Looking for a decent ebike to buy, on a bit of a 'budget'

[Nealh]

One can't have an EAPC with twist and go or speed control device working post 2016 without a V5 certificate , one must only be able to pedal for the bike to move with assisted power.
250w rated motor and 15.5mph assisted cut off speed.

Any speed control device aka twist and go or so called thumb throttle work with 5v , the signal for activation is approx . 1v . The action is either off or on dependent on the magnet position with no inbetween fine feathering for speed.

 

[saneagle]

Thanks. I assume no commercial product exists where you can just plug in a throttle and PAS sensor in then feed the output to the throttle wire on the bike and have it so the throttle only works when the PAS sensor is registering pedalling? That would allow me to choose the amount of motor power very finely with the throttle, though should still be EAPC legal as I would just be setting the assistance amount and the throttle couldn't work (unless it was set up to work only as a walk assist) unless the pedals are being used. Seems like it would be a really useful piece of kit, the throttle on the bike allows for fairly fine adjustment and isn't as stop/go as simple pedal assist is.


If not I guess I'll have to test it with a multimeter and logic analyzer, maybe bring the bike round to a mate's place and use his oscilloacope if it's an alalogue signal. If I can get that worked out I can probably use a microcontroller to lock the throttle out until the PAS is activated. Expensive cadance (and especially torque) sensors are probably on par, maybe better than a throttle, though the cheap £15 one I got is an absolute widowmaker.

Feels like the EAPC regs were drafted by someone who has never used either a motorcycle, or ebike and have just come to the assumptive conclusion that throttles are bad because they seem too much like a motor vehicle, changing PAS settings (the LCD on the bike goes from 0 to 5) would require me to take my hand off the bar partially. Whereas a thumb or twist throttle still allows me to have full control and easy reach to the brakes, so having a system that meets the requirements, but is still safe and doesn't require purchasing a torque sensor and the tools to pull out the spindle on my bike is something I'd appreciate, even if I need to make it myself.

PS: Thanks for convincing me to not go for a 1kw+ motor, this geared hub motor definitely helps out and I'm probably getting better exercise too because I don't have a massive weight on the back wheel.

Throttle control is pretty well useless on an electric bicycle. Firstly, the pedalling and bumping while riding prevents fine control. Secondly, all controllers use throttles for speed control, not power control, so you still get aggressive starts. There is a device called a Cycle Analyst that allows you to map a throttle input to a sort of current control, but it's expensive.

You don't need any of that. Speed control controllers are shite. That's what you need to get rid of. KT controllers use current control, which solves all your issues and you don't need to fit a throttle unless you want to use one legally as a power override device.

 

[Nealh]

Just to clarify that which saneagle has touched on in the very last paragraph.
A legal power override device can be a so called thumb switch or twist and go switch( non can be regarded as throttles because they don't feather speed ) .
Uk law /regs state that power must be pedal first/pedal assisted , no speed switch allowed from a standing star.
Once one is moving then an override device can theoretically power one along up to 15.5mph but one may still have to rotate the cranks ( ghost pedalling) to keep moving .
The action is known as zero start and some systems can be set up for this to be the case , thus a fitted speed device not active from a standing start isn't illegal as it won't propel/assist the bike.

 

[Mr. B Ikeman]

Throttle control is pretty well useless on an electric bicycle. Firstly, the pedalling and bumping while riding prevents fine control. Secondly, all controllers use throttles for speed control, not power control, so you still get aggressive starts. There is a device called a Cycle Analyst that allows you to map a throttle input to a sort of current control, but it's expensive.

You don't need any of that. Speed control controllers are shite. That's what you need to get rid of. KT controllers use current control, which solves all your issues and you don't need to fit a throttle unless you want to use one legally as a power override device.

Note: While you're the quoted post, I'm not just responding to you, I'm weighing in on all of the responses so far and I really do appreciate them all.

I'll have to agree to disagree on the a throttle being useless, used to ride motocross and there was plenty more bumping and movement involved than that on a bicycle, even when I did downhill (albeit not to a significant competency level) motocross was always a rougher ride, a throttle allowed for plenty of fine adjustment. Not to mention trials bikes, which also use throttle control and require an insane amount of control over extremely harsh terrain.

It's that fine adjustment of a throttle that I like and the ability to instantly kill any and all power simply by lifting off my thumb. Been riding for just over a fortnight with a throttle and I've been able to make very fine adjustments, even over bad road surfaces (tree roots and the like pushing up pavement, which are pretty bumpy given the cheap suntour forks that can either be locked out, or half way bottomed out) and I'll admit the motor controller I have is probably dogshit and not designed to work (well) with a pedal assist, though I'd wager many (affordable, first time) ebikes are going to similarly skimp out on expensive controllers, making a pedal assist significantly more hazardous than a method of control that has been tried and true, in all conditions, for well over 100 years.


