Right then <rolls up sleeves>
Sauve is actually really nicely placed for lots of good riding. Clockwise from the north :
The Cevennes – miles and miles of steep-sided valleys, forgotton trails and steep cols. Nothing marked up, but following a GPS trace would be a fabulous day out. Great place for road riding if you’re into that, from Sauve you can easily do some of the southern cols in a 2hr ride (Col du Lac, Col de l’Asclier, etc).
Sommieres/Vaunage – the hills just north of Calvisson and Caveirac, east of Nimes. At the risk of repeating myself : http://singletrackworld.com/forum/topic/anyone-ridden-near-sommieres-southern-france
North of Montpellier – The wooded hills just north of Clapiers have a good selection of singletrack, fireroads and Strava segments (like this one https://www.strava.com/segments/1600339 )
Pic St Loup – The big mountain between Montpellier and Sauve. If you only have the chance to do one ride in the area (and it’s not too hot) then the tour of the Pic is great. An example route is here : http://www.utagawavtt.com/randonnee-vtt-gps.php?topo=7531 (But be a bit careful following GPS tracks from “Randos” as they are from organised events that sometimes cross private land that was open for the event only)
The Gardiole – hills north of Frontignan. Lots of trails and Strava segments (like this one https://www.strava.com/segments/5932296 ) Bigger version of the Bois de Clapiers, near the sea.
Pézénas/Salagou – You already found one of the maps for this area, there’s another for the trails further south on this page : http://www.vtt-salagou.com/decouvrir/circuits-et-plans/ Around Salagou is very popular, and around the lake itself there’s some unique red earth terrain. The basic tour of the lake is OK (not at all technical apart from some fun swoopy trails on the north side), but can be spiced up a lot by doing loops into the hills. There’s a big organised event that does this – you can add or drop loops as you go along. There are GPS files available on their page here http://www.salagoumania.fr/modules/Circuits_2014/content.php?topic=static&id=26&page=circuit-ultra-2014
I haven’t actually ridden the black loops near Lodeve, sorry.
St Guilhem and Mt St Baudille – St Guilhem is worth a touristy visit anyway, but there are some good rides around the back of the big cirque behind the village. There are a handful of marked routes : http://www.saintguilhem-valleeherault.fr/_objets/medias/autres/affiche-topo-vtt-espace-vallee-de-l-herault-69.pdf but some of the best riding goes up the back of the cirque. Next valley over has Mont St Baudille with some very spicy descents. Things like this or this:
http://www.utagawavtt.com/randonnee-vtt-gps.php?topo=4693
http://www.utagawavtt.com/randonnee-vtt-gps.php?topo=2300
Mt Aigoual – The weather station/museum on the top is good, and there’s some good long forest loops around L’Esperou. A really good option if it’s seriously hot nearer the coast. Good road bike climbs up to the top.
So, I’d say that the FFC sites are OK (but not the best trails), Utagawavtt will give you a good idea of where to do longer rides (but watch out for private land) and Strava can show you the best little sections of trail.
That should get you going. Just don’t ask about the rock climbing or I’ll be here all day!
I’m down near Montpellier, and may be able to meet up if I’m around (but I’m very XC, so you’d have to wait for me after the descents). OCrider on here is down near the Gardiole and knows that whole side better than me, (although I haven’t seen him online for a while).
Edit: ooo he’s up there ^^^^