Bet you didn't know your valve stem could throw your wheel off-balance, because we absolutely didn't.
But there's no flies on Silca, who not only knew about this almost unnoticeable effect on performance, they've actually invented something to deal with it.
When Silca releases something, people sit up and take notice so expect to see more of these popping up in the coming months. They were, for instance, the inventors of C02 inflation for bikes.
The principle behind SpeedBalance is simple: the depth of some carbon wheels these days has led to longer and longer valve stems. Given that these are made of metal it's inevitable that they will add weight to one part of the wheel.
Silca's widget redresses that imbalance. It has been developed as part of the Tubeless collection, and it is a "rim-mounted aerodynamic magnet that can save up to 1 watt at 30mph." The kit comprises four different weights which slot into a little housing that attaches to the inside of the rim.
If you're scratching your head to see how you can add a watt by adding weight, Silca say the benefits are made from the rebalanced wheel improving handling, comfort and confidence, especially on high-speed descents.
Another thing you never knew you needed.