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Having an efficient rear derailleur is essential to a good ride. Nothing is worse than having to constantly adjust your shifting out on the trail. SRAM's GX Eagle Rear Derailleur offers the same great technology you see in their more expensive X01 and XX1 Derailleurs but for a fraction of the price. Yeah it might weigh a little more and not look as nice but you are getting the performance you deserve. Let's see what Glen thought of his recent upgrade!
The rear derailleur is the most exposed component on the mountain bike. It is the most important component for the drive train to run smooth, crisp, and accurate. The nightmare is when you bend a derailleur, the derailleur hanger, or the derailleur seizes up for some reason. Quite frankly, I have to replace the derailleur about once a year because of the riding I do. I will either clip the derailleur on a rock or boulder, eat a stick in the pulleys, or crash on the mountain.
This brings me to the GX SRAM Derailleur. This piece of equipment can cost a lot, even hundred of dollars if you go with higher end components. For me, the Gx is the perfect middle ground of low end and high end spending on components. For me, its not if you will have to replace the derailleur, but when. Therefore, I keep an extra on hand. The cost for the SRAM Gx Derailleur is $125 plus tax and perhaps some shipping. Being the neighborhood mountain bike mechanic, I have learned a lot about derailleurs. First, don’t go crazy washing your bike with a power washer. I have experienced water getting into the derailleur causing rusting and eventually seizing. The Eagle Drive Train is very sensitive and everything has to line up to work as you would expect, perfectly. This means you can set it up correctly and then put some load on it up in the mountains and start experiencing miss shifts. If the hanger is slightly bent or off, even new on the bike, the shifting can be bad.
"I used a derailleur hanger straightener tool to make sure everything is lined up perfectly, even if the hanger is new from the factory."
I have tried the Shimano XT 12 speed system. I watched videos and reviews that you could use any 12 speed cassette so you did not have to buy the new micro spline hub body for your bike. For me, this was a disaster. I could get the shifting close, but I could never get it shift perfectly. Shimano eventually sent some documentation that to obtain the optimal shifting, you must use the whole system. Some people were lucky to get it to work, some people were not, like me. It was frustrating. That’s when I went back to the GX drive train and put on a grip shifter.
"If it is set up properly, the shifting is spectacular, crisp, and spot on. I love the eagle with a 50 T to make those impossible climbs. The GX works just as good as higher end SRAM components in my opinion, and does not cost as much. I recommend the GX stuff because it functions the same, the weight penalty is negligible, and it is far more cost effective. The derailleur comes with a measuring device to properly set the B tension. This measurement is critical to setting things up correctly." - Glen
"The Derailleur has a super long cage that will almost stretch even with your rim. Therefore, it is highly exposed and susceptible to damage. If it gets bent, it is very difficult to straighten and bend back. The other draw back is the whole system of the derailleur, the hanger, the b tension screw, and the A and B screws all have to be set perfectly or you can have problems on the trail. If anyone one of those things get out of wack, then there will be rough shifting and you can lose your top gears." - Glen