Maybe try your 20 minute test outdoors, on aerobars, and then use that as a basis. Saying that, I tried this and could not get near the 0.95 number yesterday - just one of those days where 30w below hour power was a struggle.
Yeah that's a good idea, hard to get 20 minutes of open road around London but should be able to get a decent idea with some richmond laps. Did you find the same large gap in power when you started tt'ing?
Yeah true. No use crying about it - just need to get down to Regents on the TT rig more often