This 9 inch beast is the biggest and baddest disc brake rotor out there at the moment. Yes of course it’s “grabbier” than smaller 7″ and 8″ rotors, but it does provide stronger braking no matter what brakes you’re using. It’s a simple upgrade although technically not compatible with many of today’s suspension forks. It only offers a marginal brake power improvement over standard 8″ front discs used for downhill mountainbiking.
The main benefit of the Hayes V9 rotor is the increased cooling capacity.Â I recently descended some continuous 20% streets, and although the disc gets extremely hot, there is absolutely no detectable loss of brake power due to “brake fade”. Most riders will not notice any difference compared to normal 8″ rotors. If on the other hand, if you regularly ride down the world’s steepest streets, these are well worth the money.
I’ll be honest and admit that when I first got the disc from JensonUSA, I just went straight down the nearest steep street I could find to test out its performance. Since I didn’t bed the pads in properly, I looked down at the front wheel to find this disc was drastically warped within about the first two minutes of use. It was clanging about like an old errant hubcap after a multiple car pileup. The disc managed to get back into shape on it’s own, and I haven’t had any further problems since then. Needless to say, you’re supposed to gradually increase the force you apply to the levers.
After a while, I found the Hayes 9″ disc grabs once during every rotation of the wheel. There is not much I can do to prevent this. The Hayes disc is only slighty warped, but that alone does not normally affect the actual stopping power. This interferes with the ability to brake on loose surfaces and I lost a lot of confidence when applying the front brake only. A better option is the Formula 220mm disc rotor.