Self-energising chainset🤣

[bikeworkshop]

https://www.ebay.co.uk/itm/30561023...-925b-56adf5c61914|iid:1|vlpname:vlp_homepage

 

[GrahamJohnWallace]

https://www.ebay.co.uk/itm/30561023...-925b-56adf5c61914|iid:1|vlpname:vlp_homepage

There are "self-energising" chainsets that use springs to store energy that is theoretically released inbetween pedal strokes but this is not one of them. This is intended to reduce the 'dead-spot' created when the pedal crank is pointing upwards towards the rider. It works by moving the upper crank ahead of the lower one on each rotation. There is some evidence of 'marginal gain' improvements with these though at the expense of extra weight and mechanical complexity.

Theoretically, they should perform best in lower-cadence / high-resistance situations like; when hill climbing, in headwinds or high rolling resistance off-road riding . As with extremely elliptical chainrings they will be not allow for smooth high cadence pedalling.

 

[chickendrumsticks]

Sprinkle liberally with fairy dust before using, for best effect.

 

[GrahamJohnWallace]

Sprinkle liberally with fairy dust before using, for best effect.

They were originally created at a university or technical college in Millan, are UCI approved and have been subject to numerous scientific trials. In certain conditions they have been shown to make a difference though this is not necessarily in terms of improved performance.

In theory, they should make steep hill low cadence climbing more efficient and less tiring though not necessarily faster. This is because they can reduce the effort needed to keep the bike moving by reducing the amount of acceleration and deceleration between each pedal stroke.

http://autobus.cyclingnews.com/tech/?id=2002/reviews/rotor_cranks

 

[chickendrumsticks]

"not necessarily in terms of improved performance" - so what's the point?

 

[Nob]

They weighed a ton

 

[GrahamJohnWallace]

"not necessarily in terms of improved performance" - so what's the point?

My own experience of comparing extremely elliptical EggRings to round rings with the same number of teeth is the EggRings won't get you up a hill any quicker, but you will get further up a steep hill before you become exhausted.

The theory is that you need to accelerate faster to get past the dead spot with round rings as there is more time in between pedal strokes for the bike to slow down as the momentum is lost to gravity. I guess that this is similar to stop start driving using more fuel than driving at a constant speed.

So it's a matter of efficiency and better endurance. Given a rider has a finite amount of energy to expend, there will be less energy used when the power transfer to the wheels is smooth and there is less deceleration in between pedal strokes. On the flat with a tailwind, losing energy in between pedal strokes is not an issue as the energy stored in the mass of the bike will not be lost as quickly gravity or friction.

The main difference between the RotoCranks and EggRings is that the gear ratio remains constant with RotoCranks whilst with EggRings it fluctuates between a higher gear during the pedal stroke and a lower gear in between. (Incidentally this is the opposite of the Shimano Biopace system)

With both RotoCranks and EggRings the rotation speed of the pedal varies with rotation which is why neither works well with high cadence riding.

 

[GrahamJohnWallace]

They weighed a ton

Yes 1.339kg with integral bottom bracket cartridge and left crank. Whilst a 23 tooth EggRing weighs very little.

 

[pigman]

Yes 1.339kg with integral bottom bracket cartridge and left crank. Whilst a 23 tooth EggRing weighs very little.

Did you mean 23T? That's one for the cassette

 

[pigman]

Never seen this before. Wonder if it works as well as the L shape PMP crank