Self-energising chainset🤣

[bikeworkshop]

If it makes you think you'll go faster, you'll probably go faster!

 

[GrahamJohnWallace]

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

The smallest elliptical inner EggRing I use is 23T with a major to minor axis ratio of 1:0.6

 

[Nob]

I’ll stick with my PMP’s

 

[bikeworkshop]

No need for that spring-loaded or elliptical nonsense here!

 

[Nob]

I do use Rotor Q rings on my normal bike & have done for several years when in Saudi & now in the UK & soon once I’m back in Cebu.

 

[Aech]

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.

I'm calling male bovine effluent on these, since they are UCI approved if there was any possible advantage to be had from these no matter how slight they would have shown up on a grand tour winner's bike by now.

I know cyclists can be the most irrational superstitious people around so the only benefit these can possibly have is mental.

 

[GrahamJohnWallace]

I'm calling male bovine effluent on these, since they are UCI approved if there was any possible advantage to be had from these no matter how slight they would have shown up on a grand tour winner's bike by now.

I know cyclists can be the most irrational superstitious people around so the only benefit these can possibly have is mental.

A bicycle travelling along a smooth flat road at low speed is an incredibly efficient machine. As resistance increases with speed, rolling resistance or incline this efficiency drops sharply until eventually it can become more efficient to get off and walk.

Why is walking up a steep hill easier than cycling up?
And why can the average person walk up a hill that would be too steep for the fittest and strongest of cyclists to ride up?

This is fundamentally because the low RPM crank mechanism that converts the motion of the legs to rotational motion becomes more inefficient as the resistance to motion increases. This happens because a crank is only 100% effective at transferring energy when the input force rotating it is at 90 degrees. At worst a force at zero or 180 degrees will not result in rotation.

Why is it so much easies to walk up a steep hill than to cycle?

The leg has evolved to move the foot, not in a circle, but in a straight line perpendicular to the ground. Unlike with a crank mechanism, the power transfer can be maintained consistently and evenly throughout. Also, though it seems as if we take one step at a time, on steep inclines each strides slightly overlaps the one before as the lifted foot overtakes and starts pushing just before the following foot stops and lifts off the ground. In other words no mater how slow you climb it is possible to maintain a constant speed without inducing inefficient decelerations and accelerations of the upper-body between strides.

You can test this by walking really slowly and smoothly up stairs where unlike a crank mechanism the legs have no tendency to stall.

The point of all this is that the efficiency drop that takes place as resistance to pedalling increases is a real problem in bicycle drivetrain design.

In my opinion the RotoCrank mechanism is an ingenious and inventive attempt at addressing this problem. Yes, it is over engineered, relatively heavy and not suitable for high cadence use, but to categorise it as BS does a disservice to the engineering that underlies it.

In terms of competition use, the high cadence and weight issues of the RotoCrank must limit the type of race conditions it would be suited to.

However, I wouldn't use one myself as you can get the same benefit, and more, at a fraction of the weight and cost by using a well designed elliptical chainring. And with a round chairing alongside the elliptical you can switch back and forth between the two drive systems on the same bike.

 

[Aech]

Why is walking up a steep hill easier than cycling up?
And why can the average person walk up a hill that would be too steep for the fittest and strongest of cyclists to ride up?

Are you carrying the weight of the bike when you walk up this hypothetical hill ? because if your not then you aren't comparing like with like.

The hill is almost never too steep to ride up if you have a suitable gear ratio. On a road bike I've ridden up 1 in 5 slopes and I've ridden a mountain bike for decades up 45+ degree slopes, the limit is available traction and the ability to keep your balance when you don't have the centrifugal benefit from the wheels helping you stay upright.

I don't know about you but I find it hard to walk up a 45 degree slope (slope NOT steps).

The simple fact that the UCI have approved it and the pro peloton aren't using it tells you all you need to know about how effective this is.

 

[GrahamJohnWallace]

Are you carrying the weight of the bike when you walk up this hypothetical hill ? because if your not then you aren't comparing like with like.

Over the past forty years I have carried my my MTB up many hills that are too steep to ride up. And whilst carrying a bike up a hill takes more effort than walking up empty handed, it doesn't limit steepness of slope I can climb as long as my feet don't slip due to the additional weight.

The hill is almost never too steep to ride up if you have a suitable gear ratio. On a road bike I've ridden up 1 in 5 slopes and I've ridden a mountain bike for decades up 45+ degree slopes, the limit is available traction and the ability to keep your balance when you don't have the centrifugal benefit from the wheels helping you stay upright.

With good rear wheel reaction, the limiting factor when climbing hills is not having a very low gear ratio but being able to keep the body's centre of gravity in front of the rear wheel contact patch. When MTB pioneers started to experiment with super low gear ratios they ran into a number of problems with wheel spin and the front wheel lifting off the ground due to excessive load shift and torque reaction. And the lower the gear used the worse these problems get. It was this that prompted Chris Bell of EggRings and Highpath Enginering to develop alternative transmission systems to make hill climbing easier.

On a road bike I've ridden up 1 in 5 slopes and I've ridden a mountain bike for decades up 45+ degree slopes, the limit is available traction and the ability to keep your balance when you don't have the centrifugal benefit from the wheels helping you stay upright.

I think you may be confusing a 45 degree slope with a 45% one. For a 45 degree slope you rise one metre for every metre moved forward i.e. 1:1 which is steeper than the average domestic staircase. Even on an MTB with excellent climbing geometry, at around 22 degrees the rider's bodyweight starts to shift over the rear wheel, causing the front wheel to lift off the ground and the rider to fall off the back of the bike.

I don't know about you but I find it hard to walk up a 45 degree slope (slope NOT steps).

Walking up a 45 degree slope for any distance can be very tiring especially if you don't have the ankle flexibility to keep your feet flat on the ground. Though I actually find it harder to walk down steep slopes. The difference between steps and slopes is not the effort required but the low friction with the ground you can get when walking on steep natural surfaces.

The simple fact that the UCI have approved it and the pro peloton aren't using it tells you all you need to know about how effective this is.

Racing bicycles involves a lot of high cadence riding, which is something RotorCranks don't excel at. But if I lived in a hilly area and was finding it difficult to ride up the hills, RotoCranks would be one solution short of buying an electric bicycle.

It is interesting that you tend to ride in a higher gear than you would with a standard chainset, yet hill climbing feels easier and less tiring.

 

[Aech]

Over the past forty years I have carried my my MTB up many hills that are too steep to ride up. And whilst carrying a bike up a hill takes more effort than walking up empty handed, it doesn't limit steepness of slope I can climb as long as my feet don't slip due to the additional weight.

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 think you may be confusing a 45 degree slope with a 45% one. For a 45 degree slope you rise one metre for every metre moved forward i.e. 1:1 which is steeper than the average domestic staircase. Even on an MTB with excellent climbing geometry, at around 22 degrees the rider's bodyweight starts to shift over the rear wheel, causing the front wheel to lift off the ground and the rider to fall off the back of the bike.

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. I often descend "Pantani Style" to stop from flipping over the bars on steep descents.

Racing bicycles involves a lot of high cadence riding, which is something RotorCranks don't excel at. But if I lived in a hilly area and was finding
it difficult to ride up the hills, RotoCranks would be one solution short of buying an electric bicycle.

It is interesting that you tend to ride in a higher gear than you would with a standard chainset, yet hill climbing feels easier and less tiring.

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.

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.