Primarily known in the U.S. for
their line of performance motorcycle
sprockets, Sunstar is a large company
with a varied product catalog. It now
has two e-bike mid-drives that retrofit
to existing bicycles. In architecture, it
looks something like the Bafang BBS.
The unit looks very well-made, but the
website only shows dealers in Europe.
It is easy to see the vast experience
that Yamaha has in building motorcycle powerplants that they have applied
to their clean and compact mid-drive
motor. While Yamaha 250-watt drive
units, battery shape and switch design
are all unique, the basic design parameters of the center-mounted drive unit
is very similar to the Bosch design.
The Yamaha is capable of using two
front sprockets and a front derailleur, so it can have a very wide range
of gears. Yamaha claims 70 Nm of
torque. We expect to see Yamaha-powered e-bikes in the U.S. in 2016. ■