Roger Zoul writes:

This is my bike:

http://www.specialized.com/SBCBkMode...u ybug.j27008

I take it you meant:

http://tinyurl.com/2lo5v

which I bought last September. I had about 200 miles on it until
April 17, now I have almost 800 miles. I've been riding a fair
amount recently.

My bike has these wheels:

"Rolf design 700c twin spoke design high performance wheel set"

I don't know anything about Rolf but I'm getting a notion that they
are somehow designed for speed.

Not really. They are designed to make you think of speed, the
difference being only measurable with a stop watch at maximum effort.
They aren't lighter nor are they pleasant to ride in winds.

I weigh 235 to 240 lbs.

Work on that.

Last Tuesday, after riding 30 miles, I popped a spoke on the rear
wheel and it got out of true. I got it fixed on Wednesday at the
LBS. I did another 30 miles on Thursday, no problems, but the route
was fairly easy in terms of hills. Today, while on a ride at about
25 miles out, I popped another spoke on the rear wheel on a route
similar to the first one, but longer. I ended up walking home. The
LBS fixed it and trued the wheel again. The folks over in .misc
think that these spokes ought not to be popping and that I should
have the wheel rebuilt (I don't know what that means yet).

The owner of the LBS told me today that she thinks I ride up hills
in too high a gear, and doing so puts a lot of stress on the rear
wheel. I generally ride up hills (there are a goodly amount of
hills here in upstate SC - Greenville) according to cadence, trying
to keep it at or above 60.

The guy doesn't understand bicycles. The torque in a rear wheel is
independent of gear ratio for any given speed in the flat and is
smoother with lower peaks for hill climbing in big gears (low
cadence). Therefore, he is making this up as a cover for his poor
wheel building. I suspect he doesn't understand stress relieving
spokes after building a wheel.

I do end up shifting down as I go up the hill, as it's sometimes
hard to know what gear I really need to be in (I find hills
deceptive -- some look really hard but turn out to be easy while
others look easy but turn out to be hard -- what's up with that?).

I think you are confusing the effects of short hills with long ones,
or ones that you approach rested or already near your limit. RR
under- or over-passes are steep hills but insignificant as climbs.
All that has nothing to do with the reliability of your wheels. Just
the same, low spoke count wheels are not as durable as conventional 36
spoke road wheels.

Jobst Brandt