Ronno6

I had always laced my wheels with the heads down spokes in the leading position.
This gave the pulling (trailing, heads up) spokes the straightest path from flange to rim.
Just the way I learned how to lace wheels.
But a friend of mine who I regard as a touring guru and great engineer does the opposite.
Lacing the heads down spokes as trailing spokes will tend to lift chain from away from the
hub in the event that the chain unships inward.
He indicated that Peter White does likewise for that reason.

What sat ye wheel wizards?

krome

I say it really doesn't matter. Flip a coin.

gyozadude

The dynamnics of chain-spoke interactions has been debated before on which is better for the spokes. And if you have a cross pattern, some argue, that indeed, trailing spokes should be heads into the hub because the cross pattern will mean the leading ones will protect them, and likewise, maybe lift the chain back out. My opinion on that, is a) adjust the rear derailleur correctly so it doesn't shift into the spokes, and b) use a $3 spoke protector. I have a small one for my commuter road bike, even though, I have done step (a).

However, in my experience, while it makes no difference of longevity of a normal quality spoke with small radius bend on the rear wheel, the last few years of testing my own Clyde wheels with low-cost Chinese stainless spokes with larger bend radius has proven to me that it does make a small amount of difference to lace trailing drive spokes heads into the hub (spoke exiting out of the hub) and this puts a little extra pre-stress on the elbow so it isn't as likely to reverse stress even under extreme loads. The unfortunate side effect is that now I've had opportunity to break heads on leading spokes, so the solution is a small brass washer suggested by Sheldon to increase head tension. The experiment is still ongoing, but this leads me to a third suggestion: c) get quality spokes with small head bend radii and that should solve your problems.

FBinNY 

There's a continental divide on this issue, which is really 6 of one and 1/2 dozen of the other. Most European builders build with the pulling (counterclockwise) spoke elbows to the outside of the flange, which is how I've done it for years. OTOH Jobst Brabdt in his book recommends building with trailing spokes elbow in.

His reasoning is that when the spokes are laced, the inside spoke passes over the outside one at the cross, so when the wheel is troqued such as when climbing, the point of the cross will move inward away from the RD, and tereby reducing the risk of snagging.

My thinking is based on 2 factors,

1- a sneaking (unproved) suspicion that elbow out spokes are less prone to breakage. this is just a hunch supported by seeing more broken elbow in spokes in the total mix, but I've put no science behind that.

2- if a chain overderaills into the spokes the outside trailing spokes tend to lift the chain as the wheel turns. Forward point outside spokes come over the chain and push it down toward the center.

The second is my major reason for building the way I do, since I've seen too many chains pushed in and trapped under the elbows. The added strength (if any) would be a bonus, and I'm not as concerned as JB about the risk of snagging the RD because of flex at the cross. I feel there's enough clearance that the risk is near zero anyway, if the RD is adjusted correctly.

So that's it in a nutshell, decide if there's a compelling (to you) reason for one way or the other, or who you believe, or just toss a coin.

krome

So if I'm using an IGH (or single speed), it really doesn't matter eh? Everyone's opinion seems based on derailleur equipped bikes, and the potential for accidental overshift into the spokes. If that is the case, just run a spoke guard (dork disk or whatever term one wants to use).

FBinNY 

As I said, I believe that elbow out reduces spoke breakage. But this is more of an experience based gut feeling. It's supported by the fact that Europeans mostly build this way. Or you can go with JB and Americans who read his book and follow his lead.

It's really a question of which Voodoo doll you trust more.

Retro Grouch 

I build wheels with the trailing spokes heads out.

I suppose I could think up some kind of engineering reason for lacing the wheels that way but, the truth is, that's just the way I've always done it. At this stage of my life it would be hard for me to change so please don't confuse me with facts.

FBinNY 

I guess that makes you half a dozen of the other

davidad

About 15 years ago Mavic built up a number of wheels with all of the spoke patterns. Mirror, inbound pulling, etc. What they found out was the pulling spokes were less likely to break if the heads were inbound. This is also how Schraner's spoking method leaves the spokes.

miamijim

A long, long time ago I read a Mavic tech article, maybe it was DT, but it said drive spokes should have the heads to the inside. I also read some that said drive spokes with heads in was the Italian way of building wheels and building them with heads out was the other people way.

I don't like heads out on drive side spokes because if you happen to over shift your trailing spokes grab hold a suck everything into the wheel.

Kimmo 

When the chain jumps off the cassette the reflex is to stop pedalling. So if the leading spokes are heads-in, they tend to catch the chain and drive it down into the gap between spokes and cogs, causing much more spoke damage.

But hey, if you reckon the chain coming off the inside will cause you to pedal through it, lace em the other way. Doesn't seem like a great idea, given the likelihood of RD and frame death should the RD cage catch a spoke...

fietsbob

head in can radiate CW or CCW from the Hole..

mrrabbit 

The difference is so small - shouldn't waste time worrying about it...

Of course, if the hub manufacturer has a preference - that's up to you.

And if the hub has been previously used - most folks here tend to favor sticking with the previous lacing.

Otherwise, pick one...ride.

=8-)