How do you want to use them?
You're right. I didn't notice. Although I still don't understand why #1 is correct and #2 is wrong.
Do you mean "I usually ride to work a bike" when you say #2?
I don’t know. I just wondered if the two expressions may be used interchangeably. For example would it be correct to write the following:
1. “I usually go to work by bike”
2. “I usually ride to work on a bike.”
If the sentences above are correct if there is any basically the difference between them?
I think a possible difference is that you are not going anywhere if you are riding a bike around in a park, but I am not a teacher.What's the difference between them?
1. I'm riding a bike.
2. I'm going by bike.
3 is fine in BrE.