Need e-ride home after injury

[indianajo]

I'm age 67, 160 lb, ride a 27 mile route to the summer camp on a kid's mountain bike 2 to 4 times a week. I'm 68" with 28" inseam so the 18" frame length of a kid's bike is no problem.
I need a way back to town if I strain a muscle or tendon out there or get an infection cutting my wattage in third. Cell phone service out there would be $840 a year (Verizon only) and an electric bike conversion would be less expensive. I also want to pedal out to fall festivals ~50 miles away in the morning and motor home at dusk. I don't want to even ride in a car with airbags and hate motor scooter noise. I still have good high frequency hearing and enjoy music.
I don't want to pedal injured or sick, and I ride on state & county roads so pedal assist is not required. Indiana isn't licensing or regulating e-bikes yet.
I average 8 mph by sitting vertically with baskets full of groceries supplies & tire/mount tools, as low as 6 when the wind is >25 mph in my face. I ride 15% grades on the way out to camp but could take a longer route that gets grades down to 8% if on an E-bike. I want low drag when I pedal. 12 mph would be a great improvement over 8 on muscle power so 250-350 W would probably be fine. I won't be able to charge out at the festivals. My tire tools baskets water weigh 25 lb so a 11.6 AH battery wouldn't be a big strain, especially if mounted forwards of the seat.
My bikes have various diameters of crank hub so I'm suspicious of mid-drive kits with an extra driven crank. Kits assume the crank thread diameter is what? And how do you fit an extra sprocket on something with 3 already? I need 30:28 ratio to get up 15% without walking and 52:14 to fly down @ 35 mph.
My target bike is a 26"x1.75" 10 spd girl's cruiser from the 90's with flat handlebars, fenders, rim brakes, suntour shifters & sprockets. This has to be walked up 15% grades, I'll limit it to the 8% route. I have extra MTB frames but the 18 spd shimano SIS breaks axles and the 21 spd shimano SIS race comes unscrewed & drops balls. I'd like a made up 26" wheel if I can buy such a thing. The bike sits/rides in the rain sometimes so I'm a bit suspicious of LCD displays.
I've been lurking, tried to look up MAC & Bionx, the search engine finds MAC computers and suspicious vendors. ebikes.ca has a nice geared hub that would maybe work in the front but customs fees charges from CA are a PI** and freight from the west coast (Vancouver) is double what it is from Ohio or South Carolina. I could make torque rods out of aluminum window frame and I have some old heavy 26" forks from the sixties to handle excessive torque. Any suggestions?
Update 8/4/17
Okay, I found bionx.ca which is a stealth site. I'm partial to them because another thread said they were assembled in Canada, and I hate supporting bully *****, but they tell you almost nothing about their kits. You are supposed to go to your dealer. The nearest bionx dealer is in Springfield IL about 240 miles from here and not accessible by Greyhound. I'm supposed to drive my non-existent SUV there? Or ride my bike over?
People are posting about the luna mid crank drive kit sale, which I won't be buying because of unanswered questions about the five different varieties of cranks and sprockets. I don't want pedal assist. Want to hold my feet still if I pulled a tendon. But there is a lunacycle.com website, which has a geared drive 750W hub kit built into a 26" wheel for only $460. (geared good for hills right?) Optional sprocket clusters for rear drive, optional torque rod (yeah) batteries can come in the same box for $400 for 9 AH and $460 for 11.6. Optional thumb switch so the bike doesn't take off when throttle is twisted when bike falls over (which happens a lot with groceries on the back). More power than I need but I do need more description than amazon provides. Amazon has a 750W treesomething kit in a 26" wheel for $179 , no battery, probably direct drive (not for hills) and a lot of unanswered questions like which power connector.
Reason I want a wheel, I bought a 8 speed Sturmey Archer IGH, used the spoke calculator, bought spokes too short, RMA and mail back, spoked 10 mm longer are still too short, and I'm out $49 for a box of spokes because I took too long the second time. Vendor was no help when asked what length to buy for 26" wheel. I feel like I asked him about wagon wheels or something, it is not as if I don't see a dozen 26" wheel bikes on the street every day.
I'm here because bikeforums.net locks my computer browser everytime I access. Your site is responsive but the people don't want to read more than 20 words I suppose.

 

[Nutella]

There isn't a standard spoke length for 26 wheels, it all varies with the diameter of the rim where the spoke nipples rest, the lacing pattern, the number of spokes and hub dimensions. You need to use a calculator and get very accurate measurements of the parts you have on hand. Even a few mm off and they won't work.

http://www.bikeschool.com/tools/spoke-length-calculator

 

[indianajo]

