SPD's power advantage....Myth?

ride_whenever

really? linky please.

Shaggy_Dog

omegas wrote:

Making any comparisons of pedalling dynamics when riding a road bike on the road and riding a mountain bike off road is so funny, even boarding on ridicules.

Why? I ride both, there are differences but there are more similarities. XC is very much like time trial riding. Pedalling a BMX, 4x or downhill bike has similarities to road and track sprinting, Sir Chris Hoy started off as a BMX racer. Will Longden is an animal on the track. Lance Armstrong is a very good mountain biker.

meanredspider

supersonic wrote:

meanredspider

What do you mean by 'power'?

Rate of deliver of energy - measured in Watts

I'm a professional mechanical engineer with a degree in engineering. I work as an engineer. I'm a chartered engineer and a fellow of the Institution of Mechanical Engineers. I spend most of my spare time engineering my race car. I understand power and what optimises power in rotating systems. All of which is why I post in this thread. I don't give a stuff about what pedals people use but it irritates me to see so much crap posted.

supersonic

All that doesn't mean you don't make mistakes.

Have you read the studies I posted, and do you understand pedalling dynamics though?

I don't understand why lighter shoes will give you more power. You have not given enough info there. More torque and higher cadence? Explain. Or doyou mean more efficient?

snotty badger

Those red shoes are foul. No one would wear them if a non spd version was available..

meanredspider

supersonic wrote:

All that doesn't mean you don't make mistakes.

Have you read the studies I posted, and do you understand pedalling dynamics though?

I don't understand why lighter shoes will give you more power. You have not given enough info there. More torque and higher cadence? Explain. Or doyou mean more efficient?

I'm certainly not mistake-proof (jeez, am I not).

The lighter shoes one is simple. It's rotational energy being taken up in accelerating the shoes rather than the bike. Power being absorbed by the shoes isn't being delivered to the wheels. The faster you pedal, the more significant it is.

Higher cadence at the same torque - shaggy-dog gave a far better explanation of this than me. But if you halve the torque and double the rpm, you'll keep power output the same.

Efficiency is only power out/power in.

supersonic

The acceleration makes sense ie gaining cadence and energy to do that. If maximum cadence can be increased with lighter shoes at the same torque then yes, power will be increased. I am not sure minor weight differences have that much of an effect in max cadence though or limit our top cadence. The same way heavier wheels don't limit our top speed on a bike, if the overall mass of the bike is the same. At steady speed, the energy required to keep the bike rolling at the same speed is the same regardless of the wheel weight due to the flywheel effect, if the overall bike weight is the same. However, of course, the way our shoes move with the pedals, and dynamics make this a very simplified case when looking at pedaling. Generally I am all for lighter weight!

Interestingly though leg weight as been factored in in some of the studies.

Overall are so many factors to look at,and I am not sure anyone really understands all the nuances.

Anonymous

Even I make tons of mistakes, And I'm the loudest, angriest person there is. When I make mistakes, it's usually spectacular

I'm always getting my words mixed up though. I blame that on my lack of linguistic fluency, being a knuckle dragger and all that.

But, I really don't understand what meanredspider's point is. Very few people are contesting that there are advantages to SPDs in certain circumstances, what I and others are contesting is this bullcrap that pulling up makes a difference.

Boy Lard

For some reason (ok I was putting off doing some work), I have just read this entire topic front to back including the studies that Sonic linked.

The most interesting part of the whole discussion for me was actually in one of those studies, which found that the mountain bikers had a more consistent (less oscillating) power curve than any of the other disciplines of cycling. No massive jumping on pedals on the 'peak' (when the cranks are horizontal) down stroke, but a more even spread of power throughout the stroke, (all be it only downwards, so only really through half the stroke for each leg).

These tests did not specifically look at cycling with or without spds, but on technique and on how the 'perceived' action of the cyclist actually transferred into power out put.

What I have understood from all of this discussion, be it right or wrong is the following:

Pulling up on the pedals (using spds) does not increase the amount of power you can produce.

Any increase in efficiency, or a better transfer of energy from the engine (cyclist) into USEFUL power (forward motion of the bike), does not mean an increase the power produced, but a decrease in the energy needed to produce it. So having a more rigid platform through which to transfer energy (like in the sole of an spd shoe), however small an increase in efficiency, will actually mean less energy is needed to produce the same amount of power.

What I do not understand is:

If spds can help to produce a smoother power curve, (in that they make it easier to transfer power through the deadspots in the pedal rotation by pushing forward at the top of the stroke and pulling back at the bottom of the stroke), and this seems to make less difference to road cyclist than mountain bikers (again from the studies posted by Sonic) why does this discussion not happen in the Road section more than it does here?

and what I really don't understand is:

Why does it seem to bother people so much? I use flat pedals, I fall off a lot, it is always my fault, having spds would not make me fall off less, it may make the results of the falls slightly more complicated.

