[Yak] Converting Gear inches at some RPM to MPH
bicycle.bob at gmail.com
Mon Dec 10 18:03:04 CST 2007
Here's the way I see it.
Gear inches is the diameter of wheel equivalent to the that provided
by your gearing.
In one revolution it moves forward pi x diameter
So take a 100 gear inch wheel at 80 rpm
100 inches (diameter) x 3.14 (pi) x 80 rpm x 60 (minutes in an hour) =
1,507,200 inches per hour
now change that to mph by dividing by inches per mile = 5280 x 12 = 63,360
1,507,200/63,360 = 23.78 mph
which is a really good clip for a recreational cyclist to maintain for an hour
Looks like you were leaving out Pi and not converting the mph to
inches per mile.
pocket rocket owner
>From: charles voigtsberger <charles_e_voigtsberger at yahoo.com
>Subject: [Yak] Gear inches
>Logic tells me if you know gear inches, you should be
>able to get to miles per hour fairly easily. Gear
>inches equal number of lineal inches traveled with one
>revolution of the pedal. Gear inches x rpm x 60
>divided by 5280 should give you miles per hour.
>Somehow that formula is not working out for me, so
>obviously I am overlooking something.
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