As a rider, Coby became best known with the legendary black stud Ferro, with whom she won team silver at the Sydney Olympics (2000), among others.

She also achieved many successes with the likes of Ulft, Zonneglans, Pasternak DVB and Ojay DVB. She won no less than nine medals at the Dutch senior championships and finished second individually in the World Cup finals in Den Bosch (2000).

In addition, Coby is trainer-coach 6 of NOC*NSF, Knight of the Order of Orange Nassau, founder of the DVB Foundation and ambassador of Manege In ‘t Biobos in Arnhem (National Centre for Riding for the Disabled) and of the Prins Willem Alexander Manege (Vereniging Paardrijden Gehandicapten Amsterdam).