I have a Gunnar Crosshairs that will be on touring duty this summer, pulling a Burley Nomad trailer thru Spain. Right now, I have a Shimano 600 series gruppo on the bike, with a 48-39 crankset up front and an 8-speed Shimano Hyperglide cassette in the back, all road parts. At first, on the advice of a friend, I was planning on simply swapping the
rear cassette for a MTB cassette, perhaps an LX or XT one, and getting a long cage rear derailleur. I talked to a guy at REI who has a lot of touring experience about this, and he seemed pretty sure that I should also change to a triple in the front. I don't have much money for parts--I'm saving for this trip!--but I don't want to be SOL while on tour in unfamiliar territory. So I'm considering buying piecemeal a whole new drivetrain, including new shifters/brakes.

I was wondering what would be a good set-up, piece by piece? I want to remain at 8 speed, I've heard it's a little more reliable and less maintenance than 9 speed, and I need to have a bottom pull front derailleur for the cross frame. So far, I've been thinking about something like: SRAM 5.0 11-32 cassette, Deore LX or XT rear derailleur, Shimano 105 52-42-30 crankset. I don't really know what bottom bracket/shifters/otheraccessories I need to get. So does anyone have any recommendations for an (relatively) inexpensive 8-speed drivetrain set-up that could take me happily through my trip?

I've never built a drivetrain before, so I'm sure there a number of smaller components in it that I've failed to list; what are all the parts I would need to replace moving from the current 600 set-up (including the brake/shifters) to a touring triple cranket?

Now you are probably a far stronger cyclist than I am (wouldn't take much), but it might make for an easier tour if you used an MTB triple instead of the 105 triple. My bike was originally equipped with the 105 52/42/30, but I had it switched out to an LX 44/32/22 (required a new BB, too). The road triple gives you a 32x30 low, while the MTB triple gives you a 22x32. I was able to keep the 105 front derailer (for a triple). The bike has an LX rear derailer.

The LX crank is a few dollars cheaper than the 105, and the lower gears could make it a lot easier to tow a trailer through the mountains!

Since you are using 8 speed you could order a Sugino 46/36/24 road triple crankset from Rivendell. https://www.rivbike.com

I reckon you may want something more like a mountain bike crankset also. My setup is 22/32/42 at the front with a 8-Speed 11-30 set on the back. Before I went on tour I very rarely used the small ring at the front but on the tour I think I must have spent half of my time on it. I did tour some of mountainous area's of Austria though. I am not up with the brands however so can't recommend a specific model. (I have Shimano Alivio gear) Best of luck with your trip.

How low a gear you want will depend on where your tour is going to take you and how strong you are. That said, I'm not a particularly strong cyclist, but was able to get across country using a Sugino XD triple crankset (46-36-24) with a 11X32 cassette. This crankset has a 110/74 BCD, and there's a good selection of chainrings available for this BCD. It lets you get a larger chainring than is generally available with a compact mtb crankset while still getting a small inner ring. I'm using a 105 bottom pull front derailleur with it and it works fine. Have fun on your tour!