If I was doing any kind of endurance cycling where I was reasonably confident of not falling down the side of a mountain, I would use spds, because however small an advantage, they do give a more efficient transfer of energy into motion.

I am now tired and I think I'll go do some work.

meanredspider

yeehaamcgee wrote:

But, I really don't understand what meanredspider's point is. Very few people are contesting that there are advantages to SPDs in certain circumstances, what I and others are contesting is this bullcrap that pulling up makes a difference.

My point is reasonably simple: challenging some of the stuff that's been written on here that simply doesn't stand up to scrutiny (i'm not going to list it all - but the stuff about gravity is a prime example).

meanredspider

supersonic wrote:

Interestingly though leg weight as been factored in in some of the studies.

Overall are so many factors to look at,and I am not sure anyone really understands all the nuances.

For sure - I have heavy legs and it took me ages at spinning classes to reach the cadences others were generating. And, for sure, I'd have had no chance if my feet weren't attached to the pedals.

Your point about steady-state is true though, in reality, we're rarely in complete steady state (least of all arounf here - I'm either going up hills or down them). Gearing has quite an effect too.

There are, I'm sure, loads of factors. Like everyone on here, the people carrying out these studies also have a point of view (and are often being paid by someone to do the study who also often have a point of view)

Anonymous

meanredspider wrote:

My point is reasonably simple: challenging some of the stuff that's been written on here that simply doesn't stand up to scrutiny (i'm not going to list it all - but the stuff about gravity is a prime example).

That was my exact point, about the pulling up.
Which points in particular are you challenging?

The Northern Monkey

I've decided i'm not using pedals anymore.... its too confusing.

I'm just going to push to the top of a hill and roll down!

meanredspider

yeehaamcgee wrote:

Which points in particular are you challenging?

That gravity limits the power that can be applied. If you're standing on the pedal and the bike's going nowhere you're either:

- a skinny midget who weighs nothing on a 50kg bike
- In the wrong gear
- trying to climb a vertical incline
- *edit*...or you're Clare Balding on TV tonight :roll: (which only goes to prove that gravity can't be an influence )
or a combination of all 3 (or 4).

KenHardaker

I ride with spd's, and came from a road background of having clipless.

In my view spd's make power transfer better this is unquestionable, road bikers are clipped in for this very reason, so it's easier to cycle, and it's easier to stay on the pedals (on bumpy downhills).

However, it does have the disadvantage of being fixed when sometimes it would be handy to have a foot down instantly for a second or 2 to push through an impossible gap or whatever.
It would also be handy in those situations where you thought you could but it turned out you couldn't at the last second, when spd's often mean a bit of a muddy bath, gravel eating or a spot of sunbathing in the grass often occurs. Especially on the steep uphills (say 20% plus gradients) when its more difficult to instantly get out and get the foot down.

Often I ride in situation where I know I'm probably going to need to be out unexpectedly with one foot clipped and the other not.

In short, what is best will often depend on the nature of the trail as a whole, and the various sections of it.

Anonymous

meanredspider wrote:

yeehaamcgee wrote:

Which points in particular are you challenging?

That gravity limits the power that can be applied. If you're standing on the pedal and the bike's going nowhere you're either:

- a skinny midget who weighs nothing on a 50kg bike
- In the wrong gear
- trying to climb a vertical incline
- *edit*...or you're Clare Balding on TV tonight :roll: (which only goes to prove that gravity can't be an influence )
or a combination of all 3 (or 4).

Wrong again.
Amazing.

meanredspider

yeehaamcgee wrote:

Wrong again.
Amazing.

Talking bollox again
Long way short of amazing

Anonymous

Look, it's been explained. The fact that you don't understand it doesn't make it incorrect.
It's not just me with some crazy off-the-hook idea either, world class cycling coaches seem to agree.

If you don't understand it, just accept it.

meanredspider

yeehaamcgee wrote:

Look, it's been explained. The fact that you don't understand it doesn't make it incorrect.
It's not just me with some crazy off-the-hook idea either, world class cycling coaches seem to agree.

If you don't understand it, just accept it.

Aye, right - I can see wht you're a fan of flat pedals. You probably think the world is flat too because I'm sure people at the time said

Look, it's been explained. The fact that you don't understand it doesn't make it incorrect.
It's not just me with some crazy off-the-hook idea either, world class physicists seem to agree

If you don't understand it, just accept it

Quoting stuff blindly that you can't explain doesn't make you clever. Pictures of see-saws that bear no relevance to anything kinda confirms that.

