Bike shop mechanics are saying the carbon rim is old enough that fatigue is an issue ( I call BS- I am a mechanical engineer- and CFRP has superior fatigue resistance to metals.). they may have a point about cost versus useability ratio, however. the wheel is a 28 hole build ( originally for heavier riders, but I am light- 67 kg.) which means it is slightly hardier than your standard 24 hole rears.i