The large gathering of riders in Cambridge included Russians, Argentinians, Great Britons, Dutch, French and Australians.
The World Masters cycling programme began with the individual pursuit, with Rixon (Women's 60-65) winning gold, while O'Brien (65-70) continued her success from the NZ Masters with silver, and Hamlin (Men's 75-80) got bronze.
Next came the 500m time trial, as O'Brien won gold while breaking her current New Zealand record, as Rixon and Hamlin claimed silver.
Possee (Men's 75-80) rode will to earn a silver in the points race.
Last Friday was the sprint qualifying, with all the Whanganui contingent going through to the evening finals.
O'Brien won silver in a photo finish, while Rixon also got another silver and Hamlin grabbed bronze.
The last day of the module was the scratch races, where Ross (Women's 45-50) won bronze in a highly competitive field, while the Dutch and French riders made it tough for the Kiwis.
Possee got a well-deserved bronze to wrap up his campaign.
"A fantastic effort by all the riders, certainly the competition was a big step up from the NZ champs," said Hastie.
"Many world champions were competing, [and] the racing form of all New Zealand and overseas riders was top class, which was appreciated by the large crowds attending."