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Are your carbon fibre wheels correctly balanced?

Silca launches SpeedBalance counterbalance weights for carbon fibre wheels - claimed to save 1 watt at 30mph

Have you turned over every stone in the pursuit of marginal gains? Here’s one you probably hadn’t thought and which is claimed to be able to save you 1 watt at 30mph. 

It’s called the SpeedBalance, produced by Silca, maker of some of the finest and most expensive accessories we’ve ever seen. SpeedBalance is an aerodynamic counterweight that can be easily fitted to any carbon fibre wheel to cure an imbalance you might be suffering as a result of long valve extenders.

Silca SpeedBalance 1.JPG

“As carbon wheels become deeper and valve stems become longer and heavier, light carbon wheels become susceptible to imbalance - roughly 10-20 grams,” claims the company in its press release. “At high speeds this is a big deal, and the SpeedBalance solves this issue.”

With very deep section wheels you have to use long valve extenders, plus there’s the reinforcing weight at this section of the rim, so SpeedBalance is intended to offset this weight and ensure the wheel is perfectly balanced. It also doubles as a magnet for an ANT+ speed sensor.

The SpeedBalance device sticks to the rim with an adhesive backer and a selection of tungsten weights can be used to balance the wheel. Each weight come is 2.5g so you can add up to 10g to offset most valve stem weighs.

Silca SpeedBalance 3.JPG

“Balanced wheels improve handling, comfort and confidence, particularly on high speed descents, while the aerodynamic benefits of the SpeedBalance magnet over spoke mounted magnets results in a wattage savings equivalent to a full wheel ceramic bearing upgrade at a tiny fraction of the cost,” adds the company. 

Can’t say I’ve ever experienced any issues with the balance of deep section carbon wheels at high speed. Have you? Anyway, we're going to try and get some in for review to see what they're all about.  A set costs $36 with everything you need for one set of wheels.

More info at https://silca.cc/products/speedbalance-wheel-balancing-and-computer-magn...

David worked on the road.cc tech team from 2012-2020. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes

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16 comments

Avatar
Podc | 4 years ago
1 like

I have a hand built 60mm carbon/aluminium brake track rear wheel on one of my bikes and it was horribly out of balance. I think I could feel it at 30+kph and it was obvious when spun on a stand. I ended up taping strips of thin lead inside the rim under the rim tape. Wasn't sure if this was a sensible solution but took advice from a LBS who said as long as it wasn't too thick it would be fine, and it has been.

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dodgy | 4 years ago
0 likes

Holy thread resurrection time.

I have a Giant Propel with deep sections and tubeless tyres. Ever since getting the bike I've felt a kind of thud thud thud on smooth roads. It was really starting to ruin the enjoyment of this bike. Anyway, finally put my mind to it (without googling anything) and put what is essentially a magnetic sensor on a spoke opposite the valve. After a little trial and error by moving the sensor along the spoke, I finally found the sweet spot that cancelled out *ALL* sensations of bump, thud (whatever). It DOES work.

Descending in North Wales yesterday, the bike handling was transformed (yeah,  snake oil). 

I'm happy, I'd go as far as to say Giant should balance these 80mm and 60mm wheels in the factory, the valves are very long.

 

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matthewn5 | 7 years ago
1 like

If you're worried just wind a bit of solder rod around a spoke. SImple, practically free and infinitely tuneable.

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Morat | 7 years ago
0 likes

$36 for a wheel weight? Even if you REALLY need a wheel weight, $36 is about $35 over priced.

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zagatosam | 7 years ago
0 likes

While I think that this is an unnecessary expense the problem of unbalanced wheels certainly exists. Just hold a wheel by the axle and see it spin slowly one way or the other. I have a really poorly balanced set of Zipp 808s which I use for triathlon- sprint through to Ironman. My time for the 112 mile distance is below 5 hours. OK I suppose but with a poorly balanced wheel I'd be much slower. The solution was to use some split lead fishing weights on the spokes near the nipples. I needed 30g on the back wheel. Quite a lot but the wheel doesn't bounce any more. Poo poo that idea but I'm happy if you do because it's free speed for me  1

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DrG82 | 7 years ago
0 likes

Surely any tidy wheel set will be balanced to accommodate the weight of the valve required, most aluminium rims have the join (weld/pin) opposite the valve hole as a counterbalance to if you're dropping £750 a wheel you'd sure hope they would have thought of this.

