I used a handlebar mounted hydration system for a while, on my first 70.3 it was a particularly windy day and the extra weight on top made me uncomfortable to the point I had to ditch it in the first 10 miles. Switched to a frame mounted one and loved it. Holds more water and super easy to refill. A bit more expensive but totally worth it in my opinion.

Speedfil F1 Bicycle Water Bottle, Hands-Free Frame Mounted Hydration System with Refill Port https://www.amazon.com/dp/B004LY6AWS/ref=cm_sw_r_cp_api_i_V9DMDGT70X2MJCG46G56?_encoding=UTF8&psc=1