In Clayden, Greeves, Warren Organic Chemistry Second Edition Page 815, it states:
In four- and three-membered rings, cis couplings are larger than trans ...
but I did not find an explanation for the statement. That being said, why is it true that cis coupling is larger than trans coupling in cyclopropanes and cyclobutanes? Previously, the textbook stated that coupling is a through-bond effect, not a through-space effect, which led me to reason that the trans coupling in cyclopropane should be larger than the cis coupling, as in the case of cyclohexane.