When was the last time you stalled out standing with all your weight on a pedal? Please just describe the situation that gravity let you down so badly...

And please don't say "You're wrong because you don't agree with something I read that I don't entirely understand" like you have done in your last 20 posts - MTFU and explain exactly why I'm wrong.

And PLEASE stop saying I'm an SPDer - one of my MTBs has SPDs and the other has flats - frankly it's hard to be more balanced than that.

meanwhile

It's amazing how much bullshit gets talked on this topic when the facts are so easy to check using a powertap:

bikejames.com/cardio-training/top-3-clipless-pedal-myths/

Clips vs. flats: (again, using a bmx situation) I put out 2060 watts on a G-Cog (it`s like an SRM made specifically for BMX racing, and a device all of the US Olympic bmx team uses) equipped bmx bike clipped in over a 50 yard sprint. My best on platforms was just over 1800. Those results were consistent with everyone else participating, but so was the fact that the average power output got close and closer the longer the sprint was. There was a HUGE difference in how soon we hit max power clipped in.

"BMX flats" probably means pin pedals that can harness power on the 8 to 4 o'clock part of the pedaling cycle.

So that's it - clipless have the advantage in the sort of short sprints that can decide positioning. Useful if you're in the TDF... less so if you're commuting.

As for even the idea that pulling up is a good idea:

http://www.bikeradar.com/road/fitness/a ... ttle-27049

Turning the pedals round from in the saddle uses the same muscles whether you’re plummeting towards the Earth’s core or climbing into the stratosphere. When climbing, it can be particularly tempting to try to pull on the return stroke, but this is a mistake according to cycling coach Dr Auriel Forrester of Scientific Coaching: “Pulling up on the pedals decreases power output as it interferes with the all-important downstroke on the other side – specifically, you can’t pull up against gravity at the same rate or same force as you can push down with gravity!”

As you push down on the pedal – the power stroke – you engage your glutes, quads and calves. The upward – or return stroke – switches the stress to the hamstrings, ankle dorsiflexor and the hip flexors. Since your quads are a lot stronger than your hamstrings, try to concentrate on not doing anything that could detract from the downward power stroke.

..And people rarely stop to question whether there is a cost for using clipless pedals, although as someone who has some education in human factors/ergonomics, they certainly bother me:

http://www.bikejames.com/cardio-trainin ... -a-crutch/

And about clipless pedals increasing power…they do, but not how you want them too. If you have someone who has long, weak glutes and short, tight hip flexors (your average rider, in other words) they literally can not use their hips to pedal through the “deadspot” on the bottom. You attach their feet to the pedals so they can now use their already overworked hip flexors to pull through the top. It did not fix the problem, it simply made you more efficient with your dysfunction. In the face of that instant performance increase people stop there and really ingrain the “sit, spin and pull through” technique. They never really learn how to use the most powerful muscles in their body (the hips) to power through the bottom of the pedal stroke which, in my opinion, ultimately limits their development.

That is not an advantage, it is a crutch that results in an appallingly high rate of overuse injuries. There is absolutely nothing that you can do with clipless pedals that you can’t do just as well, if not better, with flats. This isn’t even taking into account how clipless pedals completely screws up the natural “rolling” motion the foot goes through. Your foot is designed to strike mid foot on the outside and roll into the arch and pushing through the center of the midfoot. This rolling action creates a natural screwing motion and avoids a linear up and down motion, which is how the leg is designed to work. By attaching the foot to the pedal at the middle-midfoot position you take away the entire roll action and place a crapload of stress on the knees and hips. 85% overuse injury rates don’t lie – something is wrong with clipless pedaling.

And

http://www.bikejames.com/cardio-trainin ... -injuries/

On my drive to Bootleg Canyon a few weeks ago I listened to the audio-book Born to Run. If you haven’t heard of this book before it is essentially about the barefoot running movement and a tribe of Indians in the Copper Canyons of Mexico. It is a fascinating book that interweaves a great story with a harsh look at the reality of what the modern running shoe has done to our feet.

It chronicles the history of running and pinpoints when things started to go wrong. An activity that our ancestors did all the time suddenly started crippling modern man with injuries. I can not recommend the book enough – even if you don’t run it is still a chilling look at what our attempts to improve on the body have inflicted on us.

At the heart of it is how the foot works. The foot contains 25% of the total bones in our body and is a marvel of natural engineering. When running the foot is designed to pronate slightly, strike mid-foot and roll in, compressing the arch from the top. This loads the arch and allows it to spring some of that energy back into propulsion.