Thanks, nutella. The version of spoke calculator you linked has a definition of the terms, so this time I put in 3 spoke crossings instead of 108 like last time. This result got me spokes that were 5 mm too long instead of 18 mm too short. Oh, well, through amazon 50 spokes are only $25. and 50 Wheelmaster spokes in a baggie instead of 100 DT Champions spokes in a box (lowest price option on niagara direct website) will ship 1st class for $4 instead of $10 for a UPS box.
Ordered an ebikling.com front wheel geared motor kit today 48v , maybe. (paypal bombed out). Tried to order lunacycle front wheel geared 750W kit but they were out of stock. Summer is fading fast. Going to order a LiFePo4 battery next payday, they are reported by wikipedia to have more charge cycles than Li Ion. Also LiFePo4 are square and I can capture the $400 battery in a frame bolted to handlebar then welded threads, instead of dangling a battery bag from the crossbar or screwing a cylinder battery to the water holder holes. I might go shopping or to a night concert with the bike chained up; a $400 battery would make a thief very happy. I can cable the $200 motor wheel to the lamppost the frame is locked to, but not the battery. I missed a Los Lobos concert last week because madison IN is 40 miles from my summer camp. I could pedal one way out in the afternoon but would be very tired trying to get up out of the Ohio Valley and 40 miles home at midnight. My usual pedal route is 30 miles in 2.5 to 5 hours depending on the wind. Whirr goes the motor! Next time.

 

[Nutella]

Having built a bunch of wheels, if the choice is a couple of mm too long or too short, choose too short. 5mm is a lot though. Make sure your IRD is accurate, the manufacturer might list it, if you have to measure, measure in several places as a bare rim is not perfectly round. I've learned all this the hard way btw.

 

[Hugh]

I have 2 e bikes, one is a Bafang mid drive that is on a KHS fat bike. When i was looking into it no one ever gave me a straight answer about what size the bottom bracket needed to be and no one could say what the bottom bracket on the KHS was and KHS was also unwilling to reply to my question. One thing for you to know about the Bafang mid drive kit is you remove your bikes crank completly. The bafang kit then slides thru the bottom bracket, it does not use the threads that are inside the bracket, instead it uses a kind of washer with raised marks on it which when the nuts they give in the kit are tightened keep the motor in place. You will then only have 1 sprocket up front. There are different sizes of sprockets available to give you some gearing options. I had to use a rat tail file inside the KHS bottom bracket to remove a bit of the casting so the Bafang unit would slide through. It,s been a year since my kit was installed and i don't remember the exact diameter of bottom bracket you need but it was think about 1.3 inches. Any bike that uses what is called JIS or BSA threads will be the right diameter. The other measement you need is the width of the bottom bracket. Most bikes are around 70mm, my fat bike needed the 120mm kit. If you go mid drive ask for some shims to be included so you can make fine adjustments.
I also have a BionX equipped road bike, it has a 500 watt HD system. It works well, has better range than the Bafang, it's a really refined system. I have 2 complaints about it, first the throttle stinks, you can't modulate it. It's a small red switch, you press it and your going 20mph then it cuts out , when the speed drops below 20 it turns on again. For me it is only useful for getting across intersections quickly. The second issue is you can only use BionX batteries, the battery and motor "talk to each other" so no aftermarket stuff works. They are waranted for 3 years, mine is that now and it still works great but they are expensive to replace. I just recently took the BionX system off the road bike and installed it on a 3 wheeled recumbent I built. So far it is very nice to pedal, I keep it on level 2 of pedal assist and it gives quite a good range, for me it works out to around 60 miles averaging about 12 to 14 mph. Going faster cuts the range down and you do not want to pedal it without some power, the magnets have what Court calls a cogging effect and it really just an extra drag when pedaling.

 

[indianajo]

Okay, thanks.Sturmey IGhub is in the wheel. Took mostly 12 mm nuts but I had to use a couple of 16 mm. Wheel was round within 5 mm. Shimano SIS Thumb downshifter is leaving a bag of fluid above my tendon, has got to go.
Hugh, thanks for the gory details on Bafang mid drive kit & bionx battery. I was afraid of mid drive because of lack of information, and going to only one crank is a non-starter. I intend to ride 30 mile pedal only, and I need 30 tooth front sprocket to get up the 15% grade hills, the 42 tooth sprocket for most everything, and use the 52 tooth sprocket on flat when a big wind is behind me, like Sunday. 30 miles pedaling can take 5 hours into a bad wind, but took 2.6 hours Sunday with 9 mph behind me. Wind can go 25 mph in winter, and I have places to go and don't want to waste that much time. Hence electric assist. With electric assist I might play piano at the Christmas eve service 30 miles out.
I bought the ebikeling.com front wheel geared kit $200 plus disk brakes $20 free freight. It will take a 7 spd gear cluster in 135 mm frame if I don't like front wheel drive. I'm going to buy btrbattery 15 ah 48v battery https://www.amazon.com/48V-15AH-LIF...504019929&sr=8-3&keywords=lifepo4+48v+battery
and mount on front above wheel. Uses LG 15000 mh cells, maybe made in Korea, which is a plus to me over another oriental bully. My baskets & supplies lift the front, I weighed MTbike @ 85 lb rear 25 lb front last week with only basket, tools, tubes & weather clothes. Supplies in baskets can add another 50 lb over rear wheel. Hoping to get >50 miles one way at 12 mph with assist, about 50% over my average speed pedaling. Not looking for high top speed, bike brakes are not that good.
Yeah, the bionx battery communication was mentioned on this site, a real downer if it fails. This btrbattery comes with charger that monitors all the cells individually - won't save the battery but would save a cell. If it is repairable with one new cell after failure that would be a plus.