Intermittent power loss when peddling

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
New to Pedelecs – need help / advice.


I’ve had a Kudos Tornado for just over 2 years now and in the last few months the power has been randomly cutting off when peddling. I’ll state the obvious in that it’s not due to me reaching the restricted speed limit and nor am I applying any pressure to my rear brake, which can cut the power.


In addition, it’s definitely not a motor issue and there’s nothing wrong with the battery either, as during the issues with having no power when peddling the ‘kick-start’ throttle always works.


Ironically, it got me through some pretty harsh & cold conditions throughout last Winter with no problems and I’ve been through all seasons with my bike having had it for 2 years, as I say. But now that we’ve hit some average temperatures I’m having all sorts of random power losses; sometimes where it seems to struggle in the mornings from the shed on a chilly morning but also other times when it’s warmer in the afternoon.


I travel 4.6 miles each way to work and the problem is so random – sometimes working ‘from the off’, then no power for a couple of miles before it then ‘kicks in’ again! Other times I can peddle (very slowly / heavy bike!) most of the way to work and then it’ll kick in for the last ½ mile. Then on the way home it can either be jittery / on & off or fully work with no issues. As I say, it’s so random!


I’ve checked all the wire connections the best I can and keep the peddle connection area as clean as I can. As I say, the ‘kick-start’ throttle always works and so I can only conclude that it’s something to do with the motion of the peddles, which is no longer always connecting / driving the power / motor.


I have a local bike shop who fixes non-electrical issues just fine. In addition, he says he has a licence to fix e-bikes in certain European countries but not one for the UK as yet. He says, therefore, that he knows about electrical bikes but I’m starting to doubt his claims as his advice so far sounds pretty poor from, ‘’…just keep peddling’’ to ‘’…you need a new back wheel / motor then’’, even though I’ve told him several times that the throttle is fine / activates the motor just fine.


I am considering taking it to Cycle Republic near to where I live in Manchester (quite costly diagnostic service apparently) but wanted to ask this community for advice to see if anyone has an idea what the issue might be.


Thank you in anticipation.
 

Woosh

Trade Member
May 19, 2012
19,407
16,387
Southend on Sea
wooshbikes.co.uk
check your magnet disc. Mud may get trapped between the disc and the sensor head. If you don't know where it is, it's on the drive side, between the chain ring and the frame. It needs to be close to the pedal sensor head and not touch anything, spin in sync with your cranks. If your sensor head has an LED, the latter should blink when the magnets pass in front of the sensor head. Push the magnet disc as close as possible to the sensor head.
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
Thanks Woosh! I wasn't even aware of the magnet disk and certainly wouldn't know where to look for it without your advice. Very much appreciated. I'll have a look and a clean-up of the area; making a point of looking for the sensor and how far it is from the disk and see if all that helps.

Once again thank you.
 
D

Deleted member 4366

Guest
As well as the gap between the sensor and the magnet disc, you should check that the disc isn't loose on the shaft. It relies on friction to turn it. After some time, they can start slipping, in which case you need to add some tape or glue to the shaft to make it tight again.

Keep well away from that guy in the bike shop. There's no such thing as a UK licence and he clearly doesn't have a clue.
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
As well as the gap between the sensor and the magnet disc, you should check that the disc isn't loose on the shaft. It relies on friction to turn it. After some time, they can start slipping, in which case you need to add some tape or glue to the shaft to make it tight again.

Keep well away from that guy in the bike shop. There's no such thing as a UK licence and he clearly doesn't have a clue.
Thanks also, d8veh, I'll keep an eye on that also. Much appreciated.

Although I don't have a bike frame to lift my bike onto for easier maintenance, I do try to keep it as clean as possible. However, on Woosh's advice I located and then cleaned the mag disk & sensor area and it was indeed a bit 'gunky' to say the least. So, on hands & knees, I've got right in there and give it a good clean (didn't even know that the sensor had an LED / was covered in a little gunk also) and I'm about to take it out for a test run.

I wasn't aware about my bike fella not needing a UK licence to repair e-bikes and that too adds more weight to the fact that I think he's talking broken biscuits with regards to that. He's good for cable & brake repairs at least...

