Carmichael also mixes in low cadence work in his climbing DVD. I have been doing them for the past few months and find it useful. If you're spinning 70rpm in the 53x13 gear, your trainer isn't at full resistance or is faulty or you're a monster. I put mine (traveltrac mag) on full resistance and can hold 50-55rpm in 53x18 right at LT. When I focus right, I can really feel the hamstrings and calves getting a good workout.