Cheetah, Last Hoorah?

echuckj5's picture

How and why did I build this bike? Design limitations

Why, not philisophical, short drive to work. My car would'nt heat up. Hard on a car to make short trips. I knew an electrical bike could be made. I googled, saw what others where building, where they were getting contollers, performance.

Now the How

I built off the work and effort of others. Eric Peltzer had just about what I considered to be the perfect E-bike. I built it. I did'nt do many calculations, just used his advice.

I am pretty big, figured I should gear it down a little more. Knew the belt he was using was wider than necessary, My motor shaft is to short to build his jackshaft assembly, so the narrower belt was important. A year later I have the jackshaft, friend of mine who made the jackshaft is kinda slow. It was a very good experimental platform. The range was'nt good, it was fast. Short coming, using it for work, hard to haul a rain suit, lunch, briefcase and all the necessaries, shopping, etc. Pretty much just transportation at its minimum.

So I bought John Bidwells book on the "Cheetah". Now, I already had 2 small batteries, 12 volt 18 amp hour. Just bought 2 more, to increase the range.
Problems, V-brakes aren't good enough. Upgraded to a 6" front disc. Adequate, barely. Certainly cannot go heavier or faster, with the brakes. Stanton rear hub, expensive, at 125 dollars, saved a lot of headache on the first bike. Causing a lot of problems on the cheetah. No where to mount a rear disc on the stanton hub. Not sure what a heavy duty down hill mountain bike hub costs, would switch to one to get a disc on the rear, but I am concerned about the load from the motor, and the weight on a bicycle hub. The stanton hub has 4 sealed roller bearings, more than adequate for increased weight and motor load. So to increase range, I can put larger batteries on it, won't be able to stop well. I want to license it, as a moped, need lights, turn, horn. The only solution I see would be to buy a motorcycle rear wheel, with a hub brake.

I built it, no real thought to efficiency. Motor was always hot, and, I was'nt getting the range I thought I should be getting. Every one else is getting farther, why am I not getting the range that they are?

About a month ago, I did some research, found the performance chart KTA services sent with my motor, did a few calculations. Calculated my motor rpm. Found a chart online of the scott motor I am using. Chart said I should lower my rpm, by over 10%. Shared this here on the 1hp scott motor thread. Did the math, some disbelievers, out there. Man, my performance is bad. Why, I was running an extremely poor rpm for energy efficiency. Should have looked at the math a long time ago. Changed the gear ratio from 10.4 to 9.1.

Lord have mercy, I have spent some serious money on this machine. I could have built a damn nice motorcycle, for what I have in the cheetah.

As is, it is extremely comfortable, nice motorcycle seat, great suspension. Have needed to move my foot pegs, just have'nt got a round tuit. Need to lower them an inch or so, be just about perfect. A real cruiser, Really this bike is comfortable. Range, should be a true 15 miles at 25 mph, since the gear change, should get 15 miles at 25 mph. Suffices for the bicycle law in Texas.

Changes,
About to buy an 8" disc for the front, thats cheap, see how that helps the stopping.
That is about as far as I'll go on the cheetah. Upgrade to a larger battery pack when this one quits. If I found a small motorcycle, cheap, will license it as a moped, go about 35 mph, use the lights, wheels etc, off it. Why not convert a motorcycle? I can put gobs of batteries on this bike, my controller will easily handle a 3 horse electric motor. 35 mph would be fast enough, cover 90% of my driving needs. 25 mph, limits my driving choices, limits the roads I can take, 35 mph is really 40 to me, really Officer, this won't go 40, flip my little limiter switch, honest Officer.

Or, if I find the right motorcycle, convert it, keep the cheetah as is, just upgrade the front brake.

Thats all for now, I've had a real long day, time for a drink, enjoy what's left of the weekend. Not that you guys, and now that Pat and Verna have joined us, gals aren't a pleasure.

Have a good weekend!

chuck

before comments

Comments

jdh2550_1's picture

Sounds like an interesting journey! How about some pics of the Cheetah?

I have Bidwell's El Ninja book - I love it! Very pragmatic and practical.

I'm about to start work on converting a CB750 (nothing like a Ninja - but I'm still using Bidwell's book for inspiration and advice!) - goal is 60mph and a 50 mile range. Based on what Bidwell achieved with the Ninja I think this is just about achievable. And if I don't make it? Well, the journey is the reward - right?

BTW, the reason I bought my XM2K was that for $1500 it was the cheapest and quickest way to a moped capable electric motor scooter. How much do you think you've spent on the Cheetah? Just curious.

John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.

echuckj5's picture

100_0353.jpg

jdh,
Costs,
I had $1500 in the Raliegh, similar to MB-1-E's bike. I dismantled the Raliegh to build the Cheetah.

So, I start with $1500

Seat $65
Front fork #1, a chili gordo, $100, v brake only, not enough spring
Front fork #2, a rock shocks dart 3, $165, enough spring, flexed too much
Wheel for fork #2, $100, had to change to a wheel that would accept a disk brake
Front disc and brake, $70
Front fork #3, wheel and fork, $525, needed another wheel, this fork is a thru axle
Two chargers, $200
Two batteries, $150
Wiring, $50, additional lugs, etc
cheap lights, $40, 3 mr16 bulbs, emt housings, switch, fuse
Cyclo meter, $30
Several gates belts, $40, moved my jack shaft, buy 2 belts, one for backup

So, about $3000, total, doing it again, really being frugal, and getting the same performance, doubt I could build it for $2000, , but in that range.

About 3100 miles,
a soneil charger, $90, quit,
Several sets of rear v brake pads,
replaced one tire, just wore out, $30
Replaced jack shaft bearings, $30, from chinese to browning,

Maintenance costs, about $170

Other costs
I am sure my batteries are about 1/2 used, $150
Electricity used, 3000 miles, about 12 miles a charge, figure about 800watts a charge, charger inefficiency, call it a Kw a charge,,,3000miles/12miles/charge= 250 charges,,
$0.14 a Kwatt*250 charges= $35 in electricity,

So, the cost to run, (maintenance + depreciation on the batts + electricity)/miles,

About 12 cents a mile

chuck

[b]AGM BATTERIES[/b]

Sounds like it was a lot of work. I am starting my project E-Ped and will use a Chrystalyte system on it probably a roadrunner. Your blogs and test and trials will be lessons for me.

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