I decided to buy a 28mm Mxus hub motor and controller from Kinaye Motorsports since he ships free in the USA but I see he isn't listing the small motor any more. Here is the big 45 mm motor but these are so big that you have to use a single cog in the back.
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MXUS 3000W "Economy" Kit – Kinaye Motorsports
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Mxus is one of the new darlings of manufacturers along with Leafbike since they are using the much finer .35mm laminations in their motors which make them more efficient.
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Electric bike motor | eBike conversion kit | Brushless hub motor - Leaf
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Kinaye also talked about custom packs but I don't see them listed now. 72V would be nice if you want to run 40 mph once in a while but you can also do it on 48V with the right motor.
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Luna Cycle also seems to be pretty stable and would be much better than ebay or Amazon for support.
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Ebike Kit 1000 watt Waterproof Connectors Hub Motor Conversion - Luna Cycle
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Of course ebike.ca is the founding father of kit sales and does the best independant testing. The new NineC motors are nice.
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Motor Simulator - Tools
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Read endless-sphere to learn all about ebikes.
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https://endless-sphere.com/
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