putting on the assist, and arrows appear at the top of the
display to suggest you shift up or down for the best performance and efficiency.
Yamaha has a nice display as well with much of the same
information. There are no shift arrows, but there is a screen
that shows speed and your pedal rpm, and that is a helpful
number to have on hand. The three assist levels are eco+/
eco, standard and power. The handlebar control unit has buttons that are smaller and a little harder to hit than the Bosch,
but it is compact and appears to be tougher than the Bosch.
To help keep things simple, all Bosch-assisted Haibike
models are Xduros and Yamaha-assisted models are the
Sduro bikes. While the Xduro Trekking RX uses a Shimano
Deore XT 1x10 drivetrain, the Yamaha-assisted Sduro
Trekking RC runs with a Shimano Deore XT 2x10 drivetrain.
ABOUT THAT POWER
Bosch rates the assist motor at 350 watts and 60 N/m of
torque, while Yamaha rates the PW-System at 250 watts, but
the torque is rated at 70 N/m. With any mid-drive there is a
range of cadence or pedal rpm where the assist provides the
best support. If you pedal too fast, you feel the assist fall off.
The Yamaha assist is supposed to stop at 80 rpm, but to us,
it felt happier at 65 rpm. The Bosch has a wider and less critical range of pedal rpm. Pedal too fast on either bike and you
are wasting energy and not getting much help.
The Yamaha is a zero-cadence motor, and as soon as you
hit the pedals, you will feel the assist. Bosch assist begins at
just over 20 rpm, but it senses whether the crank speed is
fast enough for assist, so in practice the assist has very little
hesitation. Yamaha managed to make the response to pedal
input instant yet smooth and easy to control. Riding with the
Yamaha motor is a very bicycle-like experience: you push
harder on the pedals, you get more help.
The Sduro’s 20-speed drivetrain complements the assist,
but you are doing serious climbing for the street if you are
using the small front sprocket. When the going is very steep,
you may not climb as fast on the Yamaha, but it just keeps
on climbing as long as your feet are moving. You definitely
shift more often than with the Bosch. The small front sprocket works great for climbing, but when the terrain is milder, the
Yamaha’s bigger front chainring lets you keep a better pace
with less shifting.
WHAT ABOUT BOSCH?
Bosch’s system has a smile-inducing surge to the initial
assist that is addictive. Not only does it feel faster than the
Yamaha, it is. We would say the highest level of assist for the
Yamaha is equivalent to the sport setting on the Bosch, but
Bosch has the turbo setting that is a substantial step up from
sport. On the Yamaha we rarely used assist levels other than
the highest, with only some use of the standard setting. While
we didn’t use eco much on either bikes, we used all the other
modes quite often. Until the climbing gets truly steep, the
Bosch has more response than the Yamaha. However, the
Yamaha has a lower first gear, and if you can just keep those
legs moving with even minimal pressure on the pedals, it just
All of our riders spent most of
the time riding the Yamaha-assist Sduro at full assist. With
two front chain ring the Sduro