other thoughts, in addtion to the maths above, seeing as people still don't seem to appreciate the sheer numbers and that in BR days the numbers were much, much smaller:
with so many bikes, if you're loading nothing but bikes into some trains/some carriages with the riders (who really, really need to have seats, not standing) then given that people will be on bikes from £300 to £3000 or more, you really need a check in/check out system. Which means sealing off/dedicating a platform at each end (maybe a single island, with the bike carrying service on one side and the passengers on the other), it means more staff, probably needing staff to help with loading too, long platform occupation, etc, etc
As far as I understand with the lorries and buses, this is roughly what happens. But then they're using a field, not a busy railway station.