As wheel offerings have gotten deeper over time, valve stems have gotten longer and heavier, making your expensive lightweight carbon wheels more susceptible to imbalance. Even with light valve setups like Silca’s own recent aero tubeless setup, you are still looking at least 10-20g out of whack. And while that might not seem like much, if you’ve ever come barreling down a long descent at high-speed riding a deep wheelset, you’ve probably felt that disconcerting hop of out of balance wheels. So Silca has a new solution in their SpeedBalance that combines a rim-mounted aerodynamic wheel magnet with a set of tunable weights to bring equilibrium back to your wheels. Take a closer look after the break…

The SpeedBalance joins Silca’s other Tubeless Collection offerings to get your wheels spinning fast and cheating the wind. The new aerodynamic magnet is claimed to save up to 1W at 30mph/48kph versus a traditional spoke-mounted magnet. That might help one wheel if you have a speed sensor linked to your cycling computer, but even if not balancing both wheels will result in a smoother rider, and should actually benefit handling on big descents.

Silca_SpeedBalance_aero-wheel-magnet-balancing-setup_parts-top Silca_SpeedBalance_aero-wheel-magnet-balancing-setup_kit

For $36 the kit includes a pair of stick-on SpeedBalance pods, each with a single magnet and 4 x 2.5g tungsten slugs to custom balance your wheels against the valve stem. Plus, the kit also includes a pair of the SpeedShield Aero Valve Stem pods, that claim to smooth the airflow onto the valve stems themselves (and eliminate that horrible rattling) so you will get the maximum aero setup for your wheels.


Get them direct from Silca, or through your local bike shop.


  1. Graz on

    Not to be that guy on BikeRumour, but… has anyone ever actually had this problem?
    I’m not flat out denying it, but it seems like no matter the speed, you’d never notice the slight imbalance in a nice wheel (nevermind notice the ‘improvement’ of balancing it out).
    I’ve worked on many a bike with so many tyre liners, thorn-resistant tubes, and generally awful rubber bits on that the whole stand jangles around like crazy when you really spin up the rear wheel… never once noticed it test-riding such bikes though.

  2. Collin on

    I had a pair of Zipp 808’s that really had the problem. If you put the bike in a stand and pedal while tuning the derailleur, the imbalance was so bad the entire bike felt like it would shake out of the stand. On fast sections (around 30ish mph) you’d feel it through the seat quite a bit.

    Physics says that it takes a large energy to accelerate a vibration, thus your actually loosing watts with the imbalance. So I went to a local golf store and bought some lead tape, which golfers use to balance/alter the center of mass of golf clubs. I put a few layers of that opposite of the valve stem and it lowered the vibration significantly.

  3. cracked frame on

    @ Collin – I’m glad you’re not the only one. I have the same experience with some Stan’s Grail rims where the metal piece inside the rim had shifted at the weld and causes great imbalance.

    Good tip on the lead tape. I’ll look for that, maybe that will help me too.

    (Who knew bikerumor comments could be helpful.)

      • Zach Overholt on

        @andrew, I can’t say for certain as I don’t have the Grails, but if they’re like my old Sun Ringle STX 33 rims, there was a metal sleeve inside the rim that held it together during welding. The inserts were held in place by two little punches in the rim. Over time the insert would work its way free and then twang back and forth between the nearest spokes/nipples. I found the simplest fix was to take a punch, and reset the insert with two solid blows. Again, can’t say for sure on the Grail, but that seems to be a pretty common cause of mystery twangs inside rims. Also have to preface that with the fact that the STX 33 was a super burly DH rim and could easily withstand a few blows from a hammer.

        • STS on

          Zach, you nailed it. It’s the same on the NoTubes Grail. I also add some Loctite 290 before I re-punch the two punches which fix the connecting piece. Make sure you support that section of the rim well before you punch it.

  4. Glenn on

    I have to agree with Graz, 35 years of fooling around with bikes. Not once did I think “if only we had balanced wheels!”

