Zipp Service Course SL-OS Stem

Selecting the correct stem is crucial to your fit, form and function on the bike. It needs to be stiff so you’re not flexing away precious energy in sprints and accelerations. It must be reliable and strong but light. It has to adjust to your personal fit needs.

The all-new Zipp Service Course SL-OS Stem checks off all of those boxes. In a first for Zipp, this ±6° stem is compatible with the “oversized” 1-1/4 inch steerer tubes used by frame makers Giant® and Canyon®. For those riding standard 1-1/8 inch steerer tubes, the Service Course SL-OS offers new fit options with included shims allowing the stem to be adjusted for ±4° ±6° or ±8° angles. The stem also is available in seven lengths from 70 to 130mm. All that helps you dial in your position on the bike like a pro.

Forged from high-strength 7075 series aluminum, this stem is lightweight and stiff with a 1.73g/nm stiffness to weight ratio for better control and responsiveness. Features titanium hardware and TORX® heads on all bolts for precision torque readings and ease of adjustment. (More information below.)

Available in high-polished Black with silver laser-etched graphics

It comes down to the way the tool head interacts with the bolt. Common hex tools tend to strip the bolt head if the bolt is over torqued. This is especially true with lightweight bolts. Zipp wanted to be able to use a lightweight bolt with reliable performance. Bolts on stems and aero bars are critical to safety – having a reliable bolt is crucial. The Torx® head is more robust that hex-head bolts and will not easily strip. Torx® fasteners also were designed for use with a torque-limiting wrench (torque wrench), which is needed to achieve the precise torque reading for proper installation.

We chose a bolt size, M5, that was best suited for our stems. The standard Torx tool head for an M5 bolt is a T25, although sometimes a T20 or T27 is used. The T25 is becoming a go-to bolt in the bicycle industry. It’s been used on disc brakes for years and also is in use on chainring bolts, derailleurs and shifters. What’s more, the T25 tool is a common in bike shops or hardware stores and is readily available alone or in multi-tool sets. For your convenience, Zipp includes a T25 wrench with all stems and aero bars.