Answers are of course entirely personal. For me, a good ride is enough miles to "challenge" my legs and heart rate, no falls or crashes, and no close encounters of the worst kind with any type of 4, 6, 10, or 18-wheeled motor vehicle.
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Current bikes: Unknown year Specialized (rigid F & R) Hardrock, '80's era Cannondale police bike; '03 Schwinn mongrel MTB; '03 Specialized Hard Rock (the wife's)
Gone away: '97 Diamondback Topanga SE, '97 Giant ATX 840 project bike; '01 Giant TCR1 SL; and a truckload of miscellaneous bikes used up by the kids and grand-kids
Status quo is the mental bastion of the intellectually lethargic...