Definition of granny gear in English:

granny gear

noun

informal
  • The lowest gear on a bicycle.

    • ‘He explained he, ‘never used his granny gear, so he had it removed to save a bit more weight.’’
    • ‘My blistering pace has now slowed to a mere crawl and I've been reduced to using yes, my granny gear.’
    • ‘It was a very difficult climb, requiring use of the granny gear.’
    • ‘Just shy of 12,000 feet, even the smallest uphill can test one's lung capacity and necessitate granny gear.’