Electric Bikes - Newbie Question: Torque vs. Speed?

Greetings!

I'm usually parusing the commuting threads in the summer, but commuting my 25m RT in the winter (car died) has me convinced that I should take the plunge into the world of electric bicycles! My budget is 1200 dollars. I don't need to go above 25 mph, but I do have a few nasty hills, and I would like to be able to haul 60 lbs of groceries from time to time. I am a 5'4" 135 lb female.

I've done a lot of preliminary research, and yet I cannot find the answer to a couple of specific questions, so I hope you don't mind my asking these newbie questions. From what I read, the general consensus is that I should spend the bulk of my money on nice LiFePo4 batteries (from Ping, of course), and spend less on the motor/controller. I don't mind pedalling, I do that now. I'd just like it to be a lot less tiring, and my commute time won't depend on how fresh my legs are. I would be nice to have both pedal assist and throttle control in case I don't feel like pedaling at all, but I understand that isn't common unless you are buying one of the nice (and expensive) complete kits.

I was looking at some of the pre-made phoenix systems. What is the difference between 36v and 48v? With my longish commute and some hills, I need range and power. I just can't figure out how voltage affects speed and torque vs. range.

With these things in mind, how "low can I go" in terms of components. Maybe I don't need to spend the money on a crytalyte x5 if something less expensive is going to do the trick? One more stupid question: are the adapters from the LiFePo4 batteries interchangeable with most of these power-system only kits? I am not talented enough to cut and splice!

Thanks in advance!

~Minerva

The higher voltage will have an impact on torque - but very little (if any) on range.

Hi Minerva - I've put lots of info up on our blog. We try to answer just about every question you may have. www.wattcycle.com (http://www.wattcycle.com)
Our online store is here: www.wattcycle.com/shop/home.php (http://www.wattcycle.com/shop/home.php)

Remember that a kit with nice high speed such as the Phoenix Racer system will go faster with a higher voltage. You'll also have a more balanced system if you're going to be using the more affordable SLA (sealed lead acid) batteries. My personal system is a 48 V 40 A system. It's really fast (37 mph) - maybe a little too fast for the common user - I just think it's fun for tooling down to the store a few miles and back - I can actually put it on the road and keep up with the cars.

The great thing is that you can really choose a kit for whatever you need. If you're looking at doing around 25 or so, try looking at a Crystalyte Roadrunner kit. They're cheaper and more efficient than the really fast ones and give you a longer distance.

We also have a complete electric bike that will go about 20 mph as well. It's got a range of around 20 - 25 miles depending on how you ride it. Lithium batteries as well.

Congratulations on the consideration of an e-bike!

For the kind of distance and performance you're looking for, I would suggest you steer clear of the large crystalyte 5 series motors. They are heavier than necessary, more expensive than necessary, and there's a loss of efficiency that comes with using a motor that has more torque than you actually need.

the nine continent motors (which are supposed to be more efficient than crystalyte and provide better performance as well) seem like a good choice for your situation. you can buy em at ampedbikes.com or ebikes.ca

I also recommend checking at http://www.ebikes.ca/index.shtml
They also carry a geared hub motor, the eZee which has lots of torque for hills and weights less than the more conventional hub motors. That system will eat up your $1200.00 + but they include a 36V 10Ah lithium battery. You might get away with using a Crystalyte 408, that with a contoller and throttle would set you back about $600.00 or less allowing you to shop for batteries. I hope you have somewhere to recharge when you get to work.

Thank you so much everyone for replying. I appreciate the recommendations that I've recieved, and I am looking into a couple of the systems mentioned. I feel I have a better idea now what kind of system I need, and, of course, what kind of system I don't need pay for!

Thanks again!

~Minerva