Jason Kenny, Philip Hindes and Callum Skinner beat Poland by 0.051 seconds.
Britain's women's team pursuit and team sprint squads both took silver, beaten by Canada and Russia respectively, and the men's team pursuit won bronze.
Mark Cavendish is fourth halfway through the omnium after second places in the scratch and elimination races and a 16th in the individual pursuit.
The Manxman, who is yet to win an Olympic cycling medal, is aiming to qualify for the track cycling team at the Rio Games in August but faces stiff competition from Ed Clancy and Jon Dibben for the omnium place.
Olympic champion Laura Trott leads the women's omnium at the halfway stage, from USA's Sarah Hammer and Belarus' Tatsiana Sharakova.

The union said it was as a result of concern about a range of issues including staffing levels, shift patterns and pay.
General secretary Mick Cash said the RMT would be working with sister unions.
Last month, GMB Scotland announced that a consultative ballot on possible strike action by North Sea contract workers was to be held.
The Offshore Contractors Association previously said it was a challenging time for the North Sea oil and gas industry.

Oxfordshire County Council spent £25m in 2014-15 on direct payments to support about 1,770 social care users.
But an internal review has found "insufficient controls in place" to ensure money was not being misused.
Payments were spent on utility bills, household repairs, food and parents paying themselves high salaries.
Updates on this story and more from Oxfordshire
The report added: "The deputy director has confirmed these example items may not be relevant to meet assessed eligible need."
The  authority's website said direct payments were intended to pay for "a variety of care and support services".
It said: "Unless there are exceptional circumstances, you can't use the money to employ a close relative or person living in your home.
"You must not use your direct payment to pay for [...] items such as food, drinks, utilities, gifts or for other everyday items."
A report to the authority's Audit and Governance Committee said some expenditure had not been approved "but was not stopped nor recovered".
It added the current system "does not adequately clarify what is or isn't acceptable" and "does not require evidence to support payments".
"Finance queries had gone unanswered and also questionable expenditure not challenged," it said.
Labour councillor and committee member John Tanner said he would be pressing for more investigation into direct payments, because they were "wide open to abuse".
A council spokesman said investigations were continuing into the possible misuse of "a very small proportion" of the £25m budget.
He said steps would be taken to recover any misspent money and a new direct payment policy was being developed to make it clear how it should be used.
Last year, David Cameron wrote to council leader Ian Hudspeth and said he was "disappointed" at proposed cuts to Oxfordshire frontline services.
In response Mr Hudspeth said the council was trying to cope with £72m in funding cuts and increased demand for its services.
Britain's team sprint squad started their Olympic year with victory at the Track Cycling World Cup in Hong Kong.
[NEXT_CONCEPT]
The RMT union is to ballot offshore members over industrial action.
[NEXT_CONCEPT]
Money given to people to pay for their care was spent on items such as mobile phone bills and Apple computer equipment, a council audit has found.