Scottish Cycling said it was heartbroken to hear the news.
A spokesperson said: “Iain was a vital member of the Scottish Cycling community, a member of Johnstone Wheelers Cycling Club, a stalwart of the Renfrew bunch and Georgetown TTs.
“Iain was the only person to have attended every round of Track League last year and stood as rider rep on their committee. A reliable and friendly face that you knew would be at the meet point of a ride even if nobody else showed up.
“The messages highlighting his positive influence on so many people are already pouring in, and his loss will be felt heavily in the west of Scotland.
“Our thoughts go out to his family, friends, and everyone who knew him.”
In a social media post, Johnstone Wheelers said the news would take “a long time to sink in and process”.
It added: “For now, suffice it to say that we are devastated at the loss of one of cycling’s good guys.”
The road was closed after the incident but has since reopened.
A Police Scotland spokesperson said inquiries were ongoing to establish the full circumstances of the crash.
A Scottish Ambulance Service spokesperson said: “Three ambulances, four special operations response teams, a critical care team and a rapid resuscitation response team were dispatched to the scene.
“Two patients were transported to the Queen Elizabeth University Hospital.”