The Service Course SL Seatpost from Zipp is proof of the relationship between professional teams and a manufacturer intent on learning. The new SL is an update of the old SL. Its improved, but it takes a few moments to notice how.

The shaft is still 3D-forged from a single length of 7075 aluminum alloy. It still uses titanium Allen-head bolts to secure the clamp, and the machining is still extensive, removing as much excess weight as is safe without compromising performance. If youre wondering where all the machining is done, flip the post upside down and look inside the shaft. As the forces on the post are largely directional, they relieved the interior wall material where they knew little stress is experienced.

The post has been lightened. The zero setback version is only 220g for the 330mm length, and the 20mm setback version is only 235g. Thanks to cutting the bottom on a bias, the minimum insertion length is only 90mm.

The clamp is minimal, but long enough to support the thinnest rails and wide enough to support oversized and wrapped carbon-fiber rails. In fact, the bottom half of the clamp is much longer behind the clamp than youll typically find, and makes it possible to take even the zero-setback post into the realm of a setback post, another way to save weight. Its a two-bolt design, with both bolts facing downward, and easy to access. This last point, ease of access, is no small deal. Pros are typically finicky about saddle position, and, very much like the princess and her pea, can notice a variation of a single millimeter. When clamp bolts are hard to access, it takes more time to adjust, which is something that aggravates mechanics, fitters, and most people.

The shaft just under the clamp has markings both on the clamp and the shaft. These were set at the factory so that you dont need to bring out a magic marker and deal with the imprecision of marking the clamp on your own.

Zipps Service Course SL Seatpost comes in two diameters, 27.2mm and 31.6mm