Originally Posted by
hairnet
I think maybe cadence instead of speed. There's no big limitation on speed at the low gears unless someone just can't spin very well.
Of course there's a limitation - you might be able to spin 120rpm fine, but 150? 180? more? Even if a rider can do it well, might he prefer something lower?
Your steady power output, with your preferred/most efficient cadence, gives a cruising speed. Your cruising speed, with your preferred/most efficient cadence, gives a gear ratio.