When I first switched over to rear disc brakes on my Xtracycle I got
the 203mm rotor kit from Xtracycle, which came with the caliper
protector. I had my bike shop install everything, but they could not
get the protector to work as it was.
When they told me about this they told me it might have been possible
the company sent me a rear derailleur protector instead of a disc
brake protector. I called Xtracycle to clear things up, and at that
time I was told the caliper protector Xtracycle sells IS in fact just
a slightly modified rear derailleur protector and the way it is
modified is by bending it in a specific manner. They said it may very
well be possible someone on their end of things just neglected to bend
the "caliper protector" before it was sent out to me.
Previously my bike shop actually said they thought they could get it
to work by bending it, but wanted to check with me first. After I
spoke with Xtracycle I then just gave my bike shop the go ahead to
bend it to get it to work right. Ever since then things have been fine.
If you decide to bend it yourself or have your bike shop bend it for
you, just make sure they do not apply the force to bend it while it is
mounted on the bike. That could potentially damage the frame or mount,
Good luck and ride safe,