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They were claimed to eliminate pedalling dead spots — but did they work?

Image: PMP cranks by robadod from LFGSS [This feature from the road.cc archive was last republished on April 23 2018]

We take a look at one of the more bizarre technical aberrations of recent history: the wackiest cranks ever made.

In 1981 Cycling Weekly magazine published a favourable review of an unusual new crank. The magazine gave a set to “a first-category Surrey roadman to try them out.”

The write-up said: “He fitted them in March and although our test is now over they are still on his best road bike. He has come to prefer them to orthodox cranks.”

CW’s tester “enjoyed the ‘feel’ of the cranks and reported that the slower his pedalling speed the more advantage he felt, which is perhaps why they are finding favour with big-geared time triallists.”

The tester told CW: “I didn't just get the power on the downward strokes of the pedals but all the way round the pedalling revolution as at low pedalling speeds dead centre seemed to be removed. This helped me keep a steady rhythm particularly when sitting back in the saddle climbing hills.”

He didn’t feel the same benefit when pedalling quickly in a low gear, though.

CW concluded: “So there is the verdict, whatever the theories, in practice our roadman tester felt the PMP cranks offered an advantage – and surely that is the true criterion.”

PMP crank B&W.jpg

An early publicity shot of the PMP Brevettato cranks   

That crank was the PMP Brevettato. Its unusual (but, as we’ll see, by no means unique) feature was a right angle bend about a third of the way between the bottom bracket axle and the pedal.

PMP made some interesting claims about the Brevettato cranks. They included:

  • The unique form of the PMP pedal crank means improved distribution of the energy required in pedalling and a perfectly round stroke; the result: increased equilibrium.
  • Its L-shaped design increases the pedal's propulsion power and lessens energy dispersion on the downstroke.
  • Pedalling the PMP way means to be perfectly in the saddle; in fact, the bicycle rider is forced to lean back slightly more than usual, putting him in the best possible aerodynamic position.
  • The PMP pedal crank means that pedalling is no longer an "ankle game" since the bottom dead-point is lightened to allow greater ease on the upstroke.
  • Bicycling becomes a pleasure and not a chore because the PMP pedal crank and its unique features take away the exertion and lighten muscle strain.

Bold claims, and with Cycling Weekly’s Surrey roadman finding they eliminated dead centre, you have to wonder why the design isn’t now ubiquitous.

PMPcranksadvert.jpg
An ad for PMP cranks.

That’s simple: it’s all bollocks.

A crank is a lever. The torque you generate when you load up the end of a lever depends on just two things: the force you exert and the distance between the point where that force is applied and the pivot.

Nothing else matters, especially not the route the lever takes between the two points. It can be a straight line, a right angle bend or any other shape; it doesn’t matter. All you achieve by making a crank any other shape than straight is to add weight and flexibility.

PMP cranks were even marked with the distance between the crank and pedal holes. As the Bicycle Museum of Bad Ideas remarks: “somebody at PMP understood it was simply an odd way to make a 175mm crank”.

Pretty much everyone who was paying attention in physics at school pointed this out at the time, but that didn’t stop a fad for PMP Brevettatos, especially among time triallists.

Even the great 80s time triallist Ian Cammish used them. Cammish, who won the Best British All-Rounder contest nine times in the 1980s, mentioned them when he tried to sell one of his 1983 bikes on eBay in 2013.

“Unfortunately the PMP cranks cracked a long time ago,” he wrote.

They had a bit of a reputation for that, though to be fair so did many other high-end cranks of the era.

Perhaps because of these reliability issues, and because not many were made in the first place, PMP Brevettato cranks are now rare and collectible. The most recent set I’ve seen on eBay went for US$400 — almost £300.

Other wonky cranks

The bike industry has a serious problem with knowledge loss, which leads to people who really should know better reinventing bad ideas over and over. The PMPs weren’t the first non-straight cranks (the earliest seem to have been in 1897), nor the last. Like the monster lurching back to life at the end of a bad horror movie, wonky cranks keep coming back.

