My conversion has a throttle, I rarely use it, but the option is there. Where I do use it is for hill starts, to cover that second or two before the pas kicks in. The other circumstance is for a fast get away from a busy junction, not often here 'cos I live in the country. The third is if I've stopped in the wrong gear - that's the advantage of having a hub motor.
You're making the assumption that folk only want a throttle so they don't have to peddle, this is not the case. There are those, with lung capacity issues or stamina problems etc. , who can use the throttle and not peddle.
As to legality - any bike manufactured before Jan 1st 2016 can have a full acting throttle in the UK.
There is no prohibition on throttles on kits (in the UK), this is because the legielation omits to mention them. So, any self converted bike can have a throttle. Any manufactured bike cannot be supplied with a throttle fitted but the rider can fit one themselves as this technically turns it into a self made bike.
Messy ain't it? This is what happens when politicians get involved in something they have no practical experience of.
As far as I can see the OP had to go through the type approval procedure because they are a manufacturer. I don't know what that means that the item for sale is actually classed as.
Who knows? Who gives a ****? I just want to ride my bike, in peace, with a bit of help for my ageing carcass.
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