The accident was first reported around 7:30 p.m. at Madera Blvd.
CHP says they got a call about a man wearing dark clothing was weaving across all five lanes of 101 on his bicycle, said CHP Officer Andrew Barclay.
The bicyclist was pronounced dead at the scene.
Initially all lanes were closed. Around 9:20 p.m. CHP opened one lane with traffic is backed up to Greenbrae.
By 10:00 p.m. all lanes were back open.
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