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