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The first and most important thing about any gruppo is function.The component must execute the operation that it was designed to perform. Next, would be reliability. The component must consistently execute that very same function that it was originally designed to carry out.The next feature of importance would be durability. We all expect for our components to last longer than for just a few weeks. The longer our components operate for us, the more durable they are considered to be and the more value we place upon them. Finally, when it comes to the road bike drivetrain, we expect our drivetrain to be lighter, be faster, to shift smoother, and to do it all quietly. The lighter, the faster, the smoother, the quieter, the more consistent, and the longer they last, the more value we attach to our gruppos.

Of course, durability is also related to the duration of time, in which our gruppos are in service too!

A professional road racer's drivetrain will be used much more than mine or yours. He might go through his gruppos five to ten times faster than the average club roadie.