The most common and most likely answer to this crossword clue is the 9 letter word CHINSTRAP
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More clues leading to the result CHINSTRAP
Buddy explains!

The straight part
We know that "Band of bikers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case band of bikers = chinstrap.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CHINSTRAP mean?
CHINSTRAP noun- A strip of leather or material used to fasten a hat or helmet under the chin.
- A form of beard grown under the chin.
- A band of colour below a bird's mouth, resembling the chinstrap of a helmet.