Problem is when the back wheel is in & equally aligned, the chain is rubbing on the tyre. I've tried to space the rear sproket out slightly by putting a washer behind each bolt but its still won't allow the chain to run freely. I've measured how much is needed to enable the chain to miss the tyre & its about 10mm. Can the hub in the wheel be offset by 10mm by tweeking the spokes ?? (I'd take it to a shop for that !) or is there any other surgestions ??