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Thread: Currently developping a new weight lifting shoe and need some input

  1. #31
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    Quote Originally Posted by Mark Rippetoe View Post
    Well, you asked, and I told you. Good luck with the shoe.
    Thank you very much. Most valuable input made available here.

  2. #32
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    Quote Originally Posted by anonymous888 View Post
    Mark, Bertl and I discussed your comment: "I don't think the upper leather by itself provides the support that the strap will provide."

    Yes, it does. And this is exactly the difference between our boot and all other WL shoes. Our WL boot has a very sturdy upper leather, it is just the same if you attach the strap near the eyelets or down near the sole.

    The strap does also not need to support the arch, as in our WL boot the longitudinal arch sits flat on the longitudinal arch support of the insole.
    You have spent more time analyzing this than I have, but I am a bit surprised at this response. (I use the Adidas Power Perfect II shoes, for reference.)

    The question it seems to me is what the exact role of the strap is. Is it simply to keep the foot pressed tightly against the insole (in which case, strap attachment side doesn't matter) or is it also to pull the leather of the shoe up against the concavity of the arch, adding additional support to that already provided by the insole (in which case, obviously, I think, the attachment side matters greatly)?

    Intuitively, I would say the latter is the case -- seems to be the case with my Adi-powers. That said, of course I could be wrong.

    On the other hand, I really fail to see what the advantage is of having the strap attachments "reversed". You mentioned somewhere that it makes it easier to close the strap -- I believe it was something to do with "around a protruding midsection". That doesn't really make sense to me -- ones midsection may make it hard to reach ones feet, but to reach a particular side of ones feet? Really? (Trying it just now, with a not trivial gut, I notice that I can shift my foot position laterally such that the shortest reach extends to the inside of the foot, or medially so that that point is on the outside.)

    Are you really confident enough that the strap has no role in reinforcing arch support to ignore this factor?

  3. #33
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    Quote Originally Posted by tallison View Post
    The question it seems to me is what the exact role of the strap is. Is it simply to keep the foot pressed tightly against the insole (in which case, strap attachment side doesn't matter) or is it also to pull the leather of the shoe up against the concavity of the arch, adding additional support to that already provided by the insole (in which case, obviously, I think, the attachment side matters greatly)?

    Intuitively, I would say the latter is the case -- seems to be the case with my Adi-powers. That said, of course I could be wrong.

    On the other hand, I really fail to see what the advantage is of having the strap attachments "reversed". You mentioned somewhere that it makes it easier to close the strap -- I believe it was something to do with "around a protruding midsection". That doesn't really make sense to me -- ones midsection may make it hard to reach ones feet, but to reach a particular side of ones feet? Really? (Trying it just now, with a not trivial gut, I notice that I can shift my foot position laterally such that the shortest reach extends to the inside of the foot, or medially so that that point is on the outside.)

    Are you really confident enough that the strap has no role in reinforcing arch support to ignore this factor?
    I wonder if Mr. Bertl is a lifter? He's wrong about this. I think you need to read Tallison's comment here.

  4. #34
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    Quote Originally Posted by MBasic View Post
    I guess the strap could originate from either side.
    The loop/buckle you thread in through just acts as a pulley.
    Once its buckled/locked off the force is equal in both directions.

    But whether it's either the buckle anchorage or the strap orign, it needs to start at the bottom inside part of the shoe where the arch is. (as Mark said)
    Or at least some kind of reinforcement patch that goes down to that point, and bolsters that part of the arch.

    Jordan has an affinity for lifting shoes, maybe some input????

    How about this Mark?

    Im a little bit confused, you say the strap orginates at the lateral, going to the medial with no attachment there? I just looked up those terms, but it seems those particular shoes have a strap that originates at the medial, have a buckle (attachment) at the lateral side and then cross back medially again. Indeed reversed compared to most other shoes, but im not sure it matters that much for the arch support? With the regular way it might be easyer to to pull on the arch because thats directly where the loop is but not sure....

    I have some cheap liftkng shoes where the medial and lateral attachments are pretty high, which feels like it causes more of a downward compression force then arch support, as MB basic said maybe lowering the medial attachment might help with that?

    Not sure the reason for reversing it is really justified indeed.

    P.s. Anynomynous888
    Great thinking on the insole. Is it a one size fitss all? Maybe you said it already but is the insole of the shoe flat? A lof of lifting shoes have this built in wobbels for support but for us who already wear special made orthotics thats really annoying....

    Keep up the good work!

  5. #35
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    thank you MBasic, for encouragement!

    I have just recorded a video on the insole alone.

    Tomorrow.

    Thanks a lot for your comments gentlemen, that was exactly the type of challenge I was looking for.