It really feels like some parliamentary type has had the "No throttles" law passed simply because that makes ebikes seem too similar to a motorbike in their head and has, at best, maybe been given a go on an extremely expensive high end ebike with an excellent pedal assist controller and not anything that would be described as entry level with a super sketchy pedal assist.

This isn't to say that I don't want to abide by EAPC laws, so a KT controller that can give power in the form of walk assist (3.7mph) for setting off then as I start pedalling and only unlocking the throttle when I'm pedalling is likely what I'll buy. That would be legal, right? Start off on the walk assist as I begin to pedal so there's no lag time between setting off and getting power to the motor.


As for how I ride, I don't do any ghost pedalling, I've been doing 6-12 mile rides daily and any time I'm pedalling I'm putting force onto the pedals. The motor does struggle on some of the hills even when I'm pedalling, though down-shifting helps with that. I'll only really use full throttle on hills and will need to pedal to supplement that, though the steeper inclines feel more like light slopes, only other time I use the throttle is when I'm a bit out of breath and need to be cycling at about 10 mph to stay cool, I'll still be pedalling, but not as hard, ie sitting down as opposed to standing and pedalling. Got the bike for a reason, that reason being I need to build up strength I my legs, would be pointless for me to want the motor to do all the work. Though as I've said, I live in an area with particularly brutal hills and I want to get out to good cycling spots, then get back. Given the miles I've been able to cover, over hilly terrain this motor should about do it, though swapping out the battery, controller and maybe getting a 250 watt motor if it produces more torque and less speed (I've already set the limit down to 15.5) are things I'm planning to do.

PS:
Saw that the government was given a chance to change their mind on it via a consultation (though I'd say the answers to a consultation are always pre-assigned, it was always going to be a no) and they shot that down. Kind of conflicts with their reqiests for net zero, better public health and getting people with mobility related disabilities more active.

 

[saneagle]

I'll have to agree to disagree on the a throttle being useless, used to ride motocross and there was plenty more bumping and movement involved than that on a bicycle, even when I did downhill (albeit not to a significant competency level) motocross was always a rougher ride, a throttle allowed for plenty of fine adjustment. Not to mention trials bikes, which also use throttle control and require an insane amount of control over extremely harsh terrain.

It's that fine adjustment of a throttle that I like and the ability to instantly kill any and all power simply by lifting off my thumb. Been riding for just over a fortnight with a throttle and I've been able to make very fine adjustments, even over bad road surfaces (tree roots and the like pushing up pavement, which are pretty bumpy given the cheap suntour forks that can either be locked out, or half way bottomed out) and I'll admit the motor controller I have is probably dogshit and not designed to work (well) with a pedal assist, though I'd wager many (affordable, first time) ebikes are going to similarly skimp out on expensive controllers, making a pedal assist significantly more hazardous than a method of control that has been tried and true, in all conditions, for well over 100 years.

I've been an ardent motorcyclist for more than 50 years. I know how motorbike throttles work. Ebike ones are different. You cannot get fine control on them, and it becomes a real problem when you have a powerful ebike. That's why devices like the Cycle Analyst became popular along with various other throttle taming devices.

Also, ebike throttles are all made of cheap plastic and they break very easily when you hit a bump while holding full throttle, leaving you unable to stop the motor from running at half speed unless you have reliable brake switches.

Lastly, throttles affect efficiency because whenever you increase it, it gives instant maximum power, which is wasteful, and the action of pedalling and the bumps cause you to be constantly moving the throttle position up and down. That's where bicycle throttle operation is different to motorbikes. When you press a pedal down, you have to pull on the handlebar at the same time to get the force. You don't do that on a motorbike - not even trials ones.

Many ebike controllers have cruise control, which has to be enabled in the settings, then, to activate it, you have to hold the throttle in the position of your intended cruise speed for 5 seconds, which is just about impossible if ever you try it, except for maximum, where you can hold it against the stop, as long as you don't hit a bump and break it in the meantime.

In the past when nobody cared and pedal assist functions were useless, to avoid all those issues, I used to make my own cruise controls for the throttles using a second throttle without a spring in parallel, a potentiometer in parallel with the throttle, or a friction device attached to the throttle. I wouldn't have gone to all that trouble if you could get satisfactory control of an ebike by normal throttle operation.

