MG Tech planetary gear crankset with 1.44 x multiplication. Bollocks or real benefit?

[Sacke]

I have on test for a bit less than a week, a bike equipped with the MG Tech crankset.

They describe the technology as "The patented and unique heart of each MG TECH bicycles delivers more fun, greater speed for a given effort, as you will be less fatigued at the end of a ride. A planetary gear within crankset rotates the chainrings 1.44 times faster than you pedal, resulting in your next personal best."

http://www.mgtechbikes.fr/ultim-crank.html





Now, I want to stay open minded. The pitch is that the leverage increases because the distance between the point where the power is produced, is further than on a a traditional crankset.

The same inventor had another similar product about 10-15 years ago, but apparently the power transfer loss in the planetary system has decreased from a whopping 17%, to something like 1,7% (or less, can't remember).

Their logic says that the effort needed to pedal a 37 tooth chainring (equivalent of a 53 tooth cr) is smaller, but is it?

So far, I have only done 15km with a bike that wasn't set up correctly, and with mtb pedals instead of road pedals.

I'll do the Ventoux on Sunday or Monday to see if I can beat my personal best.

The smart ones among you... is there scientific reasoning that would support the claim of planetary gears being better than regular chainrings?

[XCProMD]

Nothing. All that thing returns is a power loss of 1,7% more than chainring attached with good old bolts to the crank.


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[sungod]

pure snake oil

"greater speed for a given effort" is a lie, plain and simple, if true it'd be violating known physics

at constant cadence, if the chain rings rotate 1.44 times faster, you'll need to input 1.44 times more power (assuming external losses scale linearly with velocity, they don't actually as aerodynamic drag rises exponentially)

also, with that extra gearing, you'll have higher losses, i.e. overall you'll go slower for any given power input, if you're correct about the losses 1.7% slower (assuming going too slow for aerodynamic losses to become dominant)

that's higher losses and higher weight, you'll climb slower, the extra potential energy at the top will gain you a smidge on descent, but not enough to overcome what you lost going up

let's hope these liars go bankrupt fast before they sell this junk to honest people

[deek]

Same issues with this as with an IGH. Power is lost from the friction of the gears meshing. A normal bicycle drivetrain is actually really efficient and you won't find anything more efficient short of a fixed gear or cranks attached directly to the wheel.

[Rick]

1.7% is probably a small enough loss that many people will feel an "improvement" that is really just statistical variation in a combination of many other conditions.

But it has to be snake oil.

[Miller]

Now, I want to stay open minded.

No need, it's nonsense.

[Fixie82]

Boom! This thread is why I like coming here, such great information to be found from knowledgeable people.

My question is if this crank so plainly does not add anything and actually makes you slower how can the manufacturer/designer/inventor believe the opposite? I find it really interesting when things like this, anyone remember CrankTips, get put on the market .

[Sacke]

Another benefit they claim is the near elimination of the dead spot at the top of the pedal stroke.

I'll give the system a go and at least ride a few climbs where my performances have remained stable with different bikes and equipment choices.

If there is a gain, those hills would show it.


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[eric]

It's the moden version of this:



And even less effective (because gears, as pointed out already).
Complete bollocks. The inventor might think otherwise but if so he's using bro science.
Or he knows it's useless and is cynically expoiting cyclists.

[maxxevv]

Its nothing new actually, I wonder where did the patent come from ?

Schlumpf has been making such products for a long, long time...
http://www.schlumpf.ch/hp/schlumpf/faq. ... engl.htm#A

And as pointed out, 1.44 ratio just means that you need to apply 1.44 times the torque to get the equivalent of a larger chainring. There is no net gain at all.

There are minute but perceptible losses from the friction losses in the planetary gear meshing though. Not forgetting the additional losses from the rotational pivot points in the system.

Edit: In Addition>

Studies have actually shown that bigger chainrings actually are more efficient in transmission of power due to lower losses. So, using a smaller ring actually is counter to that.

[kkibbler]

Another benefit they claim is the near elimination of the dead spot at the top of the pedal stroke.

Rubbish. This thing doesn't change anything about how you pedal.

[maxxevv]

Theoretically, as far as I understand of deadspot mechanics and mechanical leverages through gearing, this system should magnify the deadspot rather than reduce it though?

Suppose you have 30 degrees of deadspot in your pedal stroke, the 1.44 ratio actually means turning 1.44 times the number of times the pedal stroke does. Which should mean, 1.44 x 30 degrees ....! Yes / No ??

[Nefarious86]

Also wouldn't this make any already low cadence efforts unbearable?

[sungod]

Boom! This thread is why I like coming here, such great information to be found from knowledgeable people.

My question is if this crank so plainly does not add anything and actually makes you slower how can the manufacturer/designer/inventor believe the opposite? I find it really interesting when things like this, anyone remember CrankTips, get put on the market .

i think there'll always be people, whether deluded or greedy, who will produce useless products for sale, it happens again and again

sometimes people lose only money, other times it's much worse...

https://en.wikipedia.org/wiki/ADE_651

...even after this the devices remained in use!

[JAQ1]

Same deadspot, its determined by your leg mechanics and the size of the circle your feet rotate at. If you pedal faster or slower, it will stay the same. pedaling slower just means you can control your push, scrape, pull better.