We screwed it up with running shoes by over-stabilizing it. There is a lot of evidence presented, both scientific and anecdotal, that supports the notion that we need to avoid restricting natural foot movement. Arch support and cushy heels have allowed us to develop a running style that creates lazy feet and an unnatural stride, both of which contribute to a very high injury rate. With the foot not working properly the knees, hips and low back are thrown out of alignment and suffer repetitive use injuries.

...

being clipped in locks you into the exact same repetitive range of motion for thousands and thousands of RPMs. Your body was not made for this and instead lasts longer if there can be some minor differences in how it moves.

Maybe I’m wrong but I think that some of the knee, hip and low back injuries among riders is caused by the unnatural foot movement during hours and hours of pedaling with clipless pedals. A look at the injury statistics tells me that something is terribly wrong. One website I found ... told me that 85% of cyclists are suffering from one or more overuse injuries at any given time.

The who wrote this suggests treating pedals the way that professional runners treat running shoes - having a risky but fast pair that leads to poor technique (clipless) that you use only for races and a safer training pair that builds good technique that you use for the rest. If you use clipless at all.

NatoED

ok that last qoute is bollocks . mostly cos Clipless pedals have float that does alow the knees tomove to their natural shape while pedling. A freind of mine who has just started road riding and is using Clipless pedals and has a knee that was broken in a motor cycle accident. He finds that his knees no longer hurt now he uses Clipless pedals instead of flats and cages. His foot can float and turn .

Anonymous

NatoED wrote:

ok that last qoute is bollocks . mostly cos Clipless pedals have float that does alow the knees tomove to their natural shape while pedling. A freind of mine who has just started road riding and is using Clipless pedals and has a knee that was broken in a motor cycle accident. He finds that his knees no longer hurt now he uses Clipless pedals instead of flats and cages. His foot can float and turn .

Well, there's also a very large contingent of this here forum, and several physios to back them up that would claim that SPDs can exacerbate injuries.

Anonymous

meanredspider wrote:

Aye, right - I can see wht you're a fan of flat pedals. You probably think the world is flat too because I'm sure people at the time said

I'm agnostic about pedals actually. If you cared to follow the thread you'd have realised that.
I'm actively trying to dispell some of the bullshite surrounding SPDs, that's all.

It really is YOU, who is failing to understand the issue at hand. Stop throwing your dummy out of your pram for chrissakes, you really are starting to look worse than pathetic.

Anonymous

meanredspider wrote:

Aye, right - I can see wht you're a fan of flat pedals. You probably think the world is flat too because I'm sure people at the time said

I'm agnostic about pedals actually. If you cared to follow the thread you'd have realised that.
I'm actively trying to dispell some of the bullshite surrounding SPDs, that's all.

It really is YOU, who is failing to understand the issue at hand. Stop throwing your dummy out of your pram for chrissakes, you really are starting to look worse than pathetic.

meanredspider

yeehaamcgee wrote:

It really is YOU, who is failing to understand the issue at hand. Stop throwing your dummy out of your pram for chrissakes, you really are starting to look worse than pathetic.

Coming from the guy that flamed some poor bloke because he'd not seen this thread, that's risible. I'm not in the slightest bit upset - just tired of reading you trying to "playground bully" your way around this forum without actually adding anything of substance to the discussion...

popstar

Surely to us mortal Sunday Warriors SPD's are not that benificial? Unless you going into racing perfomance then SPD foot position may benefit you in some sort, or if you are a climbing freak then hell yea SPD is the best.
Flats all the way for me. I hardly could challenge riders on uphills and actually quietly enjoy better downhills.
Pumping the bike on Flats for me, is actually easier than locked into SPD, Yeehaa mentioned that pushing away from bike while doing Aero business. SPD's give you on toes position while Flats make your feet rotate around the axle thus helping in Aero trade surely?

My little 2pence.

Anonymous

Look, I've tried to explain it to you. You haven't grasped it.
What the fuck is you problem? Move on.
You obviously lack the required level of intelligence and mechanical understanding, and have been brainwashed into a state where you will disagree with physicists, world class coaches, and several scientific studies into the matter.
Frankly, you'r a fucking fruitcake.

Northwind

yeehaamcgee wrote:

Well, there's also a very large contingent of this here forum, and several physios to back them up that would claim that SPDs can exacerbate injuries.

I have been told, no matter what, do not use SPDs (or skis) as my leg won't survive it, "It's not if it's when", both by my consultant and by the sports physio I saw afterwards. Mine you my consultant wasn't too keen on me doing anything apart from walking, and even then only if I had to, "That was really difficult to fix so I'd appreciate if you don't ruin it" was another line of his.

supersonic

Let's not try and get too heated! We ain't the commuting forum ;-)

omegas

This is such a funny thread as every few weeks people start baiting about pedals and they take the bait every time , its very sad that it causes such emotion in some people.