Want to make people go “What the hell?” get yourself a set of dpardo Sickle Cranks:

dpardo r58 cranks.jpg

It’s not at all clear what advantages dpardo claims for this design. PMP had a slight case of ‘Campagnolo spoken here’ Italglish, but dpardo really needs to get a native speaker of English to write its marketing copy. It says — and I swear I haven’t changed a letter of this:

58T gear turns once is 1.6M faster than 50TAs same as pedaling 50T Same pedaling force pedal 58T, the riding performance is 16% increasing than 50T with normal cranks

The craziest recent reappearance of wonky cranks has to be Z-Torque cranks, which came and went between 2010 and 2014.

Z Torque cranks.jpg

The shape was claimed to have come to inventor Glenn Coment in a dream. He bent a wire coat hanger into the same shape and “when he revolved it in his hands he found that this crank assembly was different from any other crank assembly ever made. Except for top dead center and bottom dead center, this crank had no dead spots. He was amazed. And in future testing would find that during a rider's maximum effort, power increases at a bikes rear wheel of 20-25% were possible.”

If true, that would be little short of astounding.

Z Torque further claimed “many advantages, including”:

  • Smoother pedaling
  • More power to climb hills
  • Less perceived effort to pedal
  • Faster acceleration
  • Less affected by headwinds
  • Ability to turn higher gearing

However, the Z Torque was really just another crank that connected the bottom bracket axle and pedal by a circuitous route, with an extra problem baked in.

As you can see, the long arm of the V shape, is really, really long. Imagine trying to pedal while banked over hard in a corner and you can probably explain why Z-Torque cranks were never even as popular as PMP Brevettatos.

Our official grumpy Northerner, John has been riding bikes for over 30 years since discovering as an uncoordinated teen that a sport could be fun if it didn't require you to catch a ball or get in the way of a hulking prop forward.

Road touring was followed by mountain biking and a career racing in the mud that was as brief as it was unsuccessful.

Somewhere along the line came the discovery that he could string a few words together, followed by the even more remarkable discovery that people were mug enough to pay for this rather than expecting him to do an honest day's work. He's pretty certain he's worked for even more bike publications than Mat Brett.

The inevitable 30-something MAMIL transition saw him shift to skinny tyres and these days he lives in Cambridge where the lack of hills is more than made up for by the headwinds.

105 comments

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srchar [1387 posts] 3 years ago
0 likes
bikebot wrote:
Bmblbzzz wrote:

So there might have been a real effect, but it was psychological. 

Basically, the latter.  As JS summarises in the article, it's entirely bollocks.  The same kind of bollocks gullible audiophiles used to fall for in droves back in the 80's and 90's.

The Cycling Weekly tester was writing shit worthy of this -> http://wathifi.com/

And for anyone still not sure, I've got some speaker cable I'd like to sell you.

Haha. I once paid twenty quid for an interconnect, but I was a gullible teenager at the time. Copper core and gold plugs, with purple sheathing, 'twas a lovely thing and, of course, being twenty quid down, I convinced myself that it sounded better than the in-box freebie.

Avatar
Canyon48 [1146 posts] 3 years ago
3 likes

Lol, this is the biggest load of rubbish ever. Forget about the shape of the crank arms, the force is applied in the same place regardless of crank shape and the torque acts in the same place. All these do is add extra weight by taking the long route between your foot and the centre of the chainrings.

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bikebot [2116 posts] 3 years ago
2 likes
srchar wrote:

Haha. I once paid twenty quid for an interconnect, but I was a gullible teenager at the time. Copper core and gold plugs, with purple sheathing, 'twas a lovely thing and, of course, being twenty quid down, I convinced myself that it sounded better than the in-box freebie.

 

You got off very lightly, a £20 interconnect is just a slightly overpriced cable.  The $485 wooden volumen knob (google it) has become somewhat legendary as the finest example of this nonsense.  It's far from the most expensive piece of hardware, it's just so utterly stupid.

Honourable mention to anyone who bought one of those pens that you were supposed to use to colour in the edge of audio CDs.

