Newbie - Advice required on conversion legals please?

[flecc]

It appears that there's been a turn round of opinion on what i was actually saying about the throttle law.

No turn around, we've known the law very well as it's developed and as I've shown with dates and details. In my own case I've watched the law relating to assisted bikes since joining the trade in 1950. What you were asking about was confusing since it was a mixture of the law on construction, the law on usage, manufactured bikes and kit bikes.

As you've seen they are all different cases, according to which law affects them, so there is often no single answer to a question.

Another Kiwi posted to you "Don't try riding it on the continent". What he meant was that the mainland EU countries use a strict interpretation of the law, no throttles usable over 6 kph. That certainly has the benefit of simplicity, their bikes have no throttles and their forums don't have these discussions.
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[Deleted member 4366]

Throttles are optional on many bikes. You should always ask the dealer about them. Some bikes, like some Wispers and Freegos are fitted with a 4 mph throttle that can be set to full range. Others, like Oxygen, have the connector for the throttle on the handlebars and they provide the throttle in a box with the toolkit for you to fit yourself if you want.

You don't need a throttle, but they are useful at times, so I'd always have one on my bike.

 

[Woosh]

You should always ask the dealer about them.

their usual reply is 'throttle is made illegal since 2017'
That's simple enough!

 

[Brummie]

No turn around
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Then i'm sorry to say that i'm confused again.

My understanding is that I'd been asking why a throttle on a new UK EAPC couldn't be legal if the control system constrained it's operation to ensure all EAPC rules were still met, and everyone appeared to disagree with me.

I thought that your post 34 was the turnaround when you understood what I had been describing all along, and you equated it to being no real difference to a multi-level power control (which is legal and operable under the same conditions that I'd been describing).

The only difference is that the throttle (or power controller) that i'd imagined may have a greater resolution than increments of most power level controllers and be more ergonomically accessible.

I'm not trying to be clever or pedantic, this is my genuine understanding.

 

[tommie]

If a throttle causes you such distress, you can always chuck it in the bin and use your ebike like the rest of us, the PAS power settings do virtually the same job.

`mountain` and `molehill` spring to mind.

 

[Brummie]

Thanks for the advice on where to try an ebike. I've just come back from Halfords having tried a few rear hub versions (some weird and some conventional MTB style). I was impressed with the performance until they reached 15mph when I tried to cycle faster but the gearing was just too low on them all!
The other thing i noticed is that you definitely need to drop the power level in low speed areas else it keeps kicking in/out (all or nothing)

 

[Brummie]

If a throttle causes you such distress, you can always chuck it in the bin and use your ebike like the rest of us, the PAS power settings do virtually the same job.

`mountain` and `molehill` spring to mind.

Thanks. It doesn't cause me distress, I'm enjoying the learning. I think I'm going to get one on a conversion where it also appears less controversial. You may not have noticed from a previous post that I used to cycle 5/6 years ago and I'm recovering from an injury. Whilst I hope to pedal, I may need to rest from pedalling and a method of back-up when If I can't pedal. Does the system that you describe permit different power levels without having to pedal?

 

[flecc]

Then i'm sorry to say that i'm confused again.

My understanding is that I'd been asking why a throttle on a new UK EAPC couldn't be legal if the control system constrained it's operation to ensure all EAPC rules were still met, and everyone appeared to disagree with me.

Some of us are cautious because so many come in with the similar question and try to manoeuvre an admission that throttles are ok when they aren't. Your inquiry initially looked like that again.

As I posted earlier, the power phase down condition cannot be met with a continuous acting throttle that is under the rider's control, so the EAPC rules are not met. The condition can be met with multi-level switched control since the phasedown can be on the final fixed power level.

I mentioned the EU's strict interpretation because it is that law we adopted in 2015, so the spirit of that is no throttles allowed.

Fortunately e-biking is on such a small scale here compared with mainland Europe that we are not policed in the same way. But I can't say to anyone that a throttle is legal without knowing the exact case in question. There are too many variations according to bike and age.
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[tommie]

Possibly the ones you`ve tested so far have been of the `torque` sensored variety whereby you have to keep putting a certain pressure on the pedals to make the motor work.
Mine are `cadence` sensored where no pressure on the pedals is needed just a tiny movement forward on the pedals will activate the motor and go to your chosen PAS level, (PAS1 - 9 in my case)
"I'm recovering from an injury and I may need to rest from pedalling."
In your case possibly a cadence system would be best...

