone have any evidence that this is true? My argument isn't that gravity is of no interest but that it's not, in any way, limiting.
    - Try this experiment: Put one foot on an 8" box and push down (as if pushing on a pedal) as hard as you can. What happens to the other foot? It lifts off the ground (in an upward direction) - sound familiar? Now put a bar in front of you and hold it. Strap your other foot to the floor and, with the first foot, press on the box again - can you push harder or less hard?

    The applies to those guys in sailing that operate the winding mechanisms (can't remember the name) - they hold on and push and pull with both arms. Try rotating this thing with just the flat of your hands without holding on just pushing.

    I don't have an axe to grind - I really don't care what people do or think - I just want this stuff considered here.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • Anonymous
    Anonymous Posts: 79,667
    meanredspider wrote:
    Try this experiment: Put one foot on an 8" box and push down (as if pushing on a pedal) as hard as you can. What happens to the other foot? It lifts off the ground (in an upward direction) - sound familiar? Now put a bar in front of you and hold it. Strap your other foot to the floor and, with the first foot, press on the box again - can you push harder or less hard?
    You can push harder, because, here is the clincher.....
    Your foot is now attached to something outside the closed system
    What you're demonstrating, is that by attaching your foot to the FLOOR, which remains stationary, you could push harder on a pedal. Which is entirely true.
    Cranks are not the same. Both your feet are attached to the same system
  • meanredspider
    meanredspider Posts: 12,337
    yeehaamcgee wrote:
    You can push harder, because, here is the clincher.....
    Your foot is now attached to something outside the closed system
    What you're demonstrating, is that by attaching your foot to the FLOOR, which remains stationary, you could push harder on a pedal. Which is entirely true.
    Cranks are not the same. Both your feet are attached to the same system

    No - the box is on the floor and so is the strapped foot. The cranks of the bike are a couple. Instantaneously, the force you are pushing down tends to lift the other foot upwards (try a standing start in the biggest gear and see what happens). The handlebars are also part of the system and so is the saddle.

    Try to see if you can cycle as hard with your hands off the handlebars (esp that big gear start).
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • Northwind
    Northwind Posts: 14,675
    meanredspider wrote:
    Try to see if you can cycle as hard with your hands off the handlebars (esp that big gear start).

    Well, you'll crash. But if you've ridden with tribars you'll know that you can put the force down without having to pull yourself "onto" the bike- you can be propped on the rests and relaxing your grip and still pedal hard. As hard as normal? Not really sure, didn't try.
    Uncompromising extremist
  • meanredspider
    meanredspider Posts: 12,337
    Northwind wrote:

    Well, you'll crash. .

    Fair enough - try it on a spinning bike with the resistence turned right up then :wink:

    I'm not saying everyone should ride SPDs - what I do believe is that it isn't a myth that SPD's give a power advantage. That advantage (and I can't quantify it) may not be large and it may not outweigh other disadvantages for certain types of riding.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • NatoED
    NatoED Posts: 480
    the whole SPD give more power is not completely true . SPD's tend to give you a more progressive power curve with less peaks and troughs. It alows a more efficant use of power in the pedal stroke.
    Think of it as an internal combustion engine. A twin cyclinder engine of 200cc has less power than a single cyclinder 300cc engine . But because the twin cyclinder engine can push one cyclinder back up the return stroke with it's power stroke then it gives an even power output. Though this does also use some of it's power to this action.

    A spd equiped rider has thae advantage of not relying just on the down stroke for power . This means that on lose surfaced or sharper climbs they can produce the torq (?) required in a smoother action . Meaning less likely to lose momentium and traction on such surfaces.

    would that be the correct synopsis for the discution so far?
  • Northwind
    Northwind Posts: 14,675
    Probably not too far off.

