Interestingly, the TGV record was broken by an unmodified Velaro-D train recently. Standard rolling stock, used the week before for normal transport, used a week after for normal transport.
Are you sure? I'm not finding anything about this.
The TGV record is about half the speed of sound, which means the wheel rims are bordering on supersonic, so it's not a simple thing to talk about exceeding it.
Why would the wheel rims rotate at twice the speed of the train? If the train advanced along the track 1m, surely the part of the wheel in contact with the track must also have moved 1m?
I think the idea is that the top of the wheel is basically super sonic compared to the ground. This has to be the case: the train is connected to the middle of the wheel at speed, the bottom of the wheel is going 0 so long as it's not slipping, so the top of the wheel is screaming along at near-sonic speeds.
It's an odd diagram to draw out, as that result is pretty counter-intuitive.
Pretty sure you're mistaken. The Velaro-D reached 403km/h without modifications[0], the Velaro-E did the same back in 2006. That's not the untuned record either, these belong to China's CRH380BL.
