The following one is working for restricting maximum number of authors for both citations and bibliography but how do we restrict to only citations.
\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[american]{babel}
\usepackage{csquotes}
\usepackage[style=authoryear,maxnames=2]{biblatex}
\renewcommand*{\finalnamedelim}{\addspace\&\space}
\addbibresource{biblatex-examples.bib}
\begin{document}
Filler text \parencite{bertram,companion,jaffe,moraux}.
\printbibliography
\end{document}
maxnamessets bothmaxcitenamesandmaxbibnames. If you want to have different threshholds, you need to set both. The same goes forminnames,mincitenames, andminbibnames. By default,minnamesis set to 1 andmaxnamesis set to 3. – jon Mar 04 '14 at 05:02