vertically center tabular element

Question

I have the following table but I want to vertically center the first line of the table (Mid-drive motors). I would I do that?

\begin{table}[h]
\begin{center}
\begin{tabularx}{\textwidth}{ X  X }\hline
\multicolumn{2}{c}{\textbf{\large{Mid-drive motors}}} \\ [1.5ex]
  \hline
  \textbf{Advantages} & \textbf{Disadvantages} \\
  \hline
  Use the own gears of the bicycle & Wear a tear \\
  Consistent in steep hills & Big contact forces changing gears \\
  Lighter & Expensive \\
  More efficient & More noisy \\ 
  Low and centered mass center & More moving parts - more maintenance \\
  Higher torques\\
  Better suited for poor pavement \\ 
  \hline
\end{tabularx}
\end{center}
\caption{Advantages and disadvantages on the use of Mid-drive motors.}
\label{tabMid}
\end{table}
\FloatBarrier

Answer 1

\documentclass{article}
\usepackage{tabularx}
\usepackage{booktabs}
\begin{document}
\begin{table}%[h]% This is for fine tuning at the very end
%   \begin{center}% just useless clutter
        \begin{tabularx}{\textwidth}{ X  X }\toprule
            \multicolumn{2}{c}{\textbf{\large Mid-drive motors\strut}} \\ 
            \midrule
            \textbf{Advantages} & \textbf{Disadvantages} \\
            \midrule
            Use the own gears of the bicycle & Wear a tear \\
            Consistent in steep hills & Big contact forces changing gears \\
            Lighter & Expensive \\
            More efficient & More noisy \\ 
            Low and centered mass center & More moving parts - more maintenance \\
            Higher torques\\
            Better suited for poor pavement \\ 
            \bottomrule
        \end{tabularx}
%   \end{center}
    \caption{Advantages and disadvantages on the use of Mid-drive motors.}
    \label{tabMid}
\end{table}
\end{document}

Answer 2

There seems to be considerable overlap between the table's caption and the first row of the tabular material (the material that you want to center vertically). I'd get rid of the first row, and I'd also shorten the caption to make it a bit snappier.

I would further use the line-drawing macros of the booktabs package instead of \hline, and I would forego the use of bold-facing the entries in the (now simplified) header row. Oh, and since the width of the \tabularx environment is set to \textwidth, there's no point in encasing it in a center environment.

\documentclass{article}
\usepackage{tabularx,booktabs,ragged2e,caption}
\newcolumntype{L}{>{\RaggedRight\arraybackslash}X} 
\begin{document}

\begin{table}
\setlength\tabcolsep{2pt}
\caption{Advantages and disadvantages of mid-drive motors.}
\label{tabMid-mod}
\begin{tabularx}{\textwidth}{ @{}LL@{} }
\toprule
\addlinespace
  Advantages & Disadvantages \\
\midrule
  Use the own gears of the bicycle & Wear a tear \\
  Consistent in steep hills & Big contact forces changing gears \\
  Lighter & Expensive \\
  More efficient & More noisy \\ 
  Low and centered mass center & More moving parts: more maintenance \\
  Higher torques\\
  Better suited for poor pavement \\ 
\bottomrule
\end{tabularx}
\end{table}

\end{document}

Answer 3

The easiest thing here is to use an invisible vertical rule. Invisibility is obtained by making it of zero width. Specifying height and depth in terms of the units ex gives you access to the current font parameters. So I suggest you write the heading as

\multicolumn{2}{c}{\textbf{\large 
  \vrule width 0pt height 3ex depth 1.5ex 
  Mid-drive motors}} \\

or (thanks to Mico) using the LaTeX \rule command

\multicolumn{2}{c}{\textbf{\large 
  \rule[-1.5ex]{0pt}{4.5ex}
  Mid-drive motors}} \\

This gives

\documentclass{article}

\usepackage{tabularx}

\begin{document}

\begin{table}
  \centering
  \begin{tabularx}{\textwidth}{ X X }\hline
    \multicolumn{2}{c}{\textbf{\large
    \vrule width 0pt height 3ex depth 1.5ex
    Mid-drive motors}} \\
    \hline
    \textbf{Advantages} & \textbf{Disadvantages} \\
    \hline
    Use the own gears of the bicycle & Wear a tear \\
    Consistent in steep hills & Big contact forces changing gears \\
    Lighter & Expensive \\
    More efficient & More noisy \\
    Low and centered mass center & More moving parts - more maintenance \\
    Higher torques\\
    Better suited for poor pavement \\
    \hline
  \end{tabularx}
  \caption{Advantages and disadvantages on the use of Mid-drive
  motors.}
  \label{tabMid}
\end{table}

\end{document}

The unit ex is the nominal height of the character lower case x in the font.

Incidentally you should seriously consider using the booktabs package with its commands \toprule, \midrule and \bottomrule for the horizontal lines.