I got a deal on a Sugino XD2 crankset and didn't think about the chainline when buying it. The seller threw in a Sunrace BBS15 bottom bracket with a spindle length of 118 mm. Now the chainring is 15 mm too far to the outside, this would mean I'd need a bottom bracket with a spindle length of (118 - 2 * 15 = ) 88 mm, or is my calculation off? I hope so, because the shortest BBS15 is 107 mm. I could also get a BLB x Tange BB with a 103 mm spindle, which their site says is designated for Sugino cranks. Would this solve my problem, or is this crank simply not compatible with my wheel / frame? I also found the Miche Primato BB which doesn't have a flange so that should allow for even more chainline adjustment? Everything I've listed is well within the money I'm willing to spend to make this work, so if one of the options is better for more reasons than chainline I'm interested in that as well.
Thanks in advance!

Your calculation is off. You don't have to remove 15 mm from each end of the spindle, only the drive side so: 118-15 = 103 mm. Take the frame and crank to a bike shop and hand fit a couple of bottom brackets and see where the chainrings fall.

BTW, how did you determine your chainline? An error of 15 mm is difficult to imagine even with a spindle way beyond the recommended length.

As per https://www.suginoltd.co.jp/english/p...d2_english.htm , you need a 110 or 113 mm bottom bracket to get the correct chainline. 118 mm is wrong for this crankset.

Good catch, hamster. This crankset throws more than a few mechanics, pro and shade-tree,

But the current chain line is 5,5 and the target chain line is 4,25, I don't see how a 8mm decrease in spindle length would solve a 12,5 mm gap?

My guess is an error in measurement or in nominal size of your current bb. Get a Shimano un55 in the correct 113 for $22 and see what you end up with. I don't see that you mentioned what frame you have....

Where are you measuring the chainline from and are you doing it correctly?

From his other posts, sounds like he has a double (actually a single with a chainguard). The standard choice for a double is 110. For a singlespeed, even smaller.

4.25 is not happening with the 110 spindle. Again from my link, 110 gives you the chainline of 45 to the midpoint between rings, and, if you're using a double crank as a singlespeed, that puts the outer ring at 47.5.

OOps, just assumed a triple, I guess because that's what mine is

OK I am confused. The reference link does not take into account the BB size, 68/72 or the rear spacing and cog cluster dimensions. Isn't the chain line determined by those references too? I assumed the datum is the rear configuration as long as the inner chain ring does not hit the chain stay. Why Sheldon starts with the crank is a bit confusing to me too. I would determine the measuremetn from the rear and then match the front as close as possible and then use the rear axle cone placement for fine tuning.

https://sheldonbrown.com/chainline.html

I am not a mechanic just a dumb mechanical engineer. How do you mechanics measure, rear first then cranK?

Ended up getting a 107 mm, since I assumed that double would target a chainline of 45mm where I needed a 42mm chainline. My measurements turned out to be correct, since the chainline is pretty much spot on now! Thanks for your replies, gave me the insight in BB measurements and sizes I needed. Cheers!