Ok.. so it took 4 hands and a bible worth of bad words to get the crappy freewheel off the NuVinci !! ( word to anyone out there who gets a N.V. don't put a freewheel on your hub that you plan to remove unless you have the right tool !!! ) but it's out.
Now time to figure out what threads on where..
I am no mathematician or physicist, so bear with me if this is all screwed up.. here goes if you feel brave enough to read thru it..
I have the choice of 2 front chainrings:
48t
39t
3 x ENO freewheels :
16t
18t
22t
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- 20†rear wheel = 50cm( Diameter ) x 3.14 = 157cm
- 50 km = 50,000m
- (50,000 meters) divided by (157 centimeters) = 31Â 847.1338 ( as per google ! )
- 31,847 rotations in 60 minutes = 530.78 Rpm to get me 50 km/h ( 30 mph )
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Now this is the part i start to have problems with..
- 3210 Astroflight 6 turn motor at 48v i think gives aprox 10,000 rpm and lets assume 8000rpm at cruising speed.. ( + or - i'm not sure )
- On Astroflight site : 275 rpm/v with LFP 15 cells 45v x 275 = 12,375pm
- 2 stage Matt-Box reduction 9:1
- 8000rpm / 9 = 888 rpm
- 10,000rpm / 9 = 1111 rpm
Geared Low:
16t on motor and 48t on cranks = 16:48 = 1:3
39t on cranks and 22t on rear wheel = 39:22 = 1:0.5
888rpm / 3 = 296rpm / 0.5 = 592
10,000rpm / 3 = 333rpm / 0.5 = 666
Geared High:
22t on motor and 39t on cranks = 22:39 = 1:1.77
48t on cranks and 16t on rear wheel = 48:16 = 1:0.3
888pm / 1.77 = 501rpm / 0.3 = 1670
10,000rpm / 1.77 = 5650 rpm / 0.3 = 18,833 ?? that can't be right ?
Now the NV has a ratio of 350%
ok. it's way late and going to bed.. will check this again in the morning and realize how horribly off track i am.. lol.