IanSmithCSE
Guru
- Location
- Worcester, Worcestershire
Good morning,
A few months ago I found some NOS Biopace cassettes, they are similar to the Biopace chainrings but a lot rarer. Like the chainrings the cassette sprockets are oval shaped, but unlike the chainrings which were general purpose, the cassettes are aimed fairly and squarely at road racers as a training aide.
As the chainring and sprockets are not the same size the gearing is continually changing slightly during the pedal stroke, the hard point is not always at the 12/3 o'clock position but changes as the position of the larger sprockets moves relative to the pedal stroke. This continuously varying load makes riding harder as you automatically "move up and down a gear or two" without actually changing gear so the legs never get into a rhythm which can let inertia take over and the legs rest just a bit.
At least that is the theory, but surprisingly it actually seems to work!
As the sprockets get smaller they become rounder and an 11t sprocket is as pefect a circle as a normal cassette, why this is so it unclear, unless the intent is to prevent riding in too a high a gear and damaging the knees.
To be completely clear these cassettes are not more efficient than a normal cassette, they are deliberately less effecient in a controlled and understood manner and are intended to producing better cycling legs for use with normal cassettes.
Bye
Ian
A few months ago I found some NOS Biopace cassettes, they are similar to the Biopace chainrings but a lot rarer. Like the chainrings the cassette sprockets are oval shaped, but unlike the chainrings which were general purpose, the cassettes are aimed fairly and squarely at road racers as a training aide.
As the chainring and sprockets are not the same size the gearing is continually changing slightly during the pedal stroke, the hard point is not always at the 12/3 o'clock position but changes as the position of the larger sprockets moves relative to the pedal stroke. This continuously varying load makes riding harder as you automatically "move up and down a gear or two" without actually changing gear so the legs never get into a rhythm which can let inertia take over and the legs rest just a bit.
At least that is the theory, but surprisingly it actually seems to work!
As the sprockets get smaller they become rounder and an 11t sprocket is as pefect a circle as a normal cassette, why this is so it unclear, unless the intent is to prevent riding in too a high a gear and damaging the knees.
To be completely clear these cassettes are not more efficient than a normal cassette, they are deliberately less effecient in a controlled and understood manner and are intended to producing better cycling legs for use with normal cassettes.
Bye
Ian
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