Which is more appropriate or grammatical to use:
He is coming on a bicycle.
He is coming by bicycle.
Which is more appropriate or grammatical to use:
He is coming on a bicycle.
He is coming by bicycle.
Depends on the context.
"By bicycle" is used to show how you got somewhere.
How did you get here so quickly?
Well, I got here by bicycle.
The road can be dangerous if you travel by bicycle; some drivers don't pay enough attention.
"On bicycle" isn't really a valid phrase as it is. "On a/the bicycle" would work. It is used to show that someone or something is physically on top of the bicycle.
It's hard to sit on a bicycle that's too large for you.
EDIT:
He is coming on a bicycle.
Please never say this. You'll be laughed at. Not for the grammar -- it is wrong, mind you -- but it's an innuendo.
"by" refers to the thing's instrumentality, the means by which.
Some people arrived by car, some by bicycle.
"on a bicycle" refers to the thing as a surface, something on which to sit:
The circus clown was riding on a child's bicycle with another much larger clown sitting on his shoulders.
"on bicycle" refers to the thing as a mode of transport:
How are the refugees getting to the Arctic Circle?
-- They are on bicycle.
In standard grammar, we do not use an article or possessive pronoun after"by" before the name of any means of transport.For example, we would say " He came by bicycle" and not " He came by a bicycle or he came by a car." In such cases , "by" must be replaced by prepositions such as "on/in/"or possessive pronouns such as "my/his/her" etc.For example, we can say : He came on a bicycle/ He came in a taxi/ He came in his friend's car etc.