Riding through Bilbao - suggestions please

Hello lovely people of escape.

I’ll be in the Basque country next year, and i’m considering getting the ferry down to Bilbao so I can take my road bike and enjoy/endure some of the big hills.

I’ve been trying to plan a route out of Bilbao towards Durango, but Strava and Garmin heatmaps seem pretty useless, unless Basque cyclists are just a special breed of nutcase who enjoy riding on elevated motorways…

I was hoping to follow the river bank path into the city centre from the port, but its not that clear if you’re allowed to cycle on all of it. After that, i’m not sure where i’m best to go. I’m aiming to reach Amorebieta, where I can get onto the cycle route next to AP-8 into Durango. From Durango, I’ll have a pretty simple route up into the hills.

Does anyone have any suggestions on the most pleasant way from Bilbao to Durango? I’ll be on a road bike, in spd-sl shoes, so I would ideally like to minimise the amount of urban stop-start riding. No motorways please.

Thanks for any suggestions!