Quoting Zog The Undeniable :
I have a pair sitting around in the spares box. I never thought they
had any more power than regular brakes when I used them (they came with
a bike).

On a normal bike, of course, any decent rear brake will lock the rear
wheel and the SE cantilevers offer no advantage.

However, on a tandem the cable run is much longer and the potential
maximum rear braking is much greater because the centre of gravity is much
further behind the rear wheel but no higher off the ground. That's the
real use of these brakes.
--
David Damerell flcl?
Today is First Gloucesterday, June.