If you're in control of the time to go on a ride, the easiest way to avoid excessive sun exposure, yet ride during the safer daylight hours, is to determine the exact time for sunrise/sunset (Canada, U.S., sunrise-sunset, timeanddate, almanac, calculatorsoup, ...) is to ride such that your ride starts at sunrise or ends at sunset, or shortly before/after.

A side benefit is that there are remarkably fewer cars on long stretches of country roads early on weekend mornings.

This adds a small complication. You might aim for the lightest clothing for an 8:30am-start group ride, but it may be too chilly at 5 or 6:00am to ride without an extra layer. That's a separate issue though.

If you're in control of the time to go on a ride, the easiest way to avoid excessive sun exposure, yet ride during the safer daylight hours, is to determine the exact time for sunrise/sunset (Canada, U.S., sunrise-sunset, timeanddate, almanac, calculatorsoup, ...) and to ride such that your ride starts at sunrise or ends at sunset, or shortly before/after.

A side benefit is that there are remarkably fewer cars on long stretches of country roads early on weekend mornings.

This adds a small complication. You might aim for the lightest clothing for an 8:30am-start group ride, but it may be too chilly at 5 or 6:00am to ride without an extra layer. That's a separate issue though.