[Tex/LaTex] Unwanted extra spaces are included before and after backslashes in biblatex URL

biblatexspacingurls

I have a biblatex reference with a URL field. However, every backslash is surrounded by spaces.

I am using

\usepackage[sorting=nyt, citestyle=authoryear, bibstyle=authoryear, isbn=false, firstinits=true, url=false, terseinits=true, dashed=false, maxcitenames=3, maxbibnames=99, backref=true, doi=false]{biblatex}

What causes this, and how can I remove them?

EDIT: MWE

My biblatex .bib file is this:

@ONLINE{Soderberg2010,
author = {Soderberg, T},
title = {Section 5.1: The origin of the {NMR} signal.},
year = {2010},
url = {http://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_a_Biological_Emphasis/Chapter__5%3A_Structure_Determination_II/Section_5.1%3A_The_origin_of_the_NMR_signal},
urldate = {2013-5-16}
}

This works:

\documentclass[11pt]{amsart}
\usepackage{geometry}                % See geometry.pdf to learn the layout options. There are lots.
\geometry{letterpaper}                   % ... or a4paper or a5paper or ... 
%\geometry{landscape}                % Activate for for rotated page geometry
%\usepackage[parfill]{parskip}    % Activate to begin paragraphs with an empty line rather than an indent
\usepackage{graphicx}
\usepackage{amssymb}
\usepackage{epstopdf}
\DeclareGraphicsRule{.tif}{png}{.png}{`convert #1 `dirname #1`/`basename #1 .tif`.png}
\usepackage{multicol}

\usepackage[sorting=nyt, citestyle=authoryear, bibstyle=authoryear, isbn=false, firstinits=true, url=false, terseinits=true, dashed=false, maxcitenames=3, maxbibnames=99, backref=true, doi=false]{biblatex}
\addbibresource{resourcename}


\title{Brief Article}
\author{The Author}
%\date{}                                           % Activate to display a given date or no date

\begin{document}
\maketitle
%\section{}
%\subsection{}

\begin{multicols*}{2}
\parencite{Soderberg2010}
\end{multicols*}{2}

\printbibliography

\end{document} 

This doesn't work:

\documentclass[11pt]{amsart}
\usepackage{geometry}                % See geometry.pdf to learn the layout options. There are lots.
\geometry{letterpaper}                   % ... or a4paper or a5paper or ... 
%\geometry{landscape}                % Activate for for rotated page geometry
%\usepackage[parfill]{parskip}    % Activate to begin paragraphs with an empty line rather than an indent
\usepackage{graphicx}
\usepackage{amssymb}
\usepackage{epstopdf}
\DeclareGraphicsRule{.tif}{png}{.png}{`convert #1 `dirname #1`/`basename #1 .tif`.png}
\usepackage{multicol}

\usepackage[sorting=nyt, citestyle=authoryear, bibstyle=authoryear, isbn=false, firstinits=true, url=false, terseinits=true, dashed=false, maxcitenames=3, maxbibnames=99, backref=true, doi=false]{biblatex}
\addbibresource{resourcename}


\title{Brief Article}
\author{The Author}
%\date{}                                           % Activate to display a given date or no date

\begin{document}
\maketitle
%\section{}
%\subsection{}

\begin{multicols*}{2}
\parencite{Soderberg2010}
\end{multicols*}{2}

\begin{multicols*}{2}
\printbibliography
\end{multicols*}{2}

\end{document}

The only difference is that the second document has the reference list inside multicols.

Best Answer

biblatex gives some small stretchability in URL breaking using url package \Urlmuskip parameter. This is there whether or not multicolumn is used, it's just that in the narrow measure of a multi column setting the stretchability is more likely to be used if available.

There is probably a higher level biblatex setting for this, but this just patches the setup command to reset the parameter to zero.

adding this to your preamble

\toks0\expandafter{\biburlsetup}
\edef\biburlsetup{\the\toks0 \Urlmuskip =0mu\relax}

produces

enter image description here