Most of the tracks around Swaledale are reasonably weather proof, obviously a couple of metres of snow might slow you down!
Stu at Dales Bike Centre near Reeth should be able to give you detailed info, he sells route maps, but for starters this is a variation on one of the classic local loops.
From DBC head up Fremington Edge and over to Hurst. Turn left and head over to Storthwaite Hall (mildly tech section through the quarries) then Langthwaite. A bit of road to get to the BW onto Reeth Low Moor which takes you to the track up onto Great Pinseat. Over this then turn R at the junction at Level House. Here you can either head over to Gunnerside Gill (very technical descent) or after a little while turn L and head south over the moor. In either case you are looking at getting to the wonderfully named Barf End. There’s now a BW descent to Gunnerside (pub here for mid ride refreshments).
If you want a longer ride then take the minor road west from Gunnerside to follow the Swale round to Keld then come back up and over the hill of Kisdon to Muker. Back down the road to Gunnerside.
Either take the permissive BW by the river to Robson and climb to Crackpot or take the minor road directly. Road to Summer Lodge then BW up to higher road. Turn left and down this road until there’s a BW on right. Climb onto the moor when you can either head over to Apedale or turn left and contour around the fell side to Harkerside and then back to DBC. If you choose Apedale, turn left at the crossroads at the bottom and climb back over to Harkerside and down to DBC.
If none of the above names mean anything to you then either get a map (always advised) or follow it on Streetmap.co.uk.