It's a bit of a UK turn for Thorn but I suppose they have to move with the times. Quote from a previous brochure.
Please don’t ask for a disc brake on
steel forks, we simply won’t do it!
We use raked blades, these are exceptionally comfortable, they will
withstand the forces of cycling (and have done so for generations) but
raked forks will not withstand the forces generated by a disc brake,
which are very different to the forces generated by V brakes, even at
the same rate of retardation. We have seen 3 ways that other
manufacturers have “accomplished” this, they all seem stupid to us
(1) We have had customers complain that a well known custom
builder’s raked steel forks have permanently bent under braking.
(2) We have seen hideously uncomfortable, thick walled, straight
blades used by another manufacturer, these forks don’t fail, but I
expect that an owner’s hands and elbows soon would!
(3) The most ridiculous “solution” of all, is a heavy left blade and
lighter right blade. The different blades must have different elastic
properties (isn’t that supposed to be the point?) and therefore the
axle must twist, when a bump is hit. If the axle twists, then so must
the front wheel. If the front wheel twists, then the bike consequently
alters course.
Isn’t hitting bumps comfortably and safely the main function of
a bicycle’s fork? Why compromise comfort and safety, in order
to fit a brake, which is inferior, in the conditions that the steel fork
will be used in?
