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PostPosted: Tue Sep 25, 2012 9:01 pm 
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Has anyone got any idea about how the flow is accomplished?


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PostPosted: Wed Sep 26, 2012 8:57 pm 
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thisisatest wrote:
na, they just need to make the pedal wider. the pedal needs to be nearly as wide as the shoe, if at all possible. front/back distance can stay the same. rotating the cleat does nothing for the contact point width-the contact surface is circular. of course, the cleat would also need to contact the widest edges of the pedal.


What?
With SP, the cleat is essentially the pedal. The circular shape can remain as-is. But the rectangular cleat which sits on the shoe in the up/down direction could be turned sideways to make the profile wider.
The rocking sense which you brought up is due to the dimension of the cleat and not the circular shape of the actual pedal.

The pedal system in this thread. It is essentially a wide cylinder with the stability (contact action) again provided by the cleat.


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Posted: Wed Sep 26, 2012 8:57 pm 


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PostPosted: Wed Sep 26, 2012 9:32 pm 
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I disagree. You could have a 1foot wide "cleat" that attaches to the speedplay lollipop and it will still be the very narrow contact width that will allow rocking in no time. What determines what is a "cleat"? What if the cleat base was molded into the shoe sole? Is it now suddenly more stable? Essentially, no.
A larger foot on a tightrope does not give the person more balance.


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PostPosted: Wed Sep 26, 2012 10:12 pm 
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Hi,

Quote:
and it will still be the very narrow contact width that will allow rocking in no time.


Exactly. The sides of the cleats don't exert pressure to the pedal.

Ciao, ;)

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PostPosted: Wed Sep 26, 2012 10:25 pm 
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thisisatest wrote:
What determines what is a "cleat"?


Nothing. Ideally, there's no distinguishing between Cleat -+- Pedal.

thisisatest wrote:
What if the cleat base was molded into the shoe sole? Is it now suddenly more stable? Essentially, no.


Totally different scenario and *not* relevant to stability. Already discussed this earlier related to hotspots.

thisisatest wrote:
A larger foot on a tightrope does not give the person more balance.


You tell us?




The interesting comment is this one.

thisisatest wrote:
I disagree. You could have a 1foot wide "cleat" that attaches to the speedplay lollipop and it will still be the very narrow contact width that will allow rocking in no time.


SP is a special case and it's difficult to highlight the crux of the issue due of the particular nature of the system's design. Better not to confuse any issues people have with SP with other pedal systems.

Bottom line is, as mentioned earlier, when engaged the SP pedal and cleat function as one unit. The rocking sensation you feel is only because the entire unit (in particular the cleat) is not as wide as the shoe.
If you increase the diameter of the pedal, you also have to increase the size of the cleat. But maximum benefit will arise from simply increasing the size/diameter of the cleat. If you keep the cleat the same size but increase the diameter of the pedal (and thereby the shoe having no additional contact with the pedal because of limited cleat size) the system will not be any more stable.

I will post some pictures and data later.







Hi,

fdegrove wrote:
Hi,

Quote:
and it will still be the very narrow contact width that will allow rocking in no time.


Exactly. The sides of the cleats don't exert pressure to the pedal.

Ciao, ;)


The "pressure" is exerted from the rider/shoe to the pedal (or cleat). You must define what "pressure" is? For now we can assume Impulse (Force for a length of Time).

Ciao ;)


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PostPosted: Wed Sep 26, 2012 10:46 pm 
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Hi,

Quote:
pres·sure/ˈpreSHər/
Noun:
The continuous physical force exerted on or against an object by something in contact with it.


Since the sides of the cleat are not in contact with the pedal..... Yes?

Ciao, ;)

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PostPosted: Thu Sep 27, 2012 12:33 am 
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It would be interesting to test a ball-and-socket cleat to test all of this hot spot theory.

Anyway, I agree pedal quality is more important then weight differences, but I'd personally like to try these anyway.

On float, I don't think I use it when pedaling, but I do like the Speedplay float when I'm coasting to shift my foot around. It may be psychological, however.

Another factor for me is riding in street shoes, which I need to do occasionally. Speedplays work fine for me when I've got reasonably stiff soles. This doesn't look too bad for that, however.

