Originally Posted by
JusticeZero
Use music; find a BPM list (easily googled) and look up some songs you know. If you recognize any songs that you've heard a lot that are in the ballpark of 90-96 or 180-190 BPM, get it in your head and pedal to the beat. After a bit of riding at a pace like that, you'll find it much more natural to pop into a halfway decent cadence naturally.
This is also a good way to drive yourself insane with songs stuck in your head.
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Bikes: 1996 Eddy Merckx Titanium EX, 1989/90 Colnago Super(issimo?) Piu(?), 1990 Concorde Aquila(hit by car while riding), others in build queue "when I get the time"