There are two main types of e-bike currently on the market: with
the motor built into the rear hub, or with the motor tucked inside
the bottom bracket area and powering via the cranks.
There are pros and cons to both approaches. The hub based
systems tend to be the lightest (adding only around 3.5kg to the
total weight of the bike), and make it easier to incorporate a
front derailleur, but are possibly less flexible. You can't simply
swap wheelsets around at will.
The BB-based systems tend to be a little heavier, and the need
to encapsulate the motor within the frame leads to slightly
chunkier framesets. It's also a little tricker, although not
impossible, to build them with a 2x drivetrain (i.e. front
derailleur) due to the added width. But they do allow you to swap
wheels at will, and can provide more torque/power.
You may also see kits to convert an existing bike into an
e-bike, usually by a bolt-on motor which drives the front wheel by
friction. These are more of a novelty, fine for occasional use
around town but too inefficient and unreliable for long
distance/long term use.
Batteries are typically hidden away within the frameset,
although many bikes will accept an additional frame-mounted
external battery for extra range. Charging will usually only take
around 5-6 hours, and there are no issues with 'topping up'. If
you're likely to struggle to get your bike close enough to a power
point it's worth looking out for a model with an easily removeable
battery, such as the Trek Domane+.
The range that the battery will give you is hugely variable,
depending on the terrain you're riding, the level of assistance
chosen and your own riding style (and weight!). You can expect
anywhere from 20 to 100 miles of assistance on a 'standard' e-bike
with a single integrated battery - but remember that you're
unlikely to have it turned on for the entire ride; those aren't
'continuous' miles. So even the longest days in the saddle should
be achieveable on a single charge (and if the battery does run out,
the bike will still ride fine).
Power assistance levels are variable, usually via a button on
the top tube, or sometimes via a controller mounted on the bars.
Either way the operation is the same - you can choose more or less
assistance depending on the terrain and how you're feeling.
Naturally using a higher setting will eat through the battery more
You might hear talk of a "speed limit" on e-bikes, but this is a
bit of a misnomer. Think of it more as a 'cap' on assistance. UK
regulations mean that power assistance can only be applied up to
15.5mph on a bike that'll be ridden on road. Otherwise it would be
classed as a motorised vehicle and require licensing, taxing, etc.
This applies to any bike that might see even the briefest use on
the roads, including MTBs.
You can still go just as fast as you want - the assistance
simply stops beyond that point, but the bike can be ridden as fast
as you, and the gearing, allows - just like any conventional
Early motor systems had two main drawbacks; the power assistance
would stop abruptly when the speed limit was reached, making it
hard to maintain a smooth cadence and causing issues with gear
selection, and when not in use the motor could produce drag on the
drivetrain, actually making it a little harder to pedal. Both of
these issues have been addressed in the current range of systems,
and any of the latest mid and high end models will essentially ride
just like a 'normal' bike.
Of course correct fit is every bit as important on an e-bike as
on any other road bike, and that's why we always start with a bike
fit to establish which model will work for you. Bikes with
hub-based motors will usually be the same geometry as their
non-powered equivalents, whilst BB-powered bikes will often have a
slightly longer wheelbase and rear triangle due to the added size
of the motor (although the actual fit geometry - i.e. the contact
points - often remain the same). But don't worry, we sort all of
this for you, it's all part of what makes Bespoke unique.