bicyclist vs bicycler

bicyclist and bicycler both are nouns.

Word	Noun	Adjective	Verb	Adverb
bicyclist	Yes	No	No	No
bicycler	Yes	No	No	No

As nouns, bicyclist and bicycler are synonyms defined as:

Other synonyms of bicyclist include biker, cyclist, wheeler.

bicyclist (noun)	bicycler (noun)
a person who rides a bicycle	a person who rides a bicycle