Lacing Used Hubs
 

I bought some used hubs on eBay to build a set of wheels. I was told I should lace the wheels in the same pattern they were originally laced. How can I tell how these hubs used to be laced?

There might be grooves. If not, just lace em and go.

It's hard to tell how many crosses based on the grooves (unless they look radial), although you can make an educated guess based on the number of holes, but the grooves should tell you which way the outer spokes went and which way the inner spokes went. As mentioned above, if you don't see any grooves, it doesn't matter.

I don't think that it's hard to tell at all.

If you examine the spoke holes on a used hub you'll find they aren't round anymore but rather are teardrop shaped. Ideally you'd like for your spokes to settle into the teardrops like the originals. Comparing the hub to a built wheel with the same number of spokes might make it easier to determine how many crosses it was previously built with.

That's exactly what I said :p

Also, for piece of mind you might want to take a magnifying glass and go around the hub and check to make sure there are no stress cracks in the eyeholes of the hub. I have purchased quite a few used hubs and have only once seen a problem with a pair that were radially laced. They should be ok and good luck with the build. Just out of curiosity what are the hubs?

The hubs are vintage 36 hole campagnolo hubs. The problem is that if I am going to lace them the same way as they were originally I need to know how they were laced so I can buy the right length of spokes. I imagine they were probably 3 cross but I am not sure. Maybe I can line some string up with the grooves and a rim and see if I can figure it out.

The spoke angles are also affected slightly by the rim depth, by the way. Also, 36 spoke wheels were traditionally laced 3x or 4x. Do the grooves look completely tangential or are they noticeably less than tangential?

+1 to the above. Unless they're really vintage, probably 3x. Most extreme method of checking: Buy 1 spoke the correct length for 3x and one for 4x. See what matches up.

Nope. You said that it's hard to tell how many crosses and I said that it's not hard. How could those two statements be exactly the same?

Me thinks he was being facetious.

Are you sure about that? It seems to me that the angles will stay the same, but the length of the spokes would change.
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If you take the outer ring as the original wheel and the inner ring as a new wheel with a deeper depth, you see that the spokes will be at the same angle, but just a shorter spoke.

Simple geometry. If the wheel was radial laced, you would be correct. However, on a cross laced wheel, the spoke hole travels in a straight line from the rim to the center of the hub as the rim gets deeper and deeper. The spoke, however, travels at an angle to one edge of the flange circumference. Therefore, the closer the spoke hole gets to the rim, the sharper the angle. As I said, these are very slight variances that won't amount to much unless we're talking very deep rims (like 30mm+), or even different rim sizes (650, 24"), but the angle WILL change some amount as the ERD changes. The larger the hub flange, the more dramatic the change as well. That's how I know this, as you have to consider rim depth and flange diameter when deciding on a lacing pattern for stuff like track wheels, which I built a lot of.

To prove my point, I would draw a straight line from the spoke hole to the center of the hub on your drawing. You would see that the red spoke would not touch that straight line on the inner circle without making a sharper angle at both the hub flange and therefore the rim as well.

You gotta read the entire sentence.

Makes sense, must have been too sleepy to think properly. Thanks.

Maybe this isn't the best approach, but I just laced a used hub opposite the original pattern to avoid the 'track marks'. It is an old S-A 3 speed, 28 spoke that was in a 20" wheel with traces of cross 3 going 'left', so I did it cross 2 going 'right' when I put it into a 16" rim.

I would think that to be the second best approach as it avoids laying the spoke on the sharp edges of the grooves should you be slightly off.

That was my thinking exactly. Going from 3x to 2x created a potentially hazardous situation of crossing over old damage. Again, it is for a kids bike, so I'm not too concerned about overstressing it.

Meanwhile, pray your wife doesn't read this forum.