N00b question here, but why is an outrunner motor design impractical?Originally Posted by tylerwatts
Likes: 16
N00b question here, but why is an outrunner motor design impractical?
I applaude your building an emotorcycle. I cringe at your destruction of one of the most collectable motorcycles in existance. RIP CB350F, Viva emotorcycle.
Csecrist12 liked this post
Funny you say that, as it relates to my above mentioned opposition to any actual permanent modification of the frame or anything else for that matter. The build is such that I could put it all back to stock if I wanted to. Entirely. Not that I ever expect to. But it is a constant lesson in elegance, and finding function in the original form and to design around this. That is a part of honoring-- rather than destroying-- its legacy and making it as relevant again today as it ever was.
Or put another way, it wasn't doing much just rusting out in the barn where I found it
If anyone is interested, I post short progress stories on IG at @blanconegroverde. Here's the bike when I brought it in earlier this year:
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Last edited by rfndzc; 31 March 2020 at 1616.
Here is the battery cage w/ spare side panels fitted. Need to finish fabrication of controller housing (within the side panels) and then I can paint the cage and housing. Motor mount is at the machinist, should have that installed by next week, then it's mostly just assembly/electronics and I can run the machine.
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Thanks Rob.
Build is looking good. How are you mounting the drive sprocket or where are you sourcing?
Cheers
Tyler
Thanks Tyler. I think maybe Thunderstruck turned me onto this outfit: https://www.rollerchain4less.com/50-...Iz6ogQBA%3D%3D
Kind of in awe. They have a very specific purpose and they fulfill it extremely well at an incredible price.
Rob
Edit: The one's Thunderstruck has linked were able to resolve my rear sprocket, which I decided not to change. This particular outfit I think I just came to thru google wander
Last edited by rfndzc; 31 March 2020 at 1711.
Ah those look like kart sprockets then. That seems like a good approach, lots of choice.
I noticed you said you were looking to use a very low gear ratio, what size sprockets will you be using?
Cheers
Tyler
The stock gearing that came with the bike is 17/38. For the chinese motor manufacturers that operate at higher rpm I would have needed a lower ratio (smaller front sprocket and/or larger rear). Because I was able to find Revolt and they offer a custom kv, I basically set kv for a factory gearing, but for a top speed of about 55mph. Again, I am into low end torque and acceleration, not top speed.
26kv at 72v gives ~1600 loaded rpm (~1800 unloaded). My rear tire is now a 4.00 on an 18" rim, thats .33m radius, and ~55mph top speed at that rpm with a 16/38 ratio, and 45mph at a 13/38 ratio with a bit stronger accel. So to answer your question, I bought a 16 and I bought a 13.
Edit: If I said I opted for a 'lower' ratio it was thinking of an inverted ratio, rear/front, so ~2 vs ~4, because I was able to use a custom kv instead of a 'higher' ratio for more torque/less speed. I think it is more intuitive to consider front/rear, but the resulting number (.4 vs .3) is maybe less intuitive.
Last edited by rfndzc; 01 April 2020 at 0541.
tylerwatts liked this post
Views of the battery cage showing the original motor mounts in use with no modification to frame. Front bracket was simply flipped upside down to accomodate the 23s. Top two bolts were previously used for cable holders and will continue to serve this as well.
IMG_1701.jpg IMG_1702.jpg IMG_1706.jpg
Last edited by rfndzc; 01 April 2020 at 0931.
tylerwatts liked this post
Really like your use of the mounts for the battery cage. How do you plan to cover the terminals etc?
Have you planned for mounting the motor yet?
Cheers
Tyler
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