 

[flecc]

Whilst I hope to pedal, I may need to rest from pedalling and a method of back-up when If I can't pedal. Does the system that you describe permit different power levels without having to pedal?

Ah ha! So you were trying to find a dodge around the law after all. Our suspicions were right.

The cadence system that Tommie mentioned only requires twirling the pedals without putting in any effort, basically simulating pedalling to look like compliance. But power still cuts when pedal rotation stops.
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[Deleted member 4366]

As I posted earlier, the power phase down condition cannot be met with a continuous acting throttle that is under the rider's control, so the EAPC rules are not met.

That's another point of the various regulations that isn't tied down. It's an idea, not a regulation.

All power phases down when you switch it off. Even when you say "gradually" phase down, that has absolutely no meaning without defining a gradient, so anybody can ignore that requirement. The only thing you need to do is make sure that you get no power above an actual 25km/h, and you'd most likely be able to get away with 27.5 km/h (25km/h +10%).

Also hub-motors consume a fixed amount of power up to a certain RPM, which is regulated by the controller's maximum current, though the power output increases up to that point. That point is where the unregulated power consumption, which decreases from very high to zero as the back emf opposes it to the point where the back emf regulates the current instead of the controller. That point depends on the motor Kv, voltage and controllers maximum current. In many cases it's at a speed (rpm) less than the 25 km/h cut-off, so your power is already "gradually" reducing before the cut-off.

Basically, the current would be a straight line ramp following an equation

Current =A-CN, where A is the current at zero RPM, C is the back emf constant (Kv) and N is the speed in rpm.

But the controller regulates say a maximum current of 15 amps, which means the first part of the graph would be truncated by a flat line of A=15

All explained here in the first graph:
https://endless-sphere.com/w/index.php/EBike_Efficiency

 

[Brummie]

Possibly the ones you`ve tested so far have been of the `torque` sensored variety whereby you have to keep putting a certain pressure on the pedals to make the motor work.
Mine are `cadence` sensored where no pressure on the pedals is needed just a tiny movement forward on the pedals will activate the motor and go to your chosen PAS level, (PAS1 - 9 in my case)
"I'm recovering from an injury and I may need to rest from pedalling."
In your case possibly a cadence system would be best...

The bikes that I tested were pedal movement sensing and appeared to deliver the full power set level at the slightest pedal movement (however slow I pedalled). There was no proportional control about it (either crank torque or cadence). I guess from what your saying, that the system you describe requires the guarantee that you to be able to pedal at varying levels, and that would cause me distress!
I'm pleased for you that you are lucky enough to be in the 'most' category and able bodied enough to use the system you've suggested that may not ideal for the 'minority' few million. Thanks for your suggestion anyway!

 

[flecc]

The only thing you need to do is make sure that you get no power above an actual 25km/h, and you'd most likely be able to get away with 27.5 km/h (25km/h +10%).

Yes, the DfT have confirmed that the usual 10% tolerance applies, so up to 17 mph power assistance is ok.
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[Brummie]

Ah ha! So you were trying to find a dodge around the law after all. Our suspicions were right.

The cadence system that Tommie mentioned only requires twirling the pedals without putting in any effort, basically simulating pedalling to look like compliance. But power still cuts when pedal rotation stops.
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I may have misunderstood. Please explain how the different torque levels are achieved by just twirling the pedals. I hoping to be able to pedal all the time that I need torque. I just don't want to be obliged to pedal at an uncomfortable cadence or force to achieve the different levels of torque required if my injury doesn't feel up to it.
I'm not deliberately trying to dodge the law. Providing I can achieve the functionality I need, I prefer to maximise the opportunities within the law. I can see how a ergonomically positioned good resolution power controller (otherwise known as a throttle) may help me on this.
I'm not sure and sorry for what's happened in the past but please don't treat me with suspicions of being devious. I assure you of my best intentions.

 

[Woosh]

I hoping to be able to pedal all the time that I need torque. I just don't want to be obliged to pedal at an uncomfortable cadence or force to achieve different levels of torque required if my injury doesn't feel up to it.

you need to experience the difference between a torque system and a (rotational) pedal sensing system.
A torque system requires you to input a fixed percentage of the energy required, typically 25%, 33% or 50%. It is a fantastic system to keep you fit but may put too much stress and strain on your legs. A rotational system lets you pedal as much as you like. As long as you can pedal a bit, you should be able to use the power to climb hills, even steep hills.
It seems to me that the latter is better for you. The cadence has no effect on the amount of assistance you can get from the motor. How steep a hill you can climb depends on the torque of the motor.
On torque, we use 3 motor sizes in hub motors and two motor sizes in crank drives to suit different riders weight and terrains. If you weigh more than 16st, the Big Bears with 160mm BPM motor would be best, between 12st and 16st, the Rios with 140mm SWX02 motor which weighs 1kg less but still give 90% of the torque of the BPM would be a good choice, below 12st, the 120mm SWX is more or less the most popular choice for the industry. All the bikes you saw at Halfords are in this category.
The crank drives let you leverage on the bike's gearing to trade between torque and speed and to climb even steeper hills with the same combo battery and controller. The drawback is you must use the right gear and keep your cadence fairly high, systematically above 60RPM to be nice to your motor.

