2 cross lacing, which one of these pictures is correct?

I've done both.
#1 was back in the day on a triathlon bike tubular front wheel.
About the only advantage is you don't get any noise from spoke rubbing.
I've never seen it on any bike since.

The second one is the correct one for 2x.

Everywhere I have seen is 3x over over under and 2x over under relative to the spokes you cross but never an explanation about why that is the case.

I suspect it might be to brace the spokes and make a stronger wheel but I haven't been able to turn up anything that explains why the cross layout is an over under type setup or the science for why that is the preferred way to go.

Thanks for the replies, I will be lacing mine like the second picture

I was going to do it that way but just thought it would be smart to ask first so I am doing it right, last thing I want is to have to take the wheel apart after building it! I want my first wheelset to be done right and work for a long time

silentG said:

The second one is the correct one for 2x.

Everywhere I have seen is 3x over over under and 2x over under relative to the spokes you cross but never an explanation about why that is the case.

I suspect it might be to brace the spokes and make a stronger wheel but I haven't been able to turn up anything that explains why the cross layout is an over under type setup or the science for why that is the preferred way to go.

Click to expand...

Been a while since I've read up on wheel building, but I think the over/under cross adds significant lateral stiffness in the wheel. Obviously you can build a wheel without that bracing, but might be less stable or require extra tension to compensate.

wolfmw said:

Been a while since I've read up on wheel building, but I think the over/under cross adds significant lateral stiffness in the wheel. Obviously you can build a wheel without that bracing, but might be less stable or require extra tension to compensate.

Click to expand...

I believe you are correct. I recall tying and soldering used to be done to try and maximize the strength contribution of the cross.

I can do the math but justification is easy to visualize.

it’s Just like wider flanges.

strength is lost quickly as flanges become narrower from x. More quickly than strength is added by making flanges wider from x. At the limit a 0 offset flange has zero lateral strength.

having one spoke hold another outboard weakens lateral strength of outer spoke, but more than makes up for it by adding lateral strength to the inner. Having spokes fold across each other at the cross also equalizes their strength and stiffness so spoke tension will be more uniform.

it’s pretty much an error to build without the cross touching. Wouldn’t you need different length spokes?

+1 to cross rub.
It's also better at holding straight pull bladed spokes in place without them winding out slightly through vibration.

I would use the first way on the drive side of a wheel where the other side is radial laced (just like in that picture). It equalizes the stresses on spokes on each side of the hub. Wheels are the strongest when impact stress is as even as possible across all the spokes. This is actually a stronger overall wheel vs using the lacing from the 2nd picture on the drive side and radial lacing on the other side.

The cross on the drive side is just to fight wind-up while sprinting, and you don't need the crosses to touch for that.

I'd use the 2nd way in any other situation besides one side being radial laced.