I'm sure I'm not the only person who has noticed similarities between bike retail today and the hifi market of twenty years ago. I'm amazed we don't see much, much more of this nonsense, although Kickstarter has its fair share.  With a health does of pseudo science, you could probably find a few Fred's ready to pay £50 for a tiny bottle of chain oil. I'd bet Cycling Weekly would still be amongst those ready to fall for it as well.

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flobble [146 posts] 3 years ago
0 likes
P3t3 wrote:

This is the first time I've seen someone troll those of us who did A-level Physics. I'll bite. Have another think about how your weak/flexible (totally different properties) axle, contained in a stiff fork and with each end attached to a single wheel rim, could possibly cause a bicycle to pull left when that axle is braked at one end.

[/quote] Surely you can twist the fork legs under heavy braking due to the caliper only being on one leg. I had a road bike where the fork legs were twisted and it gave the bike a tendency to steer one way so i had to hang a long way off one side to ride no handed. Can't see how you'd affect the axle mind.[/quote]

Well, it's not completely bonkers...

A disk brake calipers applies a force to the disk a small distance behind the axis of the left fork blade, with an equal but opposite force being applied to the caliper. As this is off-axis, it results in bending of the left fork blade roughly in a direction perpendicular to the axle, and the left side of the axle moves backwards, turning the wheel slightly to the left.

Then two things happen.

1. As forks have 'trail', ie the contact patch is behind the headset axis, the contact patch moves to the right of the bike's axis, which would create a tendency to turn to the right.

2. As the contact patch is no longer aligned with the bike axis, the bike starts to fall. In this case to the left.

3. The wheel is angled slightly left, which creates a tendency for the bike to move left, offsetting 1. above.

As for the result of 1, 2 & 3, plus no doubt something I have forogotten, I have no idea.

And in any case, I suspect the deflection is very small in any real-world bike not made of wet noodles, and completely dominated by other dynamic things such as rider balance, bumps in the road, that it's never actually noticed. 

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burtthebike [2935 posts] 3 years ago
0 likes

Well, I fitted these cranks to my bike, with the amazing electric pedals from a few years ago and oval chainrings, and my bike pedals itself!

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severs1966 [418 posts] 3 years ago
1 like
bikebot wrote:

... As JS summarises in the article, it's entirely bollocks.  The same kind of bollocks gullible audiophiles used to fall for in droves back in the 80's and 90's.

The Cycling Weekly tester was writing shit worthy of this -> http://wathifi.com/

And for anyone still not sure, I've got some speaker cable I'd like to sell you.

 

Sadly, some writers at bike magazines have come out with some prize bollocks over the years. JS himself should remember a certain writer (who will remain nameless) whose apogee was the line "the cromoly axles gave a feeling of sturdiness to the ride". This writer went on to review cars, and I often wondered if that was because he was hounded out of reviewing bikes by a pack of angry townspeople with flaming torches, etc.

Even he didn't stoop to the depths that are the norm in the hi-fi reviewing community. Their vague terminology and credulousness allowed the rise of the phenomenon that is Peter Belt. Not even the worst bike magazine entertained anything as bad. No amount of directional speaker cables can compete with his mystery foil squares... and anyone who believes that crap can not only be sold bikebot's speaker cable, but might bid for a second-hand Orgone Generator that I can source for them...?

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Toshi San [10 posts] 3 years ago
2 likes

Steve Joughin recounts that Steve Lawrence snapped one of these cranks in the Tour of Scotland, apparently the broken end made a mess of his leg - "he was cut to bits." And yes, the science behind the idea is "Bollocks."

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Paul_C [583 posts] 3 years ago
0 likes

1995, variable length crank...

http://www.google.co.uk/patents/US5636554

2002, yet another variable length crank system...

http://www.google.co.uk/patents/US6640662

oh great... yet another one, dated 2009...

https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2009101637

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racingcondor [242 posts] 3 years ago
0 likes
bikebot wrote:

This does make me  wonder why no manufacturer ever tried an elastomer crankset. It looks like they would have found a few customers.

