AZT, It must be the new bike.

To be constructive, when I cannot do the intended workout for whatever reason, rather than quit, I change the rules and default to TITS - time in the saddle. I would have been better for complete the intervals at a lower power or do a 10 minute SST interval as a substitute for the remainder.

The other aspect is were you adequately warmed up for the intervals? If I had to do 6x3 @ 370 to 390, I would definitely do the first one at no more than 370 and 350 would be okay. I need to warm up for hard efforts by doing hard efforts.

At the track motor pacing, my motor pacing coach noted that I need more warmup. He was giving me a couple of warmup laps before we hit the target speed. And he noted that I do better on my following efforts versus my first.

Power at endurance is always the lacking metric. We do not win the race at the start we win it at the finish. But we can certainly lose the race at the start by overcooking it.