Bike Ban is still very much in place, but all the trails used in the big day mentioned above (Hi Ed) are 100% legal (You were right Tom). They’re also mostly not in the Chamonix valley. Le Tour and Les Houches then Les Contamines, St Gervais and Megeve. If you’re in Chamonix for near a week and buying the week long lift pass then it’s not bad value really and you can ride all those spots, if not, it’s something like 65euro for a (big) days riding. More info here: http://www.chamonixbikeblog.com/2018/all-the-lifts/
Even with the bike ban, there’s tonnes to ride.It’s a shame Wayne’s booked out as Les Houches in particular is getting really good these days, but most of the trails are really hard to find or spot. Te complications this year are that Grands Montets is basically closed to walkers and bikers for the summer as the new lifts being built hare over most of the lower trails, so they’ve been closed for the summer. Flegere has a similar story, although for the last few years bikes haven’t be allowed on it in July and AUgust. Brevent has recently changed to let bikes up after 1615 and only to ride Charnalon, which is good step. An important thing about the bike ban is that it actually makes sense. All the centre of valley trails are so busy with walkers there’s no point in riding them. More bike ban info here: http://www.chamonixbikeblog.com/2017/unintended-consequenceschamonix-bike-ban/
As for October Bream, unfortunately you’ll fall between the times the lifts are open in Chamonix, they close late in September and Brevent or Flegere will re open in late October. Verbier will still be open at weekends then, the train will still be running in the valley and Dorenaz, Bex, Saleve and other year round lifts will still be going if you have a car and the inclination to drive an hour.