Giant Propel has an aero seatpost, and neither of three supllied Varia ' adapters' can fit onto it. So I designed and printed my own adapter. : r/bicycling
Topeak Light RedLite Aero USB - Rider Bicycle
FOURIERS Cycling Racing Number Plate Mount Road Triathlon Balance Bike Plate Holder Card Bracket fit Flat Aero Seatpost Decals|Bicycle Seat Post| - AliExpress
Giant ISP Seat Post Clamp Adaptor | Bikeparts.Com
Exposure Aero Seat Post Bracket For Tracer | Light Spares | wiggle.com
aero seat post" 3D Models to Print - yeggi
Cat Eye Aero Seatpost Adapter For Rapid X3/X2/X at TriSports
Dual-Position Aero Seatpost – Redshift Sports
Aero Seat Post Mounting Adaptor Buy at best price | Tooo Cycling store – TOOO Cycling Store