Powertap G3 laced in shimano 7900-C24

Discuss light weight issues concerning road bikes & parts.
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Posts: 71
Joined: Sun Jun 12, 2011 8:07 pm

by gb103

Hi, just seen a powertap G3 laced (20 cx-ray spokes) into shimano 7900-C24 clincher rim (approx 946 grams). For anybody who knows about wheels is this a good idea in terms of stiffness, durability and correct power readings.
I like the idea as I feel going down the powertap route is a compromise in terms of looks and weight if you don't want tubs or carbon clinchers.

Any feedback most appreciated.

Posts: 170
Joined: Sat Jul 17, 2010 11:36 am

by SpinnerTim

Well, you need to supply a bit more background.

How much do you weigh? How much power do you make? Do you plan to use the wheel for racing or training? I would want a more resilient wheel for racing.

Strictly as a hub, not a power meter, the G3 is a *better* foundation for a wheel, but it's still nowhere near the quality of an Alchemy Orc, King R45, or even a White H3. The serviceability of the hub, which allows you to remove the power measurement assembly without having to dismantle or ship an entire wheel, is a major attraction relative to the previous Powertaps.

As a power meter, most seem happy with their Powertaps. As long as they aren't damaged and you pay attention to battery condition, it should give good service. Readings will be slightly lower than crank-based systems due to drivetrain losses, but the numbers will be consistent and representative of what you are actually putting through the wheel. That's all that counts.

It's 325 grams, which makes it the lightest Powertap yet (with the exception of the fractionally lighter and unreasonably priced G3 ceramic).

The C24 doesn't seem like a common choice for for custom builds, and I'm not sure that pairing a low-profile rim with a low spoke count and any Powertap hub could produce anything other than a relatively flaccid wheel. You'd be better off with something like a Kinlin XR270 or 300 to add some rim stiffness, extra spokes for bracing, and cheap replacement if you ever damage the rim. A Kinlin or H-Plus rim would cost less and, in all likelyhood, build a better wheel.


Posts: 71
Joined: Sun Jun 12, 2011 8:07 pm

by gb103

Hi, i weight 68 kg and the wheelset would be used for sportives in the UK and frequent holidays to the Pyrenees. I do not race competitively ie road racing, crits, but that does not mean I don't train hard. I thought it was an unusual pairing and i have a relatively unused set oh 7900-C24 in the garage so thought it would be worth investigating.

Ideally i am after a srm campagnolo, but their are a few other things I would also like to purchase such as ax lightness srt 42, so a powertap would be a good comprimise to start with.

I think if I go down the powertap route ambrosio excellight with a powertap or campagnolo front hub will be a safer option. The wheels would be built up in the UK.

Thanks for the advice :thumbup:

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