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Old September 9th 17, 02:58 PM posted to rec.bicycles.tech
AMuzi
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Default program to compute gears, with table

On 9/8/2017 4:23 PM, wrote:
On Friday, September 8, 2017 at 10:45:07 AM UTC-7, Emanuel Berg wrote:
Graham wrote:

So if your definition of gear is roll out in
mm then it looks close. Do not forget to
include the tyre.


Right, perhaps I should change "gear" into
"roll out" if that's the agreed-upon term.
Perhaps I should even make it print the
formulae first thing.

And I'll include the tyre. Excellent


There's always a slight error this way. The radius of a tire and hence it's circumference changes slightly with pressure and/or weight of the rider.


The ancient and traditional method from race-rules gear
limits to computer input is a rollout.
Ride over a spot of paint and measure between marks. In
theory it's 2R*3.14159. In practice it is not. As you note,
rider weight, inflation etc have some bearing on this

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Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


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