Hi! Well, I've decided on a Sugino XD600 crankset for my 2001 Lemond Poprad cross bike. https://stores.channeladvisor.com/ebi...ems/004-CR1029

It says: Spindle Interface Type = Square Taper JIS
Spindle Length = 113,118 mm

Which bottom bracket do I use? I'm looking at the Shimano UN54 bottom bracket. Should I get the 113 or the 118 spindle? I am wanting to use this for a 9 speed. Any help anyone can give is greatly appreciated!

My guess would be 113mm for that bike (130mm rear dropout spacing), the 118mm would be for bikes with mountain bike rear axle spacing of 135mm.

My interpretation would be that the crankset comes in double and triple, 113 for the double, 118 for the triple.

I concur

It doesn't appear to come in a double. All the net searches I've done only show a triple.

Here's what Rivendell has to say about it. They agree with well biked.
https://www.rivbike.com/webalog/crank...ngs/12067.html

Thanks for that, but now I'm confused. The Rivendell site says, "For road bikes, use a 107 to 110mm spindle. For mountain bikes, a 113 to 115mm spindle." I'm sure my Lemond would be considered more of a road bike than a mountain bike. But all the net searches I've done on this crank only say 113/118.

Use the longer spindle on a bike with a 135mm rear hub. Clear enough?

You have to figure your chainline, which I've only been able to do with parts in hand. I'm running a Sugino XD triple on an older '85 Batavus Competition frame with an 8 speed cassette and 130mm OLD hub. The 113 was way too far outboard. I'm using a 107mm now (which I believe is the same as a 110mm, except it's asymetrical, shorter on the non-drive side) and I still think the chainline could improve by moving inboard. However, the chainstays on your Poprad may interfere with the granny ring when using a shorter spindle.

The 9 speed cassette on a 130 OLD hub would require an even more inboard chainline, or are the 9 speed cassettes narrower than the 8 speeds? On a 135 OLD hub, it would be more outboard, obviously. I'd go with as short as you can manage, without striking the chainstay or having the crank bottom out on the BB cup (mine is actually a couple mm inside the cup, but it clears it).

https://sheldonbrown.com/gloss_ch.html#chainline

EDIT: I'll add: Sheldon makes a good point in his write-up; if you plan to use the outer two rings most often, more outboard makes sense. If you use the inner two more often, more inboard makes more sense.

I have the same crankset with 9-speed in the rear on an Ibex mountainbike frame. It takes a 113 mm spindle for a 135mm spaced frame.

Please forgive my lameness, but I have one more question. I went ahead and ordered a Sugino XD300. I've determined that I need the 113 size bottom bracket. If I am reading this correctly, https://www.sheldonbrown.com/bbsize.html according to Sheldon Brown, the bottom bracket I have on there now should work, right? (I currently have a Shimano Tiagra 4403 triple crankset.)

Thanks again for the help. I really want to try to do this myself, but I'm starting to feel overwhelmed. All this talk of rear spacing, chainlines, spindle lengths, etc... It's starting to make my head hurt!

Yes, that should work. Figuring chainlines gives me a headache, too, and hurts the wallet. But misery loves company!