Bored at work. My job means I have an affinity with statistics and hypothesis testing.
The daily correlation between Kurt's rides and Steve's is between 0 and 0.2, depending on the number of days you offset, so only weakly mirroring each other (a 1 means absolutely mirroring, -1 means doing the opposite, 0 means basically no link).
If I look at whether the ride was more or less than the day before, (so stripping out the overall change in distance) the correlation is around about the same.
So I think the current verdict of Mathematics is "Case not proven".
There are more sophisticated mathematical tests but I am not that bored. Yet. (and also I can't remember where I've filed my actuarial exam notes about what the more sophisticated tests are!)