BBM
Sorry, it's not uncommon for posts to overlap.
You say "we are trying to determine which day he did those two things." Why? I'm not trying to be snarky, I just really don't see what difference it makes. LE has given no indication at all that they question the biker's sighting of the bikes. LE also has not indicated that the biker failed to report his information to the proper authorities in a timely manner.
Why does it seem the biker's credibility is at issue here? How does that relate to finding Lyric and Elizabeth?
Because if he reported it to the officers at the lake around 4 pm Friday - that would be extremely odd to me. For him to be riding by just prior to 12:27 and see the bikes and then still there at 3-4 pm when LE is searching for two missing girls makes it seem like he could be trying to insert himself into this case as some perps have been known to do. I am not saying that is the case, just trying to be thorough in having all of the information before making that assumption. Others seem clearly interested in this same info.
LE/Abben states he was not aware of this sighting of the bikes. That is definitely something Abben should know IMO.
You ask how his credibility relates to finding Lyric and Elizabeth - If he is found to not be credible - then one would need to find out why and if he has anything to do with this.
For all we know this could be the same guy who told the Aunt he saw the girls riding East at 2:30.