Good info, however, does it also take into account the extra torque needed for the higher speeds? The legs/motor still need to be able to maintain that kind of sustained power, and then there are the aerodynamic considerations, going from 20 MPH with X watts, isn't going to make 30 MPH with the same wattage even though you have mechanical advantage with gearing.DrkAngel wrote:For most builds, people should take into consideration the pedal assist capability of the bike.
(BPM - Beats Per Minute - pedal rate)
60 bpm is considered a casual-sustainable rate
90 bpm is, a more, top sustainable rate
Figured - bpm x ratio x wheel size = mph
(bpm x 60min) x (Front T / Rear T) x (Wheel " x 3.14) / 63360 = mph
26" wheels - My EZip Trailz (OEM)
(60bpm x 60min) x (44T/14T) x (26" x 3.14) / (12" x 5280') = 14.57mph
(90bpm x 60min) x (44T/14T) x (26" x 3.14) / (12" x 5280') = 21.86mph
26" wheels - My EZip Trailz (w/32-11T upgrade)
(60bpm x 60min) x (44T/11T) x (26" x 3.14) / (12" x 5280') = 18.55mph
(90bpm x 60min) x (44T/11T) x (26" x 3.14) / (12" x 5280') = 27.83mph
26" wheels - My Black Widow (Upgraded 34-11T)
(60bpm x 60min) x (48T/11T) x (26" x 3.14) / (12" x 5280') = 20.24mph
(90bpm x 60min) x (48T/11T) x (26" x 3.14) / (12" x 5280') = 30.35mph
27" Wheels - My old 12 speed
(60bpm x 60min) x (52T/12T) x (27" x 3.14) / (12" x 5280') = 20.87mph
(90bpm x 60min) x (52T/12T) x (27" x 3.14) / (12" x 5280') = 31.31mph
700c = 28" wheels - My Haro Express Deluxe
(60bpm x 60min) x (48T/11T) x (28" x 3.14) / (12" x 5280') = 21.80mph
(90bpm x 60min) x (48T/11T) x (28" x 3.14) / (12" x 5280') = 32.69mph
29'er Wheels
(60bpm x 60min) x (48T/11T) x (29" x 3.14) / (12" x 5280') = 22.58mph
(90bpm x 60min) x (48T/11T) x (29" x 3.14) / (12" x 5280') = 33.86mph
Yeah, I found a nice program, too ... after I did the figuring ...SoSauty wrote:http://www.sheldonbrown.com/gears/
http://www.recumbents.com/wisil/e-bent/ ... ulator.asp
Nice cat
No, just pedal speed capability.LI-ghtcycle wrote:
Good info, however, does it also take into account the extra torque needed for the higher speeds? The legs/motor still need to be able to maintain that kind of sustained power, and then there are the aerodynamic considerations, going from 20 MPH with X watts, isn't going to make 30 MPH with the same wattage even though you have mechanical advantage with gearing.
One of my earlier graphs:DrkAngel wrote: No, just pedal speed capability.
However ... variations of motor and gearings show the following, (real world), motor only top speeds, for my mountain bike style:
450 watt = 21-22 mph
675 watt = 27 mph
750 watt (1HP) = 30 mph
832 watt = 32 mph? (estimated from 44.4V pack)
(based on Li-ion batteries w/full charge)
"watts" are motors output watts ... not input watts.
I, of course, would like to keep my pedal assist capability, at noticeably past , motor only speed.
There is still motor assist applied, past the motor only speed ... it's just waiting ... for a little help, from me!
I can push my 675 watt, (27mph), EZips, past 30 mph, even to 35mph ... with a tailwind, or drafting.
Most DC motor, Watt output (HP) graphs show highest output at 40-50% of no load speed.DrkAngel wrote: One of my earlier graphs:
Demonstrates 24V(450w) & 36V(675w) and various gearing.
"Road Load-Wind Resistance" - green line - can be used to project, similar build, capability-speeds.
(48V(900w) 20T or 44.4V(832w) 16T = +30mph motor only)
Wow, where did you find this image?DrkAngel wrote:A nice guide, towards estimating, pedal assist contribution.
Pulled it from an independent, eMotorcycle developer, site.Architectonic wrote:Wow, where did you find this image?DrkAngel wrote:A nice guide, towards estimating, pedal assist contribution.