Electric Vehicle Forums - First EV

Bob, I have been looking into getting myself an ebike for my 12 mile (each way) commute. The info below is for those interested in what I have learned about the technology. The bike like you have can be gotten for less than $500, and is a great value, but I am looking for a bit more refined bike. By refined, I mean higher quality components (brakes, battery, gears), lower overall weight, better non-assisted ride ability, etc. So, I am not recommending that people avoid the under $500 machines, so long as they expect the SLA type batteries, no gears, over 100 pound, and so on.

For those looking for something under 60 pounds with lithium batteries that function well as bicycles without any power assist, expect to pay between $800 and $2500 (and up!!!!). This info covers both ready made ebikes and user-built.

Do not consider anything other than a brushless hub motor. They are available front or rear, geared or gear-less. The gear-less are getting nearly all the attention, but a good planetary geared motor will be more efficient and lighter for the same power, and nearly as quiet, with a very slight drag (coasting friction) penalty. They range from 250 to 1000 watts, with most between 250 and 500. With your legs doing less than 100W, I think 250W is plenty, giving greater range, but less acceleration than a bigger motor. All systems are electronically speed limited to 20 miles per hour and under 750W in order to be classified as a bicycle for traffic laws (permitting you, for example, to use bicycle/pedestrian passes where all other motorized vehicles are prohibited). However, that 20 miles per hour is non-pedal assisted, and with both pedaling and electric assist, 25 MPH is not too hard to maintain on a good bike.

Batteries come in sealed lead acid (SLA), NiMH, and various lithium chemistries. If you live in a hot climate, you probably want to stick with LiFePo or LiMn for good and safe performance under hot conditions. The LiFePo is the more expensive, but has the greatest number of charge cycles, making it the best value. SLA and nickel technology is way too heavy for most everyone except the tight-wads (just kidding, it is a cost/weight trade off for the most part).

10-12 AH at 36V will give a 20-40 mile range, depending on speed and assist level, with 40 miles representing a typical 50% assist on flat ground staying under 20 miles per hour, but this is just a rough estimate and can vary with a number of considerations. 24V is enough for 250W (so long as it is a 24V motor!), and 48V is better for 500W. I'm shooting for a 36V, 10AH, 250W, LiFePo system for myself. Increasing the AH and/or voltage, and/or decreasing the motor wattage will increase the range. Increasing the voltage or wattage will increase the assist level available, assuming the battery can supply the current.

There are three main control techniques: throttle (twist or thumb lever), pedal sense (usually called "pedelec"), or both. Some units have a kind of auto-throttle where you set the throttle at some position and press a button and that assist level holds without you needing to hold the throttle. This works well, and shuts off with any braking. Some have on/off pedal sense where the motor turns on at some set power level whenever the pedals are moving at all. The best is where the torque applied by the rider is magnified some set amount, say 25%, 100%, or 300%, and can even smooth out pedal fluctuations each pedal rotation.

Some systems have regen on braking, but I would not expect more than a 10% range enhancement at a high delta cost and would not expect the braking modulation to be good as it switches from e-braking to mechanical braking, which is a safety necessity. I expect this will be standard in a few years, but not quite ready for prime time today (due to cost).

A number of companies have ready-made ebike solutions, including Schwinn, Giant, izip/ezip, Ultra Motors, etc. To get reasonable quality, this is a very expensive way to go, but I expect rapidly increasing competition to bring prices way down. The Giant Twist is a good example of what can be had for about $1500 (ignore the stated MSRP of $2250!). This bike is just starting to hit US dealers. Another interesting high end bike (very overpriced, however) is the Ultra Motor's A2B. I test drove this, and was very impressed (although it does not have pedelec). The izip/ezip brand has numerous models across a wide price range, including some models available at Walmart!

One of the more interesting looking bikes value-wise is the L Martin LX1, having most of the important features, such as LiFePo battery, etc., and selling for $800. This company is in Austin. I called a friend of a friend in Austin to see if he would check out this bike for me, but he said this was in a very bad part of town that he had no interest in visiting! If anyone can give a first hand report on this company and their products, I would be very grateful.

The two best component sources I have found so far are Bionix in Canada, and Golden Motor in Taiwan (GM has components and complete ebikes). Bionix is awesome quality and features, but outrageously expensive. On the other hand, there is a lot to learn from their web site. Golden Motor has better batteries at 1/3rd the price, but is hard to get reliable specs from all the variations in parts from them. Be prepared to find hundreds of sources, almost all in China, if you start a Google search on electric bikes!

Also, make sure any bike you convert has a strong frame, and especially strong front fork if you go front motor. After adding 10 lbs of battery and another 10-15 lbs of motor and electronics, you will be adding stress to the bike frame in ways very different than added by a rider (which is like a heavy bowl of jello by comparison!). The motor will add quite a bit of torque where it attaches to the frame or fork. Assume 50 or more pounds for a reasonably light e-bike with good power and good range.

I would love to hear more from others who have investigated this technology.

-- Alan