Question on smoothness of power output of electric motor - Wisper 705SE

[wispy]

Hi all,

I just bought a Wisper 705 and am very happy with it overall but there's one small thing nagging me. Not sure if it's an issue with my bike specifically, an issue with the model, an issue with all ebikes of that type, or an issue with me! After a couple of hours on it, I'm finding the following pattern:

What I'm observing is that at ~15mph, the motor goes on full power (visual indicator shows all 5 bars of current and I can hear and feel the oomph) and then at ~16mph it "abandons" me (down to 0 bars of power), leaving me to push unassisted. As the speed drifts down to ~15mph because I can't keep up, I get another kick from the motor, and the cycle repeats...

The behaviour I would have expected is for the controller to make smaller adjustments to power output to find the level that keeps the speed constant. If I'm pedaling giving roughly constant power, and the incline/wind/drag/etc. are all constant, then there is a fixed amount of power output that ought to keep me at the legal speed limit, maybe somewhere near 2 or 3 bars of current.

So, is this an issue that others have encountered? Is there some workaround? Can controllers be configured to address this? etc.

Best,
Wispy-

 

[Wisper Bikes]

HiWispy,

Firstly thanks for investing in a Wisper.

The behaviour of your bike is very much down to the way we have set up the assistance. The regs say we must “gradually” reduce assistance power and cut off completely at 15.5mph. The choices are… 1. To start the reduction in power early at say 13mph and make the transition from assistance to no assistance very smooth so when it cuts in and out you hardly notice. The disadvantage with this is that at 14-15mph you would have a lot less power assistance available. 2. Start the reduction at 15mph this way you retain more assistance for longer. The pay off is that the cut in and out is more noticeable. We have chosen the later.

Does that make sense?

All the best, David

 

[wispy]

Thanks. Another thing I've noticed that I found a bit surprising is that the motor isn't neutralized when I'm using the brakes. Is that expected?

 

[Wisper Bikes]

Thanks. Another thing I've noticed that I found a bit surprising is that the motor isn't neutralized when I'm using the brakes. Is that expected?

That’s correct brake cut outs are not necessary on modern ebikes as power cuts out when pedalling stops.

All the best, David

 

[Andy-Mat]

That’s correct brake cut outs are not necessary on modern ebikes as power cuts out when pedalling stops.

All the best, David

I have had working motor cutouts on the brakes of both my e-bikes, and I do prefer it that way for smoothness. When on my first e-bike, a brake lever problem caused me to get a mild shock, when suddenly trying to brake against the motor - never was a problem so swiftly repaired with new brake levers, and no riding till it was fixed!!
Also, I would hazard a guess that maybe some of the people complaining of having pad wear problems, might not have the cutout working, and that is a possible cause!
Also, stopping a motor by mechanically overloading it, especially a mid motor (that chain wear problem again!), must surely, in the longterm, be bad for the motor (and the chain!), as the current taken shoots up till probably the controller finally stops it!
Nobody can convince me that NOT having the lever cutouts working to shut the motor off when braking, is either good,OK or in anyway acceptable.
Regards
Andy

 

[flecc]

Nobody can convince me that NOT having the lever cutouts working to shut the motor off when braking, is either good,OK or in anyway acceptable.
Regards
Andy

The designers on the continent where large numbers of pedelecs are made, including where you live in Germany, don't agree. Nor do the Japanese, another major manufacturing centre for them.

For them the pedelec sensor is the cutout. Given that the Germans buy half a million pedelecs a year and the Dutch buy a third of a million a year, they must find that completely adequate.
.

 

[Nealh]

Only UK users and the US are fixated on wanting mopeds with throttles or twist and go, it is this reason one should have brake sensors fitted if one is also fitted.
I no longer fit throttles as I never use the damn things, so sensors for brakes aren't needed.

 

[guerney]

My V-brakes are puny in comparison to disc, I assume, having never tried a disc braked bike... therefore I preferred to set my bbs01b to a rapid discontinuation of assist at 15mph, for safety in case my e-braking cutoff didn't work. It's a bit hard on the old knees, but I'd rather not be launched into traffic or something.

