What chainring and sprockets are used on TDF downhill

[Michel Merlin]

I would like to know better about the numbers of teeth on the crankset and on the sproket used by professional racers, not only on the UP CLIMBING of the hardes passes, on Tour de France or other big races, but also on the DOWN climbing, as well as the speeds actually reached then (I remember reading some 90-95kmh in some cases but I am not sure). TIA to any help.
Versailles, Sun 06 Aug 2017 15:23:10 +0200

 

[Irondan]

I would like to know better about the numbers of teeth on the crankset and on the sproket used by professional racers, not only on the UP CLIMBING of the hardes passes, on Tour de France or other big races, but also on the DOWN climbing, as well as the speeds actually reached then (I remember reading some 90-95kmh in some cases but I am not sure). TIA to any help.
Versailles, Sun 06 Aug 2017 15:23:10 +0200

Tour riders all have their own personal preference in gearing for both uphill and downhill sections of a Grand Tour stage. We can't possibly give you a straight answer because there's 198 or so riders in the Tour that ALL have their gearing customized to suit their strengths.

To give you an idea though, Geraint Thomas and Chris Froome have been known to use 54 tooth front chainrings when there's a big descent on a mountain stage. This choice has been the difference between winning and losing a stage for them.

 

[42x16ss]

A very typical setup would be a 53 x 39 crankset, with an 11 - 28 tooth cassette which gives good range and reasonable gaps now with 11 speeds. Riders would use both extremes of these gears in a major mountain stage.

Many domestiques (started by Adam Hansen) now use 52 x 36 tooth cranksets for greater range and minimum loss of top end.

In the Vuelta and Giro, riders have gone for full compact chainsets (50 x 34) on some of the insanely steep climbs like the Angliru or Zoncolan, paired with a 30 or even 32 tooth lowest gear. Cobo had 34 x 32 as his smallest gear when he won on Angliru in 2011.

Froome has a 32 tooth lowest gear paired with a 38 tooth small chainring for mountain stages.

Gearing is a personal choice, but most pros will use 53 x 11 unless they prefer marginally smaller gears. It's rare that they go larger unless it's for Paris Roubaix or a very important mountain stage that finishes with a descent.

 

[Jspear]

What they said. And yes, you've read correctly. They can reach those top end speeds. Of course it depends on the descent, how steep, how many switch backs, ect. I don't think you can put a number on what the average speed is. It totally depends on the mountain. I remember just this year, one of the descents in the Dauphine, they were going around 60-65 kph for large portions of the descent...of course slowing down where they needed to.