Why aren't super aero bikes that are used during triathlons used during the tour de france? What are the pros and cons of this type of bike?

To add to the earlier answers:

Very aero bikes are often heavier. It's by no means certain that they would be competitive for all of the stages anyhow.

Very aero bikes in general, and very aero wheels in particular tend not to handle well when it's windy.

Again, it's not certain that they would be the best bike for the job.

Time trial bikes are not safe to use in mass start races and are therefore banned for pack riding. The only time you will see a time trial bike being ridden close to other bikes is during a team time trial. You cannot brake or steer your bike safely when riding shoulder to shoulder in a pack of 200 riders

Time Trial bikes are not safe in packs due to the riding position and lack of control.

wider or solid disk wheels are less safe on windy mtn passes

cons - aero is always heavier

tri bars are unsafe many times, wind, traffic, lots of reasons NOT to use them

con - uncomfortable for riding 3000 miles in 21 days

wle

Time trial bikes or Tri--Bikes ARE used in the Tour de France - for TIME TRIALS. That's what they were designed for. Although they might look alike except for the aero bars - the two different types of bikes have different frame geometries.

Look & see for yourself...

http://www.giant-bicycles.com/en-us/bikes/model/tr...

http://www.giant-bicycles.com/en-us/bikes/model/pr...

They are used on the time trials and on the team time trials .... they cannot be used on regular stages because of the lack of control.

Soccerref