There's Schlegel Cycles which used to be The Bicycle Store Too at 59th & S. Western. Same owner just changed the name. And he's opening a new store on N. Broadway just north of the Bricktown area. Or there's The Bicycle Store at N 122nd and Broadway Extension. Most of the management and employees of these stores are guys who ride and/or race and really know bikes.
Ditto what Sooner said. I know the owner of the Al's in Norman but can't review their service work. He's a great young guy though and he rides. Pro Bike on 63rd near MacArthur is also OK, nice guy slow on service turnaround. It's a small Trek shop mostly.