As the heading says, I got this to replace a Garmin 130. What a mistake. The "alert" sound on this is higher-pitched (we lose frequencies as we get older) and the heads-up display, though a wider screen, is about 1/3 of the display size for my Garmin Varia. So with the Garmin 130, there was a wider, bigger set of circles "approaching" the triangle (you) at the top of the headset. With this, it's a very thin, narrow lane, and the circle is tiny (my eyes don't really catch it) and the "alert" signal is weak. There is no way to adjust the volume. I have AirShox, and if it could pipe the alert through that, I could turn it up as loud as I'd like, but no joy. But the thing that is really disappointing is the "Incident Detection" feature, which is why I bought this unit. Last May, while out on the bike, I had a stroke (I'm ok) but it freaked me out pretty bad, and my wife was a basket case. I thought this might get us some peace of mind. Instead, this thing is on a hair-trigger, and if I stop fast, or hop the bike up a curb, or speak to the Garmin 820 in a stern manner, it goes off. I had to shut the feature off. It's absolutely terrible. You'd be better off getting one of those "medi alerts" and yelling, "Help! I've fallen, and I can't get up!"
I bought this because it was cheaper than good used 520s, 520+s, and 530s. Problems: the included handlebar mount isn't tight enough on my nominal 25.4 mm handlebars. I've installed it over a couple of wraps of cotton bar tape and the thick spacer, and that looks like it will last. Occasionally it just stopes recording in the middle of a ride, and I have yet to figure out a quick way to restart it. I don't think it measures gradient all that well. That may be because I live in flatland. I think it's often off in reporting wind speed, but that doesn't surprise me. BUT ...
I find the swiping to work more than decently. It's imperfect, but buttons aren't perfect either, IME. The clarity of the display is excellent (my phone has a top notch display, and the 820 is good enough.) It seems accurate. I haven't used the mapping much, but it's a giant upgrade from breadcrumb routing. Besides, it tells you you turn by street names, and if there's no street sign, I find it easy to miss turns. :-)
I hate Garmin Express. Garmin Connect is OK. I like the customized, downloadable data fields that provide more info than standard Garmin screens do, but that's available to most Garmin devices.
I $332, I'd probably recommend a 530, unless you can stretch to $400 for an 830. On sale, though, this 820 is a very good buy, IMO. I'm 77 and ride 1000-1500 miles/year, almost all of which is on my home turf.
I bought this for my wife after she dropped her 820 and broke it beyond repair. It was part of a special offer including Garmin Rally power pedals so it was deeply discounted. My wife really liked her first 820 so no reason we wouldn't like this one!
I got this unit as a re-manufactured item. It was a very good price and functioned ell, but there are some things I didn't like about this one. The unit is very slow to operate with the touch screen, and the screen itself is made so that about half of the brightness is lost when I use my polarized sunglasses. If I rotate my head 45 degrees to one side, the display goes totally dark. 45 degrees the other side shows 100 % bright.
The advanced mapping function was not as useful as I had hoped. For what it does on-the-fly, it is cumbersome and most of the things I'd want to do with it can be more easily accomplished on my iPhone map.
Operating the unit is too complex with buttons and display screen touch buttons, especially when wearing full finger gloves. Too much info is cramped in the small display and the readout numbers are too small. Hard to read your speed. And yes the battery life is disappointing.
This is the first stand alone GPS that I have owned. Previously I was using the free version of Strava on my phone. I love the turn by turn navigation and that it syncs up with my off brand cadence and heart rate sensors.
I tried it twice but I didn't like the way to change the pages. I had to do screen swipes which didn't work well specially when wearing a glove. I prefer in this regard the 520 and the 530. I didn't see that the 820 offered any advantage over the 520. About the same size. It worked well when I didn't try to flip pages or change function.
This is the first GPS bike computer I have owned. I always got by with a speed and cadence pickup to the display on my handlebars. This is so much nicer with so much functionality. It was a "refurbished" unit, but it looks brand new and I haven't had any problems with it. Not looking back....
Pros: Mapping is nice, can configure the pages to your desires. Can setup multiple Bikes. Syncs easily. Has features to show text messages and phone calls. I got a NHO version so the price was fantastic on sale
Cons: The batter life is not nearly as good as my 6 year garmin 800. I'm slow but go long - this is gonna be an issue for me in the summer months. I also wish the device was a little big larger.