I rode NM4 from the Back Gate to White Rock today (Sunday). I rode my fairly soft riding steel frame with 25mm Ultra Gatorskins at 95 psi rear 80 psi front. It was bearable, but it is still pretty rough. The stones give it a pretty buzzy ride and the actual road surface is bumpy and I think actually worse (flatness) than before the tar & stone job. The cracks running across the road near TA-49 are still there, but harder to see. On most of the route, there are still loose stones on a 12 to 24 inch width along the edge of the road. In some areas you can’t tell where the edge actually is due to the amount of stones out onto the dirt shoulder. If you ride it, be sure not to try riding right along the edge to let cars pass.
Ancho Canyon seems to be the worst area with more loose stones and rough surfaces. The ride down the south side was quite rough and definitely worse than before the tar & stones. If you hold the record (or have a personal best time) for the White Rock time trial course, it will stand for a long time to come! The road is ultra-slow.
Hitting the smooth, new asphalt at White Rock and coming up Pajarito was a huge relief! The best rating I can give the NM4 road surface is … ANNOYING.
If you like running 120 psi in your tires… stay away J