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crank/chainrings(2 posts)

Jun 28, 2002 6:42 PM
I have a road bike with shimano 105 components on an older ( mid 80's - 90 )model with the oval shaped chainrings ( double ). I use the bike mainly for touring and longer rides. Does it make sense to change to a triple chainring for touring in hilly regions. Is this possible to do?
Biopace chainringsSpoke Wrench
Jun 29, 2002 6:46 AM
As I understand it, they way these were developed was to put a load cell on the pedals and measure the power the rider produced at different points in the pedal stroke. Then the chainring diameter was adjusted to match that power.

What it overlooked was the impact of momentum. While they work pretty well at low cadences, as your cadence increases, they tend to feel progressively less unnatural. Over their short lifespan, Shimano gradually dabbled with the shape of the rings. Granny gears had a very pronounced almost square shape and rings intended for racing applications were almost round.

So what's your pedaling style? If you're a grinder and have gotten used to them, why change? If you're a spinner, I think you'll like round rings better.