[/quote]

There is one out there that I've seen with springs connecting the crank arm to the spider. All I will say is that it doesn't seem to have caught on...

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Cantab [102 posts] 3 years ago
2 likes
hawkinspeter wrote:
wycombewheeler wrote:
hawkinspeter wrote:

To be fair, a non-straight crank could possibly be of some use with non-round chainwheels to alter the power transfer, but with a circular chainwheel, there is zero benefit for a non-straight crank.

 

just no

 

the relationship between the pedal spindle and the crankshaft is unchanged regardless of the shspe of the metal connecting them.

Yes, except for the angle. Imagine that a crank can have a square hole at any orientation (i.e. 90 degrees difference) and thus the orientation of that hole can change the relationship between the pedals and the chainring. With a circular chainring that makes zero difference, but an oval chainring could show a difference in where the peak power is applied. However, a non-straight crank is the most stupid way of changing that orientation (more flex, more weight and less strong) rather than changing how the crank fits onto the crankshaft.

I'm not trying to argue for any benefit with a non-straight crank, but the only possible way that it would physically make any difference would be with a non-circular chainring.

Ultimately the forces through the pedal arm lever resolve to a straight line between the pedal axle and the chainset axle. Regardless of the shape of pedal arm the pedal axle (and foot) still traces a perfect circle around the chainset axle (think about it, the foot does not move further or closer to the centre at any point). Thus even with eliptical chainrings, the foot is making exactly the same shape around the chainset axle, and an 'L' shaped pedal arm does not position the foot relative to the curve of the chain ring any better than a straight pedal arm going from one end of the L to the other.

Avatar
hawkinspeter [3719 posts] 3 years ago
0 likes
Cantab wrote:
hawkinspeter wrote:
wycombewheeler wrote:
hawkinspeter wrote:

To be fair, a non-straight crank could possibly be of some use with non-round chainwheels to alter the power transfer, but with a circular chainwheel, there is zero benefit for a non-straight crank.

 

just no

 

the relationship between the pedal spindle and the crankshaft is unchanged regardless of the shspe of the metal connecting them.

Yes, except for the angle. Imagine that a crank can have a square hole at any orientation (i.e. 90 degrees difference) and thus the orientation of that hole can change the relationship between the pedals and the chainring. With a circular chainring that makes zero difference, but an oval chainring could show a difference in where the peak power is applied. However, a non-straight crank is the most stupid way of changing that orientation (more flex, more weight and less strong) rather than changing how the crank fits onto the crankshaft.

I'm not trying to argue for any benefit with a non-straight crank, but the only possible way that it would physically make any difference would be with a non-circular chainring.

Ultimately the forces through the pedal arm lever resolve to a straight line between the pedal axle and the chainset axle. Regardless of the shape of pedal arm the pedal axle (and foot) still traces a perfect circle around the chainset axle (think about it, the foot does not move further or closer to the centre at any point). Thus even with eliptical chainrings, the foot is making exactly the same shape around the chainset axle, and an 'L' shaped pedal arm does not position the foot relative to the curve of the chain ring any better than a straight pedal arm going from one end of the L to the other.

I thought this thread was over.

What I meant was that the orientation of the crank-hole square will change the phase between the pedals and the chain-ring which will have no effect on a circular chain-ring. A phase change on an oval chain-ring may help or hinder by changing where peak power is applied. Again, a non-straight crank would not be an effective way of manipulating the phase difference between the pedals and the chain-ring.

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whobiggs [168 posts] 3 years ago
0 likes

You have to admit they do look good though! smiley

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Welsh boy [652 posts] 3 years ago
2 likes
hawkinspeter wrote:

To be fair, a non-straight crank could possibly be of some use with non-round chainwheels to alter the power transfer, but with a circular chainwheel, there is zero benefit for a non-straight crank.

 

No it couldn't.

