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The character doesn't know how to ride a bike and tries to remember what his friend was doing when starting the vehicle.
He then says to himself :
I can't find any info on グリッて, what does it mean?
This グリって is a mimetic adverb (擬態語) which is basically the same as グリグリ(と):
It's similar to グルグル(と)/グルっと which describes how something rotates smoothly. But グリグリ refers to a more forceful, unsmooth movement/rotation.
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