I was pretty much addicted to RAGBRAI after one day too. My first year we rode 3 days and that was enough to get completely hooked on it!
I don’t suppose you have to carry anything on your bike except water and money to buy food. You can depend on the kindness of strangers if you want to and on RAGBRAI it is probably a successful strategy in that eventually someone will help you out. Eventually. Don’t get me wrong, in a real emergency you will get help instantly. For a flat tire, being prepared to help yourself is the right thing to do and at your age and likely marital status being prepared to help others can be a good way to meet interesting people! So, yeah, a tube or two, some tube patching materials, a pump or 2-3 CO2 cartridges, and maybe a good multi-tool would be a good minimum which should fit in a small seat bag like the ones I see a whole lot of folks using. I had a friend break a spoke a couple of years ago and while this does not always happen his wheel went out of true so badly he could not ride it. But, he had a multi-tool with a spoke wrench and he was able to quickly pull it true enough to continue on. I never carried a multi-tool before then but I do now!
Lights? For most of us, no. If you want to head out before dawn, which I don’t recommend because it seems like a lot of bad accidents happen to the dawn patrol, or if you will be riding after dark in the overnight towns then you should have lights. In the latter case you don’t have to carry them all day on the bike, you could leave them in your gear bag and let the Register truck or whoever hauls your gear deal with them.
Not sure about your app question. There are phone apps that make capable bike computers but most of them rely on GPS. Some of them may be able to read an ANT+ speed/distance/cadence sensor on your bike. But phones smart enough to run apps all have GPS sensors so I don’t understand why you want to avoid apps that require GPS. Bike computer phone apps are going to be a bit of a battery hog whether they use GPS or not. You can definitely get RAGBRAI apps for your phone which will have a lot of basic and useful information, there is a link to the official apps here on this website. Bike computers come in a very wide range of prices and capabilities and I use a bike computer rather than a phone app to keep track of ride statistics. If you want to go with a phone app that is probably feasible, just anticipate that battery charging will be a major concern and be aware that apps that depend on downloading map data from the phone network (and a great many do) will not work well on RAGBRAI because we overwhelm most cell phone networks most of the time. So I would look for the simplest app that does what you want done. Any extra features will likely drain your battery quicker and may not work well with the spotty network connections you will get during RAGBRAI. MapMyRide works well for me during my general riding but I have never even attempted to use it during RAGBRAI.
General preparation consists of doing a lot of riding. Try to get 1000 to 2000 miles in prior to RAGBRAI. Try to do some rides of 50 to 100 miles and try to do rides over 25 miles two or three days in a row. Try to ride on hills as much as you can if you’ve got em, ride into headwinds every chance you get if you don’t have any hills to train on. You have a new bike, make sure you sort out any problems with your bike fit and your saddle well before RAGBRAI. Mentally prepare yourself to be patient, flexible, kind to others, and ready to have a whole lot of fun!!
I envy you, I wish I had started this adventure at your age….
