Powertap deep section wheel 20 or 24 hole?

Discuss light weight issues concerning road bikes & parts.
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Posts: 126
Joined: Thu Jul 27, 2006 7:13 pm
Location: Sussex, England

by robsbc

In 2007 I had a Powertap SL wheelset built for me the spec was :-

Front - Mig 45 hub, 16 hole LEW Pro VT-1.
Rear - Powertap SL hub, 20 hole LEW Pro VT-1.

Total weight was 1215g.

From day one the rear wheel would always rub, my weight back then was 137lbs today I'm up to 153 (injury long story) but will be getting my weight back down to around the 140-145 mark. At the time I had to open up the brakes and I swapped out the titanium quick release for a steel one to see if that would help with reducing flex.

To cut a long story, today the rim has developed a 4 inch crack on the braking track a month ago it was highlighted to me by the bike shop when a new tubular was being fitted that there was uneven wear on one side of the brake track (the side that has cracked). Looking at the other side the bracking track looks minimal wear. These wheels were only used during the summer time for 4-5 months.

According to the wheelbuilder I got my wheels from :- "The hub and lacing choice on Robs wheels will also make them a bit stiffer then a comparably laced Reynolds wheel. The front mig45 has a wider bracing angle than either a Dt or White Industries hub laced radial with the heads outside the flange. The rear wheel is laced 2x on the non drive side and 1x on the drive side. What that does is increase the bracing angle on the drive side by a couple mm's without reducing the angle on the non drive which gives it a surprising increase in lateral stiffness. Jeremy at Alchemy wheelworks has done some testing with identical wheels one 20h laced 1x drive and 2x non drive and then a 24h laced 2x both side and the 20h actually tested stiffer. "

I'm looking for advice what to do with my 20 hole Powertap hub do I get it rebuilt into a new rim or sell it and get a 24 hole hub? I dont want this flex again to wear out my brake track. When speaking to the bike shop they didnt think I should be having an issue with flex at my weight.

The rims I'm looking @ is the Zipp 404 FC and also the Enve 6.7 SES 60 mm rear rim but this is only available as a 24 hole.

In 2007 brand new these wheels cost me £1200 so very much a bargain half of me thinks I should just get some gigantex rims from Wheelsmith or from Planet X, the Planet X ones are £150 for a 50mm deep rim as they are much cheaper to replace than soemthing like a Zipp or Enve.

Are the Zipps and Enve's really that much better in terms of their aero qualities? I only use the wheels for fast recreational riding mainly riding on my own.

Cheers Rob

Posts: 2196
Joined: Tue Nov 11, 2003 9:47 pm
Location: Santa Cruz, California, USA

by eric

If it wasn't stiff enough with the Lew rim I'm not sure anything else will be stiff enough. Reynolds carbon rims are pretty stiff but I'm not sure they're enough stiffer for you.

If you have the money, a 24h or 28h hub would be better. The new PT hub is supposed to have better flange spacing, so the 1x heads in may not be needed (or possible).

Or you can get a crank-based PM.

by Weenie

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