Today's ride was pretty much all on relatively main road. From where we hit D1/D85 through Revel until close to Castres, the road was normally OK as there wasn't so much traffic. It's even designated a Tarn bike route, though that was probably by a non-bicycle rider as there's no shoulder and nothing other that we saw aside from a few signs noting the fact.
From Castres to Brassac, there was more traffic with long steady climbs that felt like a slog. The final leg from Brassac to Lacaune had much less traffic and was an absolute pleasure with nice climbing and great views.