Avatar
hawkinspeter [3719 posts] 3 years ago
2 likes
Welsh boy wrote:
hawkinspeter wrote:

To be fair, a non-straight crank could possibly be of some use with non-round chainwheels to alter the power transfer, but with a circular chainwheel, there is zero benefit for a non-straight crank.

 

No it couldn't.

It can change the relationship between the top dead center of the (oval) chainring with the top dead center of the foot on the pedal. Of course, a straight crank could be fitted in a different orientation with the crankshaft to achieve the same without all the problems of a non-straight crank.

Avatar
Shanghaied [53 posts] 3 years ago
0 likes
hawkinspeter wrote:
Welsh boy wrote:
hawkinspeter wrote:

To be fair, a non-straight crank could possibly be of some use with non-round chainwheels to alter the power transfer, but with a circular chainwheel, there is zero benefit for a non-straight crank.

 

No it couldn't.

It can change the relationship between the top dead center of the (oval) chainring with the top dead center of the foot on the pedal. Of course, a straight crank could be fitted in a different orientation with the crankshaft to achieve the same without all the problems of a non-straight crank.

Except there is a much better solution for that used by all modern oval rings - a series of bolt holes on the chainrings to interface with the crank arm at different angles. Never use any other material when the same can be accomplished with holes.

Avatar
hawkinspeter [3719 posts] 3 years ago
0 likes
Shanghaied wrote:
hawkinspeter wrote:
Welsh boy wrote:
hawkinspeter wrote:

To be fair, a non-straight crank could possibly be of some use with non-round chainwheels to alter the power transfer, but with a circular chainwheel, there is zero benefit for a non-straight crank.

 

No it couldn't.

It can change the relationship between the top dead center of the (oval) chainring with the top dead center of the foot on the pedal. Of course, a straight crank could be fitted in a different orientation with the crankshaft to achieve the same without all the problems of a non-straight crank.

Except there is a much better solution for that used by all modern oval rings - a series of bolt holes on the chainrings to interface with the crank arm at different angles. Never use any other material when the same can be accomplished with holes.

Exactly. That's why 'L' shaped cranks are completely useless.

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fenix [1195 posts] 3 years ago
0 likes

I give you Powercranks - used by triantelopes and ooh Vino.  So MUST be the cranks then...

 

https://www.powercranks.com/

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Mungecrundle [1481 posts] 3 years ago
0 likes

The only excuse (apart from just liking the shape) for curved crank arms might be that with modern composite materials, it's possible to create a stronger, lighter piece.

I'm trying to think of an example from nature, and very few structural bones are dead straight or of uniform cross section along their length.

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DrJDog [481 posts] 3 years ago
0 likes
Mungecrundle wrote:

The only excuse (apart from just liking the shape) for curved crank arms might be that with modern composite materials, it's possible to create a stronger, lighter piece.

I'm trying to think of an example from nature, and very few structural bones are dead straight or of uniform cross section along their length.

 

Like a pre-stressed H-beam. 

Avatar
Canyon48 [1146 posts] 3 years ago
4 likes

As an engineering student, this keeps on bugging me. Anyone who thinks, let alone tries to sell a stupid shaped crank, claiming it to be better than a normal crank, needs to be beaten over the head with said stupid shaped crank.

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Al__S [1298 posts] 3 years ago
0 likes
bikebot wrote:

With a health does of pseudo science, you could probably find a few Fred's ready to pay £50 for a tiny bottle of chain oil. I'd bet Cycling Weekly would still be amongst those ready to fall for it as well.

Not quite there- but £18 for a 50ml bottle is pretty ridiculous

Avatar
Shanghaied [53 posts] 3 years ago
1 like
Al__S wrote:
bikebot wrote:

With a health does of pseudo science, you could probably find a few Fred's ready to pay £50 for a tiny bottle of chain oil. I'd bet Cycling Weekly would still be amongst those ready to fall for it as well.

Not quite there- but £18 for a 50ml bottle is pretty ridiculous

 

"Hand-blended" & "hand-crafted in the UK". LOL. I myself only drink hand-poured beer.

 

Mind you the price still compares favourably to Loctite, which might as well be champion racehorse semen.

