...I think I will bring a spare GPS on future bike tours...
For my multiweek solo adventures in the back-of-beyond, I bring my Garmin 400T and 600T with routes, ... ...
I bought a lightly used Garmin 64 ST last winter on Ebay. I like the 64 series, runs on AA batteries and I can charge NiMH batteries in it with a mini USB cable, which I often do on a bike tour. (To charge AA batteries in it, you need to do a work around to make it think it has the Garmin battery pack installed in it.) I do not know how much longer Garmin will keep making models that run on AA batteries when everybody seems to want Li Ion batteries now. So, I thought having a spare would be a good idea while I can still buy them.
I can load Open Streets based maps into it for free, so as long as those maps are available on the internet, I can keep it updated with current roads, etc. Thus, I have not had to worry about obsolescence.
Since I also use my GPS units for backpacking, canoeing, kayaking, I prefer a general recreation grade GPS, not a cycling specific one. I leave for a backpacking trip in a bit under a month, I will bring enough AA batteries to last for the 9 day segment, followed by a 6 day segment. I have a bunch of AA NiMH batteries for this purpose.
I have never had to go to a store to buy disposable AA batteries for it, but that is one more reason to have one of these for bike touring, there is that option available if my dynohub or USB charger fail. I have not bought disposable AA or AAA batteries for over a decade, but I like having that option.
On the tour divide race this year, I was surprised to see two people brought Etrex models for their navigation, and one person used paper maps.
https://bikepacking.com/bikes/rigs-of-the-2024-tour-divide-stats/But I had read elsewhere that one of those Etrex users was using it for the ability to swap out batteries, but he brought a cycling GPS along as a backup in case there was a problem with his Etrex.
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Regarding finding repair videos on youtube, that certainly is an option. I try to look at three or more videos before I try fixing something, because some of those videos have incorrect info. I hope that when I see a few videos saying the same thing, that it is correct. I replaced the internal battery in my Asus Windows 10 laptop computer a few months ago, with the help of youtube videos that told me how to open up the case.