Originally Posted by old's'cool

I hope everyone is aware that yield strength is normally higher in importance that ultimate tensile strength. If the yield strength is exceeded during operation, then the component will not return to its original shape, and operation and/or performance of the machine will be impaired, perhaps to an unacceptable degree in the scenario of limping to a repair site. Ultimate strength, UTS, is the stress at which the component will fracture, which can be obviously quite dangerous if it occurs while riding. Typically, the higher performance the material, steels included, the smaller the difference between the yield strength and UTS. This increases the probability of a catastrophic failure under riding, road or collision loads. We have all seen photos and videos of such failures that occurred in competitive or other cycling.