The Cycling Road sign glitch is a glitch in Generation I where the player is unable to read a sign north of the Cycling Road.
- The player should stand here, facing up, and holding the B button as not to go down.
The sign affected by the glitch.
- Even when pressing A, the player won't read the sign.
When in this position, the player is standing in Route 17.
The sign is in Route 16, and so it has "sign interaction" defined - but when the player is in Route 17.
tl;dr : the game doesn't make a sign interactive across routes.