So I have an Italian frame that I'm putting Japanese parts on.

The crankset being used is a Sugino Mighty Compe double.

I'll only be running 5 gears out back.

What spindle length do I need? How do I figure out what spindle length I need for future projects as well?

You need the length of spindle that, while matching the offset of the drive-side crank, lines up the chainwheel(s) with your cog(s) -all the while fitting the BB shell width and the bearing races lining up with the cup locations within the shell.

Simple!

Fantastic!

You need to find out what Sugino recommends for a bottom bracket spindle length. If you can't find any published specifications, or you don't have the original spindle it was mated to, you will need to try spindles until you find the correct length.

There is no easy way to figure this out unless you know what size spindle the crank uses in an English 68mm BB. The crank calls for a 115mm spindle so I think a 118 will work with your Italian bb. I'll look into it a bit further.

There's a site (icelord, I think) where you can download old editions of Sutherland's and Barnett's handbooks. Both have pretty good sections on spindle selection and matching and BB matching for nearly any crank to nearly any frame. It's a rather exacting process but it REALLY works.

No good, quick answers to this one!

I found Cobrabyte's old thread via Google. https://www.bikeforums.net/showthread...spindle-length

Apparently, the consensus is 113-115mm spindle length. Now do you think that would work for my application?

I found the site. I'm going to give it a look.

Italian bb's are 70mm not 68mm so add 2mm it should get you close enough.

I'll stick with 115 right now.

I was under the impression these cranks were JIS taper. Velobase has them listed as ISO. What is it?

118mm will only be 1.5mm longer on each side. A mm or 2 longer works a mm or 2 shorter does not. Those cranks have a Campy taper.

I thought that the 68/70 was the diameter of the BB shell.

Spindle length would have nothing to do with that.

Seems like the real issue is going to be clearance on the chainstays, the chainline, and Q-factor.

Someone correct me if I'm wrong, educate this pilgrim.

You are wrong.

https://en.wikipedia.org/wiki/Bottom_bracket

Relevant quote:

"There are a few standard shell widths (68, 70 or 73 mm). Road bikes usually use 68 mm; Italian road bikes use 70 mm; Early model mountain bikes use 73 mm. Later models (1995 and newer) use 68 mm more commonly. Some downhill bikes even use a 83 mm bottom bracket shell. Snow bikes use a 100mm shell."

Hey - that was fun!

I'm glad you enjoyed that.
Now, what about the shell diameter? If I recall, my English bb cups will sit right inside the Italian shells....
Maybe I'm wrong again, but in addition to the opposite threading, are not the cups of a different diameter?

Yes, also different diameters. Look at the chart, son... look at the chart:

https://en.wikipedia.org/wiki/Bottom_bracket

SO/English or BSA 1.37 in x 24 TPI Cup Outside Diameter 34.6-34.9mm Left-hand thread drive side
Shell width 68 mm

Italian 36 mm x 24 TPI Cup Outside Diameter 35.6-35.9mm Right-hand thread both sides
Shell width 70 mm

French 35 mm x 1 mm Cup Outside Diameter 34.6-34.9mm Right-hand thread both sides
Shell width 68

Swiss (very rare) 35 mm x 1 mm Cup Outside Diameter 34.6-34.9mm Left-hand thread drive side
Shell width 68

Sutherland's lists the Mighty Competition as having almost the same length spindle for both Italian and English, 115 and 114 respectively. Makes sense: if both have the same OLD for rear dropouts, why would the chain want to be 1 mm farther from centerline? I'd even bet that Sugino actually only made one length spindle for these cranks -- have you ever measured several spindles that were supposed to be the same length? If they all fall within a mm, you're having a good day. What you want is a Sugino MW-70 spindle. I think that whoever put ISO into Velobase was incorrect -- Sugino/SunTour (and I think some years of Dura-Ace too) used Campy's pre-ISO taper, basically; because they were the big dog in racing equipment. Now that Campy has gone ISO (1992 or so), everyone thinks that those older spindles were ISO, but they were somewhat "stubbier."

Aren't they different widths from race to race between Italian and English spindles? So what taper do I need then?

Forgive me, why would the spindle length be affected by the bottom bracket shell width? I would still think you would want the correct spindle length to match the desired chain line.

