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Old 10-10-09, 07:06 PM   #1
esther-L
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questions about BionX and cadence

Does anyone have experience with using the instructions at http://www.lightfootcycles.com/bionxprogram.php to set proportional assist sensitivity?
If you are getting satisfactory performance from your BionX, what is your typical cadence?


Due to some knee issues, I have learned to pedal at a cadence of 90 rpm most of the time.

I rented a bike with BionX from a local dealer, and the motor assistance did not kick in much when I pedaled at my usual cadence. It was quite surprising to be going up a hill at 7 mph on a bike with a motor, and on assist level 3.

When I concentrated on using slower cadence, I did get more assist from the motor.

This rental unit seemed to be having some problems. On my 13.5 mile round-trip commute test, I used 3 of the 8 battery segments (from full charge). This is my commute to work
http://www.bikely.com/maps/bike-path/355332 I used assist level 2 much of the time, and used throttle up 2 of the hills. I tried to use assist level 0 on the "no motor vehicles" 3 miles, but I wimped to level 1 because it took a lot of effort to move this bike forward.

Thanks for your input.
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Old 10-10-09, 09:04 PM   #2
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Hello,

I own a bike equiped with a BionX Pl350 system. I have not played with proportional assist setting but have played with some other settings with benefits found. It's worth giving them a try, you can just set it back to the orginal setting if you see no benefits to you.

Yes, the system prefers a slower cadence to a faster spin for motor to provide steady stream of assistance.


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Old 10-12-09, 10:18 AM   #3
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As it comes from the factory, the Bionx unit is designed to INCREASE SPEED ... not REDUCE EFFORT (see my posts under the Bionx Tourer).

A long term concern for most Bionx users is whether their knees will hold up under the stress of using the higher gears that the strain gauge needs to keep the motor engaged.

In my experience, consistent riding at level 2 drains the battery in about 25 miles.
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Old 10-12-09, 08:13 PM   #4
esther-L
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Quote:
Originally Posted by Nate1952 View Post
As it comes from the factory, the Bionx unit is designed to INCREASE SPEED ... not REDUCE EFFORT (see my posts under the Bionx Tourer).
What I experienced on some hills was increased effort combined with decreased speed. I was spinning at my 90 rpm and working harder to get a heavier bike up the hill at a slower speed, with the console showing no assistance supplied. I don't know how many tick marks the rider should expect to see on the BionX console for the assist amount. Even at level 4 assist, I never saw more than 4 tick marks, and that was brief.

Someone in my bike club uses a BionX PL350 on a recumbent trike. He says that he routinely sees more than 4 tick marks of assist at level 2 when he's pedaling up hill. His average cadence is 58. I am trying to figure out whether this rental unit was malfunctioning, whether different settings would help, or whether my knees are unlikely to be compatible with a BionX. The local dealer from whom I rented did not have answers for my questions about cadence.
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Old 10-13-09, 01:28 AM   #5
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Use the smallest front chain ring if not already. You can generate higher tension in the chain for the same effort and you should see higher assist bars. And of course, use the highest assist level.
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Old 10-13-09, 02:00 PM   #6
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Hills are typically the place where a Bionx unit will perform at its best ... so it's possible the unit you were using is malfunctioning. For any type of climb, the strain gauge is under stress all the time so you typically feel a strong "push" up the hill.

High winds are the other situation where the unit is valuable. Once again, the wind resistance increases the strain on the drive train and the motor is cued to "push".

Riding on the flat is the primary problem: where you have to essentially "outsmart" the system by choosing a bigger gear than you would normally use.

If you have had knee issues in the past, I would approach this unit with some caution.
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Old 10-13-09, 05:34 PM   #7
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Quote:
Originally Posted by Nate1952 View Post
Hills are typically the place where a Bionx unit will perform at its best ... so it's possible the unit you were using is malfunctioning. For any type of climb, the strain gauge is under stress all the time so you typically feel a strong "push" up the hill.

High winds are the other situation where the unit is valuable. Once again, the wind resistance increases the strain on the drive train and the motor is cued to "push".

Riding on the flat is the primary problem: where you have to essentially "outsmart" the system by choosing a bigger gear than you would normally use.

If you have had knee issues in the past, I would approach this unit with some caution.
All these requires pedalling harder. The strain gauge does not know if there's a hill or wind. But the rider knows, so as a result of facing a hill or the wind, you tend to pedal harder.

If you just drop to a smaller front chain ring, you can get more assistance from the bionx motor for the same effort.
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Old 10-13-09, 08:27 PM   #8
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There is the possibility that the particular BionX installation was faulty... the obvious being a misalignment of the "notch" positioning on the back wheel. In that case, the tension on the chain won't get registered correctly on the strain gauge. If you're going relatively quickly, the other standard motor issue of course is the speed limiter... it can make it seem like the motor is doing very little. The performance of my bike became much more predictable and pleasant (although not much faster) when I disabled my limiter (code 3773). I normally keep my bike in the top gear and max out on cadence at ~19mph.
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Old 10-13-09, 09:29 PM   #9
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This is an interesting tipic and in the past I have asked a simular question. Using the Bionx on a slow LWB recumbent. I am wondering how long the battery would last on level 1 just running around 12 mph spinning at a fast rate. With my 210 lbs would the assist still last around 60 miles? Or would it last longer because of the slow speed?
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Old 10-19-09, 07:50 PM   #10
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Quote:
Originally Posted by adamtki View Post
If you just drop to a smaller front chain ring, you can get more assistance from the bionx motor for the same effort.
I got very little assistance to kick in from this rental unit when I was on the smallest front chain ring. I should call the shop where I rented it and ask them to examine the bike for malfunction. Although I think I've already given them enough description to lead them to conclude the unit needs troubleshooting.

Unfortunately, this rental did not help me make a decision.
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Old 10-20-09, 04:57 PM   #11
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I agree. It would be hard to make a choice without a true "test drive".

Even knowing everything that you could know about the unit might still mean that you would have a "period of adjustment" after purchase.

I've had mine for 7 months and am still trying to understand the finer points of how the unit works. I was completely unacquainted with the sensitivity adjustment, for example, that you mentioned in your first post in this thread.

Now I have to test that option, as well, as I continue to use the Bionx over the winter.

We went 30 miles on Sunday. I just chose a knee-friendly gear in advance (M4) that would give me about 10MPH ... and just allowed the motor to come in and out at Assist Level 2. The ride was easier on my knees, I still had the throttle for the small hills on the route, and had roughly half the battery power available at the end of the ride.

So I tend to think that my relationship with the unit is starting to improve.
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Old 11-01-09, 09:55 PM   #12
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1. I can verify that increasing those values does, in fact, help for those of us who try to use high cadences.

2. I was also informed by my dealer that making those changes actually voided my warranty. I checked the text of the Bionx warranty, and he is correct.

Those settings help, but use them at your own risk. Like some others, I've had occasional issues with my Bionx system locking up. I haven't been systematic enough about it yet to verify whether it has anything to do with those settings, so I haven't yet proven otherwise.

Charlie
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Old 11-07-09, 10:28 PM   #13
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I've test-ridden a BionX system once - it kicked in fine for me, and I'm a high-cadence rider (around 90 as well). I can't recall if i was riding at my usual cadence on that ride, though.
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