Someone asked me about this. This is a snippet of the Albuquerque Journal article sent me by Ben Savoca and Diane Albert. Sounds like he lost control of the bike.
I'm not sure where exactly Spence Hot Springs are, but plenty of fast descents on NM-4 where things can go badly wrong. No definitive information in the entire article on why he lost control. Speculation includes a blown front tire. On a fast descent, a lot can happen to make things go wrong.
Condolences to the family.
Bicyclist Killed in Charity Ride
Journal Staff Writer
...Michael S. Berry, 40, was participating in the Rio Grande Bike MS Atomic Ride, a fundraiser for multiple sclerosis.
The event began Saturday in Bernalillo and went through the Jemez Mountains to Los Alamos. The cyclists then returned to Bernalillo by the same route on Sunday.
Berry was riding on N.M. 4, near the 24.5 mile marker, about 9:20 a.m. when he lost control at a turn, went into a ravine and hit his head on a rock, according to Sandoval County Undersheriff Tim Lucero. Berry was pronounced dead at the scene, just south of the Spence Hot Springs parking lot.
The cyclist was thrown 8 to 14 feet before crashing into the rock. He was wearing a helmet, Lucero said....