Cheers!
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
check your magnet disc. Mud may get trapped between the disc and the sensor head. If you don't know where it is, it's on the drive side, between the chain ring and the frame. It needs to be close to the pedal sensor head and not touch anything, spin in sync with your cranks. If your sensor head has an LED, the latter should blink when the magnets pass in front of the sensor head. Push the magnet disc as close as possible to the sensor head.
Hi Woosh.

As I've just posted to d8veh...

Although I don't have a bike frame to lift my bike onto for easier maintenance, I do try to keep it as clean as possible. However, on your advice I located and then cleaned the mag disk & sensor area and it was indeed a bit 'gunky' to say the least. So, on hands & knees, I've got right in there and give it a good clean (didn't even know that the sensor had an LED / was covered in a little gunk also) and I'm about to take it out for a test run.

I'll let you know and thanks again - I've learnt more from both of your replies in minutes than I've ever known since owning my first ever e-bike in 2 years!

Great advice & forum fellas!
 
D

Deleted member 4366

Guest
Dirt doesn't stop the sensor from working. It uses magnetism that can go straight through dirt and anything else. The two important things are the gap and the slipping.

Having said that, it's possible that if you had enough dirt wedged in there, it could put enough force on it to make the disc slip, and it's surprising how much magnetic dust accumulates from the dirt, but I think it would be exceptional to get enough build-up to make a difference.
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
Dirt doesn't stop the sensor from working. It uses magnetism that can go straight through dirt and anything else. The two important things are the gap and the slipping.

Having said that, it's possible that if you had enough dirt wedged in there, it could put enough force on it to make the disc slip, and it's surprising how much magnetic dust accumulates from the dirt, but I think it would be exceptional to get enough build-up to make a difference.
Cheers d8veh, excellent advice that makes sense. I'll keep an eye on he slipping and gap.

Test run, albeit 1.5 miles less that I'd do to work, went 99.9% well - just a little jittery from the initial 'off' and once after parking up but only for a few seconds. All fine after that and so far...
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
Hi Woosh.

As I've just posted to d8veh...

Although I don't have a bike frame to lift my bike onto for easier maintenance, I do try to keep it as clean as possible. However, on your advice I located and then cleaned the mag disk & sensor area and it was indeed a bit 'gunky' to say the least. So, on hands & knees, I've got right in there and give it a good clean (didn't even know that the sensor had an LED / was covered in a little gunk also) and I'm about to take it out for a test run.

I'll let you know and thanks again - I've learnt more from both of your replies in minutes than I've ever known since owning my first ever e-bike in 2 years!

Great advice & forum fellas!
Hi Woosh.

Test run, albeit 1.5 miles less that I'd do to work, went 99.9% well - just a little jittery from the initial 'off' and once after parking up but only for a few seconds. All fine after that and so far...

Thanks to both you & d8veh for all advice.

I do have another question for you / you both / anyone soon but I'll leave that for now and thank you once again!
 
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D

Deleted member 4366

Guest
You should be able to feel whether it's loose enough to slip. You shouldn't be able to turn the disc easily with the pedals still, or, the other way round, you shouldn't be able to stop it with one finger when you turn the pedals.
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
You should be able to feel whether it's loose enough to slip. You shouldn't be able to turn the disc easily with the pedals still, or, the other way round, you shouldn't be able to stop it with one finger when you turn the pedals.
Thanks d8veh, I'll check that also. Cheers.
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
You should be able to feel whether it's loose enough to slip. You shouldn't be able to turn the disc easily with the pedals still, or, the other way round, you shouldn't be able to stop it with one finger when you turn the pedals.
Hi d8veh.

Okay...

So the cleaning of the mag disc and general sensor area on Saturday SEEMED to work - as I said, I took it for a 2.5M test run and no issues, apart from a LITTLE juddery from 2 'offs'. Then, after seeing your last reply, I did what you said and with resistance checked that the disk wasn't spinning and it wasn't; it's sedure fast.

I put it away in the shed and got it out for work and...