  5. Joshua Poertner on

    The one thing I will say about the ‘not a problem’ comments (we’ve heard that a lot) is that it really might not be a problem with your particular setup. The issue is primarily caused by stackups in imbalance caused by the full the rims will be heavy at the valve hole by a variable amount, the tubes will be heavy there to reinforce the valve stem, the stems and valves will have variance etc.. also the total system weight plays a factor as 10 grams of imbalance on a 300 gram rim with 180 gram tubular tire feels much worse to the rider than 10gm of imbalance on a 500 gram rim with 300 gm of tire and tube.

    As LowRider points out, there are wheel companies who already address this issue with various features because they know it’s a real thing, Fulcrum and Campy use brass nipples opposite the valve stem for instance, and Lightweight embeds a magnet in the layup opposite the valve, but at most they are only balancing the wheel before tube and tire are installed as they have no idea how much additional imbalance those items are bringing to the table.

    With this, you can tune in 2.5gm increments (and you get the benefit of the aero spoke magnet) so for some wheels the magnet may be all you need (the magnet weighs exactly the same as a 48mm valve stem w/core) and then as you add valve extenders and such you can add tungsten.

    My only other comment on the nature of the phenomenon here is that riders who’ve never balanced don’t see the need, and those that have been on balanced wheels will never go back.. We had this at CSC years back where Fabian was sensitive to it on his TT bike (the 100mm valve stem on a tubular 808 is about 18 grams of imbalance on a pretty light setup) so his mechanic and I balanced those wheels in the spring, then some other guys tried it at the Dauphine based on his feedback, and before you know it I was sitting in a Euro hotel room before the TdF balancing 80 wheels because everybody was talking about the improvement on the super fast descents.

    Like i said in our launch materials, this is a product I’d have killed for 10 years ago..this one’s based on some serious history and lessons learned first hand.
    Thanks for listening

  6. Daniel Parrett on

    If the manufactures would put a mark on the tire signifying the heave spot there would be no need for something like this. No reason they couldn’t as it’s already done in the auto industry.

    Also couldn’t the magnet speed be too high for some sensors to read. I have know clue of their capabilities but just a thought.

  7. JBikes on

    Wheel balance – most precision high speed machinery will be balanced to 4W/N. For a normal carbon deep section wheel (say a Zipp 404) with 25c tires, total weight will be around 1100 g (front). Allowable imbalance will be 7.7 g at 45 mph.

    Josh’s comment about stacking imbalances is valid, but one need perform a static balance to determine where that correction weight needs to be applied (it may not always be opposite of the stem). If one pulls the seals from your bearings, you can probably just use the hub on the front wheel. Same with the rear (remove the chain!), but that’s a little harder to do. You can probably leave the seals, but the precision of the static balance may not be as good, probably good enough

    • Collin on

      @ JBikes, on my 808’s, I did a static balance and sure enough, 10 out of 10 times, the valve stem+extender was the heavy spot.

  8. Andrew Spaulding on

    If you’re going to add weight to a wheel and charge $36 for it, I’d expect an integrated gyroscopic-powered LED, or a GPS beacon, a speed sensor, a bluetooth speaker, a patch kit, pillbox, a spare Di2 battery. Get creative guys.

  9. ginsu on

    Honestly, you have to balance THE ENTIRE ROTATING ASSEMBLY! You can’t just assume it’s opposite the valve hole that needs weights. And you should balance with the same mass, and how much does a valve stem weigh in isolation? 2-5 grams?

    Maybe if you are a professional cyclist, I could see being this retentive, but seriously, you have to pick your battles man.

  10. Josh Deetz on

    I never felt my rolling resistance, nor seen air, yet both are real and effect cyclists. If nothing else Josh does not trade in fantasy, as Josh said many makers have worked on balance issues. As a person who has opted to work in Asia I can say my comments about imbalanced automotive wheels in taxis have been met with driver skepticism by answering “no problem I can still drive and steer”.


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