South of Mexico City, the Cuernavaca area has excellent mountain bike trails.
To get to Cuernavaca, fly into Mexico City and drive south for an hour and a half. The weather is perenial spring.
Note: Prior to 1997, the topographic maps developed by the federal government used the NAD27 CONUS datum. Starting in 1998, the government transitioned to the ITRF92 datum (some maps show both datum), which is pretty much identical to the WGS84 datum.
Overall, Cuernavaca is the 4th most popular mountain bike trail of all 24 mountain biking rides in Mexico.