1. Nothing from 'the off', I got about 20 seconds of power soon after and then nothing for my whole 4.6M journey to work apart from about 5, 1/2-second blasts of power.

2. On the way home I got the same; vitually nothing apart from a few, 1/2-second blasts. :eek:

3. Not having a bike rack, I got the bike on a garden table and with my reading glasses on I THINK I can see a tiny nick in the wire very close to the sensor.

4. Under the advice of someone, I contacted Cycle Replibic in Manchester; explained the issue and he was so unhelpful it was annoying. He said that unless I've bought it from them they didn't want to know; that buying the likes of a 'foreign bike' like a Kudos Tornado was 'unsafe to use' and suggested 50Cycle in Altrincham, which is nowhere near me (haven't tried). :mad:

5. I decided to phone an Evans shop near me; they can't fit me in for a full week and even THEN, when I told him the make/modle, said that they only get their parts from 3 different suppliers and wasn't confident but ''...would have a look at it''. o_O

Have I bought a lemon (been fine for almost 2 years / looked after it best I can)? Seriously, can no-one fix / replace a broken e-bike part?!

I'm SO reliant on this for work it's starting to stress me out... :(
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
check your magnet disc. Mud may get trapped between the disc and the sensor head. If you don't know where it is, it's on the drive side, between the chain ring and the frame. It needs to be close to the pedal sensor head and not touch anything, spin in sync with your cranks. If your sensor head has an LED, the latter should blink when the magnets pass in front of the sensor head. Push the magnet disc as close as possible to the sensor head.
HI Woosh.

Just gonna 'copy & paste' what I sent to d8veh and thank you for all advice so far / any future...

Okay...

So the cleaning of the mag disc and general sensor area on Saturday SEEMED to work - as I said, I took it for a 2.5M test run and no issues, apart from a LITTLE juddery from 2 'offs'. Then, after seeing your last reply, I did what you said and with resistance checked that the disk wasn't spinning and it wasn't; it's sedure fast.

I put it away in the shed and got it out for work and...

1. Nothing from 'the off', I got about 20 seconds of power soon after and then nothing for my whole 4.6M journey to work apart from about 5, 1/2-second blasts of power.

2. On the way home I got the same; vitually nothing apart from a few, 1/2-second blasts. :eek:

3. Not having a bike rack, I got the bike on a garden table and with my reading glasses on I THINK I can see a tiny nick in the wire very close to the sensor.

4. Under the advice of someone, I contacted Cycle Replibic in Manchester; explained the issue and he was so unhelpful it was annoying. He said that unless I've bought it from them they didn't want to know; that buying the likes of a 'foreign bike' like a Kudos Tornado was 'unsafe to use' and suggested 50Cycle in Altrincham, which is nowhere near me (haven't tried). :mad:

5. I decided to phone an Evans shop near me; they can't fit me in for a full week and even THEN, when I told him the make/modle, said that they only get their parts from 3 different suppliers and wasn't confident but ''...would have a look at it''. o_O

Have I bought a lemon (been fine for almost 2 years / looked after it best I can)? Seriously, can no-one fix / replace a broken e-bike part?!

I'm SO reliant on this for work it's starting to stress me out... :(
 
D

Deleted member 4366

Guest
You're wasting your time with those shops. Instead, your local bike shop should be able to fix it, but you need to tell them what to do.

First, you order the pedal sensor from Kudos. When it arrives, you can take it with your bike to the local bike shop and ask them to fit it. They need to remove the cranks and the bottom bracket to get the sensor in, which is the same as any bike, then they can reassemble it. That only need someone to unscrew the plastic cover off the controller box, unplug the old connector and plug in the new one. Nothing could be simpler. It's nothing that you can't do yourself without the right tools, which you can get from Ebay for a fiver:

https://www.ebay.co.uk/itm/Bike-Bicycle-Cycle-Crank-Wheel-Puller-Remover-Repair-Extractor-Mountain-Tool-Set/282200322652?hash=item41b473325c:m:m6cOfykjoABA-2O-L-I4Jog
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
You're wasting your time with those shops. Instead, your local bike shop should be able to fix it, but you need to tell them what to do.

