misslexi

I test rode a Bionx PL-350 equipped bike yesterday and was impressed, a very refined system. It was raining like no tomorrow (rain? Seattle?) so I couldn't really get a good ride in.

I was wondering about one thing that maybe some Bionx owners could comment on: Are there ever situations where the braking effect of the regeneration mode, which is substantial, causes the rear wheel to lockup? I know this wouldn't happen on asphalt but what about roadside gravel?

recumelectric

It hasn't happened to me, but I tend to squeeze the brake levers slowly. I also use both front (regular v-brakes) and rear brakes (Bionx) at the same time. ...I'm not too fond of flying over the handlebars.

LesMcLuffAlot

Could you clarify if you mean while using the rear brake or going downhill and using the regen feature alone.

borland

What recumelectric means, is he is applying the rear brake handle just enough to activate the BionX magnetic switch, but not enough to contact the rear brake pads. That's exactly what I do on my bike with a BionX rear wheel hub motor.

Without regenerative braking feature, you typically coast fast down the hill, applying the brakes heavily at the bottom. However with regenerative braking, you apply regenerative braking during the entire length the hill, or if not, much earlier from the end. The net affect is you go down the hill at reduced speeds, which is usually safer, saves on brake pads, and allow recapturing battery power for later.

The BionX system takes a while to fully learn, that is, to use to your advantage. But first impressions are, that it is a pretty well designed system.

LesMcLuffAlot

I know what recomelectric means. I was asking the OP.

misslexi

I'm not really concerned as to how the system goes into regen mode, I don't know enough about the system at this stage to fully understand it's intricacies.

Let me restate the question:

Lets say I'm using the rear brake of any bike, electric or otherwise, on asphalt. Suddenly I find myself in a gravel patch and the rear wheel starts to lock up and skid, I can stop the skid by simply releasing the brake.

It occurred to me that if this was a Bionx bike that went into regen when I was a stage one above, on asphalt, that once I hit the gravel patch and started to skid, releasing the brake would not take it out of regen mode which may cause the skid to continue with no way to stop it.

I suppose I should get a question in here somewhere, is there a way to deactivate regen in an emergency like I described above?

The test bike I rode for example, would enter regen as soon as I applied the rear brake and would not exit regen until I started pedaling again, releasing the brake lever did not make it exit regen. If I were in a skid, it would be counter-intuitive for me to consider pedaling as way to unlock the rear wheel and end the skid.

borland

If the rear wheel completely locks up, there is no regenerative effect. The rear wheel has to turn in order for the motor to act as a generator and recharge the battery.

You loose traction in gravel even if you don't apply the brakes.

cerewa

What this means, in relation to misslexi's question, is that if the turning speed of the wheel is at or near zero, the "braking" force exerted by the bionx regen feature will also be at or near zero. The regen feature does not have any mechanism by which it could possibly keep the wheel locked up because it doesn't exert any force at zero speed.

misslexi

It sounds like Bionx has done their homework then, a good thing. Figures I would go looking for trouble where there is none

We get more than our fair share of rain here in Seattle, the conditions I frequently encounter while riding on city/suburban streets is runoff from driveways will wash gravel onto the side of the road where bikes are expected to ride. There could be no gravel today and it's there tomorrow, you never know. It's generally not enough to cause a crash; it's just enough for me to keep totally off the front brake and to very gently feather the rear brake, assuming I feel the need to slow. And of course there's automobile traffic to contend with. It's just not the best time for a person to lose control of the bike.

recumelectric

That's weird. I don't think mine does that. Brake goes on when I pull on it and off when I release...
unless I've been missing something.

LesMcLuffAlot

Well the motor wouldn't kick in again untill you started pedalling again, unless you use the throttle. So maybe you were just feeling the extra weight and drag of the system while coasting.

misslexi

I didn't mean to say the brake stayed on after I released the brake lever, it was the braking effect of the regeneration that continued after I released the brake lever. On the demo bike, the only way I could get it to exit regen mode once it became engaged was to start pedaling. I had no idea the thing even had a throttle but I'm sure that would have worked too.

It's not out of the question the demo bike was not operating in a text book fashion; it sure looked like it had seen better days.

Kermit 43

There is also a setting that can be changed to reduce or increase the amount of regenerative braking incase you need to tweak it so it feels comfortable to you.