The rear wheel of my recently purchased singlespeed (IRO Rob Roy) is way off-center between the chainstays, which I hadn't noticed until I tried to adjust the rear V-brakes. Is this a normal set up? And how do you center and adjust the brakes when the wheel is so far to one side? Turning the little screw that adjusts spring tension is not doing it. I know it's possible because the bike arrived with the brakes well adjusted, but I don't know how to do it. Thanks.