Why Roth asks for two side videos of the same setup

Riders and phones both change from moment to moment

Pedaling pace, posture, fatigue, hand position, phone setup, and one brief movement can change what a single recording appears to show. A result may look precise even when it cannot be repeated.

Do not change the bike or phone between recordings

Record the first side video, then repeat it from the same phone position before adjusting the bike. Keep the lens, indoor bike stand, bike, clothing, pedaling pace, and room setup fixed. The goal is to see whether the same setup gives a repeatable result, not to create a before-and-after story.

• Do not change the saddle or handlebars between the two side recordings
• Do not move the phone or switch lenses
• Use the same riding instructions and hand position
• Repeat any failed setup or video-quality check first

If the recordings disagree, precise guidance should stop

If two recordings of the same setup pass their checks but do not agree, Roth should ask you to record again or stop. It should not turn conflicting information into a confident answer.

Roth cannot claim an exact comparison limit until the process has been tested with real riders and reviewed by qualified people.