Yes possibly a bit loud on tarmac, but they're drowned out for me by the ancient Sturmey Archer 3-speed transmission (this is on a butchered 1970s Dawes Kingpin shopper). And it gets most use on unsurfaced paths 'round my local nature reserve, anyway.
I have them on a 24" bmx, do you not find them a bit noisy?
Good option though.