The only city on the trail that stretches from Victoria to Queensland, Canberra's leg traverses rural grazing country, nature parks, the National Arboretum and suburban streets.

Groups of riders set off at 7am from Hall, the longest leg of Sunday's ride over 37 kilometres, Belconnen, the Cook horse paddocks and Kambah. They arrived at Equestrian Park, Yarralumla, about 1pm, where they received a commemorative key ring, before returning to their starting points.

Sunday's cold snap and showers did not deter the riders.

Helena Corkhill, 9, was among the youngest, while the oldest was 71-year-old Simon Bain, who has spent much of his life in the saddle across many equestrian disciplines. These days, he is an endurance rider.

Bicentennial National Trail co-ordinator Jenny Costin said some riders used the new underpass under John Gorton Drive, along a trail that re-opened access to Equestrian Park, which had closed during the construction of Coombs and Wright. ''Now the southern riders have access to Equestrian Park from places like Weston and Kambah, it completed the trail,'' she said. Ms Costin said Canberra had exceptional riding opportunities, with numerous agistment paddocks and 16 community horse paddocks for the territory's 2000 recreational horses. ''It is the only city you can see Parliament House while on a riding trail.''

The ride, which was 12 months in the planning, involved police stopping cars on the Barton Highway and other roads, three St John Ambulance first-aiders on horseback following the younger riders, an ambulance, rescue float and two on-call vets.