Supertick

I have been told that a 32 spoke wheel in 26" (559) is sufficient for touring as long as it has a heavy duty rim. I have a mountain bike with good hubs and Sun TL-18 rims. Sun does not make these rims anymore and they have not answered my email. Does anyone remember these rims and if so are they considered heavy duty rims?

NoReg

32 will work, I never broke one touring off-road, so I don't think it should break on the road. I'm heavy.

I don't know your rim. If you are talking about the kind of road touring where you use 1.5" tires or lighter, then you have to be careful that the rims aren't too wide, over an inch say. Otherwise they will be too heavy and prone to puntures. I'm not saying they won't work, but that's about where I would start to bail.

cyccommute 

Overall, 26" rims are stronger than 700C. One of the reasons that they are used in mountain bikes is their smaller diameter and greater strength. A 32 spoke wheel should be fine for touring but you are missing 1/3 of the equation for wheels...and it probably the most important part of the whole equation.

Most people think that if they have a good hub and a good rim they are done. But what holds the whole thing together...air? You need to look at the spokes too. In a touring situation you will probably never break a rim and I can almost guarantee that you won't break a hub. But you probably will break a spoke...maybe lots of them. Get good ones. Don't go with straight gauge (you can read why here, look at the section on Double butted spokes). If you want the best spokes for touring currently available, in my opinion, go with the DT Alpine III spokes. They have less problems with head breakage because of their tighter fit at the hub than other spokes. I've been riding the same mountain bike wheel -hard- for 5 years that was built with them and I think I've broken a single spoke.

For the front wheel, you probably don't need the Alpines but I've found them for cheaper than double butted spokes, so why not just use them all the way around?

GeoKrpan

I've used the lightest 26" rims available, 32 spokes, and still have had no problems. What's more important is the quality of the build. If you want to play it on the safe side buy new rims and have your wheels rebuilt by hand. It would be economical because you would not have to be buying new hubs.
I've use the lightest Mavic racing rims that weigh around 400 grams and have had no problems touring or mountain biking. The thrashing they take on the trail far exceeds what they would go through on the road.

Supertick

Well, thank you to those who have responded. I feel much better now that I know the 32 spokes will work for me. The spokes are DT and should also be fine for touring. I plan on using 1.50 or larger tires for touring so I should also be good in that respect too. Good to hear from those that have toured on a mountain bike.