Zipp Service Course SL stem

The Service Course SL Stem, crafted from 7075 aluminum, features a redesigned shape that’s strong and lightweight, resulting in a best-in-class 1.85 grams per newton meter of stiffness. That results in no-flex sprints and accelerations. To meet every rider’s fit needs, the stem is available in ±6° and ±17° angles and seven lengths from 70 to 130mm as well as a 140mm length for the ±6° stem only.

Features titanium hardware with TORX® heads on all bolts for precision torque readings and ease of adjustment. (More information below.)

Zipp chooses Torx®-head bolts for its stems and aero bars - why? It’s simply a better bolt:

• Won’t easily strip.
• Provide more accurate torque readers.
• Are durable.

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 – T25 – for 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.