I often like to do thought experiments while #cycling and sometimes I can't think all the way through to the end of the answer. Here's a recent one for #physicists who specialize in #relativity. A #bike's #wheel rotates such that the bit in contact with the #road is instantaneously at rest with respect to the #ground (as long as you're not skidding), at least in #NewtonianMechanics. On the other hand, the bit diametrically opposite to it is moving at precisely twice the speed of the #bicycle.
Now, imagine a #cyclist with the speed of #Hermes and the strength of #Heracles who can go as fast as possible but within the confines of what we know about the real world. If the above still holds, about the #tyres of the bike, then, in the limit, the top of the wheel can go no faster than the speed of light, c, and the mass of that bit of the wheel increases without bound. Does that mean that the bike itself cannot exceed c/2?