PowerTap SL, 32H, 24H 440 rim 16/2x 8/1x?

carpediemracing

I have a "stock" PT wheel, DT 1.1's, 2.0 straight spokes. The PT part is great. The wheel part (rim, spokes) is not so great. I'd like to lace on a deep section aero rim, tubular if possible. I happen to have an new/old Zipp 440 (yes, it's 10 years old, but it was used perhaps 40 days back then).

I was thinking of lacing the 440 onto the PT hub but I'd have to do the following:
1. 16 spokes right side
2. 8 spokes left side
In order to get the spokes crossed, I'd do 2x right (essentially 24H 2x) and 1x left (essentially 16H 1x). The angles of the spokes relative to the hub will be about the same (over 7 degrees, same as a 32H 3x setup) so it should let the PT register torque.

However, I'm worried about the angle the spoke enters the rim. The Zipps do not allow the spoke nipple to exit at an angle - they point straight out at the hub. With short spokes (254mm right, not a problem, but 242 lefts??) the angle may be too severe for the rim. The old Zipp rims tend to split when you try and force the nipple to pivot a bit in the rim (due to spoke tension).

Anyone have any experiences with a similar type of PT build?

My alternative is to put on a GL330 (32H) or buy a new rim. I spent a bit more money than I wanted on the PT so am not looking forward to buying a Zipp 404 or similar. I really prefer a deep section rim.

thanks in advance,
cdr

The Flash!

Check the manual. I believe it has to be at least double crossed on both sides to make it work. I ordered a custom carbon rim from American Classic with 32H drilling. Rock solid for racing and training....

Flash

carpediemracing

I checked up on this only after I got the wheel - I was planning on doing a 2x drive, radial left, a sort of normal build to put a 24H rim on a 32H hub. Then I read that both flanges contribute to torque calculations. Arg.

The "cross 2" recommendation is based on either 24H or 28H hubs. They basically want you to have some push-pull angle on the hub on both flanges. So a 24H 2x is fine. The angles for a 16/8 setup would be equivalent of a 32H/3x.

thx for pointing it out though,
cdr

mises

I've done triplet lacing with a number of zipp rims. You have to take a small rat tail file and angle the spokes holes in the rim. Helps to put some masking tape on the rim to label which holes will be going which direction to keep it straight while you work.

Go slow - too little can be fixed but too much can't - and recheck them once it's laced up before you start to put much tension to make sure they are all angled correctly. Don't overlook that they must be angled in 2 directions - the angle that creates the dish is less of a problem than the angles of the triplet pattern.

If you chicken out on doing it yourself Ligero Wheelworks does a lot of triplet laced zipps.