It depends. Last year around Saint Sorlin, Croix de Fer, La Touissaire etc, we found them very inconsistent. Some wouldn’t let you even ride a bike on the day of the race even though it would be 6,7, 8 hours even before the race came through.

Will probably partly depend how busy it is.

We went to three stages last year in and around St Jean du Maurienne, I agree with mtbtomo, they can be very inconsistent with access to the roads the race will be on. However, what I found surprising was how easy it is to get close the the route without there being any hint of traffic.

Last year we checked out all sorts of permutations for parking and riding in. We ended up driving to within a couple of hundred metres of the route each day. (I was with Jnr and the OH and it was about 40c most days, hence the reason for not just cycling everywhere).

On one of the days we were stopped from riding up the climb to La Toussuire. We had to dump our bikes and walk up. But as we had no lock we just waited where we were a bit disappointed. As it was even though we were only about 1km up the climb they were already riding pretty slowly and well spread out. Bonus then was we were low enough down to make it to a big screen and watch the finale even after the whole race and support vehicles had gone through.

You might be lucky, have you thought about driving up the opposite side of the mountain and not the route the riders will be taking? I did that last year in the Vosges and missed loads of traffic (but I know the area well) took blinking ages to get back down mind, 300+ motorhomes and scores of cars but what a blast watching 100’s of cyclist blasting downhill whilst following them..

All I would now add is relax, you’ll no doubt get held up in a queue at some point but there’s no point in loosing your temper, if you get my gist.