Self-energising chainset🤣

[GrahamJohnWallace]

Personally I find getting sufficient traction is usually the limiting factor when climbing slopes, when I was in my teens & twenties there was a short patch of 60+ degree slope (yes 2 foot accent for 1 foot horizontal) that me and my mate regularly rode up with a combination of momentum and the back wheel scrabbling for grip. It was impossible to "walk" up, we could just about climb it but needed both hands, good gripping trainers and frequently slipped back down.

I understand the difference between 45 degree and 45% slope, I can ride a 45% slope seated easily enough, I'm 6 foot 3 but I deliberately ride an 18" frame, so I have a stupidly long seat post and a long steerer and bar ends that stretch me out on the bike so I can easily move my weight over the front wheel to keep it down if required.

As you say, a far steeper slope can be ridden when bike has lots of momentum going into the slope. In fact if the slope curves upwards, and the rider is going fast enough an almost vertical slope can be ridden momentarily. Or even beyond vertical as is the case with motorcyclists riding the 'loop-the-loop'



The above diagram shows the direction of the 'torque reaction' vector and how the rider can reduce the magnitude by moving their weight further away and forward of the rear axle. This explains why being tall can help to keep the front wheel planted.

Though accurate for a stationary bicycle the top diagrams are an over simplification as the pedalling forces push upwards against the rider's CoG whose inertia pushes backwards causing more 'load shift' or weight transfer onto the back wheel. This can cause the bike to wheelie even before the CoG moves behind the rear contact patch. There is also a rear wheel torque reaction which further adds to the problem.

The lower the gears used the greater 'load shift' and 'torque reaction' forces that combine to lift the front wheel.

Training yourself to pedal at a higher cadence in a lower gear is a simple way to make climbing easier than bolting on some dubious gizmo that may improve your performance.

Pedalling with a higher cadence means that there is less time for deceleration in-between pedal strokes. But with hill climbing the use of very low gears increases the 'load shift' and 'torque reaction' forces that induce suspension bob. Very low gears can also overwhelm rear wheel traction.

I'd say RotorCranks are a solution looking for a problem since the pro peloton have generally adopted higher cadence as the solution to efficient pedaling for hours at a time. I used to be a plodder with a slow cadence style, I can't ride at the 90rpm the pro's do but I pedal faster than I used to as a means to climbing hills effectively. I have a cycle computer with a cadence sensor which helps stop me labouring on climbs..

I used to use low gears and high cadence for steep climbing but now I find using them more tiring than pushing higher gears. When out training I use as high a gear as I can, to build up muscle strength. Rider's who prefer low cadence hill climbs may like the smoother feel of a device like RotoCranks. But I doubt that it would make them faster. In fact it's likely to make them slower due to the additional weight.

 

[foz]

I'd be interested to know where this rideable-when-seated 45% slope is?
I see this model of rotor crank fairly regularly, if they were any good then they would still be making them but rotor dropped them in favour of their Q rings, I wonder why? There have been other products that claim to be "self energising", "create more power" etc. over the years. I am never sure if the companies that produce them just have a complete misunderstanding the basic physics, or some of the most inventive and outrageous marketing departments around!

 

[GrahamJohnWallace]

There have been other products that claim to be "self energising", "create more power" etc. over the years. I am never sure if the companies that produce them just have a complete misunderstanding the basic physics, or some of the most inventive and outrageous marketing departments around!

Einstein said, "Energy cannot be created or destroyed, it can only be changed from one form to another".
(First law of thermodynamics)

Therefore it is impossible for a mechanism to give out more energy out than you put in. The best the engineers can do is reduce the energy losses inherent in every machine.


I just had a look at the claims Rotor made for the RotoCranks:

* "Raise your lactate threshold by eliminating the dead spot, making pedaling more efficient and reducing the lactic acid in the bloodstream."

* "The rotor enables you to raise your wattage output, making you climb easier, faster and further; whilst eliminating knee soreness.
("This extra wattage is the equivalent of 2minutes per 40km time trial". "In the same way Rotor also enables the cyclist to climb hills easier and faster".)

* "The highest £ per second performance improvement available".

I wonder if the advertising standards people vetted these claims back in the day?