The most likely cause is too much pressure during the initial calibration phase. If the rollers are loaded too hard while the machine calibrates, it sets the baseline too high. In the pull phase, you then need much more force to reach the green zone, which can overheat the pads and tint the rotor.
Quick fix and best practice:
1. During the first calibration phase, insert the wheel and hold it stable. Apply only minimal pressure to both front and back roller, enough to keep the wheel from wobbling.
2. In the pull phase, you should apply a little more pressure on the rollers — about the same amount as you would put on handlebars while pushing the bike up the hill. Remember to push down and forward so both rollers are under the same amount of pressure. Apply the brakes slowly and monitor your progress on the load bar.
3. If you have a feeling that you need to pull really hard on the brakes and put a lot of pressure on the handlebars to get to the green zone, STOP and start the process again.
4. During the pull phase, if you notice that you are slowing down or stopping the machine with your brakes, that means you are applying too much pressure on the rollers and applying too much brakes at the same time.
5. If you see any smoke, stop and let the rotor and pads cool completely before starting the process all over again.
6. The Sinter SBM machine is designed to be easy to use. If you get a feeling that you are applying too much brakes and are struggling to get into the green zone in the LOAD bar, then you are doing something wrong. Stop and reset the process.