I've never seen any calcs for either feat so I wouldn't know how fast they are. I didn't call it the best feat in the OG material period, I said that about Gae Bolg alone. As in, we don't have any other feats for the speed of Gae Bolg that I know of. I mean, 100 meters per second is 360 km/h so at 500 km/h it is already possible to perform that feat. I'm not aware of any evidence within the 3 OG Fate works that contradict the speed of Bellerophon. If anything it seems consistent with Iskandar's chariot and Artoria's bike going at 400 km/h. No, the context here in that debate is that we don't have access to better feats like with Tao's one. While it's true those feats are better than Mach 2, I don't know how applicable they would be to the argument of how fast Gae Bolg being thrown would be. I don't see any logic to scaling wildly different attacks to each other. At most you could argue Gae Bolg as a Noble Phantasm should easily outstrip the Mystic Code of a modern magus like...