pedaller vs biker

pedaller and biker both are nouns.

Word	Noun	Adjective	Verb	Adverb
pedaller	Yes	No	No	No
biker	Yes	No	No	No

As nouns, biker is a hyponym of pedaller; that is, biker is a word with a more specific, narrower meaning than pedaller:

Other hyponyms of pedaller include bicycler, bicyclist, cyclist, wheeler, unicyclist.

pedaller (noun)	biker (noun)
a person who rides a pedal-driven vehicle (as a bicycle)	a person who rides a bicycle