Sharing a new tool (unfortunately only in French for now apparently) : cyclograde.fr
Based on the GPX or TCX of a previous ride, it calculates a speed profile (estimation of the speed you ride on a climb at 4%, 5%, …), then you can apply it to a ride you will do and estimate the time it will take. Then you can plot the profile of the ride with the estimated times.
Nice (Free) tool and works well. (Example with Etape du Tour 2026)
