Torque Sensor v. Cytronex System?

[OTH]

I went for my first proper test ride on an electric bike (Trek FX+) this weekend. This raised a question that is probably obvious to experienced e-bikers, as follows. With a torque sensor, the more effort you put in the more assistance you get – it seemed to me. I need to limit the amount of effort I put in. Consequently, the amount of assistance I could get was also limited. Would the Cytronex system be more appropriate, as it appears to give full boost at the push of a switch when assistance is needed?

Two supplementary questions:

1. The display went from showing ¾ full battery to empty in about 3½ miles. About a third of this was on top assist level uphill. I was told later that the battery had only been on charge for about 45mins and a full charge would give much further. Presumably this is true? (A pity, as I’d given them two days notice and had been promised a fully charged battery.)

2. Can anyone explain the bike's tendency to veer, quite sharply, to the left when braking and signalling to turn right?

 

[HarryB]

I wouldn't say the cytronex is the best system for you if you want maximum assist (I think that this is what you are saying in your post). The Bionx (as used in the FX) is much more powerful than the Tongxin set up in the Cytronex and if you are not happy with that amount of power then maybe an Ezee would suit. I found the Bionx to be the most powerful system when I tested many bikes a year or so ago. The sensing system works as well as the panasonic but I didn't like the battery (power or where it was positioned) in the FX+. In my experience the battery meter does exactly as you say but unlike the Panasonic will recover so what you see is not exactly what you get.

 

[NRG]

To answer your first question, yes. The Panasonic system is not really suitable if you are unable to contribute something yourself, although there are three levels of assist you can select it still requires your input to work. The thumb throttle option available on the Kalkhoff is really for just walking the bike, it provides no meaningful power to the motor. So you may be better off with a hub motor system fitted with a twist or thumb throttle...

 

[flecc]

Can anyone explain the bike's tendency to veer, quite sharply, to the left when braking and signalling to turn right?

You'll probably instinctively deny this answer, but please pause to consider it carefully.

When you have your arm out to signal right, there is a natural tendency to rebalance the body to a more upright position as the bars are not being evenly held. At the same time, you are pulling on the left hand brake lever.

Also in preparation for turning right you are balancing your weight slightly to the right in anticipation of the right turn which will involve banking that way. That tendency, coupled with the likelyhood of pulling the left hand handlebar minutely back due to the above braking action and body rebalancing will bias the bike more sharply left than one might expect from such slight bias. That's because the minutest lean or weight shift right will need to have a fractional turn right to maintain direction and bike balance.

Try to hold the left hand above the bar and squeeze brake to handlebar with the fingertip and thumb tip experimentally to demonstrate that is the problem.

My own bike tends to be extremely twitchy also under the same circumstances and I have to consciously apply a slight forward pressure bias to the left bar when carrying out that same braking and signalling manouvre.
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