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

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Sacke
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by Sacke

Could one then assume that planetary gears, such as MG Tech, would have

- Equal power output at the rear hub (as pulled by the chain), as traditional cranks?
- Equal torque at the pedal, as with traditional cranks?

Why torque matters: http://cyclingtips.com/2009/06/power-vs-torque/

With the assumption that:

- Number of chainring teeth is calculated to be same equivalent, considering the 1.44 multiplication
- Planetary gears would have 0% power loss from meshing gears?

If so, one could argue that:

- MG Tech cranksets only have drawbacks due to increased weight, complexity and power loss due to friction in the system itself?

If friction only causes 1.7% power loss, then I assume if all things being equal, it would be a gimmick that neither improves, nor deteriorates pedalling efficiency? EDIT: (apart from the 1.7%)
Last edited by Sacke on Fri Jul 29, 2016 7:23 pm, edited 1 time in total.

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Svetty
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by Svetty

Sacke wrote:If friction only causes 1.7% power loss, then I assume if all things being equal, it would be a gimmick that neither improves, nor deteriorates pedalling efficiency?


If it causes 1.7% power loss then, by definition, it deteriorates pedalling efficiency. Nothing more to say....

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Rick
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by Rick

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Sacke
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by Sacke

Yes, yes... bollocks it is then. :)

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Rick
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by Rick

I would consider buying some HG Tech or Z-Torque cranks just for the hilarious nutcase factor when showing up on the starting line!

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Sacke
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by Sacke

I did a 100km ride with a group, where I more or less know where my level is compared to the people around me.

A couple of observations...

- The MG Tech cranks seem to prefer a high cadence. The lower the cadence, the "stickier" the crankset seemed.
- The salesrep talked about out of the saddle efforts being easier. Maybe they were... Didn't feel bad, even at low cadences.
- The harder you go, the more you wish you were on regular cranks.

Not convinced. It wasn't that bad, and I suppose that for some that would want something different, it could be nice.

However, I doubt there is any benefit from the crankset, and maybe there is a penalty in terms of friction. We got two rain showers over us, and the crankset towards the end started to have some dry noise coming from within. Maybe a problem with water resistance.

Not my thing, but definitely not utter bollocks either. :)

wingguy
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by wingguy

Fixie82 wrote: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 .


Because they don't understand basic physics. At any given time there are thousands of people working on perpetual motion machines. Hope overrides knowledge.

Plus, some people are just con-men.

wingguy
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by wingguy

Sacke wrote:- MG Tech cranksets only have drawbacks due to increased weight, complexity and power loss due to friction in the system itself?

Wow, only those drawbacks for no gain? Sign me up bro, I'll take 10! :lol:

wingguy
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by wingguy

Sacke wrote:Not my thing, but definitely not utter bollocks either. :)

What would it have to do to meet your definition of 'utter bollocks' - explode?

(In which case don't speak too soon, 'cos it looks like it might just do that after a thousand miles or so.)

perwjensen
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by perwjensen

Sacke wrote:Could one then assume that planetary gears, such as MG Tech, would have

- Equal power output at the rear hub (as pulled by the chain), as traditional cranks?
- Equal torque at the pedal, as with traditional cranks?

Why torque matters: http://cyclingtips.com/2009/06/power-vs-torque/

With the assumption that:

- Number of chainring teeth is calculated to be same equivalent, considering the 1.44 multiplication
- Planetary gears would have 0% power loss from meshing gears?

If so, one could argue that:

- MG Tech cranksets only have drawbacks due to increased weight, complexity and power loss due to friction in the system itself?

If friction only causes 1.7% power loss, then I assume if all things being equal, it would be a gimmick that neither improves, nor deteriorates pedalling efficiency? EDIT: (apart from the 1.7%)




Exactly. No difference whatsoever aside from the additional friction loss.

The only advantage is that is provides a different gear range. Changing chain rings or cassettes does the same.

mattr
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by mattr

Hasn't this been done before? But in 2x mtb flavour.
A locked out low ratio for winching up hill, then a planetary higher ratio for coming back down.

That died a death too.

andrew9
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by andrew9

Yes, the Hammerschmidt.
That had the benefit of better ground clearance with the smaller chainring, and the ability to effectively have 2x chainrings and still use a proper chainguide. Neither of these apply to road, or even XC.


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kgt
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by kgt

Fixie82 wrote: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?

It happens all the time. It's called marketing actually.

jih
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by jih

One use could be folding bikes, where there are sometimes chainring clearance issues when big chain rigs are used to get a higher gear.

However, Schlumph already makes a multi-speed version of the same.

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Sacke
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by Sacke

wingguy wrote:
Sacke wrote:Not my thing, but definitely not utter bollocks either. :)

What would it have to do to meet your definition of 'utter bollocks' - explode?

(In which case don't speak too soon, 'cos it looks like it might just do that after a thousand miles or so.)


I would call it utter bollocks if the system clearly wasn't an alternative to regular cranksets.

The loss in friction of the system is small enough, that I can imagine that some riders could "feel" how the system is smoother.

If the system is durable and maintenance free, it would provide a creak free BB/crank -solution for riders that want something different.

Yes, their marketing claims are just marketing claims.

I would have loved to test, with a power meter, a Focus Cayo with regular cranks and the same wheels at constant watts to see if there is any time difference at all.

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