26″ AM Tubeless
Width: 30mm (24mm Internal)
Weight (rim): 395g
Weight (Chris King): 1,554g
Weight: (DT180): 1,372g
Weight (DT240): 1,444g
Hole Count: 28, 32
Days Tested: 25
Test Locations: Salt Lake City, Park City, and Moab, Utah
The use of carbon composites in mountain bike design and technology has progressed immensely in the past few years. Initially the stuff of 140-pound World Cup XC racers, carbon has come a long way in a rather short time. What we once all thought was insane—a carbon DH bike—is quickly becoming standard in the upper echelons of racing, and very quickly trickling down to amateur levels.
Likewise, the very idea of a carbon-rimmed mountain bike wheelset seemed outlandish, the stuff of sponsored XC racers. All the while, carbon composite engineers and evangelists continued to speak of the material’s immense strength and kept insisting that it’s not merely about saving some weight. Strength-to-weight ratios, impact strength, fatigue life, and tune-ability are other very significant factors when considering carbon.
ENVE Composites of Ogden, Utah, have been on the front end of the mountain bike carbon revolution, pushing what we think is possible, largely through a collaboration with the Santa Cruz Syndicate DH Team. What better test lab for a material than beneath the brute strength of Steve Peat and the consummate race tactician, Greg Minnaar?
The Twenty6 AM rim is one of the results of ENVE’s constant product progression. ENVE originally built lighter weight, narrow, XC rims (see our review of the ENVE XC, AM, and DH rims), but seeing where the market was going in terms of sub-30-pound, uber-capable all-mountain bikes, they took what they learned with the Syndicate and built the AM.
Handmade in Ogden, the Twenty6 AM rim is 395 grams of sexy, raw carbon. With a 24mm internal width, it’s a refreshingly wide, modern shape that allows for excellent tire profile with 2.3” and wider tires. It also has a fairly tall 31mm rim profile that undoubtedly adds to its strength and wheelset rigidity, and helps to shed mud when necessary. (Mud buildup on a flat rim surface can render a nimble bike quite sluggish with a considerable addition of rotational weight.)
The wheelset I have been riding was built in-house at ENVE. The Twenty6 AM rim is laced to a Chris King hubset with 32 DT Swiss Aerolite spokes. ENVE goes to great lengths to achieve the stiffest, strongest wheel possible by molding the rim complete with the valve and spoke holes all at once. By using continuous fibers throughout construction, rather than drilling spoke holes, the rims remain as strong as possible, and spoke tension loads are more evenly distributed throughout the rim. The spoke holes have a conical seat shape so that the nipple can match the spoke angle without bending and fatiguing the nipple or spoke.
By using this unbroken fiber technique, the spoke holes, and thereby the rims, are capable of taking a higher spoke tension, which allows a builder to create a stiffer wheel in terms of tension within the system, rather than just depending on the structural rigidity of the rim itself. There is no danger of rim collapse under higher tension, which can be an issue with alloy rims of a similar weight.