> > I have a 26.6 seatpost, labeled "JPR"...
> > Curious about any history; especially any
> > reputation for breakage.
I saw these in many French bike shops when I was over there in 1983. A bit later - i.e. 1985 - I bought a Peugeot that came with one.
In my experience, these posts are strong enough but the
clamp uses an inferior design which does not have sufficient
grip on the seat's rails. So the seat will have a tendency
to slip, especially if you try to mount it offset towards the
rear. I weigh about 125 pounds - so I imagine this problem
would be even more pronounced for heavier riders.