Victoria Pendleton - levels of power too crude and abrupt

[Philclock]

Hello. We have a VP electric bike and though it is very good value (though heavy and crude in places) the power delivery is not good. The 3 power levels seem to be FULL power up until 5kph then cuts out, FULL power up to 10 kph then cuts out, or FULL power up to max speed then cuts out. Only the last one is usable because the drag from the motor when it's off is noticeable. What I would prefer is something like 33% power on all the time, 67% all the time or 100% all the time - is it possible to programme the controller or purchase a replacement to do that or something similar? (I guess what I really need is to spend a lot more cash on a torque sensing model?!). Thanks

 

[sjpt]

What you have is called a speed controller; what you want is called a current controller. Those are both variants of cadence sensor controllers; a torque controller is more sophisticated than even the current controller.

Speed controllers are the simples and cheapest, which is why many fairly basic bikes fit them.

It almost certainly won't be possible to change that bike for torque control. You may be able to change controller and display (for about £100??) and keep the battery and motor. I'm not sure about that model; somebody else will probably be able to post a more complete answer.

 

[saneagle]

The drag from the motor is an illusion. Lift the motor wheel off the ground and spin it. If it spins freely, there is no drag. If it doesn't, something is wrong.

The only way you can improve your power system is to fit a KT controller and LCD that uses current control instead of speed control. Cost is about £80 and you have to do a small amount of wiring and a bit of soldering.

 

[cyclebuddy]

Forum member @Bikes4two wrote about upgrading their Pendleton here.

 

[AndyBike]

there is no drag.

Drag isnt the best dsescriptive, but the effect is indeed there, it is tangable and has been pointed out by many riders.

On hub motors, the effect is from the internal gears COUPLED with the weight of the bike. After all 50-55lbs is a heavy old thing to get moving. On your bike the effect is simply from the added weight.
Just select a few gears up and you shouldn't notice it too much.

 

[saneagle]

Drag isnt the best dsescriptive, but the effect is indeed there, it is tangable and has been pointed out by many riders.

On hub motors, the effect is from the internal gears

It's an illusion. All geared hub-motors have a clutch. Most of them have the clutch between the motor and the axle so the motor and its gears are completely disengaged. Only the hub turns on the bearings just like any bicycle hub.

Even the hub-motors that have gears that turn with the hub, still disengage from the motor and there is very close to zero drag as I demonstrated here with a MXUS motor because when the motor freewheels the gears hardly turn. The ratio reverses so instead of turning at 5:1, it's 1:5. This is the motor spinning after power was switched off:

 

[AndyBike]

Lifting the wheel off the ground is an indicator of nothing. you have the weight of the bike and the rider too. Wheres that in the lift wheel up calculation ?.

 

[saneagle]

Lifting the wheel off the ground is an indicator of nothing.

It shows whether or not there's any drag unless you can find some new laws of physics, which should get you a Nobel prize!

 

[AndyBike]

It shows whether or not there's any drag unless you can find some new laws of physics, which should get you a Nobel prize!

It tells you nothing, unless you can measure drag by mind control.

Lift bike of ground, spin up motor and let it run, when it then takes time to slow and stop.
What is the time it takes to stop. Have you done testing by applying drag ?.

 

[Philclock]

Great info on current vs speed control - i will definitely look into changing that if it's not too drastic. There is definitely some drag, not much but more than zero and I have noticed it on every (cheap) electric bike i tried in the shop (i.e. lift up wheel and spin). It is so small I can imagine people saying it is practically zero, but even a tiny bit is annoying imho. If you spin a normal bike wheel it'll spin for 10 minutes - I have never seen an electric one do that. But that's a cheap bike for you, I don't expect miracles, but the motor control is noticeably very crude now I've owned it for a year or more. Like I say, even 33% assistance all the time would be far more helpful than 100% up to some slow speed then 0%, that's too crude and hard to keep a steady pace. The current control method sounds much more sensible. Is there a plug and play device or is it definitely soldering stuff? I don't mind I'm fairly handy/technically minded but obviously would prefer a simple way! (edit: I'll read the link, thanks!) Thanks again, really helpful forum cheers

 

[saneagle]

Great info on current vs speed control - i will definitely look into changing that if it's not too drastic. There is definitely some drag, not much but more than zero and I have noticed it on every (cheap) electric bike i tried in the shop (i.e. lift up wheel and spin). It is so small I can imagine people saying it is practically zero, but even a tiny bit is annoying imho. If you spin a normal bike wheel it'll spin for 10 minutes - I have never seen an electric one do that. But that's a cheap bike for you, I don't expect miracles, but the motor control is noticeably very crude now I've owned it for a year or more. Like I say, even 33% assistance all the time would be far more helpful than 100% up to some slow speed then 0%, that's too crude and hard to keep a steady pace. The current control method sounds much more sensible. Is there a plug and play device or is it definitely soldering stuff? I don't mind I'm fairly handy/technically minded but obviously would prefer a simple way! (edit: I'll read the link, thanks!) Thanks again, really helpful forum cheers