 

[tommie]

The bikes that I tested were pedal movement sensing and appeared to deliver the full power set level at the slightest pedal movement (however slow I pedalled). There was no proportional control about it (either crank torque or cadence). I guess from what your saying, that the system you describe requires the guarantee that you to be able to pedal at varying levels, and that would cause me distress!
I'm pleased for you that you are lucky enough to be in the 'most' category and able bodied enough to use the system you've suggested that may not ideal for the 'minority' few million. Thanks for your suggestion anyway!

possibly you`re misunderstanding,
as long as you move the pedals forward slowly the motor will input whatever power level you`ve selected, it doesn`t need any pressure from you on the pedals as it does with a torque based system. Think of it as if you would sit on a bike with the chain off, it`s easy to turn the pedals then, right?

 

[Brummie]

possibly you`re misunderstanding,
as long as you move the pedals forward slowly the motor will input whatever power level you`ve selected, it doesn`t need any pressure from you on the pedals as it does with a torque based system. Think of it as if you would sit on a bike with the chain off, it`s easy to turn the pedals then, right?

Isn't that the less convenient poor resolution throttle that people call a power level controller?

 

[flecc]

I may have misunderstood. Please explain how the different torque levels are achieved by just twirling the pedals. I hoping to be able to pedal all the time that I need torque. I just don't want to be obliged to pedal at an uncomfortable cadence or force to achieve the different levels of torque required if my injury doesn't feel up to it.

Forget torque control, that is a different system that needs effort put in to get power, but it's usually combined with a cadence sensor that demands pedal rotation.

Cadence control only needs the pedals to rotate at any speed for the motor to run. You said above that you've tried some like that, turn the pedals and get instant power. The cheap ones give full power instantly which is disconcerting.

The sort that would best suit you is like the cadence one Ezee used to have on their e-bikes. Turn the pedals with or without effort to get the power to run, but with a twist throttle to regulate how much power you get. I've owned two of those.

They are currently not on sale here, but perhaps someone knows other makes with this system.
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[Brummie]

The sort that would best suit you is like the cadence one Ezee used to have on their e-bikes. Turn the pedals with or without effort to get the power to run, but with a twist throttle to regulate how much power you get. I've owned two of those.
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Thanks. But that's EXACTLY what I've been describing all along that caused all the kerfuffle. Are you playing me up now?
Anyway... If my understanding is correct, I can have a fully active throttle on a conversion kit anyway!

 

[Woosh]

Isn't that the less convenient poor resolution throttle that people call a power level controller?

you need to experience a bike with throttle to appreciate the difference.
The assist levels are programmed via the LCD in two ways, current and speed. The users don't often get to change the parameters but for the sake of clarity, let's assume they can. A bike with a Bafang BBS01 is in this category. You can program the number of levels, 3 to 9 or even more. More is certainly inconvenient. 5 is about the right number of assist levels. For each level, you set a percentage of maximum power, for example level 1 @ 40%, 2 at 50%, 3 at 70% 4 at 85% and 5 at 100%. At each level, you can set the ramp of power, which depends on the cadence and the speed. The controller is programmed to take you to a set speed as quickly and smoothly as possible.
On the other hand, the throttle delivers a voltage to the controller, between 0.5V and 4.5V. 1V gives you 25% of maximum power. It is a very intuitive power tap.
The maximum power is equal to Voltage of the battery * the maximum Amp rating of the controller * motor efficiency at the speed you are riding at.
That's why I said in an earlier post, you should not believe in the marketing hype of the 1000W motors. A 36V battery when fully charge delivers 41.5V, if your controller has a maximum Amp rating at 17A and your motor is in sweet zone, its efficiency is around 85%, the amount of mechanical power at your command is 41.5V * 17A * 0.85 = 600W mechanical at your rear wheel and it is legal for you to use until you hit 15.5 miles or the set speed whichever the lower.