Converting an S5 for time trials or sprint triathlons usually means bolting clip-on extensions to a standard round handlebar, but the S5's integrated cockpit doesn't accept conventional clamp-on aerobars. The Cervelo S5 HB14 Handlebar Aero Extension Mounts solve this with a purpose-built mounting system that interfaces directly with the S5's proprietary handlebar shape. This kit works with both the current HB14 handlebar found on 2023 and newer S5 builds and the previous-generation AB08 handlebar from 2019 through 2022. You get everything needed to attach extensions except the extensions themselves, which means you can choose whatever shape fits your position: short, flat, J-bend, or ski-style.

The kit includes base mounts that bolt to the handlebar's integrated mounting points, arm rest plates with adjustable positioning, padded arm rests, and all the stainless steel hardware for assembly. Extension tilt adjusts from zero to 15 degrees, letting you fine-tune the angle of your forearms for comfort and aerodynamics. The arm pad carriers move fore and aft and adjust for width, so you can dial in your position without being locked into a single configuration. Any extensions with a 22.2mm outer diameter clamp into the mounts, which covers most aftermarket options from Profile Design, 3T, Zipp, and others.

Installation requires attention to the left and right base mount orientation, as the components are side-specific and labeled accordingly. The system removes cleanly when you want to return the S5 to road bike configuration, making it practical for riders who race both formats or want extensions only for certain training sessions. For electronic shifting setups, the mounts include routing paths that keep Di2 or eTap wires organized and out of the way. This is the factory-correct solution for adding aero position capability to the S5 without compromising the integrated cockpit design or resorting to aftermarket workarounds that may not fit the handlebar profile.