Minnman you are assuming that is the same to TT in the road than in the track and believe me, the two are so far appart than you cant assume that because a guy can do 60 km/h in the road he wil b able to do 50 km/h w/o breaking a sweat in the track. If it was that easy that record would had been done by many riders every year and if you look at it this the last record was made like 6 years ago and nobody I know of had even tried it after that. There is a misconception that in the track is easier, there is a reason why trackers are that big compared with roadies.
I'll explain the differences, in the road you have multiple gears, in the track you go with one, you pick the wrong gearing and you are dead. The wind and road in a road TT varies so if you suck in one section you can make it up in another one. In the track believe or not (even in roofed wooden tracks) you have a darn wind all the way around, the faster you ride the faster the wind you hear and feel, it sucks
I did track for many years and for example my best time in 1 km TT in the road using my road bike is 58 seconds, in the track never did less than 1:09, in the road was cheating using 52x14 but was starting from 0 with 52x16, in the track had to move 51/50x15, wind... in the road remember had 2 place where I had no wind. The track was 333, concrete and open, so you have darn wind everywhere. The road in 2 places was going kind'a downhill and that helped a lot.
So pretty much 49.7 is darn fast in the track... after seing 2 hour records back in the day it is insane to see the guys doing 1:05 per km with 53x14 or so. Personally I dont see cancelara or martin hitting 55km at the end of the hour at all, they will do as much as 2 km more in the best case scenario, in the worst they will ride faster just by a few meters.
Wonder if wiggo will do it, I see him doing better than cancelara and martin because of his tracker background.