Why don't you use Shimano SPD?

richbee
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Re: Why don't you use Shimano SPD?

Postby richbee » Mon Aug 01, 2016 1:07 pm

No point arguing with the ignorant, you just get dragged down to their level and beaten with experience.

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Re: Why don't you use Shimano SPD?

Postby trailgumby » Mon Aug 01, 2016 1:15 pm

UH-oh....

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g-boaf
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Re: Why don't you use Shimano SPD?

Postby g-boaf » Mon Aug 01, 2016 1:32 pm

trailgumby wrote:If you have stiff carbon soles and you're still getting hotspots you need to go visit a cycling podiatrist and get some decent insoles fitted up.


That's the bit that makes an enormous difference.

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Re: Why don't you use Shimano SPD?

Postby human909 » Mon Aug 01, 2016 1:34 pm

richbee wrote:No point arguing with the ignorant, you just get dragged down to their level and beaten with experience.


You posted some plainly wrong assertions. When this was pointed out by people who have a professional knowledge of the aspects being discussed and you respond with insults.

I suggest you reconsider your approach.

richbee wrote:
Trevtassie wrote:Really, 45 degrees? Best you go google some basic engineering principles. Here's a hint... Bridges don't have the piers spaced so the force vectors are at 45 degrees

Wow, what an amazing deduction, from somebody who clearly has no idea of the principles of bridge, or any structural design for that matter. How about you go google the difference between shear stress and bending moments and enlighten yourself as to how bridges and structural members are actually designed. Then when you understand the difference between force, pressure and stress, come back and talk from a position of knowledge not ignorance.
Or better yet, go do a four year degree in engineering, choose between civil, structural or mechanical, they all have the same foundation, then follow it up with 30 years experience in the field, before making such ill informed and inflammatory statements and suggestions.

Are you implying you have 30 years experience in civil, structural or mechanical engineering? If you are a professional engineer please come back to the discussion and support your statements with commonly accepted engineering principles. You know. That is what any professional should be capable of doing.

QUOTE: Even with the stiffest of soles the pressure cannot be distributed at a greater than 45 degree angle. What the stiffer sole does do however is allow the manufacturers to make them thinner and hence lighter.

richbee wrote:You think I'm rewriting the laws of physics to suit my personal views, how about maybe you go get an understanding of the laws of physics, then we can talk

As a structural engineer I would welcome a technical discussion on this matter. Though I'm sure even some of the non engineers on this forums would be interested to hear your explanation.
Last edited by human909 on Mon Aug 01, 2016 1:48 pm, edited 2 times in total.

swaz
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Re: Why don't you use Shimano SPD?

Postby swaz » Mon Aug 01, 2016 1:45 pm

As much as a love a good "my engineer is bigger than yours" argument. I was mearly asking for non- double blind, non- Newtonian points of view on the topic and interested to see WHY people run two different show systems and the cynic in me thinks it is some rouge for companies to sell more stuff

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Re: Why don't you use Shimano SPD?

Postby Uncle Just » Mon Aug 01, 2016 1:47 pm

I use road pedals on my road bike and spd on mtbs, Cx and touring bikes. Always have and I rarely unclip as I track stand at lights etc. I use DA/Ultegra pedals because they offer comfort and the road shoe gives stiffness with a broader footplate for road riding. SPDS with their double sided entry are obviously designed for trails and for shoes which are better for walking in off the bike unlike road pedals. I observe many struggling to clip in out on the road so spds may offer an easier, perhaps safer interface. Whatever works.

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Re: Why don't you use Shimano SPD?

Postby human909 » Mon Aug 01, 2016 1:48 pm

swaz wrote:As much as a love a good "my engineer is bigger than yours" argument.

:mrgreen:
My 'engineer' is smaller than many. But it is about how you use it. :wink:

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Re: Why don't you use Shimano SPD?

Postby Nobody » Mon Aug 01, 2016 2:02 pm

Well it looks like I'm not going to find out how heavy "richbee" is and whether that's a factor.
I haven't experienced the hot-spot problem myself and I run cheap plastic Shimano shoes for both SPD and Speedplay pedals.

So who out there get hot-spot problems? How much do you weight and what's your shoe size?

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Re: Why don't you use Shimano SPD?

Postby richbee » Mon Aug 01, 2016 2:16 pm

trailgumby wrote:
human909 wrote:
richbee wrote:Even with the stiffest of soles the pressure cannot be distributed at a greater than 45 degree angle. What the stiffer sole does do however is allow the manufacturers to make them thinner and hence lighter.

This is 100% false. It is not in accordance with fundamental physics and engineering.

If you were right then it is a puzzle how every beam in buildings and structures other across the world work. In fact how do you suppose pedals transfer their load to the cranks?

