Matheus0312

Revisiting the topic with the solution to my problems if other also have it. Blurry images are generated by a long shutter speed, not fps.

I was capturing videos with my phone's stock camera, which adjust the shutter speed automatically in accordance with the image brightness, since I was not using sufficient lighting in my setup the shutter speed was reduced and I got the blurry result. To solve the issue I increased the lighting (filmed outdoors during daylight) and used a camera app which let me fix the shutter speed (the stock app with auto shutter speed may be enough if sufficient lighting is used).

To quantify the blurriness generated by shutter speed: 90rpm=1.5rps, this means that in 1 second the pedal travels 540°, multiplying this number by the shutter speed results the angle which the pedal travels "during" each frame. With my previous lighting setup the shutter speed was automatically set to 1/15, which results in 36° for each frame; outside in a cloudy day I was able to record at 1/2000 which results in 0.27° for each frame which is more than enough.

TLdr: pay attention to lighting when recording high speed video, stock cameras set shutter speed automatically, specific camera apps let you fix this setting.