Originally Posted by
2wheeladdict
Not in all cases.
Take XT or Ultegra derailleurs for example. If I get more then two seasons out of these I am lucky.
XTR and Dura Ace on the other hand have lasted me for many years.
Edited to add: I worked for a bicycle drivetrain manufacture for years and witness this first hand over and over again. Some derailleur products do wear better then others for a variety of reasons.
As a marker- for performance- then LX or 105 parts are the standard to work from. Below these grades and you do get a lowering of life or performance if you are a hard rider. Personally- I ride XT and Ultegra. The parts are slightly lighter and do have better bearing surfaces to make them last longer and have that all important "Quality" factor. However- I have one bike that is hard on parts. An offroad Tandem that is used aggressively. This thing breaks and wears out parts just by rolling it out of the shed. A rear XT mech for example will have to be changed every year due to wear. Couple of years ago I got a deal on an XTR R'D' and there is no way I would normally fit this grade due to cost. However- It was a last years model and a low price so went for it. When it wears out I will be getting another one. Rear deraillers do take a lot of punishment so this upgrade was worth it.
If I were buying replacement parts for the MTB's or Road bikes- then I would go for XT or Ultegra. But if a deal came up for Dure Ace or XTR- then I would go for it again.