Sorry, rich, human is right. Following your logic to its conclusion, down through the layers of carbon sole, pedal interface, pedal structure and bearing to the pedal axle, it would be the diameter of the pedal axle that matters most for getting hotspots, and it doesn't.

If the shoe's sole is stiff enough, the size of the interface with the pedal is irrelevant. What matters most then is how closely the inner sole fits the structure of the user's foot. If you have stiff carbon soles and you're still getting hotspots you need to go visit a cycling podiatrist and get some decent insoles fitted up.


It's very much in accordance with the principles of physics and engineering design. Pressure is a very simply function, basically force applied over area. The larger the area over which a force is applied, the lower the pressures. You can demonstrate this to yourself by standing on a large flat object and a narrow angular one. The force applied (your body weight) remains the same, however the area is greatly reduced for the narrow angular one compared to the large flat one, and you can feel the increase through the sole of your foot. By inserting various plates between your foot and the narrow angular object you can reduce the pressure you feel according to the stiffness and thickness of the plate. That's the principle of distribution, but, no matter your perception, the rate of distribution of the pressure is the same constant angle dependent on the stiffness of the material. In engineering that pressure is the shear force that needs to be considered to stop a beam failing at the point of support, or more accurately, on a plane consistent with the angle of internal friction of the beam, which for stiffer materials is the 45 degree angle I used as an example before.
The transfer of the forces is something completely different again. In a beam the forces are converted to a moment which is dependent on the stiffness and length of the beam. The sole of the cycling shoe is the beam. The stiffer the beam the greater the moment transfer, and also the longer the beam the higher the load that can be resisted. It's not quite that simple, but short of writing a thesis on the subject will suffice for the moment. Nylon isn't as stiff as a carbon fibre sole, so achieve a similar stiffness (and resistance to bending) a nylon soled cycling shoe needs to be thicker than a carbon fibre sole. Hence the weight saving in carbon fibre shoes. In a concrete beam, the stiffness is achieved by the combination of the tensile strength of the steel reinforcement acting together with the compressive strength of the concrete to resist the forces, which allows for bridge piers to be spaced as far apart as they are.
These principles are pretty much the same whether the material is steel, timber, concrete, nylon, or carbon fibre.

I was rude to Trevtassie because his inflammatory comment had the desired effect. With you guy's (Trailgumby and Human909) if you'd like a civil discussion of the engineering, by all means lets have a civil discussion without the silly my engineer is bigger than yours nonsense.

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Re: Why don't you use Shimano SPD?

Postby trailgumby » Mon Aug 01, 2016 2:19 pm

I have had hot spot problems, once, but it was with flexy Vittoria MTB shoes that were long past their retirement date, and I broke my seat post saddle clamp earlier in the ride. :oops:

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Re: Why don't you use Shimano SPD?

Postby swaz » Mon Aug 01, 2016 2:22 pm

human909 wrote:
richbee wrote:No point arguing with the ignorant, you just get dragged down to their level and beaten with experience.


You posted some plainly wrong assertions. When this was pointed out by people who have a professional knowledge of the aspects being discussed and you respond with insults.

I suggest you reconsider your approach.

richbee wrote:
Trevtassie wrote:Really, 45 degrees? Best you go google some basic engineering principles. Here's a hint... Bridges don't have the piers spaced so the force vectors are at 45 degrees

Wow, what an amazing deduction, from somebody who clearly has no idea of the principles of bridge, or any structural design for that matter. How about you go google the difference between shear stress and bending moments and enlighten yourself as to how bridges and structural members are actually designed. Then when you understand the difference between force, pressure and stress, come back and talk from a position of knowledge not ignorance.
Or better yet, go do a four year degree in engineering, choose between civil, structural or mechanical, they all have the same foundation, then follow it up with 30 years experience in the field, before making such ill informed and inflammatory statements and suggestions.

Are you implying you have 30 years experience in civil, structural or mechanical engineering? If you are a professional engineer please come back to the discussion and support your statements with commonly accepted engineering principles. You know. That is what any professional should be capable of doing.

QUOTE: Even with the stiffest of soles the pressure cannot be distributed at a greater than 45 degree angle. What the stiffer sole does do however is allow the manufacturers to make them thinner and hence lighter.

richbee wrote:You think I'm rewriting the laws of physics to suit my personal views, how about maybe you go get an understanding of the laws of physics, then we can talk

As a structural engineer I would welcome a technical discussion on this matter. Though I'm sure even some of the non engineers on this forums would be interested to hear your explanation.



You're going to have to build a bridge and get over it :lol:

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Re: Why don't you use Shimano SPD?