    OK, here's one, discuss:

    "Many SPD users will rarely if ever actually use the pedals in such a way as to recieve the claimed power benefits"

    and

    "Despite this they'll still post on internet forums about how effective the pedals are"

    :wink:
    Uncompromising extremist
  • meanredspider
    meanredspider Posts: 12,337
    NatoED wrote:

    would that be the correct synopsis for the discution so far?

    I honestly don't follow that analogy at all.

    I think that SPDs allow some additional power from the other leg to be applied to the crank in addition to the downward power stroke. In your engine analogy, that's like having some power delivered from the return stroke of the piston.

    I also believe that SPDs also allow you to spin your feet faster at the limit. That, in your engine analogy, is like having a stronger, better-balanced, engine that means it revs higher. Since power is energy delivered over time, more revs often means more power.

    I know I get power benefits from using SPDs as well as more flexibility in pedalling and faster spinning. Whether others do, I don't know or care.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • jason23
    jason23 Posts: 71
    Thewaylander wrote:
    Well you can apply force at this point on flats.

    Thats part of the point, its a bit easier on spd's but on flats its more about technique, mostly you can just forget on spd's.

    SPDs increase power and effieciency= FACT

    This question has been answered by the pro's.

    Do Tour riders use shoe/pedal connection systems?

    Yes, End of debate.
  • Northwind
    Northwind Posts: 14,675
    jason23 wrote:
    SPDs increase power and effieciency= FACT
    This question has been answered by the pro's.
    Do Tour riders use shoe/pedal connection systems?
    Yes, End of debate.

    The question that is left to be answered is "is this relevant"? Pros on the Tour use drop bars, should we? They all shave their legs, should we? Pros on the Tour also have no advantage to gain from flats so no counterbenefits, unlike us. They're also top end athletes, unlike us, and already have exceptionally honed fitness and technique, unlike us. A tiny efficiency saving is worthwhile at that level, it doesn't mean it's worthwhile at all levels.

    Not end of debate.
    Uncompromising extremist
  • meanredspider
    meanredspider Posts: 12,337
    Northwind wrote:

    The question that is left to be answered is "is this relevant"? .

    I'm no longer sure what question we're discussing. I thought it was about SPDs giving a power advantage? If the question is now "Should everyone use SPDs" then the answer's No.

    My race car has high-lift cams, high compression, hard suspension etc Does it have more power than the equivalent road car? Yes. Should all road cars have these features? No.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • Northwind
    Northwind Posts: 14,675
    "power advantage", you say, key word being advantage. We know it gives a theoretical power benefit, I don't think anyone argues with that but does it give us an actual advantage?

    If you throw go-faster kit at an engine, lighten the flywheel etc, to the point that it's massively powerful at peak but hard to get off the line and slow through the midband, is that a power advantage? Or is it just more power?
    Uncompromising extremist
  • meanredspider
    meanredspider Posts: 12,337
    I think we're now getting into semantics. It's a bike - the addition power is only useful if you're going to use it. I'm sure I do so, to me, it's an advantage. You might not - then it isn't.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • ellieb
    ellieb Posts: 436
    Wow this is the geeky-ist pedal argument I have ever read :shock:
    I studied history at uni so what do I know, but it seems to me that a lot of the discusiion seems to be based around around physics & engineering and ignores biology. The fact is that you generate power through your muscles. They work by contracting against their various attachment points. Pulling up doesn't act against the other leg: You are using different muscles on each side. The muscles act against the pelvis and various back muscles and doesn't affect the other leg.
    Lie on your back with your knees half bent and then out with one leg. Now do do it pushing one leg out while pulling the other in. It doesn't affect your pushing leg.
  • Anonymous
    Anonymous Posts: 79,667
    ellieb wrote:
    Wow this is the geeky-ist pedal argument I have ever read :shock:
    I studied history at uni so what do I know, but it seems to me that a lot of the discusiion seems to be based around around physics & engineering and ignores biology. The fact is that you generate power through your muscles. They work by contracting against their various attachment points. Pulling up doesn't act against the other leg: You are using different muscles on each side. The muscles act against the pelvis and various back muscles and doesn't affect the other leg.
    Lie on your back with your knees half bent and then out with one leg. Now do do it pushing one leg out while pulling the other in. It doesn't affect your pushing leg.
    Are you serious?
  • ellieb
    ellieb Posts: 436
    yes indeedy
    doesn't mean that I'm right