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hawkinspeter replied to DrG82 | 7 years ago
0 likes

DrG82 wrote:

Surely any tidy wheel set will be balanced to accommodate the weight of the valve required, most aluminium rims have the join (weld/pin) opposite the valve hole as a counterbalance to if you're dropping £750 a wheel you'd sure hope they would have thought of this.

I'm not so sure - at typical bicycle speeds you're very unlikely to notice any slight imbalance in the wheels so it's hardly worth the manufacturer spending the extra time.

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Rapha Nadal | 7 years ago
0 likes

I wonder how many amateurs regularly travel at a 30mph average to warrant a saving of 1watt. 

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sizbut | 7 years ago
1 like

The 60 kilo plus mass transfer damper fitted to all bikes is not always an intelligent device.

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Al__S | 7 years ago
1 like

Just brilliant. Bravo to Silca for finding another way to part fools and their money.

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madcarew | 7 years ago
1 like

Deep section rims that when spun make the bike hop in the stand like it's on bolivian dancing dust....On glass smooth boards at 60kph in a team TT... undetectable.  At 80 kph on a glass smooth Mallorcan descent the effect will be 75% more than at 60 kph, at a frequency of 600Hz (providing both wheels are perfectly in sync). I'd put money on it that you can't detect it physically. Would be completely drowned by any road and wind 'noise' (effect of wind turbulence around spokes and frame parts)

However, if you believe it makes a difference while riding, it probably does. You could wear the weights on your wrist for the same effect though. Wouldn't work quite as well on your ant+ sensor though.

Just wondering if the hypothetical 1W power saving takes in to account the effect of the extra weight at the rim. 50 kph requires approx 450 W. Wonder what power testing equipment they've got that is accurate to +/- 0.22%?

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Jez Ash replied to madcarew | 7 years ago
0 likes
madcarew wrote:

At 80 kph on a glass smooth Mallorcan descent the effect will be 75% more than at 60 kph, at a frequency of 600Hz (providing both wheels are perfectly in sync). I'd put money on it that you can't detect it physically. Would be completely drowned by any road and wind 'noise' (effect of wind turbulence around spokes and frame parts)

Not 600Hz. More like 10Hz. How much money?

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madcarew replied to Jez Ash | 7 years ago
0 likes

Jez Ash wrote:
madcarew wrote:

At 80 kph on a glass smooth Mallorcan descent the effect will be 75% more than at 60 kph, at a frequency of 600Hz (providing both wheels are perfectly in sync). I'd put money on it that you can't detect it physically. Would be completely drowned by any road and wind 'noise' (effect of wind turbulence around spokes and frame parts)

Not 600Hz. More like 10Hz. How much money?

Doh, My bad. 600 rpm / 10 hz

Give you a fiver if I can feel it on my bike  1

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Tjuice | 7 years ago
0 likes

I totally get the concept. When my bike is in the workstand and I turn cranks to spin the rear wheel at a fair speed, the bike shakes strongly in the stand. Very clearly unbalanced wheels. Not too surprising, given wheels are less than 1400g for the pair and then there's the long valve extender, the reinforced rim, and the reinforced bit where the valve attached to the tubular tyre.

But riding the bike on normal roads, I do not detect this in the slightest, at any speed.

And if I did, no way of spend significant money fixing it - I would probably just put some blutac (or more realistically stick some lead shot) on the other side of the rim.

Think this product will be very, very niche

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earth | 7 years ago
2 likes

It's not snake oil.  I have been folding a piece of lead flashing around the rim of my carbon tubulars since I got them.  Without it I can feel the wheels pulse.  It was most noticeable on the incredibly smooth roads in Mallorca.  If you are decending at speed it can be quite unnerving.  The process of balancing them I use is trial and error.  Hold the wheel by the axel and spin it and you can feel the imbalance.  Tape some lead around the rim opposite the valve in a similar way to the photo above and repeat until you find the amount that counter balances the valve.

I might even give this solution a go.

Avatar
ChrisB200SX | 7 years ago
3 likes

Oooh, a new brand of snake oil. How do you actually balance the wheel though, is there an app for that? 1 watt will make an enormous difference, especially as that speed balance weight is bound to have a little drag. Seems more useful as an aero ANT+ sensor magnet... except your ANT+ sensor is probably causing more than 1W of drag.

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