Go on Cycling Road without a Bicycle
This glitch allows you to gain access to Cycling Road without a bike.
Procedure
1. Go to Celadon city and walk towards Cycling Road. Make sure you do not have a bike with you.
2. Go north as far as you can and start walking towards the left exit.
3. When the guard starts talking to you, keep pressing B. You will get past him and onto the road.
4. When you exit you will find that you are on a bike, regardless of whether or not you actually have a bike. This is because the game assumes you have a bike if you are able to get past the guard.