PARIS – With 21 stages, 23 tough climbs in five mountain ranges, three mountain-top finishes and two time trials, the route for the 2017 Tour de France, unveiled Tuesday in Paris, promises an array of challenges for the wide variety of skill sets in the professional cycling peloton.

Here is a quick look at what to look forward to at the 104th edition of cycling’s greatest race:

OFF WITH A BANG: At just 8 miles, the opening time trial on Day One in Duesseldorf, Germany, is short enough for a good number of riders to harbor ambitions of winning it and becoming the first wearer of the race leader’s iconic yellow jersey — a guaranteed highlight of any rider’s career.

It also isn’t long enough for riders who are strong against the clock, like defending champion Chris Froome, to open up big gaps over weaker time trialers like key rival Nairo Quintana.

That is good for fans, because it will mean the race isn’t decided early on, but perhaps not so good for riders. With most of them still in contention after the time trial and full of nervous energy, they will race hell for leather over the next three flattish stages, increasing the likelihood of crashes that could take out top contenders.

SPRINTERS SHINE: Sprinters like Mark Cavendish, who can hit speeds of 40 miles per hour over short distances, will be looking for victories on the stages between Duesseldorf and Day 5, when the Tour veers sharply uphill in the Vosges — spiky, hilly terrain where bulkier, muscly sprinters struggle. They will get more opportunities for victories in Burgundy wine country at the end of week one, in week two before the Pyrenees and, of course, on the cobblestones of the Champs-Elysees boulevard at the end of the final stage in Paris on July 23.

OUCH, THIS HURTS: In their perpetual quest to innovate at the 113-year-old race, Tour organizers have slightly cut down on the quantity of climbs in 2017 but ratcheted up their steepness. Six particularly steep ascents stand out, starting with 20-percent gradients up to the Planche des Belles Filles ski station in the Vosges in eastern France. Froome won the stage there in 2012. The Col du Grand Colombier, in the Jura mountains on stage nine, has the sharpest gradients next year — 22 percent, steep enough to burn out the clutches of reporters who follow the race by car if they’re not careful.

Also in the Jura are the 15-percent gradients of the Mont du Chat, last climbed by the Tour in 1974.

“One of the hardest climbs in France,” says Tour director Christian Prudhomme.

Other gradients of note are 16-percent slopes to the Peyragudes ski station and 18-percent stretches on the Mur de Peguere, both in the Pyrenees, and a 14-percent section on the Col de Peyra Taillade, on stage 15 in the Massif Central.

QUEEN STAGE: Every Tour has a stage that stands out for its difficulty and the drama that is expected to generate, the so-called “Queen stage.” Next year that appears to be the unprecedented mountain-top finish at the Col d’Izoard in the Alps. The lunar and hostile terrain of sun- and snow-scorched rocks and the thinning mountain air on the long climb to an altitude of 7,742 feet could make the Izoard, at the end of stage 18, the last big battleground among surviving contenders for the winner’s check of $550,000.

LAST BUT NOT LEAST: The 14-mile time trial in the Mediterranean port city of Marseille on the penultimate stage 20 should settle overall rider placings before the largely ceremonial final ride into Paris the next day. The clock-race will start and finish in the Velodrome Stadium that is home to the city’s football team, and will scoot through the Old Port, with a short climb to the white basilica that overlooks France’s second-largest city.