Saturday, July 24, 2010

Elliptical Chainrings....ugh!

What makes the elliptical chain ring so controversial is that there are two schools of thought which are completely opposite of one another. Let's examine:

1. Theory 1 slows down the area just before the dead spot at 3 and 9 o'clock (on bents) where the momentum normally speeds up. This is an attempt at evening out the stroke to make it more smooth and therefore efficient.

By cycling backwards, riders will notice that the stroke is naturally very jerky. It's not smooth at all. Before heavy training, this is normal for most people. I've ridden over 2,000 miles in 4 months and I found my stroke to be super jerky during the reverse stroke test.

In this example assuming an elliptical chain ring has an effective 42T at its widest point and 40T at it's shortest point, the chain ring should be installed with the 42T just after the power stroke before reaching the dead spot.

This theory is adopted by Shimano Biopace and Sugino Cycloid (the one I bought).

2. The second theory attempts to increase potential power my offering more teeth during the power stroke and less teeth at the deadspot to get you through it more quickly. The effective 40T portion of the ring is installed at the dead spot so the rider can quickly get through this less efficient part of the stroke and get to the power stroke faster.

Assuming the least power is delivered during the dead spot, theory 2 makes riders feel as though they have a smaller chain ring at this portion of the pedal stroke and a larger one during the power phase.

This theory is adopted by Rotor Q-Rings.

Before trying anything out physically, I'm leaning towards Theory 1 to even out the speed and smoothness of the stroke. I'll have more updates after I give both theories a test run.


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