Creating segments in Garmin Connect

Maybe you can try riding slower, at the desired starting and ending points, so that the density of points is higher all around them. You can then move the starting and ending points when creating the segment in the activity. Also, since I use the smart GPS recording, not the 1s recording, I have quite high density of points at turns, so you could try turning around, or reversing the direction at the desired start/end points.

I just though about another way you could use to set the starting and ending points exactly where you want, without the need of a new ride. Export the concerned activity into a TCX file, open it in Notepad or another text or HTML/XML editor, and modify the coordinates in the starting and ending points, to the values of your choice. Then import back the activity to GC and create the segment from it.

I tired starting and stoping but it seemed to ignore those point or stop recording.  I have noticed that turns are easy to indent if you. So next ride I will try your suggestion and post results.

That might work but I will have to figure out the coordinates to look for.  Maybe looking at it in Basemap?  Not sure if it will import TCX file.

Another way: enable the lap button in the settings of the cycling ativity, and then press it at the beginning and at the ending point of the desired sector. I believe it will record the exact coordinates. The lap button may differ depending on the model of the watch, but in my case (Garmin Instinct) it is the BACK button.

I tried making the segment by searching for 0 speed, which is the location I stopped at but the satellite photo did not match to where I recollect stopping at.  It may be just GPS error.  In any case due to the header and footer have data for the whole ride the segment metrics for time and avg speed are all messed up.  I will try your other recommendation first.  It should work since I did turn around somewhere an the ride and more data point were present to show the location. 

You can also export the file in Google Earth format (KML) and edit the track in Google Earth. Though I do not see an option for reimporting the KML file back to GC. But there are also online tools for editing GPX and TCX files, so you can use those too for editing the track on a map.

... and, of course, you can use Strava segments too, in Garmin Connect. Since you mentioned Strava yourself, I guess you are aware of it.

If you are starting or stopping a segment near a turn it does not seem to be an issue.  It appears that the density of GPS points near turns are much greater than if trying to select a point along a straight piece of road.  The only way I figured out how do do a small segment or a segment I am having trouble defining on the Garmin Connect software is to ride the segment, then passing the start go up the road 50 yards and do a u-turn.  Go back just past the start of the segment and do another u-turn.  Ride the segment.  When you get to the point you want to finish do a u-turn for 50 yrds and come back.  Now you can take that activity and make a segment selecting the start and finish.  It should come out accurately.