 

[georgehenry]

The rear hub motors on my pair of old (2011) Oxygen Emates can run on for what seems an age after you stop pedaling.

The assist does stop eventually, and I am very used to them, but they both have brake cut outs which kill the power as soon as you start to pull the brake levers which I find very helpful.

 

[Wisper Bikes]

The rear hub motors on my pair of old (2011) Oxygen Emates can run on for what seems an age after you stop pedaling.

The assist does stop eventually, and I am very used to them, but they both have brake cut outs which kill the power as soon as you start to pull the brake levers which I find very helpful.

Hi George, the reason cut outs were necessary back then was most cadence sensor bikes had 6 magnets in the cadence sensor disc each magnet would send a signal to the motor telling it that the pedals were turning and therefore assistance was required. As two signals are required to tell the motor in which direction the pedals are turning, (So the motor is not activated when back pedalling) It can take up to half a rotation to turn the assistance on. And therefore the time it takes for up to half a rotation to turn the assistance off. Hence the need for cut offs. Now modern cadence sensors have upwards of 12 magnets and three sensors giving upwards of 36 signals per rotation. Therefore the assistance will cut in and out at least six times faster negating the need for brake cut outs. With a torque sensor the cut out happens even faster.

Regarding throttles on an EAPC, much like with powerful motorcycles the law doesn’t require the power to be cut off when braking. I understand that some motorcycles have very powerful brakes, however they have to deal with much more power, weight and speed. Bicycle brakes are more than adequate to deal with the power, weight and speed of an EAPC.

All the best, David

 

[Wisper Bikes]

Only UK users and the US are fixated on wanting mopeds with throttles or twist and go, it is this reason one should have brake sensors fitted if one is also fitted.
I no longer fit throttles as I never use the damn things, so sensors for brakes aren't needed.

Hi Neal, our Dutch and Belgian dealers have told us they would love to be able to offer a full throttle so they too could make cycling more inclusive. Our NZ distributors offer a throttle on all our bikes.

A full throttle is not compulsory but I strongly believe that that they should be available to those that need one. If you could meet the people to whom we supply our full throttle bikes, and share their sheer joy at being given the opportunity to be able to ride a bicycle again… or even for the first time I’m sure that you would understand the need for these machines.

All the best, David

 

[georgehenry]

Hi David,

Thank you for your reply. I should try a modern cadence bike, I am sure they have moved on a lot from my old Oxygen Emate bikes of 2011.

I do also have a hard tail Haibike Yamaha motored crank drive bike of 2015 vintage that has a torque sensor, and something called zero cadence, which assists impressively quickly (feels instantaneous) in proportion to how hard I push on the pedals and seems to also stop assisting the moment I either remove pedal pressure or stop pedaling.

My old Oxygen bikes both have unrestricted throttles, and although fortunately physically I do not need them, I do actually find them very useful on occasion. I am sure you will know better than me, but I think the EEC changed the rules at some point to outlaw unrestricted throttles.

Regards.

 

[wispy]

That’s correct brake cut outs are not necessary on modern ebikes as power cuts out when pedalling stops.

Thanks David.

One more question. In the SE digital screen, holding both arrows down together enables a setting whose values are 16, 18, 20, 24, 26, 70, 28 (if memory serves, in that order). Though it looks like a speed limit, I don't think it is. Feels more like a wheel size maybe from the behaviour that I've observed? Though the motor does feels like it behaves slightly differently across the modes. Could you clarify what each of these does and which one is best?

Thank you,
Wispy-

 

[Wisper Bikes]

Hi Wispy they are wheel sizes and describe inches the wheel size, all apart from 70 which refers to C700, or 28".

It is massively important that you do not attempt to change these settings, it will invalidate your warranty and could cause the bike to behave erratically or become illegal to use in the UK. If you have a 26" wheels bike it MUST be set to 26 if you have 20" folder it must be set to 20 etc.

All the best, David

 

[Andy-Mat]

The designers on the continent where large numbers of pedelecs are made, including where you live in Germany, don't agree. Nor do the Japanese, another major manufacturing centre for them.

