I have a set of ENVE 6.7 that I have been using for TT, and I am planing to upgrade the rig with a disc. This should hopefully give me some second at the end.....

But, I thought maybe the new ENVE 8.9 rear would be better option?

It is suppose to be faster than some disc wheel (does`t say which), better handling in windy condition.

Any thoughts??

I'm still waiting for my set so I can't speak first hand. I'll report back when I get them in and have some miles on them. Even if they are as fast as a disc (not faster) the ride and handling should be better so you will have a rear wheel that can be used on a TT bike and on the road bike as well.

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I've wondered the same thing. They're not slowing down this chap:
http://www.saddleback.co.uk/NewsDetail? ... test-Again

If this is for racing only, I would go with the disc. A rear disc is not that affected by the wind, it is the front wheel that it is the problem.

It is only for racing, but the .9 rear could be used for mass start as well.

I'd say if it's only for the purposes of time trialing, then go with the disc. Discs are easy to handle, despite what ever lore is out there.

Discs also tend to work better in the rider/bike system due to the splitter plate effect. So even if the 8.9 is faster on its own than some discs, which I would not be surprised by, I would expect in the rider/bike system most discs would be faster. Obviously a well designed disc like the Zipp Super 9 or Hed Stinger is going to be best.

FWIW, Tour tested both the ENVE 8.9 and 6.7 tubulars to be faster than a HED Stinger 9 FR/disc combo in a Trek Speed Concept.

A pair of Zipp 808 clinchers came out faster than all three, a 404/808 combo slower.

Don't know what tires they used, but that's because I didn't read the article yet.

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