Postby trailgumby » Mon Aug 01, 2016 2:28 pm

swaz wrote:You're going to have to build a bridge and get over it :lol:

:lol: :lol: :lol:

@richbee, I understand the math and I'm not saying there isn't a greater likelihood of flex with the smaller pedal platform, nor that it doesn't present greater engineering challenges; you're plainly right. However, with an appropriately engineered carbon sole the effect can be rendered minimal if not eliminated.

You don't necessarily need to go thicker. Higher walls on the side of the sole plate offer considerable stiffness advantages over a flat carbon plate. That said, a thicker walled U-channel will still be stiffer than a thin-walled one.

It is those shoes I choose to buy - stiff ones.

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Re: Why don't you use Shimano SPD?

Postby Trevtassie » Mon Aug 01, 2016 2:37 pm

Yep, no idea. As somebody who does have an engineering background, there is a he'll of a lot more going on in the sole of a bike shoe than an upside down house footing. Give me a list of stuff you've engineered so I can avoid it.

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Re: Why don't you use Shimano SPD?

Postby mikgit » Mon Aug 01, 2016 2:51 pm

swaz wrote:As much as a love a good "my engineer is bigger than yours" argument. I was mearly asking for non- double blind, non- Newtonian points of view on the topic and interested to see WHY people run two different show systems and the cynic in me thinks it is some rouge for companies to sell more stuff


I would say (so not based on facts or anything), when Look (was it look? I think so) invented the clipless pedal, they did it based (somehow, no idea how) on their ski bindings and so that has kind of been the default style on road for ages with a few changed going on. But the style of shoe/cleat is craptastic for mtbing. when shimano invented the spd, it was a small cleat to fit inside tread and metal so you could walk on it and not fall apart and the pedal is double sided because that is way better for mtbing. (sorry if thats all obvious info)
But spd pedals arn't really designed with weight in mind but mud shedding (in theory), reliability, sturdiness and working with a treaded pedal. Road shoes are the opposite, designed around lightness and working with a flat bottomed shoe (and the wide cleat that comes with it). nothing stopping people using spd's on a road bike, they work perfectly well just a bit heavier with a heavier shoe.nothing stopping someone riding mtb with a road pedal/shoe, but it'd be a bit iffy... but the whole road system is lighter, whether that lightness offsets the double sidedness and walkability is the thing I guess...oh and the roadie stuff on a road bikething.
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Re: Why don't you use Shimano SPD?

Postby kb » Mon Aug 01, 2016 2:59 pm

If you guys are civil engineers, I'd hate to meet the uncivil ones ;-)
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Re: Why don't you use Shimano SPD?

Postby human909 » Mon Aug 01, 2016 3:08 pm

richbee wrote:It's very much in accordance with the principles of physics and engineering design. Pressure is a very simply function, basically force applied over area. The larger the area over which a force is applied, the lower the pressures.

I think we can all agree on that.


richbee wrote:By inserting various plates between your foot and the narrow angular object you can reduce the pressure you feel according to the stiffness and thickness of the plate.

And that.

richbee wrote:That's the principle of distribution, but, no matter your perception, the rate of distribution of the pressure is the same constant angle dependent on the stiffness of the material.

That is not accurate. It completely depends on the opposing forces, their position and the stiffnesses. (Since we have interfaces of materials of different stiffnesses it matters very much!)

richbee wrote:In engineering that pressure is the shear force that needs to be considered to stop a beam failing at the point of support, or more accurately, on a plane consistent with the angle of internal friction of the beam, which for stiffer materials is the 45 degree angle I used as an example before.

I'm not understanding your phrasing here but your 45degree angle statement is not really applicable here. In fact Trevtassie 's example of a bridge was quite apt, his example does need to be addressed in order to have a fair discussion.

The way the load is distributed depends on the stiffness. For uniform block materials 45degrees is reasonably accurate but your foot is not made of carbon fibre. Likewise the air under the bridge is MUCH less stiff than the piers. Likewise skis are much less stiff than snow. (Thus skis are much longer than a 45 degree contact patch from where the pressure is applied to the ski.)

richbee wrote:The transfer of the forces is something completely different again. In a beam the forces are converted to a moment which is dependent on the stiffness and length of the beam.

I'm uncomfortable with this phrasing. But lets put this down to a communication issue. "Forces" don't get converted to "moment".
Last edited by human909 on Mon Aug 01, 2016 3:28 pm, edited 3 times in total.

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Re: Why don't you use Shimano SPD?

Postby queequeg » Mon Aug 01, 2016 3:21 pm

I use both - Road Bike(s) are SPD-SL for the simple reason that there is more options for shoes that take a 3-Bolt cleat than there is for the SPD Cleat, which really needs to be recessed into the sole of the shoe unless you want to slip over when walking on them.