Clearances between the inside of the crank arms to the shell.

Don't forget that there are thin cups and thick cups as well. IMHO, I don't think you can interchange 68mm and 70mm spindles routinely. Maybe if you used 'thin' cups on the 68mm and 'thick' cups on the 70mm you could make it work but in my experience, once you deviate from a known solution things quickly devolve into trial and error.

I have a Dura-Ace 7400 cup set if anyone has an Italian 115 spindle. Can you get replacement outboard rubber seals for these bottom brackets?

As I said before, "no easy way to figure this one out". You'll have to try different spindles till you get the correct one. Also remember that the spindle races ARE wider apart and this will cause the spindle to act shorter, and this is the other reason to go with the 118mm spindle.

I also assumed you know that you cannot use the English cups......

But Capecodder told you the Sugino Mighty has a Campy taper,
which my copies of various Sutherland's manual editions also
state. So you can probably get by with either ISO or JIS,
but https://sheldonbrown.com/bbtaper.html
(This is an excellent link and you ought to bookmark it if
you plan on doing this very much in the future.)

There are also pages of charts and explanations in Sutherland's
that are too detailed to post here, suffice it to say i think that if
you are dead set on simply finding a spindle that will work
with your current loose ball cups and take your Mighty
cranks, you will need some luck and a box of candidates
from which to choose.......like at a bike coop or other
vintage parts place. There are bearing race width issues,
bearing size issues, cup and spindle compatibility issues,
issues with where the bearings actually ride between the
spindle cones and the cup races........muy problemas, amigo.

Were I doing this conversion, I'd probably just go with a
sealed unit and some sort of cups for installation similar
to the Phil Wood ones that allow you to move the entire
cartridge side to side by 4-5mm to allow chainline adjustments.

Look here for a photo of all three tapers side by side:

https://www.philwood.com/products/bbhome.php


Look here for a general idea of the sorts of sizes and
tapers and offsets available.......at least from Phil Wood.

https://philwood.com/store/page30.html

This presumes you can invest this much money in your
project and that it is worthy of the investment.

If you have this sort of info, you can sometimes source
the actual unit you buy elsewhere.

These paragraphs are right on the mark. If you're going to go spindle
and use the methods to nail down the final answer, you need to have
one to use as an example and then the ability to measure it's positionings
rather exactly. Then you need to use the procedure sheet to correct the
fit factors that may not fit well (chainline, chainring/stay clearance, spindle
bearing position, spindle clearance in the BB cup, and whether the cups
are thin or thick. Based on all this and your first-try spindle dimensions,
you can pick the best possible fit from listed parts, and the acceptable
compromises. If you can find the best parts and buy them (spindle or BB,
you're golden and will probably have a better-than-OEM crankset fitment.

But's it's not easy, and you need to find an LBS with a box-o-spindles.
Used ones are good enough for fitting purposes.

But not least is actually finding the parts you need.

If you can identify and buy the parts that Sugino intended, that's your best
first try. Or if you can measure them, you can identify the best choice of
sealed BB for a first try. Sugino stuff (some of it) has been pretty dear on
Ebay, same for Campy NR or SR spindles. Shimano or Token BBs will be
much cheaper if you can identify and source the correct part.

There are cases where the same spindle or BB length is used for ISO and JIS BBs. For this to occur requires that the crank arms don't fit too close to the BB cup end in the Italian (longer) case. It won't always be true that you have to lengthen for Italian. Campy Record Triple (111mm assymmetrical) is one I've lately encountered.

Yes, they are; that's the difference between Sugino MW-68 and MW-70 spindles. As I said, Sutherland believes that they're a similar taper to Campagnolo, pre-1992. But just using a Campy spindle in the 115 mm length may not work just right, because the distance between the two bearing tracks, and the location of the bearing tracks on the width of the spindle (symmetrical? non-symmetrical and by how much?) is probably somewhat different. If you want theoretical answers to stuff like this, you need to get and immerse yourself in Sutherland's, which is quite complete on the subject. If you want real-life answers, of course, you need to get some spindles, cups and BB shims, and immerse yourself in trial-and-error. There's no simple answer where BBs are concerned.