Time trial racing rewards riders who can shift without breaking their tuck, and Shimano built the SW-R9160 specifically for that job. These are the bar-end switches that plug into the tips of your aero extensions, giving you a single programmable button per side so your fingers can find the shift without your eyes leaving the road. They're an 11-speed Di2 component in name and generation, but with the current firmware they cross over to the newer 12-speed ecosystem as well — worth knowing if you're building a TT bike now with an eye toward upgrading the drivetrain later.

The single-button-per-side layout is deliberate. Rather than trying to fit a two-button shifter into the end of a narrow extension, Shimano paired the SW-R9160 with Synchronized Shift, letting the Di2 system handle front derailleur changes automatically. You press one button to move toward an easier gear, the other toward a harder gear, and the front shifts happen when the system decides the chainring change makes sense based on where you are in the cassette. Hold the button down and the derailleur will run through multiple gears in sequence, which is the quick way to dump gears heading into a headwind section or drop into the small ring for a sharp climb without sitting up.

Installation drops the switch bodies into the ends of standard aero extensions, and each unit connects to the Di2 system via an SD50 or EW-SD300 e-tube wire back to the junction box or battery. If you're running a full cockpit, these can be the sole shifters on the bike, or they can supplement brake-lever-mounted Di2 controls on your base bar for sprint-position shifting. The switches are programmable through the E-Tube Project software, so you can assign either button to upshift or downshift depending on which hand you prefer to have controlling which direction.... Read More