You only get significant drag on direct drive motors that don't have clutches. As I said, when Aikema and modern Bafang hub-motor motors freewheel, the only part turning is the hub running on two bearings, the same as any hub without a motor, and the bearings are more or less the same. If you get drag, it's more likely from a badly adjusted brake or incorrectly assembled axle hardware. Some bikes with rack batteries have the battery connector integral with the controller, in which case you have to unsolder it and solder the new one's battery wires to it and find some way of fixing it in place. You need to show exactly what you have if you want more precise guidance.

Did you watch the video I linked?

The new controller will only be plug-and-play if you're very lucky. Normally, there are one or two connectors to change and some settings to make in the LCD.

 

[Philclock]

You only get significant drag on direct drive motors that don't have clutches. As I said, when Aikema and modern Bafang hub-motor motors freewheel, the only part turning is the hub running on two bearings, the same as any hub without a motor, and the bearings are more or less the same. If you get drag, it's more likely from a badly adjusted brake or incorrectly assembled axle hardware. Some bikes with rack batteries have the battery connector integral with the controller, in which case you have to unsolder it and solder the new one's battery wires to it and find some way of fixing it in place. You need to show exactly what you have if you want more precise guidance.

Did you watch the video I linked?

The new controller will only be plug-and-play if you're very lucky. Normally, there are one or two connectors to change and some settings to make in the LCD.

Really appreciate the advice, I will investigate further.
But no, the wheel is no zero drag as the video shows, and I do understand why it should be in principle. It is not draggy like a rubbing brake block, more like if the grease was super think or something. Like I say, not awful, but definitely not zero and I spun a few wheels out of curiosity and they were the same... Maybe they have something chafing internally? A wire sheath? Bearings too tight? (I've never checked tbh, maybe that should be the next job !). Actually, the bike was from Halfords so maybe I should definitely check the bearings!

 

[Bonzo Banana]

Really appreciate the advice, I will investigate further.
But no, the wheel is no zero drag as the video shows, and I do understand why it should be in principle. It is not draggy like a rubbing brake block, more like if the grease was super think or something. Like I say, not awful, but definitely not zero and I spun a few wheels out of curiosity and they were the same... Maybe they have something chafing internally? A wire sheath? Bearings too tight? (I've never checked tbh, maybe that should be the next job !). Actually, the bike was from Halfords so maybe I should definitely check the bearings!

Every wheel has some drag and the weight of the hub motor may not be completely balanced plus sealed bearings can have drag at the seals. I think compared to direct drive hub motors and most mid-drive motors a geared hub motor is typically drag free effectively. Although I personally don't see an issue with direct drive or mid-drive drag really. The extra power of the motor nullifies all issues for me. Some people have welded the clutch of geared hub motors so they can use regen like a direct drive hub motor. So the gearing is always operating.

Personally I think a throttle is the best way of controlling that ebike. You simply operate the throttle when you need power and you vary it instantly to how much you want. It's the most efficient control system for an ebike and the most popular in the world. It also can massively extend range if you only use power when you need it. It can extend the lifespan of the battery pack (lowers average discharge rate) and keeps component temperatures lower. Ebikes that constantly use power even when you don't need it are pointless in my opinion. The most sophisticated computer on an ebike is in the rider's head and that computer can determine much more efficiently when power is needed.

 

[Nealh]

The percieved hub motor drag on a geared hub is purely the extra weight/mass centralised in the wheel that one must overcome when no power is used.
Unlike a normal bike wheel which has a small 200g spokes hub the motor can be anything form 1.4kg - 4.4kg , most OEM hubs will be 3kg or more so one has to over come the extra weight to rotate.
Simply use the lowest gears when riding unpowered and the bike will ride normally unless you have a hill then the weight and the extra central mass to move will show it self.

Any mass centrally positioned is harder to rotate then the same mass positioned equally on the outer circumference.

 

[Bikes4two]

Hello. We have a VP electric bike and though it is very good value (though heavy and crude in places) the power delivery is not good. The 3 power levels seem to be FULL power up until 5kph then cuts out, FULL power up to 10 kph then cuts out, or FULL power up to max speed then cuts out.

Yes, we had the same bike and issue - the joys of a 'cadence sensing' motor system - NOT!

As mentioned in post #4, I changed the controlled to a 'simulated torque' KT controller and it transformed the ride experience to something much more enjoyable. The price of the bits then was around £80 so a bit more now I'd think but worth every penny to take a bike from a 'dog of a ride' to something much more enjoyable IMHO.