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PostPosted: Thu Sep 27, 2012 12:53 am 
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There is nothing that says "the cleat and pedal behave as one" in reality. They are two separate parts held together by a spring loaded clip. The limiting factor will always be whichever is wider (in contact only, of course).
When shimano updated their spd-sl 7800 pedal to the 7810 with a steel top deck, they also made the pedal wider, pretty much to match the width of the cleat. Same with look keos to the keo2max.
Speedplays allow rocking when the edges of the pedal bodies round off. According to you (phone doesnt allow me to look back at posts while replying), the rounded off bodies would not even contribute to foot rocking, because the cleat is still the same size. Would a cleat standing on the edge of a razor positioned longitudinally, would the cleat/razor system behave as one, or would your foot be able to roll off (rock)?
This is a rhetorical question for most people.
Hotspots- with regard to hotspots, an extremely stiff cleat mounting area can make the contact size a non-issue. You may still get hotspots, but for other reasons.

Mods, i think this ought to be separated into its own thread. Sorry for going way off-topic, i just get a little excited.


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PostPosted: Thu Sep 27, 2012 11:28 am 
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That analysis is incorrect. Considering worn out Speedplays, how much wear are you talking versus a noticeable sensation in rocking? Very little.
Look and Shimano made the pedal wider because it was feasible to do so. Still the cleat tries to maximize the available width of the shoe. With Speedplay if you change the size of the pedal you also change the size of the cleat.

Power transfer, stability and hotspots are all distinct issues. The term Pressure (Force per Area of Surface) is not appropriate. It is actually Impulse and is also known as change in momentum. This change is really very close to a step change and happens in close to No time as power is transferred from the rider to the drive/pedal. Pedal shape has no bearing in this. For power transfer, the Impulse is a distribution like this:

Image


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PostPosted: Thu Sep 27, 2012 4:55 pm 
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power transfer- yes, pedal shape has no bearing on that. great. no arguments there.
foot stability in ROLL- how would pedal width not play a part? this is blowing my mind that you are not grasping this.
no silly gifs please, they help nothing.


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PostPosted: Thu Sep 27, 2012 5:07 pm 
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Failing to grasp and ignoring for the sake of argument are different things... Not sure which one is happening here :wink:

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PostPosted: Thu Sep 27, 2012 5:30 pm 
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:popcorn:

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PostPosted: Thu Sep 27, 2012 6:31 pm 
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horse wrote:
Considering worn out Speedplays, how much wear are you talking versus a noticeable sensation in rocking?

with zeros, i'd call it moderate. the body is more squared off vs their others, resulting in a WIDER AREA to BETTER SUPPORT THE FOOT. the others take very little wear.

horse wrote:
Look and Shimano made the pedal wider because it was feasible to do so

feasible for what purpose? certainly if they could make it smaller, they would be making it lighter. shimano especially isnt in the business of doing something just because they could.

if the cleat/pedal interface is 10cm wide, and there is 1mm of wear at the sides, it would allow for 0.57degrees of roll.
if the cleat/pedal interface is a mere 1mm wide, and there is 1mm of wear at the sides, it would allow for 45degrees of roll.
the load on the edges of the cleat with respect to foot rolling forces would also be 100 times as great as the 10cm pedal/cleat, greatly increasing the wear rate.

is a horse in any way genetically related to a troll?

i believe im done with this.


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PostPosted: Thu Sep 27, 2012 10:30 pm 
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Hi,

Quote:
The term Pressure (Force per Area of Surface) is not appropriate. It is actually Impulse and is also known as change in momentum.


As of today we'll all be applying Impulse to our pedals..... :roll:

Quote:
im·pulse/ˈimˌpəls/
Noun:
1.A sudden strong urge or desire to act: "an impulse to giggle"; "impulse buying".
2.The tendency to act in this way: "he was a man of impulse".

Synonyms:

impetus - impulsion - urge - stimulus - incentive - spur


Of course feel free to switch from common plain english to the language of physics whenever it suits you but from what I've read so far it's still not clear what the point of all this is other than arguing for argument's sake....

Still, for your information, during the time the impulse occurs whilst pedalling a force is apllied to an area of the pedal. At this area a pressure is then present and distributed over that area.

Since pedals, together with the handlebar and saddle, belong to the three areas that physically support the rider of the bike the pressure on the supporting areas is pretty much constant whereas the impulse to the pedals is only there during a short period of time.
Therefore it is not the impulse applied to the pedals that is the source of the problem even though it will inevitably contribute to it, it is in essence the pressure area that is the main concern.

Ciao, ;)

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PostPosted: Fri Sep 28, 2012 2:56 am 
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As a long-time speedplay user and "fan", I think there is definitely some room for improvement to the design. But it should probably be kept to a separate thread. This thread is about the Ultralight pedals.


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Posted: Fri Sep 28, 2012 2:56 am 


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