Yes that’s the first loop we done of the area on bikes back in 2003. It’s always the one I choose to do as my favourite although the descent into Annat is a topper. Fit a good pair of tyres if you want to rag down towards Achnashellach on the return! Its fairly rough compared to the Annat descent in a different way (the rocks just after the wee loch at the top would no doubt shred some tyres compared to the Annat descent unless you take it easy)
From Bealach Ban towards Coire Grannda it will look like the track vanishes into nothing. Stop and have a close look up to your right and you will see the Mountain Druid has just posted a pic of over the top of the hairpins.If you look closely you will see the track winding up in the foreground.
Once past the small loch at the top,after 15 mins or so you can hang a left down Drochaid coire lair towards the waterfall if you want to extend it a bit,then head right to finish off on the coulin pass towards Acnashellach. It extends the loop but its not as technical as the descent straight down into Achnashellach.