hard to say. a lot of a wheels strength is in the rim and hub and how high spoke tension can be run. the number of spokes don't necessarily tell you a whole lot. i have run mavic ksyrium sls for years without issue (not even a truing) and they are 18 front 20 rear and i would say they are stronger than my other sets of tubular wheels that run 32 spoke, double laced front and back which i have taco'd one and otherwise constantly have to retrue. i think a lot of that is b/c the ksyrium rim is more solid than the mavic reflex cd rims. or maybe its those crazy spokes and nipples. or maybe its my imagination. another big (no pun intended) variable is your weight. if you are sub 200lbs i can't imagine you'd have an issue. my last comment - shimano wheels are usually very solid - they seem to lean towards strength and low maintenance that the crazy lite wheel than needs constant attention.