Rebuilding my Powertap/Enve3.4 rear wheel

[nhluhr]

So I've had this wheelset for awhile. Front is fine. The rear (24h, Powertap G3, the 45mm "3.4" rear rim) I originally built with 2x both sides with CXRay spokes.

It worked well enough but I noticed on higher torque pedaling (like sprinting over a hilltop) it would flex laterally a fair amount whether it was just rubbing the brakes or completely de-tensioning the NDS spokes during those events. Over time, the wheel has been less than durable in terms of trueness and the NDS tension does drop pretty regular. I built it to 120kgf DS and this resulted in a pretty low NDS tension of about half that since the G3 has a pretty bad dish needed.

I later rebuilt it with DT AeroComp spokes, 2x again, hoping to boost the lateral stiffness a bit. This did prove a hair better but still not great. I realize now I should have left the NDS spokes as CXRay and just done the thicker AeroComps on the DS to keep those NDS spokes a little more in their elastic range and hopefully balance the stiffness a hair. Not sure if that'd do it or not but alas...

Now, and observing minimum cross requirements in the owner's manual for the hub, I'm thinking of an ultimate rebuild. I'd put those CXRay 2x back in for the NDS spokes and do DT AeroComps 1x Heads-in on the DS. This would improve the tension ratio significantly so I could actually get those NDS spokes up to a healthy tension so they won't slack on sprints and 1x drive side should be no issue for the hub since Powertaps transfer torque thru the middle into the NDS (thus the reqquirement of 2x on NDS in the manual).

My concern with this is what kind of clearance I'll have with a heads-in 1x DS spoking arrangement. It's a reasonably deep rim so the angle should be pretty good (getting it out of the way pretty fast) but at the same time I'm planning to replace the old 10spd HG freehub with their 11spd one and swapping to 11spd on the bike this wheelset will be used for. Given that, clearance between chain/rearder and the heads-in spokes becomes a question.

Anybody got any builds with 1x heads-in Powertap G3s with Shimano 11spd that they could share a clearance pic of? Will this work or will it be too tight? I did find a Flickr album from "Ligero Wheels" that has a bunch of 1xDS powertaps but none of them mention 11spd use - in fact, all of them have the bronze freehub which is the 10spd version.

[ergott]

I have a feeling that you don't have significant tension. Bring it up to 130kgf with the current Aero Comps and you should be fine if the tension is nice and even.

How much do you weigh?

Are you using the newer brass nipples from Enve? They have a mechanical locking thread in them so the nipples should not back out.

[nhluhr]

I'm 180 and my average ride has about 100ft/mi climbing, much of it over 8% (so my wheels spend a lot of time at high torque)

[ergott]

I'd stick with the Aero Comps on both sides and bring the tension up to 130-135kgf. The rims can handle that no problem. Also, make sure you are using the newer brass nipples.

If that's built up right, it should be fine.

[nhluhr]

OK fair enough but would there be an issue (mainly the derailleur clearance) rebuilding it with 1x heads-in elbows-out drive side to improve the tension balance (and hell, improve the DS lateral stiffness)?

[ergott]

I tried that pattern and didn't like it. In high torque situations like low gear, steep climbs I could hear creaking. It was torque flex (for lack of a better term). The drive side spokes don't have enough of an angle to transmit torque well. This puts more load to the non drive spokes. Tension is lower and they will subject to more stressful fatigue cycles.

I even rebuilt a couple of wheels with that pattern I built for some local racers.

[nhluhr]

And you did this with a Powertap that specifically transmits torque to the NDS first since the drive pawls are not attached to the hub body at the DS?

[eric]

1x heads in on the DS:



I don't do that any more. Even this hub transmits torque ok as it's fairly large diameter (compared to say old Campy hubs which have tiny center sections).
I estimated the twist using Jobst's equations and if I remember right its in the 2-3% range.
The PT shell will transmit torque via both flanges since it's so large in diameter. It doesn't matter which side of it is driven.

But the problem with the 1x DS spokes is not torque, it's the tension and the angle that the spoke is pulling on the flange. You can see from my hub that the first spoke to pull out was a pushing spoke, not a pulling spoke.

I thought that 1x heads lacing in was stiffer, but I did not measure it. After going back to 2x and 3x I think some of that was in my head.

You could use smaller gauge spokes on the NDS. They will have to stretch more to reach a given tension. So the wheel can flex more before they go completely slack. I've been doing that on all my training wheels. (race wheels get cxrays)

[HermesSport]

Exotic lacing patterns like that are definitely better served by complete wheels designed around them, and even then they're not broadly used, aside from Mavic.

[ergott]

And you did this with a Powertap that specifically transmits torque to the NDS first since the drive pawls are not attached to the hub body at the DS?

Yes. And no, it doesn't make a difference. The hub shell is stiff enough to transmit torque from either flange.