Specialized Camber Pro Carbon 29er, FSR EVO, Auto Sag and 2012 Bikes » Specialized Tarmac SL4 S-Works Head Tube Detail
UNIQUELY SHAPED, TAPERED HEAD TUBE
Strategically designed head tube on SL4 frames tapers from 1-1/8” at the top to 1-3/8” at the crown and facilitates massive top and down tube junctions.
Increases strength and stiffness for greater steering precision and responsiveness during out-of-the-saddle efforts.
The wider base creates a stiffer, stronger junction, and the gradual transition of carbon fiber from top to bottom eliminates the potential for weak spots due to sharp angles-carbon is at its best when it keeps a smooth line. Uber-oversized top and down tubes “wrap” around the front of the head tube, creating the ultra-stiff and tapered “bulges” at the junctions. The design requires a smaller lower bearing (compared to last year’s 1-1/2″) which saves weight.