"Neutral" Mode?

From what I've read so far, it seems like BionX has two modes:

- Assist: The system is reducing the effort needed by the rider to maintain a given speed.

- Exercise: The system is charging the battery and making it harder for the rider to pedal at given speed than if there were no BionX at all.

Have I got it right?

Or might there be a third mode where, except for the added weight, the BionX does not affect pedaling effort at all?

The third mode might be the "off" mode, where there is but the slightest drag from the powered off system. Barely noticeable. However, there another parallel mode: throttle. You can use the throttle with or without the pedal assist. I typically ride with the minimum assist (level 1), but will occasionally add throttle when I come to a hill. This allows a bit higher climb speed without too much more leg power. I also use the throttle at the end of a long ride to cool down for the last quarter mile or so. That is, while I ride comfortably on level 1 to work each morning, I push all the way home for added exercise, and then run electric only my last few blocks.

Note that there are four levels of assist (1-4) and four levels of generate (1-4), and a zero mode where only the throttle will add power.

I have well over 4000 miles on my PL350 in the 13 months I've had it. My first month was mostly level 4, decreasing the assist another level every few months. Since about month 10, I've been using level 1 90% of the time. When I started, level 1 seemed like it was hardly doing anything at all, but now it is just right! Now level 4 seems like ridiculously too much assist!

-- Alan

1) Cold-weather commute. Right now I have to quit riding to work when the temp falls below a certain lever bc I wind up coughing my brains out if I exert myself. Seems like the electric assist could help get me to work without exerting beyond a certain threshold and then, once day has warmed up, I could ride home after work in non-assisted mode.

Not sure I can give meaningful guidance on this one. Here in Phoenix, our winter lows are rarely below freezing. On the rare days when I leave for work and the temp is below about 35, I'm probably going to drive instead! At these temps, I generally keep the assist low and the speeds low. I need the exercise to keep warm, and the speed low to avoid the biting wind (and I am wearing a face mask at those temps!). But you are correct, that you can up the assist and minimize the exertion level at any temperature. If your ride is not too long, or if you keep a second charger at work, you could use throttle all the way and have no exertion. My throttle rarely gets used, except for at the end of a long ride when I want to cool down for a few blocks.

My temperature issue is on the other extreme, when the summer highs are around 105, the limit of the battery. I discussed this with Bionx, and they told me to just keep the assist level low, and keep the battery inside when not riding, and I should be fine, which is what I do. The battery seems fine, and I don't mind riding in the heat at all, so this is no problem for me.

2) I enjoy the occasional ride with a close family member, but he's not a regular rider and we have to go painfully slow. Seems like if I put him on a bike with the assist, we could cruise at my normal pace.

This is exactly what I do with my wife. I am a much stronger rider than her, so when we ride together, she gets my Bionx commuter, and I ride my mountain bike. Works great for both of us. Her using level 2 or 3 assist is what I can keep with on all but the hills and take off from stops, but she just backs off a bit from the normal Bionx assist in those cases and we have no trouble riding together for long rides. She can turn the assist down to 1 if she wants more exercise, or if I want less. At 4, I cannot keep up with her.

Also, does anybody know how the controller senses rider effort so that it can supply the appropriate assist?

The Bionx motor has a torque sensor that can tell how hard the chain is pulling. It works very well, regardless of what gear you are riding in. The sensitivity is easily programmable from the handlebar control unit. The assist varies with the pedal effort, is very responsive, and smooths out the pedaling. When the pedaling stops, there is a bit of a lag while the motor assist tapers off. If the brake is used, the assist stops immediately.

-- Alan

My take on variable cost for this thing is 13 cents per mile maximum,
assuming the cost of electricity to charge it is negligable.

- $1,200 replacement cost for the battery (assuming the 350 watt unit)

- 30 miles per charge

- 500 charges per battery (they claim 900 but....)

- 500 * 30 = 15,000 miles/battery

- 15,000 miles/$1,200 = $.125 per mile.

How does this match up with your reality?

I think 900 charges is probably more fair. Nearly everything I've seen shows me the Bionx specs tend to be conservative. The number of charges is highly dependent on things like cutoff voltage and current limits, so it is hard to compare to other systems that use the same LiMnO cells. That is, I would assume the 900 number is a reasonable number.

A charge requires about 11AH*42V (allowing for losses between the AC and the charger output, and in the charge/discharge cycle, and assuming a 42v charge) = 462 WH, or about 0.5 KWH. My electric company charges me about $0.12/KWH, so I pay about $0.12/KWH * 0.5KW / 30 mi = $0.002/mi, so the electric cost is about $50 for the 900 charge * 30 mi * 0.002 $/mi life of the battery.

I figure the cost per mile (for $1200 battery and $50 electricity, exclusive of tires, maintenance, and other wear items that would be about the same without the motor) to be: $1250 * 1/900 charges * 1/30 charge/mi, which is just shy of a nickel/mile ($0.046). This also assumes you will be able to find a small discount off the full retail price of the battery, for which I think $1200 is reasonable, including shipping.

-- Alan

Hey Pete - I live in the Philadelphia area - Cherry Hill, NJ, actually.

I have had the Bionx 350 on my bike for nearly 18 months and have put about 5000 miles on it.

It's been great fun and I have really enjoyed it. At level "0" ( no assist) I can barely tell anything is on the bike, other than the extra 15 pounds from the system.

But right now my battery is back at Bionx being examined by them.

When I first got the system, I could go about 36 miles, at level 2, on a charge. Recently, it has fallen to about 28 miles for the same flat route.
This seems like a fast degradation of the battery and at this rate I didn't think I could get 400 cycles on the battery before it fell below 70% capacity.

Bionx said 5 to 10% reduction in range per year was typical. I don't know if they meant typical for typical ranges. They seem to think 3000-4000 miles a year is unusual.

Anyway, I'll update in the thread on battery issues when I find out from Bionx what is going on.

But if I can expect only, say, 250 charge cycles on the battery, that certainly increases the cost per mile.