A rarely untouched beast, motif cycling is occasionally heard in classical music and is mostly present during the time a modulation occurs.
Motif cycling involves the 'cycling' of a 'motif' up a set amount of intervals.
Most diminished passages can and are repeated up a minor 3rd. Motif cycling is the exact same idea except instead of applying it exclusively to diminished passages and minor thirds, we apply it to absolutely any line we want.
For example we could play the first 5 notes in a C major scale
And cycle this pattern of intervals up in major thirds
As you can see, just from two cycles, we are in unknown territory. It often has a slightly jarring effect depending on the intervals you choose but it is always an interesting thing to 'throw off' the listener.
Cycling tends to work best with non-scalar passages. With a scalar passage it sounds too obvious and the listener can quite easily catch on to what you are doing. With a triadic or chordal passage it's far more outside and unexpected.
Just to re-iterate. Motif Cycling is playing a phrase and then playing it again up a set amount of intervals. It's fairly unknown so don't get too hung up on the details.