Descent from the top of Stake Pass into the valley has just been ‘fixed’ – it’s now a smooth, raised zigzag then you follow the beck down to the bridge. Don’t follow the bridleway on the map, sticking to the right hand side of the beck – it’s more fun to cross the bridge and follow the (unmarked) path on the left side. It’s a techie rock garden before you drop down to Stonethwaite.
Not ridden the second half of your planned route over Greenup Edge I’m afraid (keeping meaning to) – I know Lining Crag is a steep carry though.
Less interesting alternate route if you need it – Rosthwaite up to Watendlath, up by Blea Tarn, down to Thirlmere is the bridleway; the cheeky / quicker route is over High Tove. Then it’s tarmac from Dunmail Raise to Grasmere.