tartosuc said:
I actually dont know excatly what to do as far as conversion goes...
I can go with systems like bionx or crystalite journeyman that would be expensive but not too bulky(read here easy to hide) and probably enough for my 35km commute.
or i could go with a complete custom setup with external motor. thats why i was asking about the e-tek, i knew it was probably overkill but i did not see anything done with it yet and i dont have any reference as far a power goes(what enough, whats not)!
The ETEK is overkill in the sense that it's designed to happily run at around 15,000 watts. This is about 20 hp -- enough to shred any typical, unmodified bike frame. Enough that you'd have to dial back the power in order not to get dumped off the rear end. And if you have to dial back the power to even ride it, then you probably don't need or won't want the ETEK because there are lighter, stealthier options that still produce gobs of power compared to an unelectrified bike. In other words, for a bicycle, I don't see the sense in an ETEK unless you really, really want to modify the frame extensively, and then use it for drag racing.
As far as power:
An elite long-distance cyclist can maintain 450 watts for hours; an elite short-track cyclist can generate bursts of about 1800 watts for 5 seconds.
If you don't have an ebike nearby to try, to get an idea what you might want or need, I'd suggest playing around the bicycle speed and power calculator:
http://www.kreuzotter.de/english/espeed.htm
i also saw smaller motors like kollomorgen 400w motor that seems to be reliable and simple to use(internal controller to use with 5k potientiometer)and also cheap! I could go chain drive, belt drive of maybe friction drive on the rear tire directly...anyone ever tried that?
Though I haven't tried a friction-drive, I read many user reports before deciding myself what kind of ebike I wanted. In sum, friction drives are reported to be notoriously problematic, requiring lots of adjustments, wear on tires, problems when wet. I'd go chain or hubmotor. I went chain and hubmotor.
I love the quiet stealth and power of my brushless crystalyte hubmotor. I feed it 2,500 watts from lithium batteries through a 35 amp controller. It has a top speed of 44mph and can climb the steepest hills cars typically climb at around 15-20mph with or without pedaling.
I modified my chain-drive Currie ebike to run at about 1,100 watts (from a stock of 840 watts). Not nearly the get-up-and-go of my 2,500 watt hubmotor -- but enough to cruise at 23mph without pedaling, and provide moderate assist up medium steep hills. My Currie has a brushed motor, so it's much louder, less efficient, and the brushes need replacing every few thousand miles or so. But at $300, it was comparatively cheap.