Avatar
hawkinspeter [3719 posts] 3 years ago
0 likes
Al__S wrote:
bikebot wrote:

With a health does of pseudo science, you could probably find a few Fred's ready to pay £50 for a tiny bottle of chain oil. I'd bet Cycling Weekly would still be amongst those ready to fall for it as well.

Not quite there- but £18 for a 50ml bottle is pretty ridiculous

I've been suckered into buying this stuff: http://www.dry-fluids.com/dryfluid-bike-2.html

€18.90 for 50ml but at least it's trying to be a different type of lubricant. (I like it and would buy again).

Avatar
StuInNorway [296 posts] 3 years ago
0 likes

 

[/quote]

Yes, except for the angle. Imagine that a crank can have a square hole at any orientation (i.e. 90 degrees difference) and thus the orientation of that hole can change the relationship between the pedals and the chainring. With a circular chainring that makes zero difference, but an oval chainring could show a difference in where the peak power is applied. However, a non-straight crank is the most stupid way of changing that orientation (more flex, more weight and less strong) rather than changing how the crank fits onto the crankshaft.

I'm not trying to argue for any benefit with a non-straight crank, but the only possible way that it would physically make any difference would be with a non-circular chainring.

[/quote]

 

Still "NO",

 

Regardless of chainring forming, the "lever" in a pedal arm is always a straight line in terms of the forces applied. Adding a bend, be it 90 degree, 120 degree, or a corve merely increases the amount of material in use to create the same lever action from pedal to bottom bracket.  If you REALLY wanted you 'could' make a pedal arm with a set of zig-zags out to the pedal and claim the increased pedal arm length (from the zig-zag) means more power. But it would still be quackery, as the raw physics looks at 2 things. power applied to pedal, and direct line of sight distance from centre of bottom bracket to centre of mount for pedal.
The only way to avoid the "deadspots" would be to not have the pedals set to 180 degrees to each other, so have the sueare hole in one pedal offset by maybe 15-20 degrees. But this would result in a very ungainly pedalling rythym, and while "technically" avoidint a total deadspot would result in a more uneven application of power with a highpoint as (for example) left foot comes over top before right passed the bottom point, and a low point as both pedals are in the act of coming back upwards (good luck without cleats)  

 

Pop into your local school and ask a physica teacher to help with some forces diagrams to see what we mean if you don't follow.

Avatar
hawkinspeter [3719 posts] 3 years ago
2 likes
StuInNorway wrote:

 

Yes, except for the angle. Imagine that a crank can have a square hole at any orientation (i.e. 90 degrees difference) and thus the orientation of that hole can change the relationship between the pedals and the chainring. With a circular chainring that makes zero difference, but an oval chainring could show a difference in where the peak power is applied. However, a non-straight crank is the most stupid way of changing that orientation (more flex, more weight and less strong) rather than changing how the crank fits onto the crankshaft.

I'm not trying to argue for any benefit with a non-straight crank, but the only possible way that it would physically make any difference would be with a non-circular chainring.

[/quote]

 

Still "NO",

 

Regardless of chainring forming, the "lever" in a pedal arm is always a straight line in terms of the forces applied. Adding a bend, be it 90 degree, 120 degree, or a corve merely increases the amount of material in use to create the same lever action from pedal to bottom bracket.  If you REALLY wanted you 'could' make a pedal arm with a set of zig-zags out to the pedal and claim the increased pedal arm length (from the zig-zag) means more power. But it would still be quackery, as the raw physics looks at 2 things. power applied to pedal, and direct line of sight distance from centre of bottom bracket to centre of mount for pedal.
The only way to avoid the "deadspots" would be to not have the pedals set to 180 degrees to each other, so have the sueare hole in one pedal offset by maybe 15-20 degrees. But this would result in a very ungainly pedalling rythym, and while "technically" avoidint a total deadspot would result in a more uneven application of power with a highpoint as (for example) left foot comes over top before right passed the bottom point, and a low point as both pedals are in the act of coming back upwards (good luck without cleats)  

 

Pop into your local school and ask a physica teacher to help with some forces diagrams to see what we mean if you don't follow.

