113mm or 118mm bottom bracket
 

Is there a huge difference between the two? Or, is it way better to try to determine exactly which one you "should" use? Also, does it make a difference if you're using a wheel with 130mm or 135mm OLD?

It depends ... on the crankset design/type, you have.
Oh yea, thats another factor.. FD swing is only, so.. far.

As I understand it, (but I could be wrong), the fatter your seat tube, (where the FD clamps on), the longer the BB spindle needs to be, to keep the FD in proper position relative to the chainrings.

Which crank are you using? As mentioned above, the crank determines the BB spindle length.

OK, well, on the Sugino XD600, it says either 113mm or 118mm. I have a Nashbar touring frame that takes a 31.8mm front derailleur. I currently have a rear wheel with a 130mm OLD but I may change to 135mm in the future. The FD I plan to use is a Shimano Exage ES (yeah, new old stock on eBay lol).

Chuckle; I thought it was just coincidence that you mentioned 113mm and 118mm, because those numbers were quite familiar to me. Just a couple weeks ago I finished building a bike with an XD600. It had:
- 28.6mm seat tube
- 68mm BB
- 135mm dropout spacing.
- Ultegra 6503 FD.
I used a 113mm BB and it works like a charm.

http://www.dim.com/~ryoder/soma-buena-vista.jpg

hybridbkrdr, I dug up this thread, 113 mm might be what you want: http://www.bikeforums.net/archive/in.../t-431643.html .

Brad

Well, I was going to use a SKS Chainboard so I guess that might add at least 1mm. Thanks to the two above posters. Hey Shimagnolo, nice looking bike! It even has an invisible seat. :D

It was for the GF. She brings her own saddle when she comes in from IL to visit.

For the record... 113 to 118 are 5 mm, thats divided in 2 means 2.5 mm at each side. Now doesnt look like a big difference, does it?

That's true. But, I was casually interested if someone could point out some advantages/disatvanges of going wider/shorter. Actually, I think you could also choose 115mm. I just wasn't sure about showing up at a bike shop with two bottom brackets asking them to test both.

Well if you go shorter usually the chainline will have less problems, your legs will be closer to the frame too.

I'd use the 113mm spindle for a 130mm OLD frame/rear wheel and the 118mm spindle for a 135mm OLD frame/rear wheel. A 135mm OLD frame has the cassette outward 2.5mm compared to 130mm OLD, so there's the 2.5mm driveside difference between 118 and 113 spindles.

I know this sounds off-the-wall. But, what if you want to be on the safe side and get 115mm? I don't know if I exhausted this question.

Sheldon Brown's site lists appropriate bottom bracket spindle legnths to use on different crank brands/models. For example, per Sheldon's lists, most forged aluminum double ring Stronglight cranks of the 80's and 70's eras used the 118mm spindle legnth for best chainline alignment. Longer for triples, of course. 80's Shimano DA worked best with 113mm spindles for their double ring cranks. I suspect that this will be similar for other Japanese double cranks with JIS tapers. I think his lists are based on installation on typical 68mm bottom bracket shell widths.

Chombi