Thanks everyone! So, just to clarify, I would be able to find attachments for my current bike. Also, 29" or 27.5" tires are not required in order to have an enjoyable ride.
However, I was wondering if anyone could compare riding on variable with 29" or 27.5" as opposed to 26". Also, I've ready some articles about how to properly switch from a 3x to 1x gear system and was wondering if doing so would be an advantage? Finally, what are the advantages to riding with a trailer compared to panniers?
I can give you some answers, but a lot of this will be my opinions and I think you should get others thoughts as well.
Consider a wash boarded road. Cars tend to be of a certain length and height, and so all wash board tends to be similar. A 26" wheel will pretty much roll completely into a wash board rut before rolling out. In other words, if you were to take the arc of a wash board rut and extend it to draw a circle, that circle would have a diameter of about 26 inches. The larger wheel sizes do not roll completely into a washboard rut, instead there is a point where the wheel is supported by the rut peaks and part of the wheel is in air spanning the two rut peaks. So the impact of the rut is not as severe. If you are able to bring in a soft tire as you tend to see in tubeless mountain bike tires, the ride quality is even better. Because they are smaller, 26" wheels accelerate more quickly.
As for 1X, 2X, and 3X drivetrains.
A 3X drivetrain has redundant ratios that show up because you have both 3 front chain rings and in your case, 9 rear chain rings. That is neither good nor bad. The upside of 3X drivetrains is that you can chose from your redundant combination a combination that minimize how much the chain has to flex side to size.
In a 2X drive train, you will give up some redundant combinations, and you may give up some range (probably on the high end). If you use one of the new derailleurs designed for 1X drive trains (they have longer cages and more powerful springs which can span bigger chain rings), you might not loose any range at all. Riding is simpler because there are fewer redundant combinations to decide between, and you only have to visualize what you can do with two front chain rings. 2X chain life is probably shorter than 3X chain life since the chain will have more side to side flexing.
In a 1X drive train there are no redundant combinations. 1X is possible because they use a derailleur that spans 42 teeth instead of the 32 teeth found in traditional long cage derailleurs. Compared to a 3X drive train, there will be less range, so you will have to decide what range you need to cover. This is done by changing the front chain ring. Shifting decisions are easy to make as there is only a rear derailleur. I would expect chain life to be shortest of all for 3X drive trains.
My touring bike is a traditional 3X9 drivetrain. I opted to use bar end shifters with a non indexed shifter on the front derailleur and I have to problem keeping the front derailleur in a happy position. I took a mid-90's steel mountain bike frame and made a gravel bike out of it by putting drop bars on it and converting the 3X8 drivetrain into a 2X10 drivetrain. The low end of the range is enough for anything I will find where I ride, but there is no high end to the range. I do not find chain life for a 2X drive train to be intolerable. Finally, when I bought a Salsa Cutthroat and it came in a 1x11 configuration. I would like more low end, so at some point in the near future I will put a smaller front chain ring on the bike which will give me more low end capability and less high end capability. I have only been riding the bike for a couple of months so I cannot comment on chain life.
A loaded bike needs more low range gearing than non-loaded bike. When I did part of the Great Divide in New Mexico with my buddies, we carried a lot of water because you could not resupply every day. We also rode in March and had temperature spans of 20F to 85F. So I cannot see doing this ultra lite. I do not think I would want to do this with a 1X drivetrain.
As for trailers vs panniers. I generally prefer panniers, except when off road (I prefer a trailer as the bike is too wide with panniers). I started with a trailer because it was cheaper. In New Mexico, none of us had road bikes geared low enough, so we all used mountain bikes. We wanted to leave the front suspension forks alone, so trailers allowed us to use the mountain bikes pretty much as is. I later migrated to panniers as the coupling between trailers and bikes has certain amount of back lash and I found that annoying. A lot of what I remember about riding the Great Divide Trail in New Mexico was that there was gravel two track and hard pack two rack and some narrow roads that had wash board. I think riding over wash board with panniers would be unpleasant.
