But this year, another Ballarat institution, the Cycling Australia Road National Championships, moved its criterium races to that same Friday.

Both events will be at the same place, St Patrick's Cathedral on the corner of Sturt and Dawson Streets - or the gardens in the middle of Sturt Street at Dawson Street - at the same time.

The end of the criteriums is basically a massive street party, with the final race of the day attracting thousands to watch Australia's greatest cyclists struggle past the Golden City Hotel, which has a balcony packed with spectators.

Meanwhile, the opening night of the Organs festival brings the headline act, which last year was the intricate and confounding Arvo Part's Passio Domini Nostri Jesu Christ.

That's not a piece of music you would want to hear performed while cyclists pop open bottles of champagne in front of a cheering crowd - nor while teams pack up hundreds of metal barriers to reopen the road.

January's Organs showcase is something truly special, St Mark's Passion by Johann Sebastian Bach, and organisers were terrified it would be affected by the party.

They contacted Cycling Australia, which offered to delay dismantling the barriers and stage, and turn off its public address system, but the Organs volunteers didn't want to ruin the RoadNats party either.

Organs assistant director Judy Houston said the Cycling Australia team was very helpful, but her team decided to think more creatively.

"They should be allowed to have a street party, and should be able to enjoy it and announce their winners, all of that, we didn't want to cause them any trouble," she said.

"I thought of St Alipius' because we needed a church for that kind of music - it's not for the Civic Hall or Her Majesty's.

"It's a beautiful old church, it's very much a part of Ballarat history, and they're very welcoming up there.

"We put on the lights when we were up there, it was quite beautiful."

Father Justin Driscoll, who's the administrator for St Patrick's and St Alipius', took the call from Ms Houston.

"The Organs festival has been a great opportunity for Ballarat to celebrate buildings, music, a whole lot of culture that's been part of our heritage," he said.

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"St Alipius is certainly a smaller building, but the musical director has been in, they've decided it's certainly a good space to offer the Passion, acoustically and aesthetically, and spiritually I think, too."

To mark 25 years in the city, the Organs team invited Dr Gary Ekkel to direct his reconstruction of St Mark's Passion, which was first performed in 1731 and retained only in fragments.

Ms Houston explained parts of it have been recycled in cantatas, but recently, the fragments have been reassembled.

To real classical buffs, she said this is a work on par with the famous St Matthew and St John Passions.

"It's a big deal, many people have tried to reconstruct the parts but written their own to fill the holes," she said.

"This has never been done before, they've been working on it for years."

It's lucky it will be performed at St Alipius', she added, with its high ceilings, though the organ won't be used.

"The orchestra is the Melbourne Baroque Orchestra, all playing instruments from the 17th or 18th century, all authentic, and there are very good soloists, like Sally-Anne Russell, she's a soprano," she said enthusiastically.

"I'm feeling quite positive about it now after a few sleepless nights."

The Organs of the Ballarat Goldfields 2020 program is online now, with concerts in historic buildings across the district, many of them using the original organs.

St Mark's Passion will be performed at St Alipius' Church on January 10 at 8pm.

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