I use SPD on the commuter bike where clipping in quickly is required. I have been on my spare road bike the last two weeks while I sort the cranks on my usual commuter bike, and I haven't bothered changing the pedals over. I have had a few "misses" with the pedal taking off from lights. The main issue is when on steep hills, it is next to impossible to get a positive clip-in first go. With SPD you just mash your foot down and off you go.

As others have said too, SPD cleats are dependent on the sole of the shoe for a solid engagement. As the sole of the shoes wears down, it creates a gap and the shoes will move up and down in pedal (as well as having side to side float). This means replacing shoes as well as cleats. You don't have that issue with SPD-SL.
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Re: Why don't you use Shimano SPD?

Postby richbee » Mon Aug 01, 2016 3:27 pm

trailgumby wrote:You don't necessarily need to go thicker. Higher walls on the side of the sole plate offer considerable stiffness advantages over a flat carbon plate. That said, a thicker walled U-channel will still be stiffer than a thin-walled one.

It is those shoes I choose to buy - stiff ones.

That is true on both counts. The quest though is always for the lighter, stiffer shoe. A U-channel allows the designer to go yet thinner on the soles as the forces will be attracted to the walls rather than the sole plate, at least under the heel, the forefoot still needs a substantial depth for the cleats fixings and to act as a stiff bearing plate.

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Re: Why don't you use Shimano SPD?

Postby human909 » Mon Aug 01, 2016 3:30 pm

So we now agree that the 45degree statement said earlier is not accurate? :wink:

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Re: Why don't you use Shimano SPD?

Postby Trevtassie » Mon Aug 01, 2016 3:52 pm

Is pretty simple, trying to pedal a bike with your bare foot using a surface area the size of an SPD cleat plus the additional surface area subtended by a 45 degree line from the edge of the cleat to the top of the sole would be very uncomfortable. So bugger me if the sole isn't acting as a beam, what with the fibre, moulded box beams and stuff. And if shear forces come into play it's a warranty or refund issue.

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Re: Why don't you use Shimano SPD?

Postby jaseyjase » Mon Aug 01, 2016 3:57 pm

As mentioned by a few members above, i fall in the both category.

I use Look Keo Max 2 carbons on the weekend warrior roadie, comfy doing 75-100km regular loops in them, no worries. Usual rides are early morning so traffic is much lower, and i feel like theres far less clipping in and out.

Ive recently been using SPDs on a rigid MTB while commuting during the wet weather. 30km round trip, also no worries. Ive been enjoying it so much ive decided to put them on my dry weather commuter, as mentioned clipping in and out at traffic lights and uphill starts is a breeze! There maybe a tiny bit of loss in efficiency but as a commuter im not that fussed, ease of use during critical times in traffic is far more important.

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Re: Why don't you use Shimano SPD?

Postby Kalgrm » Mon Aug 01, 2016 4:28 pm

kb wrote:If you guys are civil engineers, I'd hate to meet the uncivil ones ;-)

Too true.

Guys, there has already been one report generated from this thread. Please try to keep things civil, including the bridge engineering.

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Re: Why don't you use Shimano SPD?

Postby Hergest » Mon Aug 01, 2016 5:22 pm

I'm a double sided SPD pedal bloke on my bikes. I'm more of a grinder than a spinner and at around 82kg am no flyweight and nearly always climb out of the saddle. With Shimano SH-XC61W shoes that are stiff but not solid carbon like stiff I get no hotspots or notice any pressure on the area where the cleats are. I'm always amazed when I see riders struggling to get into SPD-SLs moving away from the lights why they don't go for SPDs.
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Re: Why don't you use Shimano SPD?

Postby richbee » Mon Aug 01, 2016 5:27 pm

human909 wrote:So we now agree that the 45degree statement said earlier is not accurate? :wink:

I didn't say that, I simply agreed that the addition of flanges to a flat plate increases the overall stiffness. The distribution of the pressure through the flat plate to a surface bearing directly on it is still governed by the same rules. If you don't like a simple 45 degrees, pick any angle you fancy, I'm sure there's a range for every material you and I can think of.

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Re: Why don't you use Shimano SPD?

Postby redned » Mon Aug 01, 2016 5:51 pm

Swaz:

I am not an engineer (a geologist*, but I can't think of any relevance to pedals!). My answer is: I use SPDs on both my mountain bike and my road bike. My MTB is used for back road touring and the touring shoe is extremely convenient. My road bike use is hardly high-end (although I do clock up the K's) and I find the common shoe and familiar action convenient. Also better for walking into coffee shops and pubs.

* Our mining engineering colleagues often suggest that if you have three geologists you will get four opinions. Reading this thread, I am not sure its geologists at fault.

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