MTS, Gilesgate, (Durham) Jim's only interested in you if you want to spend lots of money.
Evans, Gateshead, I wouldn't touch 'em with yours.
Steels, Gosforth, Good shop if you get to know them, but can be a bit snooty if you don't.
Bike Place, CowGate, Not been to the new place, but they were always friendly and helpful before they moved. Never really stocked much though…
Denton's, Scotswood road, Sad to hear they've closed down, but not surprised. Used to be a good shop before they moved. Last time I was in they had 3 bikes on display, and only one was new!
Low Fell Cycles, Gateshead, great if you want to be told "you don't want to buy that", then get ripped off. Otherwise, not so great.
Edinburgh, Byker, Stock lots of stuff, but you've got to choose the right member of staff if you want a knowledgable answer, and they're not cheap.
Cestria Cycles, Chester-le-st, very friendly, and stock way more than you'd think for a tiny shop. More of a roadie shop though.
Nothing in Sunderland worth bothering with.
If you're prepared to travel, Bike Scene in Guisborough is probably the best MTB shop in the region.
If you only need a repair, give me a shout… 🙂