Originally Posted by
Doug Fattic
No 1 mm makes a noticeable difference. A bit off in chain or seat stay length is more important that other places. That is because of the ratio of length difference between the hub width and the distance to the rim/tire. That means 1 mm of stay length difference will move the tire/rim over almost 3mm. The tire won't just be 1mm closer to one side. [...]
Getting the chain stay lengths exactly right is one of the biggest challenges in building a frame.
Agree 100% and I found this out the hard way for myself
I thought you meant the chainstay length in terms of the length they both are. It doesn't matter if they are both 1mm too long or short. But if one is 1mm longer than the other I agree that's a disaster. I am super stoked that on my last two frames (out of 5) the rear wheel is absolutely bang-on in the right place with no filing of the dropouts. But it took me a lot of head-scratching and modification of my crude jigging facilities and procedures to get there.
I do wonder if this is why bikes always used to have sort of diagonal horizontal dropouts. There's a bit of adjustment there for both CS and SS alignment just when fitting the wheel.
If the OP uses an eccentric BB with vertical dropouts there's wiggle room in one axis and potential to file a bit in the other as a last resort. Similar with horizontal dropouts unless he goes with the diagonal ones. The least forgiving dropouts are of course thru-axles.