Rebuilding Zipp 404 w/ Powertap

[nhluhr]

I have a 2011(?) pair of Zipp 404 Carbon Clinchers that I haven't ridden much in the last year because my other wheels have a powertap. I figured I could grab one of the clearance priced Powertaps off chainlove and go ahead and build this thing up. So what I've got is:

Zipp 404 20h x58 rim
Zipp firecrest rim washers
Powertap G3 20h 11spd Shimano
DT Aero Comp spokes (wanted a stiffer wheel than CXRays or Aerolites would yield)

I am definitely doing 2x on the non drive side (required by the powertap) but I figured I have some options as far as drive side lacing goes. If I go 2x, it looks like it might be tough to get enough spoke tension on the NDS since spokecalc says it'll be a 46% tension ratio and Zipp recommends 100kgf for build tension. If I go 1x, it'll be slightly better tension balance, at 48%. If I went radial heads-in, it could potentially be a lot better, but then I'm depending on the G3 hub to transfer ALL the torque of the driveline.

I figure I could just build it up 2x (since I have that length spoke ready to go) and see if the NDS gets to an acceptable tension... Then re-do it 1x if I feel I really need to.

Would doubling-up on the DS rim washers allow me to use a higher tension?

[Ceebers1]

Doubling up can cause shifting. I would not do a radial lace with heads-in, because of the increase in approach angle of the spokes to the rim. I see a lot of broken spokes on 404 Powertap wheels..

[nhluhr]

Thought I would post this here since a web search didn't turn anything up for me.

I knew the Zipp rims have a recommended upper tension of 100kgf, however I the conversion table card that came with my Park TM-1 Tensiometer doesn't have an entry for the DT Aero Comp spokes.

These spokes are 1.2x2.3 (basically a thicker version of DT Aerolite, ideal for adding stiffness to a wheel with minimal drawbacks).

I rigged a spoke hanging from my bench vise and loaded it using a right-angle piece of thick metal with a thin slot and a big 'eye' loop so that I could rig weight from it. From the sling I hung a super heavy duty milk crate that I could easily stand from, then added enough free-weight plates to bring the total weight (including myself) up to 220lbs (100kgf). The whole assembly was about a half inch off the shop floor so if anything broke, minimal chance for injury.

As it turns out, 100kgf reads at 16.5 on my Park TM-1.

[kavitator]

good job for calibration of TM1

i get new from parktool and it show much higher tension than actual

[WMW]

You can do 1x heads-in on the DS, and use stiffer DS spokes (DT AeroComp from Fairwheel) to help keep the NDS spokes from losing tension.

[nhluhr]

I ended up doing Aero Comps, 2x, both sides. Should I have stuck with lighter stretchier Aerolites on the NDS?

I see for 2014, Zipp has even gone to 2x both sides, but with 24 spokes. I guess they were getting some feedback that the old 20spoke CXRay build just wasn't stiff enough.

[ergott]

2X both sides and get the tension up to 120kgf. Zipp doesn't even listen to that 100kgf with their in house builds. I've measured 125-130kgf before I disassembled them. I've rebuilt several FC 404s to PTs and had no problem with higher tension.

Any rim that has washers and a 100kgf limit would be the biggest piece of crap ever.