Filippo Ganna said Saturday evening that while his numbers were "good" ahead of his attempt at the world time record, it would take the "biggest effort of his life" to pass the 55.548 km record set by Dan Bigam in August.

The Italian spoke ahead of his attempt at the Grenchen Velodrome in Switzerland, where the Englishman, a performance engineer for Ineos Grenadiers, set the record.

Ganna's challenge had long been anticipated, with most pundits predicting that the record would be out of reach for some time for the time trial and track specialist.

"The power meter numbers are good. But I don't know what will happen tomorrow. Tomorrow you will have to make the biggest effort of your life."

"I don't know what to think about for the last 30 minutes. Maybe I'll just breathe normally and try not to feel the pain in my legs and butt.

The 26-year-old reportedly completed the 35-minute trial run at an average speed of more than 56 km/h, a considerable difference from one hour.

He said he tried the one-hour run before the recent Road World Championships, but that he would determine his true pacing as he ran.

"Tomorrow is 60 minutes, so it changes a little bit. Maybe if it's 35 minutes I can say it's really east, and if it's 36 minutes I'll want to die," he said.

"I tried a more moderate pace before the World Championships. I found I could run a little harder and stronger than they thought. I will decide my real pacing during the race."

Ganna revealed that he has been clocking lap times of 15.8 to 16 seconds in training for the challenge, which, when converted to an hour, translates to a distance of 26.250 km to 56.962 km, a significant improvement over Big Ham's record.

Bigham, who broke Victor Kampenaerts' record by 459 meters, told Cycling News that in the run up to Ganna's challenge, he had helped design the bike, assisted in training, and had even broken the record himself as part of his preparation.

Of his bike - a €75,000 3D-printed Pinarello Bolide F HR 3D with a 64-tooth chainring - Ganna said that despite its high weight, it "flies on the track" as the laps go by.

"It's heavier than normal, but fast. Nine kilograms is a lot, but it's not a problem." You might not feel super fast for the first three or four laps, but within five minutes you're flying on the track, and I'm hoping to fly for an hour [As for gears, he tried with 65 and had the idea to use 66, but just to be safe, he prefers to keep the cadence a little higher.

"On the track I usually run around 170 or 120 rpm, but tomorrow it will be more like a road race at 96 rpm.

Ganna's impressive list of accomplishments includes six Giro d'Italia stages, two world time trial victories, multiple team and individual pursuit gold medals at the world and European levels, and a team pursuit gold medal at the Tokyo Olympics.

The hour record, if he achieves it, would be another major accomplishment to add to a long list, but Ganna said it would not top his career.

"If I have my best ever performance tomorrow, it will definitely be second only to the Olympics," he said, noting that a merely "good" performance would drop down the rankings for him.

"That win is at the top level. I think if you have teamwork with everybody, it's a personal thing. It's more important to win together than to win alone. That win is top level."