I have been a longtime fan of Mavic rims since I started riding mountain bikes 9 years ago. My first wheelset I ever built was a 517/Chris King and it lasted better then any wheelset Ive ever owned. When I started riding downhill, the first rims I had were Mavic 321s. They are expensive, they are not very light, but they are extremely strong and worry free. In fact, for me it is safe to say the Mavic 321/729 is the best DH rim ever made. I have used them for 7 years, ridden them with a flat tire down some knarly courses, and never once destroyed a wheel.
However, in an effort to try new things and shed much needed weight on my downhill rig, I decided to give DT Swiss a chance for the last 6 months. Their 6.1 DH rim is about 50 grams lighter then a 729, and their 5.1 rim is over 150 grams lighter then a 729.
My first experience was with the 6.1s. And it is good to note these wheels were all professionally built and tensioned. Riding home one day on my hardtail, I happened to just kiss a curb. So small that I didnt even slow down or pay attention (ie Ive nailed my rim 10x harder before with nothing to show). High PSI. Feel a wobble. Look down to find there is a gigantic dent in the sidewall. How? Where? When? Those were my thoughts.
That was the start. After riding trails with the 6.1s, I would come back and find these knarly dents. Like dents so big they would disrupt a tubeless system. Now, one must understand that this rim is DESIGNED to be soft, so that you can make it down a race instead of breaking the rim. Well unless you run an abnormally high pressure, this essentially means the rim can withstand a race or 2 and is done. The dents can be pulled out...but I dont ride aluminum thats been reshaped.
My next experiment was with the DT 5.1. The 5.1 rim is designed to be a much much tougher and harder metal compound, so it doesnt dent but can then be more susceptable to failure. First ride out, average pressure, the rim gets nearly as banged up as my 6.1s. Next rides out, abnormal pressure because Im paranoid...and each day I still have to true the wheel considerably. Now, this is a lightweight wheel. With double butted spokes and aluminum nipples and a 500 gram rim, I am definitely not expecting 321/729 performance here...however I am expecting a wheel to be able to withstand the mellow dirt and lack of rocks in the Santa Cruz mountains where I ride.
Fast forward to the Utah National. Second run down the mountain, quickly checked tension on both wheels. Knocked off line, hit a rock, wheel folds in half. The front wheel was not a DT built wheel, however before I left for Utah I had the wheel once again professionally tensioned to be absolute sure. I didnt even pinch the tube when the wheel tacoed. Head to the pits, start talking to a lot of people, start to find that this aparantly happens all the time. Guys telling me they are on their 6th-7th rim. DT tells me that since it is not a DT built wheel, they cant really do anything. Finally they offer to relace a new rim onto the wheel (if I buy it). This is nice of them, but they tell me that they dont have problems with their rims and that this is abnormal. However walking down the mountain and around the pits with the wheel, I got all kinds of people asking me if that was my 3rd or 4th DT wheel and how many problems theyve had.
Race run, put my 3-4 year old Mavic 321 wheel on front, I flat at the top of the rocky course, and ride everything including the drop at the end with the flat. The freakin wheel isnt even out of true. 2-3 more small dings but nothing else. The Mavics have considerably less damage from 4 years of riding then my DTs have from a few weeks of riding.
Aparantly I went too light, and I was aware this may happen. 5.1 is a good trail or training wheelset, 6.1 is a great 1 race use rim in my opinion. But maybe I just need to run more pressure and I am running a bike with a little less travel.
I just wanted to share my experiences and see if anyone else here specifically on this forum has had the same issues. I know all of my friends will NOT be riding DT/Swiss rims after seeing the problems Ive had first hand. That said, they still make a great spoke and hub. Time to add a little weight to the Big Hit, I cant be relacing new wheelsets every race.
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