SkyCaptain wrote:Awesome looking rear whhels man!!!.
Hey I have a 5404 here that I would really love to get into a smaller rim than the current 26incher that is on it.
Something similar to what you have done in your pics. Either an 18 or 19 inch rim, with a nice tire like that.
Trouble is here in Oz I don't know where to find a similar rim? I am happy to buy from oversea's but still can't seem to locate any 18 or 19 inch rims.
Once I have the rim here, I can probably get spokes made at the motor bike shop and think I can build it up myself.
SO, can anyone please direct me to where I could buy a similar 18 or 19 inch rim similar to the ones in your pictures "Oatnet"?
Or, is there anyway I could order the same rim and spokes from the guy you got it from? And then get it posted to Oz, and I will just build it up here myself. That would be the most awesome solution!.
nicobie wrote:Nice tire and wheel set!
Think you could measure the total dia. with the gazelle tires on?
JRH wrote: I've yet to find a rim factory from china that makes round wheels. Taiwan is the place to go.
Diameter measures to exactly 23.5" - which I guess makes sense 18"+2.75"+2.75".
The widest part of the tread is 2.9"/74mm, so It turns out I could have fit the 3.00" gazelles instead... although 3" is the only size that is sold as rear only, all the others are front/rear by reversing the tread direction.
oatnet wrote:... all the others are front/rear by reversing the tread direction.
John in CR wrote:oatnet wrote:... all the others are front/rear by reversing the tread direction.
How does that work? It's not just a single direction for rotation if it's directional?
The purpose in the eyes of eBike designers is quite simple... Although some hub motors are really torquey, most just arent... to that end, you need the most torque when launching from a dead stop and so...
An engineer decides what wattage and determines the motor's torque output based on 1355 / No Load KV * Amps... Then depending on the requirements, for instance a max load weight of 300 lbs the engineer needs to find a way to get that mass (the 300lbs of you bike batteries and motor) moving along quickly... though accelleration takes more power, it only needs that power for a short time... hence Block time is supposed to be the delay in seconds before the limiting kicks in and brings you back to the programmed primary current.
Another bit you may or may not have realized is the purpose of Phase Current and why it is different than Primary or Battery Current...
At lower speeds the controller can multiply the current at the cost of voltage which is only needed (the higher voltage) once the motor is trying to gain speed.... That's why people with 9C usually recommend 2.5 X the Primary Current for this setting and it's the current your phase windings are slammed with on startup... the block time allows for a momentary surge of Primary Current to enable the output which is current amplified (the FETs do this) which in a 26" DD 9x7 Rear (Loaded kV of 10.10 @ 48v - load rating 100KG / 220lbs) - these motors don't have enough torque at 45A to get you moving and thus reduce duty cycle and power handling of the FETs, phases and every other component... then when you approach speed... you will see your current taper down because "An object in motion stays in motion unless acted upon by an outside force".
By comparison - I have found that using Phase Current of lower multipliers of Primary Current like 1.5 X will result in higher top end speeds because the voltage sag is less in the current amplification process.
If your using geared hubs... these are the most fun, here I begin at 1:1 with block time at about 5 (I do run 69A limit on a 9FET shunt soldered and reprogrammed infineon with stock fets and caps) - I can't keep the nose down and my top speed reaches 30+ mph where as when I had the Phase Current at 2.5 the max speed was 27mph... Next I increased the multiplier until my top speed on a flat without wind dropped measurably... This gives me the absolute best combo of slamming accelleration, higher top speeds and better efficiency since the motor spends less time at low inefficient speeds.
Alan B wrote:This sounds like a Cromotor, or pretty close. I'm getting 37 mph at 70 volts with a 3.0 Gazelle 23.5 inch tire.
oatnet wrote:Alan B wrote:This sounds like a Cromotor, or pretty close. I'm getting 37 mph at 70 volts with a 3.0 Gazelle 23.5 inch tire.
Yep, the Cro ended up at 9.26kv, 9.65kv is a little faster, but short of the 11.5kv that would be my ideal. My 18" wheel with 2.75" gazelles is 23.5" (18+2.75+2.75=23.5) - wouldn't a 3" gazelle on 17" rim be 23" unloaded?
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