steveo said:
ok..
Is there huge differences in acceleration between 20" & 26" or even 16" & 26"
whats the difference in amperage draw between the two different wheel sizes? ..
snip
thanks
Steveo
Human power:
I Hate 16 inch wheels on anything for me. They just bury themselves too deep in the potholes around here. I have 26 inch wheels on some things, but when its time to get tractor like low gearing at a reasonable price, it gets harder on 26" wheels.
Which leaves us with 20" and 24"; I like 20's except that the chain and derailler are soo close to the ground and get dirty and banged more often.
A little problem getting higer speeds out of 20" with standard hardware. but a 52 th front and 11 rear give a 95" gear, not too bad for top end.
The differnce in 24-507 and MTB 26 actually works out to be 10% due to something about ERT0.
That 10% is good for about one lower gear for hill climbing, using the same hardware as on a 26er.
Down side of 24 is there are several common sizes in use and, not the greatest selection in tire types and values in 507 erto.
so I like 20's and 24's for the above reasons. If you are doing a 'bent, tire size and human size have a less direct relationship than on an upright DF where small tires are mainly for small ppl.
Now on the epower side.
The same single speed hub motor in a smaller wheel does what you know it will do. E-motors spinning faster on hill climbs usually draw significantly less current as there are closer to their peak efficiency point, and closer to ther max available power. For me hill climbing is what the "E" in ebike is for. And yhes, 10% speed can make a difference.
But if you go toooo far on the hillclimbing scheme, there is nothing left at even 20mph for much emotor contribution.
However, if you are using a variable ratio chain drive like a cyclone, you do get the best of all worlds for power, efficiency, low end and top end --within limits. Those limits- to get close to tractor like hill climbing you will have to use a big tooth rear end on a 26" wheel, and to get decent topend on a 20" you will need a tiny 11" rear.
On a faired bent, the emotor would pretty much be for hillclimbing, as the bike is so fast and efficient on the flat e-assist is not much needed till the speeds are over 20mph, and hill climbing on a bent can be pretty challenging without e-power.
While my favorite is a 24", as it seems to make the compromises more centered, 24's are not a very common stock size on anything but juvenile bikes.
So, Wheel size gives a person the ability to fine tune the match between human and epower systems, and the ability on hub motors, and chaindrives to a smaller degree, to fine tune the emotor itself.
And by keeping both the emotor and the human motor closer to their "happy spots" you not only increase their power, speed and range, but get more smiles per mile.
YMMV of course
my 2 watts worth
dick in colorado
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