    as I'm sure you are about to tell me :wink:
  • ellieb
    ellieb Posts: 436
    Alternatively. Someone on this forum must have access to a turbo trainer like a Tacx imagic and can do a quick test using flats and spds. That would surely end the argument. I'd do it myself but there are technical problems in the turbo trainer dept at the moment :roll:
  • meanredspider
    meanredspider Posts: 12,337
    ellieb wrote:
    Alternatively. Someone on this forum must have access to a turbo trainer like a Tacx imagic and can do a quick test using flats and spds. That would surely end the argument. I'd do it myself but there are technical problems in the turbo trainer dept at the moment :roll:

    I don't need a turbo trainer - just a speedo on my bike. I can go faster if I push and pull. I can't sustain it at peak for particularly long but that's not the point - I do generate more power.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • ellieb
    ellieb Posts: 436
    Yes but isn't the argument that doing so is more efficient. Peak power isn't important. I thought the idea was that by using more muscle groups you could keep going for longer by not fatiguing one set of leg muscles.
  • meanredspider
    meanredspider Posts: 12,337
    ellieb wrote:
    Yes but isn't the argument that doing so is more efficient. Peak power isn't important. I thought the idea was that by using more muscle groups you could keep going for longer by not fatiguing one set of leg muscles.

    The OP quote was this
    Dr Auriel Forrester of Scientific Coaching: “Pulling up on the pedals decreases power output

    which I believe is wrong - peak or not. My harder-core cycling friends do the pulling more consistently. Until I read these threads, I thought my technique was crap.

    You're absolutely right though. Spreading the load across other muscles is another of the benefits I find - especially standing & climbing.
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • biff55
    biff55 Posts: 1,404
    i'm amazed that folk care enough about this non-issue to write 10 pages of tedious crap.
    good work men , keep it up. :D
  • Northwind
    Northwind Posts: 14,675
    meanredspider wrote:
    I think we're now getting into semantics. It's a bike - the addition power is only useful if you're going to use it. I'm sure I do so, to me, it's an advantage.

    Well, OK, maybe. But what I'm saying is that that enough of a power difference to be worthwhile for a Tour rider isn't neccesarily enough of a power difference for us to even be aware of it. They do all sorts of bleeding edge stuff that we don't because we don't consider it relevant, or worthwhile.

    As far as pulling up for sprints, I've seen people unspd themselves while pulling up on climbs that I can just mash up with my flats. On very steep stuff I run out of traction or pop the front wheel before I run out of leg power. Extra power when you're already wheelying or spinning isn't an advantage.
    Uncompromising extremist
  • Anonymous
    Anonymous Posts: 79,667
    biff55 wrote:
    i'm amazed that folk care enough about this non-issue to write 10 pages of tedious crap.
    good work men , keep it up. :D

    lets not forget that 2 pages ago i mentioned that someone had posted a symbl which looked like a tiny ballbag. no one seemed to care.
  • Anonymous
    Anonymous Posts: 79,667
    ellieb wrote:
    yes indeedy
    doesn't mean that I'm right

    as I'm sure you are about to tell me :wink:
    When you're lying on your back, your weight is supported on your, well, back.
    Both legs are in this case are independent.

    When pedalling, your weight is supported on your feet.
    If you could attach your trailing foot to the floor, or a moving contact point on the ground, you could use it as an anchor point to put more pressure through the leading foot.
    Unfortunately, when it's attached to the trailing pedal, you can't because this pedal is directly connected to the other.
    You cannot brace yourself against the thing you're moving.

    The see-saw example a page or so ago should explain this.

Categories