Originally Posted by
kyselad
I'm sort of stumped. All the info I find online seems more focused on lateral rather than vertical alignment issues. There's no apparent damage to the frame, but it's definitely a cheap mass-market model that may have had loose tolerances for tube lengths, welds, etc. Is there some way to fix this problem, or is it hopeless?
Check the head tube and seat tube are parallel. Do the string test to ensure the dropouts are centered on the front triangle. If you have a hefty bench vise firmly fitted to a bench you can clamp the faces of the bottom bracket and tug on the stays until they pass the string test and are correctly spaced in. If not you can support the frame on wooden blocks on the floor and with an assistant stand on it to set the stays. Set the dropouts parallel. Now when you check the rear triangle with a properly dished wheel you know that any misalignment is in the dropouts rather than the stays. You're aiming to get the rear rim coplanar with the front triangle, rather than centred in the stays - any apparent misalignment on the stays is now only cosmetic.