Slow pedal assist:

[billyx22]

Hi,
I was hoping someone might know what my problem is, or even if I have a problem.
Have just bought a Z6 Zipper
I already have a cyclomatic power plus and I had a 20 inch wheel one before that for a very short time.
Bought this new at a good price.
The thing is it is pedal assist and throttle, I have only been to the top of the road and back twice, stopping along the way.
The pedal assist takes quite a while to kick in, about 8 or 9 full revolutions of the pedals.
The other two bikes the motor kicked in as soon as I pedalled.
Has anyone else come across this, I really think something is not right.
Thanks.

 

[Benjahmin]

I don't know this particular bike, but....
Have you tried a lower gear so that the start up cadence is higher? The other trick is to blip the throttle as you start to pedal, power should continue when you let go of the throttle.

 

[billyx22]

Hi,
Thanks for replying.
I started of in low gear both times, I also did the throttle but it didn't help.
I am quite puzzled because the throttle works great.

 

[Geebee]

Are all the magnets still on the PAS disc or even more likely is the magnet ring close enough to the sensor?

 

[billyx22]

Are all the magnets still on the PAS disc or even more likely is the magnet ring close enough to the sensor?

Hi,
Thanks for that.
Excuse my ignorance, I may have had two bikes before this and have learned some stuff along the way but have never messed about with sensor magnets before.
To check what you are saying does that involve removing the crank shaft?

 

[Geebee]

You should be able to at least check it with the pedals still fitted.
It should look remotely similar to the black disc in the below picture, the black box with the wire is the sensor for the PAS and it detects the magnets on the disc rotating past, if the gap is to big it will need to spin faster to tell it it is working as some of the magnets may not register if the gap is to big it won't work at all, if the disc is loose it may not spin with the pedals correctly either or a magnet missing etc.
Good luck

 

[billyx22]

You should be able to at least check it with the pedals still fitted.
It should look remotely similar to the black disc in the below picture, the black box with the wire is the sensor for the PAS and it detects the magnets on the disc rotating past, if the gap is to big it will need to spin faster to tell it it is working as some of the magnets may not register if the gap is to big it won't work at all, if the disc is loose it may not spin with the pedals correctly either or a magnet missing etc.
Good luck

That's made it clear, thanks.
I have looked at mine, it is on the side where the gears are.
Just rotated the pedals by hand, it looks very much like the magnet disc itself is out of shape with the sensor then being close then further away as it spins.
Could that cause my symptoms or would that make the assist cut in and out... just thinking aloud.
If the disk is bent, home it's not the cog, can it be straightened?

 

[anotherkiwi]

Yep you found it! That used to happen to mine if I touched it with my foot while pedalling. You should be able to adjust it by hand so that it runs parallel.

 

[billyx22]

Yep you found it! That used to happen to mine if I touched it with my foot while pedalling. You should be able to adjust it by hand so that it runs parallel.

As I said earlier I have not messed with disc magnets or sensors before, or cranks.
To get at the disc do I need to take the whole crank out or just the disc side, I bought a puller tool last year but have never used one before, I am just a bit wary of the process, even though I do like to have a go if I can.

 

[OldBob1]

The disc is just a friction fit to the crank shaft, you can adjust it with your fingers to run parallel and about 1 - 2 mm from the sensor.

 

[anotherkiwi]

Without taking anything off you should be able to adjust it. It is just slipped on over the BB axle. Maybe you will need to use a screwdriver because there us no space for your fingers? Can we have a photo?

edit : posted at the same time as oldbob

 

[billyx22]

Thanks to all.
I will give it a try tomorrow.

 

[billyx22]

I got it straight then took it out, about a mile there and back.
No change I still have to pedal a lot before the motor kicks in, when it does it feels just the same as when using throttle, not a gradual help but a burst.
I have enclosed two pictures trying to show the sensor and disk.
The sensor is on a bracket but the bracket is tilted upwards which makes the sensor tilt upwards.
I know nothing about these things but it appears to me that where the sensor has been fitted it would not directly face the disc, it would be too low so it has been levered up somehow.
The gap also appears too wide maybe?

 

[OldBob1]

I would suspect the PAS sensor is working OK, could be a problem with the controller? causing a delay, maybe worth contacting the supplier?

 

[billyx22]

I would suspect the PAS sensor is working OK, could be a problem with the controller? causing a delay, maybe worth contacting the supplier?

I intend to, well the bike seller anyway, I just wanted to be armed with a bit of an idea what the problem could be in case they try to blind me with science!
Does my sensor look right, in my pictures, it looks to be angled upwards to me, as if the bracket it is attached to has been bent upwards?

 

[anotherkiwi]

Nope doesn't look right. As you reasoned it should be parallel. Something has hit and the sensor has been knocked up and your disk was also displaced before you straightened it.

Maybe the sensor doesn't have enough magnet surface coming by to detect it like it should?

 

[billyx22]

Exactly what I thought.
Anyway I have written to the seller but I won't hold my breath for a reply or any help from them even if they do reply.

 

[Geebee]

Have you tried bending the sensor bracket back into line so the sensor sits flat to the disc, basically you want the magnets in line with the sensor as they go past.

 

[billyx22]

Have you tried bending the sensor bracket back into line so the sensor sits flat to the disc, basically you want the magnets in line with the sensor as they go past.

Can't do that, it looks like that's why it's bent in the first place.
If it was straightened out as it should be the sensor would be below the disc.
Seems the sensor should have been put in a different place, that's just me thinking.

 

[anotherkiwi]

Looking more closely it looks like the disk diameter isn't adapted to the sensor position? Very strange.