 

[Philclock]

Every wheel has some drag and the weight of the hub motor may not be completely balanced plus sealed bearings can have drag at the seals. I think compared to direct drive hub motors and most mid-drive motors a geared hub motor is typically drag free effectively. Although I personally don't see an issue with direct drive or mid-drive drag really. The extra power of the motor nullifies all issues for me. Some people have welded the clutch of geared hub motors so they can use regen like a direct drive hub motor. So the gearing is always operating.

Personally I think a throttle is the best way of controlling that ebike. You simply operate the throttle when you need power and you vary it instantly to how much you want. It's the most efficient control system for an ebike and the most popular in the world. It also can massively extend range if you only use power when you need it. It can extend the lifespan of the battery pack (lowers average discharge rate) and keeps component temperatures lower. Ebikes that constantly use power even when you don't need it are pointless in my opinion. The most sophisticated computer on an ebike is in the rider's head and that computer can determine much more efficiently when power is needed.

I totally agree. My only concern is if there was (God forbid) a serious road traffic accident then the insurance companies (e.g. of a car driver) may point out the illegal use of a throttle and wriggle out of paying...

 

[Philclock]

Yes, we had the same bike and issue - the joys of a 'cadence sensing' motor system - NOT!

As mentioned in post #4, I changed the controlled to a 'simulated torque' KT controller and it transformed the ride experience to something much more enjoyable. The price of the bits then was around £80 so a bit more now I'd think but worth every penny to take a bike from a 'dog of a ride' to something much more enjoyable IMHO.

Really good to know thanks, it is now on the definitely to do list... behind about 258 other items

 

[Philclock]

The percieved hub motor drag on a geared hub is purely the extra weight/mass centralised in the wheel that one must overcome when no power is used.
Unlike a normal bike wheel which has a small 200g spokes hub the motor can be anything form 1.4kg - 4.4kg , most OEM hubs will be 3kg or more so one has to over come the extra weight to rotate.
Simply use the lowest gears when riding unpowered and the bike will ride normally unless you have a hill then the weight and the extra central mass to move will show it self.

Any mass centrally positioned is harder to rotate then the same mass positioned equally on the outer circumference.

Appreciate the help but this isn't true in my experience: I'm not talking about the effort to move or rotate the hub. I'm talking about the wheel being spun up (as in the video, off the floor) and it then slowing more quickly than a normal hub due to some drag. Most cheap hub motors I've looked at in the shop have a little drag. Not a lot, but you tend to notice 'not a lot of drag' on a push bike .

It also isn't the case that mass in the central hub has the largest effect, it is the other way round in that mass on the outer edge of the wheel would be felt more clearly as inertia (or greater angular momentum). If this perceived drag was just angular momentum then the trade off would be it would carry that momentum for a longer time and spin longer, so the effect would fine. E.g. harder to accelerate up to speed (due to angular inertia) but carried the speed for longer (angular momentum higher). What I'm describing is just drag.

 

[Bikes4two]

Personally I think a throttle is the best way of controlling that ebike. You simply operate the throttle when you need power and you vary it instantly to how much you want. It's the most efficient control system for an ebike and the most popular in the world. It also can massively extend range if you only use power when you need it.

• I'm with you on only applying power when you need it for the benefits you describe
• I was out last week with a group doing a ride that was a bit longer than the range I knew my battery would give me
• I have a tsdz2 with the simple vlcd6 display which places the controlling buttons within thumb reach whilst on the handlebar grips, so it was easy to go to zero assist (not off) and back up again when needed.
• So for the first time I rode parts of the ride with zero assist (the flat or slightly down hill bits) and on returning home after 60 miles I was amazed to see how much there was left in the battery.
• Normally I'll get around 45 miles in ECO mode but I reckon I'd have been good for 75+ that day as average consumption over the whole ride was around 4Wh per mile vs 6.5 to 7Wh per mile.

 

[Philclock]

• I'm with you on only applying power when you need it for the benefits you describe
• I was out last week with a group doing a ride that was a bit longer than the range I knew my battery would give me
• I have a tsdz2 with the simple vlcd6 display which places the controlling buttons within thumb reach whilst on the handlebar grips, so it was easy to go to zero assist (not off) and back up again when needed.
• So for the first time I rode parts of the ride with zero assist (the flat or slightly down hill bits) and on returning home after 60 miles I was amazed to see how much there was left in the battery.
• Normally I'll get around 45 miles in ECO mode but I reckon I'd have been good for 75+ that day as average consumption over the whole ride was around 4Wh per mile vs 6.5 to 7Wh per mile.

I like this idea too. Are you worried that if there was an accident then any insurance companies involved might point out you are actually riding an uninsured illegal motor vehicle? (i.e. independently powered, not power assist)?