Feature request enhancement "route recalculation" feature

I doubt your issue will be resolved. The 830 is nearing the end of its lifespan and updates will become less frequent. The 1040 has just been introduced which means a 840 is not far away. Perhaps it will behave similar to the 1040 on routing.

I hope you're wrong.  If this is true, then maybe it's worth considering another brand of gps cycling devices.  My plan is not to invest in a new gps device every 6 months.

The feature you want is only on models 1030 plus and the new 1040. I recall reading that Garmin will not be moving that feature to any other device.

Anyway, if you are off course, it's very easy to return to the course by simply viewing the map.

Yep.  That's what I've done since starting with Garmin Edge devices back in 2010.  The touch screen makes it way easier to pan and zoom the map than the versions without it so you can more quickly and easily see how to proceed to rejoin the course.  Once back on it, the Edge starts navigating again as if you never left it.

Panning and zooming around manually on the screen is a workaround to me. From a recent "high-end" gps device I bought less than 6 months ago, I would expect it to behave as a 100% gps device, not only for 50%.

Garmin is notorious for having poor software. In fact the current sensor drop-out issue was introduced by one of their updates. Garmin has an extremely poor cohort of programmers on their staff. Garmin apparently has no regression testing prior to update release and at best their software is always in the beta stage as it's up to users to find and report issues.

I tried the route recalculation for the first time after reading this as I always have it turned off.

What I found was, it does take me back to the nearest point on the route, initially it wants me to turn round to rejoin the route. But if I ignore it, eventually it will replot another route to get me back on my route that is shorter than turning back.

But, towards the end of the ride, it did start doing odd things, why would it want me to turn back to rejoin the route and ride 5 miles to the finish of the route, when the finish point of the route is only about 2 miles away. In theory, it should have calculated a route to get me to rejoin the route at the finish as its closer.

I've had the re-calc direct me to u-turn after re-joining the route. I've had this bogus direction for up to a mile when i was on the route. Your one time experience is not indicative of the poor quality of navigation algorithm. 

This was for not "my one time experience", it was my best evidence of this issue.  After this trip, on the map I could clearly see that for this course, after a "blind" loop of about 10 km, I got back to about 50 meters of the place I wrongly deviated from the course I should have followed.  And, last but not least, for about 5 km of this "blind" loop, I was on the course, but just in the opposite direction !

On Garmin units older than the 1030+ recalculating when you go off course creates a new route to your destination point.  This is usually different to what you had planned.  The newer 1030+ and 1040 have recalculation options that work as people expect them to - navigate you back to your planned route and then go back to navigating you along your planned route.

This is why it is better having recalculation turned off on all units except the 1030+ & 1040.