For them the pedelec sensor is the cutout. Given that the Germans buy half a million pedelecs a year and the Dutch buy a third of a million a year, they must find that completely adequate.
.

I know how it works, but I don't have to accept being the best system, simply because probably many are simply not fully informed, but IMHO the brake lever cutouts simply work faster, and work, even if you haven't quite managed to stop your feet moving!!
I am, like many here, one who manages to have his own opinion on the subject of what I prefer......Nobody else needs to take it on if they do not wish to.....
Have you anything against that, or are you going to allow me to retain my personal preferances?
Andy

 

[Wisper Bikes]

There are many views on every area of eBiking and all are valid and should be considered, opinions are formed on individual experience so will differ from person to person.

My experience is…

After 17 years developing ebikes and more importantly servicing them, the singular biggest problem we have ever had to deal with is brake cutouts failing. The problem is that they are fail safe so when they fail the bike cuts out and cannot be used until they are disconnected or fixed most people disconnected them. As they tend only to be used on cheaper brake sets this happened a lot. We were pleased to see the back of them.

All the best, David

 

[flecc]

I know how it works, but I don't have to accept being the best system, simply because probably many are simply not fully informed, but IMHO the brake lever cutouts simply work faster, and work, even if you haven't quite managed to stop your feet moving!!
I am, like many here, one who manages to have his own opinion on the subject of what I prefer......Nobody else needs to take it on if they do not wish to.....
Have you anything against that, or are you going to allow me to retain my personal preferances?
Andy

As far as I am concerned, everyone is entitled to have and practice the own preferences. But as for the Dutch and Germans, who have long designed and bought more pedelecs pro rata to population than any other country, being simply not fully informed about about pedelecs, really! Their knowledge of designing and buying electrically assisted cycling goes back to the 1920s.

Wisper is right, brake cutouts have been a constant source of trouble as the large numbers of problems reported with them in this forum over the last 16 years shows.
.

 

[Andy-Mat]

As far as I am concerned, everyone is entitled to have and practice the own preferences. But as for the Dutch and Germans, who have long designed and bought more pedelecs pro rata to population than any other country, being simply not fully informed about about pedelecs, really! Their knowledge of designing and buying electrically assisted cycling goes back to the 1920s.

Wisper is right, brake cutouts have been a constant source of trouble as the large numbers of problems reported with them in this forum over the last 16 years shows.
.

Maybe I have been just lucky, but I also try and take care of the wiring at all times, and I do not remember a brake cut out problem for a good many years on my own e-bikes.
But when I see the state of some e-bike's wiring, all loose and pulled about, it is no surprise to hear that problems can happen in this area.
So many thanks for the "heads up" on this, and maybe I will make a simple switch to negate the possible problems, while out riding, "just in case!" in the future, as it is not something that I have given much (any!) thought about!!
regards
Andy

 

[flecc]

Maybe I have been just lucky, but I also try and take care of the wiring at all times, and I do not remember a brake cut out problem for a good many years on my own e-bikes.
But when I see the state of some e-bike's wiring, all loose and pulled about, it is no surprise to hear that problems can happen in this area.

You're right Andy, it is that bikes with wiring festooned around them are recipes for trouble. And of course it is mostly hub motor e-bikes with low grade add-on pedelec sensors that can end up like this due to all the separate components.
.

 

[Andy-Mat]

You're right Andy, it is that bikes with wiring festooned around them are recipes for trouble. And of course it is mostly hub motor e-bikes with low grade add-on pedelec sensors that can end up like this due to all the separate components.
.

I completely believe you, as when I have mentioned in the past, the state of the wiring to colleagues on their e-bike being possibly the (future) source of problems, the same sort of answers come back:- "don't touch a running machine!" or "it works, don't touch!"
So I don't! Some of them have been riding with a ratsnest for ages AND IT STILL WORKS apparently!!
UGH!!!
All sorts of e-bikes, not just hub motors by the way, which are fewer generally than other types here in Germany, as Germans want German production, and hubs are generally cheap imports (as far as I am aware!).....
So I am one of the few here with a rear hub bike.....some are front, some are mid, and I have not checked numbers accurately at all, as I have little to no interest in that....That is their problem(s).
regards
Andy