If you can space them out vertically, then you can put them quite close. If you want them all in a line, assume that the handlebars will hit the saddle of the neighbouring bike, so space by half the width of the widest handlebar + half the width of a saddle.
If you can space them out vertically, then you can put them quite close. If you want them all in a line, assume that the handlebars will hit the saddle of the neighbouring bike, so space by half the width of the widest handlebar + half the width of a saddle.