    I shall split the shoe mechanics up into
    - contribution of the insole
    - contribution of the strap in closed state
    - influence of the position where the strap is connected with the upper leather
    - influence of the side of the boot to which the strap is closed
    and record videos on each one of these aspects.

    What I can tell you already now is that this will lead into a discussion about whether or not it is desireable to have a shoe that is so tight that the closed strap would "... pull the leather of the shoe up against the concavity of the arch". My short answer to this latter issue is: "no, you don't want shoes that are so tight that the pulling foce of the strap provides a support for your longitudinal arch". The long answer is following via video, soon.

    Back to the origin. The strap inherently cannot provide a supporting force. If you expect the strap to directly support your arch, this is comparable to expecting a rope that is installed as a pillar in order to to support a ceiling slab.

    Having said this, I admit: you can expect some extra pulling and supporting force on your longitudinal arch from a strap that closes from the inside to the outside. Such a strap would indeed pull the longitudinal arch upwards. But this extra force is transmitted from the strap to the foot bones via a frictional connection between the upper leather and the skin tissue of the foot. We mechanical engineers don't like that concept as it is not re-producable and not predictable. We want solutions that work in any given situation. (boundary condition: Lack of space or weight limitations are not an issue here, we are building boots and not aircrafts)

  6. #36
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    Quote Originally Posted by Mark Rippetoe View Post
    I see an important problem now. The metatarsal strap should function not only to pull the foot down and back into the shoe, but also to reinforce the arch. I didn't notice this previously, but the strap -- coming from the lateral to the medial, with no medial attachment at the inside arch -- cannot support the arch from the inside, as it could if the strap was reversed. I see no advantage to the strap working from the outside in, particularly if it sacrifices this important arch support function in the process. I don't think the upper leather by itself provides the support that the strap will provide.
    Mark, could you elaborate on the technical function of the metatarsal strap in relation to the arch and how it reinforces the arch?

  7. #37
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    I can, but you cannot see this without my help? That it provides some circumferential pressure against the arch if it is correctly positioned?

  8. #38
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    Isn't the doubling back of the metatarsal strap key in it's functioning? With a single pass (either medial-lateral or lateral-medial) you won't get as good of a pull circumferentially right? I would guess that taking the shoe shown in MBasic's post and flipping the strap direction with the origin medial, the ring on the lateral side, and the velcro on the medial again, you have the cinching effect of the strap. This should apply the same forces as the shown configuration, unless the friction portion is significant, but I don't think it is.

  9. #39
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    The strap can work from either side, as you say. The problem with this design is that the strap on the medial side stops well above where it should insert at the mid-sole under the arch. The maker claims that the tension is carried by the leather of the upper, while I think the circumferential squeeze can be best provided if the circumferential pressure starts at the plantar surface of the foot.

  10. #40
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    Quote Originally Posted by Mark Rippetoe View Post
    I can, but you cannot see this without my help? That it provides some circumferential pressure against the arch if it is correctly positioned?
    Quote Originally Posted by Mark Rippetoe View Post
    The strap can work from either side, as you say. The problem with this design is that the strap on the medial side stops well above where it should insert at the mid-sole under the arch. The maker claims that the tension is carried by the leather of the upper, while I think the circumferential squeeze can be best provided if the circumferential pressure starts at the plantar surface of the foot.
    That explains. The direction of the strap doesn't matter in terms of the hoop force itself. But it does make it easier for adjustment of the snug fit the it doubles down medially than laterally (because that where the maximum slack is). I agree with the observation that the strap should start near the plantar surface of the foot. A strap is meant to apply localized hoop force around the arch. Farther the strap starts from the plantar surface of the foot, more it distributes the hoop force concentration away widely and less localized it is. I mean, the laces too do that job to an extent, limited by the fact that their hoop force is evenly distributed throughout. This is a major design issue with my Sabo Powerlifts but they seem to have addressed this in the Sabo Deadlift shoe design.

    But hoop force from the strap itself isn't the most important contributor to lateral stability. A bit like a clothesline that is held very taut but slacks off when an insignificant load (insignificant in comparison to the tension that's holding the line taut) is hung from it. Its contribution to lateral stability does become significant as the circumference decreases. But still in any modern lifting shoe design, it's the tub shaped plastic molded soles at the heel that provide most lateral stability. The lifter's body-weight and the weight he lifts that squeeze feet into the tub shaped sole and root them safely. That's the primary shortcoming of traditional leather shoe design stitched into a flat sole. One might include a stiff plastic insole but you can't beat shoes like Nike Romaleos or Sabo Powerlifts that have the entire load-bearing structure as one rigid piece, on stability. Equivalent to how F1 cars have engine as a part of chassis as opposed to everyday cars that have engine mounted on to the chassis.

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