Tikz: increase arrow head size

Question

Given the Tikz example here http://www.texample.net/tikz/examples/double-arrows/

how do I increase the size of the arrow head? I'd like to make it way bigger but, after manipulating the code, I was only able to increase the angle of the arrow (up to 90 degrees).

Answer 1

One option would be to scale it (and change the shorten value accordingly):

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{arrows, decorations.markings}

\tikzset{
vecArrow/.style={
  thick,
  decoration={markings,mark=at position
   1 with {\arrow[scale=2,thin]{open triangle 60}}},
  double distance=1.4pt, shorten >= 10.5pt,
  preaction = {decorate},
  postaction = {draw,line width=1.4pt, white,shorten >= 4.5pt}
  },
innerWhite/.style={
  semithick, 
  white,
  line width=1.4pt, 
  shorten >= 4.5pt
  }
}

\begin{document}

\begin{tikzpicture}[thick]
  \node[draw,rectangle] (a) {A};
  \node[inner sep=0,minimum size=0,right of=a] (k) {}; % invisible node
  \node[draw,rectangle,right of=k] (b) {B};
  \node[draw,rectangle,below of=a] (c) {C};

  % 1st pass: draw arrows
  \draw[vecArrow] (a) to (b);
  \draw[vecArrow] (k) |- (c);

  % 2nd pass: copy all from 1st pass, and replace vecArrow with innerWhite
  \draw[innerWhite] (a) to (b);
  \draw[innerWhite] (k) |- (c);

  % Note: If you have no branches, the 2nd pass is not needed
\end{tikzpicture}

\end{document}

I changed the old \tikzstyle to the more appropriate \tikzset syntax.