A 2011 Mavic Aksium wheelset weighs 1795g, so tzivia's estimate of weight is correct, the Fulcrums would be less than 1/3 lb lighter. The Aksiums are good wheels, in my experience. $150 sounds like a fair deal on the Fulcrums if they 4s are close to the 3s (which retail for ~$640, while the Aksiums go for ~$250).