With a bar clamp diameter of 31.8mm, the Vuka Alumina Clip also is compatible with the Zipp Vuka Alumina and VukaBull base bars and three Zipp drop bars types, Service Course, Service Course SL and the SLC2. It also is compatible with many other base bars and drop bars on the market.

Vuka Alumina Risers (sold separately, cannot be stacked), which come in 10, 25 and 50mm sizes, allow for even more fit options. The Vuka Alumina Risers are designed for use only with the above-bar system of the Vuka Alumina Clip.

The Vuka Alumina Clip weighs 310 grams for the above-bar system and 295 grams for the below-bar system. The clip does not include aero extensions.

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

• Wont 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 than 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 required 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. Its been used on disc brakes for years and also is in use on chainring bolts, derailleurs and shifters. Whats more, the T25 tool is 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.