Kick bikes have no pedals but the sturdy riders say that a combination of passion and great fitness - and no doping - should suffice to complete the almost 3,500-kilometre (2,175-mile) course for this year's race.
Fame is not an issue. They say they're doing it to put their sport on the map.
"If we succeed, nobody will remember our names anyway," Czech team member Michal Kulka said during a recent training camp in southwestern Czech Republic. "Who cares?"
Starting each stage a day before the actual race means they will miss some of the hype of the June 29-July 21 race. But they have more practical obstacles to deal with: traffic lights will slow them down, one-way roads may force them to look for alternate routes — and they're still waiting for permission for their support vehicle to enter mountainous stages.
A more mountainous route also makes the challenge enormously tough this year.
The riders will have to climb the towering Alpe-d'Huez twice in the 18th stage, just four days after another classic climb — Mont Ventoux — at the end of the 15th stage, the Tour's longest this year.
After two years of hard training, the grueling ascents of the Tour don't seem to bother them too much.
"I'm more afraid of trucks," said Jaromir Odvarka, another Czech member.
For the bikers, who all belong in the top echelons of the sport, time is a constraint.
"The long stages may take about 15 hours or more," Odvarka said. "Sometimes, we won't get enough sleep."
The team's budget of 600,000 koruna ($30,200) means they will sleep in tents and instead of using a plane for two long-distance transports, they will spend hours in cars.
That each of them will have a tent of his own is the only luxury.
Their support team includes a masseur, a physiotherapist, a driver and a translator. The crucial question about how to get proper food was solved after the father of one of the men — Dutch rider Rene Konig — offered to serve as a cook with his girlfriend.
The four Czechs, all former track and field athletes, got the idea several years ago while sitting at a bar watching a report on Josef Zimovcak, who covered the 2005 Tour on a penny-farthing bicycle.
"I said that if the 50-year-old guy made it on a bicycle, I'd do it on a kick bike when I'm 30," Vaclav Liska said.
Others followed suit.
"It could be that some of us won't make it. But we're a team and we want to promote this beautiful, small sport," Liska said.
Their idea looked crazy enough for one of the biggest names in the sport — Alpo Kussisto of Finland — to join them.
"It's a wonderful idea," said Kussisto, a two-time world champion and a world record holder. "I hope that we can even enjoy it. France is a beautiful country."
The 2013 Tour offers plenty of beauty as it runs past famous sites such as the Mont Saint-Michel monastery and the palace of Versailles.
But Kussisto, above all, loves the mountains and is looking forward to "riding Alpine roads down."
Kussisto hopes the training and team spirit will help them overcome any obstacle.
"We switch the kicking leg and the standing leg all the time, like three kicks, switch, three kicks, switch," he said. "And you need to be able to micro relax your muscles for a tenth of a second."
Kussisto said he considered riding the Tour in 1998 but gave it up because "I was riding mostly alone. Now we have a really good team. I think it's possible."
While the Tour is still clouded by doping concerns after Lance Armstrong was stripped of his seven titles, the six kick bikers say they'll be as clean as can be.
"Doping makes no sense for us," Kulka said. "We don't race. We just want to be the first to make it."Suggest a correction