I always noticed that my wheels were unbalanced but I thought it was due to the valve extender. Well, now that the wheel is stripped down (removed tubs, glue, skewers) I did the same test and got the same results. So it is the wheel itself.

I spun the wheel. As it slowed down and stopped, it would always stop in the same position. If I placed that spot at the top, it would cause the tyre to rotate back down (and forth, depending on the position) so the heavy spot was at the bottom.

The heavy spot is the valve hole apparently.

Both wheels, Zipp 404 tubs 2010 (pre FireCrest).

Do I need to do anything about it? Are these wheels fine like these? Just wondering.

I had the same problem with my HED wheels and could actually feel the imbalance when riding. I assembled the wheels/tubs and then used stick on lead tennis raquet weights cut to size covered with black insulation tape. They ride much better now.

http://www.amazon.co.uk/Tecnifibre-Lead ... 139&sr=8-2

Hi! thanks for the tip, I'll buy one you suggested!

Where do you suggest I should put the lead? on the side of the rim just like Zipp sticker? Silly question but not sure how big/small the lead sticker is from the pic. Clearly on the opposite site to the valve stem in my case, as that's where I've got the extra weight...

Like you I can actually feel the imbalance. If I lift the bike and hold it and give it a good spin I can hear and feel the imbalance, the bike is jumping up and down and making an irregular sound, until it slows down and the sound disappear.

I started having these problems when going downhill at around 67 km/h.

Thanks again! Brilliant.

Don't assume the valve is the heaviest part but it usually is. Turn the bike upsidedown and spin the wheel gently. The heaviest part of the wheel will end up at the bottom of the wheel so stick the weights opposite. Add weights until the wheel spins normally. You can layer the weights if needs be and then cover with black electrical tape.

Thanks will do.

....and balance only with tire mounted. EM3

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My 2011 Cervelo R5

Only ever so slightly off topic, but does anyone have the weight for an 80mm valve stem, or just about how much should one aim to make corrections for when counter balancing? Are we generally talking 5, 10, 15 grams or more? If the wheel is in balance without the tube that is ofcourse...

I don't have a spare tube to dissect.

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Roadbike
Kinesis RaceLight T2

Mountainbike
Van Nicholas Zion Ti

Thanks again for the advice, these weights look well designed.

But there is a problem.

I've run out of weights!

In the box there are 15 pieces of 2grams each. I applied 20grams to front wheel and 10 to rear wheel and they are both unbalanced!

What crap wheels have I bought???

Clearly the Vittoria valve extensions added a few grams here and there but surely they should have factored it in when designing these wheels? Very disappointed. If I keep adding the weights the wheels will end up heavier than their clincher counterparties and look ugly with sticky weights and black patches of tape...

I had the same problem with my old zipp 404s 2010. by experimenting with pennies taped to the wheels I found that it took 16 and 13 grams of tape and penny weight to balance the wheels. I never corrected them on the road and they self- destructed in pot holes in 2011.

Hi,

For the pennyless, Miche just introduced a new product said to fix the unbalance as found in most carbon wheels:

http://www.miche.it/en/news/42/78/New-2011-MICHE-range

Towards the bottom of the page.

Ciao,

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Being a snob is an expensive hobby.

here is theYouTube link:

http://www.youtube.com/watch?v=MGnG2qMl ... ature=plcp

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My 2011 Cervelo R5

Unfortunately the Miche Zero Point doesn't go well with Zipp wheels because it'd cover one decal...But thanks for trying.
Right now I've got 20 grams on the rear and 10 on the front, and they are still unbalanced.
To give you an idea, if I lift the bike and give the pedal a proper spin (with 1 foot), the bike jumps visibly and vigorously up and down, and it makes an irregular sound too. I noticed it when descending at 65+ km/h. It was quite annoying and dangerous.

Try putting some tyre sealent in the tubes. On landrovers we do this to balance the wheels and tyres off road. the liquid moves around to even out the spin

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Cervelo S3 2011. Blinged 6.718 Kg

I'd rather not put anything in my precious Veloflex...

Is it universal for all wheels then, since I noticed it in mine too and all wheels uses valves? I am not sure it is considered dangerous though...can it?