Throttles on E-Bikes are legal in Britain. How and why?
There is a lot of misinformation on the web, where people claim throttles are not allowed on e-bikes. That's because the first legal definition of an-ebike comes from EU Directive 2002/24/EC, which was adopted by UK. Under that law, e-bikes were not allowed to use the motor without pedalling, and that's where all of pedal assist came from.
In 2019 DVLA has created a new category of low powered mopeds, L1e 250W LPM. They are basically the same e-bikes, but with throttles. There are a few requirements, such as a functioning kickstand and lights. Full details are avaliable in Motorcycle Single Vehicle Approval (MSVA) Inspection Manual.
“Because of the particular benefits for elderly and disabled users, pedal cycles providing electrical assistance without use of the pedals — usually called “Twist and Goes” — are included”
DVLA, UK
The basic fact is that DVLA examined the issue and legalised throttles on E-bikes. Why did they do that?
Because there is no scientific research showing that PAS has any safety benefits whatsoever. On the contrary, we have documented evidence of PAS causing crashes and accidents. At this point we can be fairly confident that PAS systems have killed a few people by sending them into an obstacle or off a cliff.
How does pedal assist work?
A traditional throttle tells the machine exactly how much power you need, and it’s on you to control it. Pedal Assist Bicycles have to monitor different sensors and guess what you are trying to do and how much power you need.
There are a few approaches, but 95% of bicycles on the market have a ‘Cadence sensor’ — it’s installed at the crank and measures how fast your are turning the pedals.
Pedals are a ‘noisy’ source of signal /information— they vibrate, move with bumps in the road, often they literally hit a rock or a curb. So you have to turn the pedals 20 degrees or so before the motor kicks in. When you start pedalling, and there is a significant delay before the motor kicks in. When you stop pedalling, there is a big delay before the motor stops.
No help in Uphill start
If you were going uphill and you stopped, you could get stuck — you can’t turn the pedals without the motor’s help, and the motor won’t start untill it detects pedals turning. A catch-22 situation.
No Speed control
Suppose the bike detects that you are pedalling slowly. The machine has no way to know if you want to maintain that speed, or if you are struggling to go faster, maybe uphill, and need help. That’s why most bicycles are programmed to give you maximum power at low speeds.
So if there is a grandma cycling right in front of you, the motor will try to speed up and crash into her.
If you own a decent e-bike, it will have a +/- control to set the level of motor power. Setting it low will allow you have good control of the bike at lower speeds. Then you have to mash the button again to speed up — it’s like a throttle but stupid.
If you rent e-bike from Lime or a similar rental company, you don’t have access to settings, there is nothing you can do, as soon as you start pedalling it will keep trying to crash you into the grandma.
How Pedal Assist Causes Accidents
If you stopped pedalling, pedal assist sensor takes time to realise this, and there is half a second delay before it cuts power to the motor.
The MORE you pedal the less the motor applies power. Once you learn to adjust to this, it becomes quite natural. However for many people it can be hard to adjust to. If you are mountain biking you almost certainly will want to disable the PAS system as nothing is worse than winding through the trees and having the bike accelerate you out of control into a tree.
For the woods, it’s throttle only
Mountain biker on e-bikes
To deal with this issue, we have to install sensors on bicycle brakes. When the sensors are triggered, they cut power to the motor immediately. We even have a practice for turning off the motor called 'feathering' - that's when you press the brakes just enough to actually start slowing you down.
What's the learning?
The conclusion is that PAS requirement needs to be removed from EU law, and we should require at level of scientific proof before we put requirements into law. We have produced an accident prone system just because someone wanted an e-bike to behave like a normal bicycle, and it made sence to them. In practice, it turned out to be a terrible idea.