DANVILLE, Calif. (KGO) -- Bicyclists are rallying for change following some close calls between riders and large buses on Mount Diablo. A cycling safety advocacy group posted video online showing large buses crossing the double yellow line and narrowly missing cyclists.The video shot by the advocacy group Mount Diablo Cyclists shows a too close for comfort moment on the narrow winding roads of Mount Diablo."This all happened within seconds and when I did there was a large 40 foot bus that came around the blind curve," recalled cyclist Rosie Sipes. In the video you can see Sipes coming downhill as a large bus drives up hill around the tight curves.Sipes says moments before the encounter another cyclist told her to get as far right as she could.Fortunately, she reacted quickly."If I had not moved over as far as I could it would not have been a good day for me," said Sipes.A spokesperson for California State Parks says the agency contacted the school in charge of the bus. Large groups are required to have a permit and talk with the agency about driving safety prior to the trip. It's suggested buses utilize a pilot car to warn of hazards.For Mount Diablo Cyclists those efforts don't cut it."I mean a bus that size that it's not able to maneuver and take those sharp curves it should not be on a mountain," said Sipes.Following an I-Team investigation in 2015 and work from cycling advocates double yellow road striping and safety signage were installed. But, the corners are simply too tight for a large bus to stay in its side of the roadway double stripe or not."If there's nothing done at this point unfortunately I feel like a tragedy will happen probably sooner rather than later," said Sipes.A state park spokesperson told ABC 7 there have been no collisions between buses and cyclists since 2000. The CHP is reaching out to school groups regarding safety measures for future Mount Diablo field trips.