Edit: lots of changes to this project. Updates at end of thread.
So it is time to start a thread for my 3rd ebike build. I got just enough done so far to take it around the parking lot, but I need to fix the mount so it doesn't flex. My chain popped off as I gave it more than 1/8 throttle.
This bike is sooo light. Should be at 40lbs. And it's going to be extremely aero, since it's a road racing bike with TT bars. I am going for pure speed AND efficiency on this bike. It's going to the bike that will enable me to sell my car, the bike that will take me 16 miles to my gf's place, on 60mph highways (riding the shoulder, bikes allowed) and roads with no shoulders.... It will enable me to cruise at 35-40mph (with pedaling), to keep me safer and have the least amount of cars coming up behind me. I am calculating (and from anecdotal evidence) that I should be able to 40mph on around 1000watts, while on the aero bars. That may be 1000w from the motor (800w real), and 200 from me. Or I can hammer out 500watts myself and approach mid 40s.....maybe. For easy cruising, I should only be drawing about 250watts at 20mph if I don't pedal. It's all about aerodynamics.... I think we need more of that on this forum.
I'll put up some relavant pics, but I have many more to take.
Currie 36v xydj type motor, I think it's 750w, seller on ebay stated 1.4hp and 34amps continuous which would be 1200watts.... It has the 15 tooth roller bearing clutch for a sprocket.
I will be using my 5 Bosch Fatpacks for 36v 11ah. 320 usable watt hours
The rest is just cheap scooter parts, 80 tooth #25 sprocket, chain, mounting plate for the My1018z geared motors, but I made it work for this one. Cheap 30amp Chinese controller, has been working well for 450miles already. It has a 'lock' on it for an on/off switch, which is essential to prevent battery drain or sparks, or the bike coming alive without any throttle. I may move to a 40amp controller to get more power, but then I will definitely need to go to 10ga wiring everywhere, which will be a pain, and the whole system will just be less efficient. I think 30amps will be plenty of power (1200w), especially on such a lightweight bike which i will be pedaling as if I was road biking.
Bike coasts as a normal bike thanks to the freewheel front sprocket.
I tested the no load speed, and it's 70mph or higher... I was freaked out watching the chain at 65mph on 3/4 throttle.
I made a 'custom' adapter that bolts onto the left side of a my rear road wheel... this allows me to keep all my normal road gearing and not try to bend my frame getting a mtn bike disc hub in there.
Best thing about this bike: it is practically silent at low speed, and very quiet otherwise. It's also by the far the lightest ebike I've done.
Even with a gearing of 70mph no load, the motor still can accelerate me about the same as an easy riding cyclist below 15mph (1/8 throttle). That's very impressive for a $60 Currie motor.
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Last edited by veloman
on Fri Jul 30, 2010 1:40 pm, edited 1 time in total.
Mush! Mush you electrons! Push harder!
Main ride: Old School Specialized Stumpjumper FSR, Clyte HT3540, 63v lifepo4, 12fet Infineon set to 26amps. And a bunch of others... viewtopic.php?f=6&t=34236&p=497325#p497325