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I don't get it. What am I looking for?

The paths ridden do not line up with the actual roads. I am not sure what the OP is actually trying to tell us about that though.

There seems to be a chinese decree that all maps must be skewed so that in the case of being attacked, an attacker can presumably not find its way around the chinese capital.

Bike maps are likely created directly from GPS paths, which are unskewed. When you look at Bejing, you can easily see that difference.

Exactly, similar to that thing in the US before they opened up civilian GPS accuracy...

Not quite, the difference between the two situations is the difference between accuracy and precision.

E.g. http://academics.wellesley.edu/Chemistry/Chem105manual/Appen...

The Chinese Street maps are very precise but consitently inaccurate (the skew). The GPS tracks shown are relatively precise and accurate.

The change to the GPS signals (by not encrypting as much of the timestamp data) improved precision.

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