The question is not how fast electric bikes go - it's how fast they are legally ALLOWED to go WITH electric assistance.
As long as you do the work by pedalling, an ebike can go as fast as you can manage. UK speed limits such as 30mph or even 50mph, don't apply to bikes, although if you exceed them you could be charged with dangerous or careless cycling under s28 and s29 of the Road Traffic Act 1988.
Some places, like London parks, have bylaws setting cycle speed limits - you do have to obey those. And they can be enforced - people have occasionally been fined for speeding in Richmond Park (magistrates ignored one accused's justification that police were hiding behind a tree).
How fast do electric bikes go with assistance?
The Electrically Assisted Pedal Cycle (EAPC) regulations say that ebikes must have pedals with the bike providing assistance only when you pedal - and above 15.5mph, ebikes must stop providing that assistance. Follow these rules, and the ebike can be used anywhere and like a normal bike.
Some off-road bikes have a button that removes that limit - the government says they don't count under the EACP regulations (which we think is ridiculous, especially as many models are imported or exported).
All this means mean that speedier bikes DO exist. EAPC-compliant ebikes are limited to 250W power output, but more powerful motors exist, which can propel the bike even faster or accelerate quicker.
These bikes are known as speed pedelecs, a category with assistance up to 28mph using a more powerful motor (typically 500W). Due to this speed, they count as a light moped (L1e-B) and so you'll need tax, insurance, mirrors, a strong helmet, a number plate etc.
This Stromer ST5, for instance, has a 850 W motor, costs £8,000 and couldn't be ridden in the UK like the picture - there is no number plate for a start.
Anything providing assistance faster than 28mph wouldn't be legal on UK roads.
Here are some of the models that you can buy in the UK that DO go quicker than 15.5mph, as well as their continuous power rating.
How fast can an ebike go?
This doesn't mean faster bikes don't exist - you can get models doing 50 or even 60mph. Obviously safety is an issue at those speeds and they aren't legal to ride in the UK.
The most extreme ebike is probably the Swind EB-01, which has a 15,000-watt rear-hub motor (and which Simon Cowell was riding when he broke his back). This is more of a rocket than an ebike though, although it does have pedals.
The rules in other countries can be different. EU rules match the UK's, whereas in the US there are three classes of ebike:
- Class 1 - 20mph limit (no throttle)
- Class 2 - 20mph limit with a throttle
- Class 3 - 28mph limit
Conclusion: Ebikes and speed
To sum up in the UK:
- An ebike can go as fast as you can pedal, as long as you do so safely.
- In terms of electric assistance, this can't be provided above 15.5mph on UK roads if you want the electric bike to be subject to normal bicycle rules.
- You can ride models giving electrical assistance up to 28mph but there are rules around bike and user safety.