Thirteen years ago:

Home made Cruise Control

I had a bell that was not very good, so I cut the bell off and used the bracket that goes around the handle bar. I drilled a hole in a small piece of plastic and screwed it in from the top rather than how it was through the bottom. I then put the bell bracket on after the throttle and then...

www.pedelecs.co.uk

 

[sjpt]

Ebike ones are different. You cannot get fine control on them ...
ebike throttles are all made of cheap plastic ...
Lastly, throttles affect efficiency because whenever you increase it, it gives instant maximum power,

Is there any good reason why ebike 'throttles' are different? (I'll stick to the term throttle.)
Your arguments above are more about the limitations of the implementation of todays 'throttles' and controllers, rather than the unsuitability of ebike throttles.

You mention devices such as Cycle Analyst and your modified bell, but why are they necessary? Why not build a robust throttle and make the controller interpret the throttle input as current control? eg
current = selectedCurrent + throttle * (maxCurrent - selectedCurrent)
where selectedCurrent is the current the controller would give with given settings and no throttle attached,
throttle ranges from 0 to 1, and maxCurrent is the max current the controller can provide.

Probably a slightly more subtle formula with some appropriate non-linearities.

Given everything else a controller does, doing that seems a very easy extra; but you know much more than I do about the implementation of today's controllers so I await you clarifications.

 

[saneagle]

Is there any good reason why ebike 'throttles' are different? (I'll stick to the term throttle.)
Your arguments above are more about the limitations of the implementation of todays 'throttles' and controllers, rather than the unsuitability of ebike throttles.

You mention devices such as Cycle Analyst and your modified bell, but why are they necessary? Why not build a robust throttle and make the controller interpret the throttle input as current control? eg
current = selectedCurrent + throttle * (maxCurrent - selectedCurrent)
where selectedCurrent is the current the controller would give with given settings and no throttle attached,
throttle ranges from 0 to 1, and maxCurrent is the max current the controller can provide.

Probably a slightly more subtle formula with some appropriate non-linearities.

Given everything else a controller does, doing that seems a very easy extra; but you know much more than I do about the implementation of today's controllers so I await you clarifications.

Good suggestions. Unfortunately, manufacturers don't have the same ideas. Actually, the change to thumb throttles has made some improvement since the force through your arms goes to the grip, which is what breaks the twist type. The lever type only break when you drop the bike. There are controllers that can map the throttle to power control, but they're hellishly expensive.

Throttles and speed control pedal assists work fine on low powered bikes, where you hardly notice whether the power is on or off, but the higher the power the system gives, the worse it gets. When you have a motor with 90NM torque it can become a bucking bronco in the low gears or at startup.

Manufacturers like Bosch and Yamaha devoted a lot of effort to program their power algorithms to avoid that. Cheap Chinese hub-motor systems are a long way behind. there are a few OEMs using current control pedal assist, but the most you might get from the best of the rest is a ramp on the pedal assist power.

 

[Mr. B Ikeman]

Some interesting posts, some things I'm not understanding though.
"Throttles instantly give maximum power when increased"
Can you explain more? I'm using a thumb throttle and there's a very noticible difference between rolling my thumb over it slightly (holding the grips and rolling my thumb seems to give far more precise control than pushing it in, as I can easily lock my thumb up, basically treating it almost like a twist throttle and relying on the elasticity in my palms/gloves to allow for it to be turned as well as some flexibility in my thumb) and shoving the throttle down into the end stop. The controller/LCD also shows it ramping up and this is especially noticible when reaching about 14mph by pedalling and pushing in the throttle, even at max throttle it'll only give a tiny bit of power, but if I set the controller to 20mph or allow some speed to bleed off, it'll immediately allow the bike to floor it.
Is this more of a current instead of voltage control thing? I'd have to assume so, as I doubt the ESC and LCD I have are anywhere near high end.

Making a good (thumb) throttle can't be that hard. Even if it would need to be home made. 3d print it from carbon/glass reinforced filament, or order a metal 3d print/CNC'd version online, use a magnet and hall sensor. Similar for a twist throttle though it would likely need to be tougher, if my dirt bike throttles could survive plenty of hard landings as well as bike drops (at considerable speed, enough to rip the brake lever clean off, multiple times yet the throttle was always fine, the grips maybe not so much), an ebike throttle could too, even if it meant using a motorcycle (off road) throttle on an ebike and attaching the throttle cable to a potentiometer or hall and magnet setup back where the ESC is. If the ebike market is shite, adapt things from markets that see rougher use.
I mean, I can't be the only one who has thought of this, it's not a complex idea, so is there a huge barrier in the way I'm missing?

As for programmable controllers and ESCs, how on earth are they so expensive? End of the day it'd just firmware that gates some FETs or IGBTs, right? Surely there's got to be some open or semi open source ESC or LCD if the throttle input can be routed through that I can just plug into a PC and program. They were expensive parts a decade ago, though if I can find multi-horsepower inverter drives online at reasonable prices, surely there has to be an equivalent for ebikes.