[/quote]

You're missing the point of the phase relationship between the position of the (oval) chainring and the position of the pedals. Yes, a force diagram shows no difference as there is no difference in how much force is applied.

Pop into your local academy and get an electrical engineer to explain phases to you if you don't follow.

Avatar
kcr [154 posts] 2 years ago
0 likes
hawkinspeter wrote:
StuInNorway wrote:

 

Yes, except for the angle. Imagine that a crank can have a square hole at any orientation (i.e. 90 degrees difference) and thus the orientation of that hole can change the relationship between the pedals and the chainring. With a circular chainring that makes zero difference, but an oval chainring could show a difference in where the peak power is applied. However, a non-straight crank is the most stupid way of changing that orientation (more flex, more weight and less strong) rather than changing how the crank fits onto the crankshaft.

I'm not trying to argue for any benefit with a non-straight crank, but the only possible way that it would physically make any difference would be with a non-circular chainring.

 

Still "NO",

 

Regardless of chainring forming, the "lever" in a pedal arm is always a straight line in terms of the forces applied. Adding a bend, be it 90 degree, 120 degree, or a corve merely increases the amount of material in use to create the same lever action from pedal to bottom bracket.  If you REALLY wanted you 'could' make a pedal arm with a set of zig-zags out to the pedal and claim the increased pedal arm length (from the zig-zag) means more power. But it would still be quackery, as the raw physics looks at 2 things. power applied to pedal, and direct line of sight distance from centre of bottom bracket to centre of mount for pedal.
The only way to avoid the "deadspots" would be to not have the pedals set to 180 degrees to each other, so have the sueare hole in one pedal offset by maybe 15-20 degrees. But this would result in a very ungainly pedalling rythym, and while "technically" avoidint a total deadspot would result in a more uneven application of power with a highpoint as (for example) left foot comes over top before right passed the bottom point, and a low point as both pedals are in the act of coming back upwards (good luck without cleats)  

 

Pop into your local school and ask a physica teacher to help with some forces diagrams to see what we mean if you don't follow.

[/quote]

You're missing the point of the phase relationship between the position of the (oval) chainring and the position of the pedals. Yes, a force diagram shows no difference as there is no difference in how much force is applied.

Pop into your local academy and get an electrical engineer to explain phases to you if you don't follow.

[/quote]

But you can set any "phase difference" you like with a straight crank by just offsetting the angle of the crankset spider. There is no point in using a bent crank to do it!

Avatar
IHphoto [122 posts] 1 year ago
0 likes
ColT wrote:

Hmm. Magic wristbands, anyone?

 

 

 

*cough* ... Mr Thomas....

Sports people falling for snake oil ... well I never...

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yupiteru [56 posts] 1 year ago
0 likes

Its just clever marketing at the end of the day. The same type of people who have been conned into using disc brakes, wide rims, reinforced plastic (carbon fiber) etc on their road bikes.

All a load of bollocks and totally unnecessary except on an off road bike of course and in 10yrs time we will look back and laugh our heads off!

Oh and don't even mention gravel bikes - Jesus! The old saying, 'A fool and his money is easily parted' has never been more true.

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scrapper [76 posts] 1 year ago
0 likes
mylesrants wrote:

i love them. Hope they make a handlebar stem to match

Arent mountain bike riser bars (with stems with positive reach) very similar in principle ?...

The contact points are at the same position as a flat bar bike with a stem at a more upright angle?

Avatar
ROOTminus1 [60 posts] 1 year ago
2 likes
scrapper wrote:

Arent mountain bike riser bars (with stems with positive reach) very similar in principle ?...

The contact points are at the same position as a flat bar bike with a stem at a more upright angle?

No, riser bars don't change the length of the lever between riders hands and the axle of the steerer tube. What they do is allow fine tuning of ergonomic fit; getting the contact point at the correct height without changing spacers (e.g. if the the steerer's been cut too short to stack)

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