Rather than address comments piecemeal (though thanks for the comments — wow, somebody reads!) I will use this post to briefly share some of the evolution in my thinking as I get deeper into this thing.
First: let’s hear a big shout-out for blind optimism. 🙂 Years of working on motorcycles has given me a sense of what can and cannot be done, but except for the broadest outlines that understanding goes by the boards when we talk about bicycles. A setup that would push the limits a little on a motorcycle pushed the limits too far on the bicycle.
What’s happening is that the choices I made constrain the range of choices I can make. Well, that and money. But whining should stop before analysis begins. I’m over it.
Frame: the old Trek steel frame I’m using seemed fairly stiff as a shortbike, but make a longbike out of it and it reveals its inner flexible nature. Some of the problem is the compromises worked by the Xtracycle attachment scheme. Some of the problem is the loading.
Fork: I have an old frame with a 1-inch headset. The local bike shop (Spoke ‘n’ Motion) found ONE suspension fork in 1-inch. It’s by RST, a model that is adjustable and takes a disc brake like I wanted, but it’s on the bike because it was what I could get, not because it’s the best one made. It needs much heavier springs to hold up me and the power pack, even with the preload honked way up.
Motor: I have a Crystalite 408. It’s actually a pretty good motor. It will take the bike up to 40 km/hr and still have throttle left. I’m a very careful rider, because I know crashing sucks. I’m also aware that there’s a very thin line between “in control” and “out of control” on this bike. Perfect riding conditions keep me on the “in control” side of that equation. Part of my discomfort is from the knowledge that if you hang it all out over the edge, sometimes things come along and cut it off for you. I want more margin for unexpected situations.
So, the motor is a good motor, doing all I can reasonably ask of it, but in a bad setup. The biggest problem with the motor is there is ZERO torque at very low speeds. Getting me and the bike up my driveway means pushing while using the throttle. It’s steep and it’s gravel. If I’m not moving there’s no torque. I have to push hard enough to get a 150-pound machine going uphill on my own before it gives me any help. Even then, if I hit a bump just right the back end starts hopping. When that happens, I let off the throttle and let things calm down, then start up again.
I think I would like to try a separate motor — one that could spin fast enough at low vehicle speed to get it up the hill. With the hub motor I can often pedal fast enough to hold 15-20 km/hr up a hill, which I can pull nicely with about 1200-1400 watts going to the motor. I expect to hear the pop of controller electronics frying when I do that, though. Chicken:egg — less weight would mean less amperage needed to get up a hill.
Actual usefulness is another factor. I basically built the bike because I wanted an EV and some experience with the process. I’m getting that. I periodically ride a motorcycle to campus, and wanted to try this out and see how it works. Other problems intrude, however. One being that we have an organic farm. We collect coffee grounds from the Tim Horton’s and Starbucks outlets on campus every day — during summer that means two partially full 5-gallon plastic buckets, about 30 pounds of coffee grounds. (During winter it’s sometimes four full buckets — close to 80 pounds of coffee!)
Can’t carry that on the bike, and it needs to be done every day. So there’s a logistical issue. Basically I have to bring double the buckets the day before I want to ride, or else depend on my wife to drive into town to get the stuff. That “thud” you heard was a big carbon footprint.
If we lived in town it’d be cool to get one of those flat-bed cargo trikes like the Chinese use. I saw lots of them in Beijing with little gas or electric kicker motors on them. For where we live, well…heavier vehicles need more Ah to move, which means bigger/more expensive batteries. Here we go around that circle again.
I still want to play with an ebike, though. I love the concept. As a long time two wheeler I love being on two much more than on four. I could build a e-offroad-bike. Problems there are that getting to somewhere to ride it usually means putting it in the back of a gasoline powered vehicle and driving it into the bush. “Thud” again.
I will likely work out another frame design that will let me use a converted car alternator as a motor, and be more of a motorcycle rather than a pedelec. I would design the thing for farting around in my village area: down the road to get the mail, over to the neighbour’s, down the road about half the battery pack and back home. Might do something like the “Long Ranger” from Atomic Zombie.
So I’m up in the air. For now, I’ll keep fiddling with this thing. At some point I’m going to get fed up and scrounge up a stiffer frame for it. But I think there’s a lot I can do to optimize it as it sits. Keep yer cottage tuned to our wattage — more updates on the way.