Garmin segments - is it accurate and reliable?

[Machoman121]

Have the 530 and for the first time i was able to use segment on the 1-20 two weeks ago. It recorded that i had bested my previous time in 2018 by 1 minute....a time of 26.38minutes up 1-20. i noted the segment page was showing a positive timing (i'm thinking a positive timing means i'm slower than the 'leader') Frankly that was damn good - i wasn't even trying - most of the time i was playing with the 530 screens so the pace was moderate and comfortable.

Today i thought i'll like to better that 26.38m - so i pushed harder.....right from the start the segment time showed a negative timing this time - eventually i got to about a negative 60 seconds.....but upon completion of the segment it recorded my ride at 28 min !!!! So i was slower than 2 weeks ago where i wasn't even trying.

What's your experience with segment and do you use it?

[queequeg]

Have the 530 and for the first time i was able to use segment on the 1-20 two weeks ago. It recorded that i had bested my previous time in 2018 by 1 minute....a time of 26.38minutes up 1-20. i noted the segment page was showing a positive timing (i'm thinking a positive timing means i'm slower than the 'leader') Frankly that was damn good - i wasn't even trying - most of the time i was playing with the 530 screens so the pace was moderate and comfortable.

Today i thought i'll like to better that 26.38m - so i pushed harder.....right from the start the segment time showed a negative timing this time - eventually i got to about a negative 60 seconds.....but upon completion of the segment it recorded my ride at 28 min !!!! So i was slower than 2 weeks ago where i wasn't even trying.

What's your experience with segment and do you use it?

It depends on the segment, because it's using the GPS to track your progress for both the segment start and finish, as well as you overall position. Segments that feature lots of hairpins, or are in the trees and have poor GPS reception are going to mess with the live updates.
I have had a similar experience where I'll go into a segment hot trying to get a PB, and barely 5 seconds into the segment it's telling me I am 18 seconds behind pace despite the fact I am giving it everything, then it will jump and show me 10 seconds ahead.
To be pretty honest, I never rely on the segment data. If I am actually going for a PB or pacing myself, I use my power meter and flick the segment screen off because not only is it a distraction, it does not show the data I need on the overlay.

I did a climb on a charity ride last weekend, which had a designated KOM for each group. I'd done the same climb two weeks prior on a training ride, so I knew roughly the effort needed. Anyway, on the day the live segment came up on the Garmin and I immediately just flicked it off and back to my main page. I let my legs dictate the pace, and a bit of cat and mouse with one of the other riders who was about the same level as me. We got flogged by another guy by a country mile, but myself and the other rider both did massive PBs over the top (I was 38s quicker then 2 week prior!) and not once had I looked at the time during the climb. It was just "Shut Up Legs! Shut Up Legs!"..."Oh crap, he's got 10m on me...legs, give me more!", "That's it, reel him in, sit on his wheel...now go!"...and that is how it went for the 6km of the climb.

[vosadrian]

I've always found it pretty accurate for long segments... but not so good for short segments. Normally I find my time in strava once uploaded is a few seconds faster than what the Strava segments feature said. Does not make much difference on longer segments but can be a game changer on short segments.

I also agree that on segments with hairpins or similar that cros back over themselves, it can confuse things, so not great in that situation.

Like queequeg, I don't find the screen very helpful as I can't see the data I need when I am putting in a sustained effort (power/HR), so I usually flick over to my normal data page..... unless it is a shorter segment (1-5 minutes) and I don't need to manage my effort as much. It still gives you your time at the end and does audible alerts (when you or competitor finishes) when using another data page.

I've been meaning to investigate if you can make custom data page with Strava segment data (like time offset) along with you usual helpful data (power etc.). Anyone know if this can be done?