Cycloalkene Stability
The presence of a ring only makes a difference in stability if there is ring strain. Rings that are 5 carbons or larger easily accommodate double bonds, and such systems behave like straight chain alkenes.
The ring strain in cyclopropene and cyclobutene is greater than that in cyclopropane and cyclobutane. Thus cyclopropene and cyclobutene are less stable than the analogous alkanes.
In cyclic alkenes, the cis isomer is generally more stable than the trans. The trans isomer is rarely observed unless the ring contains 10 or more carbons.