Longer than "standard length" axel-are they available?

[night cycler]

Is it possible to obtain an axel (back wheel on mountain bike) that is a bit longer than the standard length ? I want to fit a steel bracket on either side for towing a small cart (NOTE: cart not car)

 

[Dusty Bin]

Depends what you mean by a 'standard' length - there are several....

 

[Rickshaw Phil]

Axles are available in different lengths & diameters. Any of these any good to you?