Alex Simmons/RST said:
Despite the manner in which it distorts performance, I think the issue of environmental variation is part of the "charm" of such records, however for the topic at hand, if people want a climbing record it'd make more sense to simply have an MTT on fixed courses. Conditions on the day are part of the luck of the draw*.
Besides the issue of suitable locations to get a full hour, accurate measurement of vertical metres gained for a set duration would be problematic. The hour record is recorded at and can be set in increments of ~0.002%. For a vertical ascent that would require nailing down altitude to the nearest 3cm, which would not be feasible. No one is going to survey the precise altitude of a random bit of road. Even the nearest metre would be difficult to nail down precisely, GPS is not overly accurate for altitude measurements. You'd probably have confidence in something like nearest +/- 5-10m. That would be like a regular hour record rounding to the nearest number of full laps.
* The UCI used to have different categories for hour records for indoor and outdoor tracks and for above and below a certain altitude (I think it was 600m IIRC). So, e.g. you could hold the amateur indoor record above 600m.
They also used to have a pro and amateur distinction, which has sort of been replaced by those who are in the bio-passport program and masters age category records.
I think accuracy to within a meter would probably suffice to begin with. An accurate topographic survey of a mountain pass wouldn't be that big a deal; most of these roads probably have pretty accurate surveys already done, there's probably benchmarks and monuments set. A survey crew could have the elevation difference from start line to summit pretty well worked out, and then mark multiple "finish lines" on the road at about where the competitor thinks they'll reach after 1 hour. So if our climber thinks he'll make it 20 km up the road, the survey can put altitude markers on the road for every 1, 5 and 25 m of elevation gained between 19.5 and 20.5 km.
The prep would be considerable, but the survey crew's time would be a minor expense compared to closing the road, security, all the usual accoutrements that go with a pro bike race.