BlackBird Send 1 Alloy MTB Rim - Black Introducing the Send rims and wheels from Blackbird, a new component brand for Ibis Cycles. When we set out to improve our industry-leading Ibis aluminum S35 rims our mission was simple; eliminate pinch flats and keep the tire sealed no matter what you hit. Pinch flats occur when you hit your wheel hard enough to pinch the tire between your rim and that rock or root that you didnt see coming. Hit hard enough and the edge of your rim, the bead wall, will slice clean through that brand-new tire you just installed. To eliminate pinch flats, we designed our bead walls with a hollow box-section profile to remove the sharp edges and create a broad contact point with the tire. This box-section results in a stronger bead wall that doesnt slice tire sidewalls and it doesnt add any additional weight. Our unique bead wall is used on both the Send 1 and Send 2 rims, but our Send 2 gets a little something extra. If you ride hard, you know youre going to dent your aluminum rims eventually and its your rear wheel that takes the brunt of the damage. You can bend back a bead wall but dent your bead seat (where your tire seals) and youll be walking back to the trailhead. You cant bend the bead seat back, which means you cant run your tires tubelessat that point theyre worthless because tubes are dead to us. To reinforce the bead seat on our Send 2 rims, we added a pair of ribs directly beneath our bead seat. The Send 2 gains 45 g per rim because of this reinforcement but it is a small penalty compared to the weight of the insert you need to protect flimsier rims. Are you looking for a lightweight aluminum rim with good strength? Youll want our Send 1 . Need something a bit burlier? Choose our Send 2 . Our Enduro World Series Team has been testing the Send 1 on the front and a Send 2 in the rear for the last two years. Four EWS racers, several EWS stage wins, three EWS podiums, one Swedish National Enduro Championship, and weve only had one flat on race day. Mission accomplished. Specifications: 6061 Aluminum Intended use: Mountain Biking Internal Rim Width: 35mm (both Send 1 and Send 2) 27.5 Rim Weights: Send 1: 543g Send 2: 590g 29 Rim weights: Send 1: 565g Send 2: 625g 7-year warranty.