First, you order the pedal sensor from Kudos. When it arrives, you can take it with your bike to the local bike shop and ask them to fit it. They need to remove the cranks and the bottom bracket to get the sensor in, which is the same as any bike, then they can reassemble it. That only need someone to unscrew the plastic cover off the controller box, unplug the old connector and plug in the new one. Nothing could be simpler. It's nothing that you can't do yourself without the right tools, which you can get from Ebay for a fiver:

https://www.ebay.co.uk/itm/Bike-Bicycle-Cycle-Crank-Wheel-Puller-Remover-Repair-Extractor-Mountain-Tool-Set/282200322652?hash=item41b473325c:m:m6cOfykjoABA-2O-L-I4Jog
Sounds like more excellent advice, d8veh. I'll start to look later today for a replacement sensor from Kudos; hoping that the news I got a while ago from the place I got my bike, Fosse Electric Bikes in Leicester, that Kudos no longer make the specific Tornado bike doesn't also mean that the sensor isn't available. Assuming I can get it, I think I'll try my local shop fella as you say to see if he can fit it, if I'm not confident enough to do it myself by then.

As for those types of shops I tend to agree - they rarely fill me with confidence and their customer service is often appalling!

Thanks for the link too!
 
D

Deleted member 4366

Guest
It's a standard sensor that you can buy from anywhere, but if you get it from Kudos, at least the wires will match your controller without having to mess about. Give them a call. report back if there are any problems.
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
It's a standard sensor that you can buy from anywhere, but if you get it from Kudos, at least the wires will match your controller without having to mess about. Give them a call. report back if there are any problems.
Thanks again, d8veh. I've now ordered the sensor part (includes a mag disk too) via another company (don't have name in front of me, soz) who are shipping it to me. Sounds like what you've said; he said it's OK for all Kudos E-bikes.

I've now also text my local bike fella who said he can fix E-bikes but can't practice in the UK without a licence; told him that the part is on its way and advised him also that's it's unlikely that he needs this licence to carry out repairs. We will see what he says.

But, at least, if the sensor IS the issue and I can get it fitted then fingers crossed...

Thanks again for all your valued help & advice and I'll keep you posted. Cheers!
 
D

Deleted member 4366

Guest
If it's a standard pedal sensor, it will work on any bike, but there's no standard for the sequence they put the wires into the connector, so you need to check that before you connect. if it has heatshrink over the back of the connector, peel it back to see the colour of the wires and make sure it goes red to red, black to black and whatever the other colours are go together.
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
If it's a standard pedal sensor, it will work on any bike, but there's no standard for the sequence they put the wires into the connector, so you need to check that before you connect. if it has heatshrink over the back of the connector, peel it back to see the colour of the wires and make sure it goes red to red, black to black and whatever the other colours are go together.
Thanks d8veh. I've text my local bike fella; told him that I'm getting the part delievered, told him also that I've been told he doesn't need a UK licence to work on the electrics of an E-bike and asked him if he'll fit the part to which he said, yes. So thanks again, if it has a heatshrink area I'll let him know about the wires etc.
 

Drake-601

Pedelecer
May 13, 2018
34
5
52
Greater Manchester
If it's a standard pedal sensor, it will work on any bike, but there's no standard for the sequence they put the wires into the connector, so you need to check that before you connect. if it has heatshrink over the back of the connector, peel it back to see the colour of the wires and make sure it goes red to red, black to black and whatever the other colours are go together.
Hi d8veh - SUCCESS! I took the new sensor & mag plate to my local bike fella and although, for various reasons, it took just over 2 hours for him to fit with my (little) assistance; it was indeed the issue (a nick in the wire of the old sensor) and is now working just fine! He couldn't get the sensor QUITE as close to the new mag plate as the last one was and I expressed my concern about this before he secured all else and, so, he managed to get it a little closer. But, as I say, it's been working just fine since and thanks to your help at least I know what I'm talking about a lot more that I did before coming onto this forum.

You're an absolute star for all your advice and I can't thank you enough. CHEERS!
 
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