I can't see a way to embed a video, so here's a link. https://mrevil.asvachin.com/cycling/bra ... 13_A-1.m4v It's hosted over my home internet connection, so it might be slow if too many people view it at once.
Notable things include:
- The camera unfortunately doesn't embed the scale in the video, and it auto-ranges to the highest and lowest temps in each frame, so you can't tell what the absolute temperature is.
- Occasional pauses in the video are where the camera recalibrates itself.
- Different materials radiate heat differently, so you can't directly compare the apparent temperature of different parts of the bike.
- At the start, I had been standing at the top of the hill for a minute, which was long enough for one side of the tyre to absorb heat from the road. This is why one side appears slightly orange as I start the descent.
- I start dragging the brake at around 0m40s.
- By about 1m00s the rotor is much hotter than anything else in the picture.
- I come to a complete halt right at the end of the video.
And here's a second video from a short while later showing much quicker heating from hard braking to stop at a junction. At the start, you can see that the caliper has warmed up a bit compared to the first video: https://mrevil.asvachin.com/cycling/bra ... 13_A-2.m4v
The brake caliper is a Hope RX4, and the rotor is a Shimano RT81, which is one of the ones with an aluminium core.