Highway 51 in Saskatchewan
 

Has anyone out there any recent experience in cycling Highway 51 in Sask? It is one potential route for me across the province on a planned Cross Canada trip. If it is not very good are there other potential cross province routes nearby. Please not the TCH or Highway 16. If Hwy 51 works are Hwy 14 and then Hwy 5 usable to complete the crossing?

Unfortunately, none of the highways going across Saskatchewan are up to the volumes of traffic they have to handle. Definitely avoid highway 7. Highway 51 might be quiet, but unfortunately it ends and you have to get onto highway 14, which isn't so quiet.
Hopefully people who've lived here a lot longer than me can chime in. One possibility that I can think of is highway 44, which comes off highway 570 at the provincial boundary. Not in great shape, but quieter than 7. From there you can either cross the river at the Gardiner Dam and get onto 219 and then 15, or go left at 45 and cross the river further north. Highway 219 is brand new and has a wide hard shoulder, so is pleasant to ride on. From there I'm not sure what your best bet is. Highway 5 isn't bad until you get to the Clavet turn-off (316), but has no hard shoulder from then on. If you take it very early in the morning or after 6:00 pm it might be okay. You're right to want to avoid 16, especially up to Colonsay. The potash mine on the junction of 16 and hwy. 2 is undergoing a major refit, so there's even more traffic than usual.
However, Little Manitou lake is worth a visit. Soaking in it's healing salty waters will help you recover from being battered around by our horrible potholes. Did I mention that almost all of the roads here are full of potholes and in really bad shape? Use your sturdiest tires.