malcomm <
[email protected]> wrote:
>
>Some interesting software for figuring out gear inches and ratios etc
>from your drivetrain.
>Tells you the max speed in each gear combination adjusted for
>cadence....
>Runs on the PC
>
>www.income-software.com/GearCalc/
Took me about 20 minutes of doodling in a spreadsheet
(the OpenOffice.org one in this case) to get the same
effect.
Cut and paste shown below. The notations on some of the
rear gears are old; I now warm up in 52/18 and then do the
entire ride in 52/16, thus using the hills for anaerobic
intervals.
--Blair
"Runs on bananas."
Ratios
42 52
24 1.8 2.2
22 1.9 2.4
20 2.1 2.6 warmup/down
18 2.3 2.9 Cruise
16 2.6 3.3 Sprint
14 3.0 3.7 Descent
inches/crank @ 27 tire compressed 1/8 in
(unused gears deleted from table)
24 147
22 160 199
20 176 218
18 243
16 273
14 312
cranks/mile
24 431
22 395 319
20 359 290
18 261
16 232
14 203
Mph @ 84 rpm
24 11.7
22 12.8 15.8
20 14.0 17.4
18 19.3
16 21.7
14 24.8
I was going to save a .csv file and post it, but apparently
that doesn't preserve the formulae.
It's pretty simple, though.
Each gear_ratio is just chain_ring_teath/rear_cog_teeth.
Then each inches_per_crank is just 3.14*(wheelsize-2*compression)*gear_ratio.
Then each cranks_per_mile is just 5280*12/inches_per_crank.
Then each mph@rpm is just 60*rpm/cranks_per_mile.
