Tried for new 8min PR. Failed. It's an erg bike. I made the mistake of going out of saddle at around 5min in and it ups the resistance to match the cadence to hold the power. But, when starting to spin again it doesn't let off very quick and you're left with a mammoth effort to get it spinning again after already dying for 5min. It made me spin over 400w for a few seconds before it "let off" and that was too much. That put a fork in it. Also, going up a full 30w in one bit was a bit adventurous. Maybe 10 or 15w more and I'd have made it.
I will do it this year though. 8min at 350w. Sometime.