Does any one know the common wheel sizes used in central and or south america? 27"(iso 630), 700abc or d(iso 622), 26"(iso 559), other crazy size. I may be taking a long tour there, need to choose a wheel set, and being tires are consumables I would like to be able to buy tires en route rather than using fancy shipping arrangments or schlepping them the whole way.

--Cap

There are a few spanish-speaking groups from Central America on Yahoo that you could look for. I did a search on https://espanol.yahoo.com https://ar.groups.yahoo.com, https://mx.groups.yahoo.com and found these :
- https://espanol.groups.yahoo.com/group/ciclovidaperu/
- https://mx.groups.yahoo.com/group/bicitekas/ (for transportation cycling)

But I have also been a subscriber of another Yahoo bike touring group in Spanish that was covering South America Issues. Can't find it, though.

Basically, as far as I remember, it's 26" and 700c - ISO-622 (in that order) that are the most common sizes. I remember reading that there was no problem finding these sizes in cities, especially if you are looking for a thin 700c (no wider than 28 or 32) or a very aggressive 26" (ISO-559) knobby, but that finding a typical touring or cyclocross (700x32-37 or 26 x 2" slick or fairly smooth) tire wasn't that easy. In more remote areas, I can't remember if it was the 26" ISO-558 or another flavour of 26" that was available.

IOW, definitely bring one spare with you and try to plan your tire changes in large cities.

Ok so I'll be fine with either 559 or 622 though I might have to use a slightly skinny 30mm or a full nobby tire.

Any second opinions?

I don't speak much spanish yet BTW. I'm slowly learning though.

You might want to read the travelogue on www.downtheroad.org for good information on conditions of all type in Central and South America. This is an excellent site and you should learn a lot.

good site.

26" it is.

Noww for the hubs....high flange low flange, repackable or cartrige?
I am quite good at repack and adjustment and if sand got in there I could do it on the side of the road with a moderate fuss and during initial setup I could use the grease of my choice.
Cartrige are sealed fairly well(not totaly) so the chance of grease washing out or dirt intrusion is much lower, and grease washout can be fixed with a syringe of light grease(if you know the kind they used, not all grease is compatible), dirt however is fatal to cartriges.
hmmm.......

and spokes; double butted straight gage, 3 cross 4 cross, 36 38 40 42 count

AAAAHHHHHH!!!!! I'm going to bed. I have a year to figure it out.

double-butted 14/15 guage spokes. low flange. 36 hole, 3x. XT hubs. there you go. thats what I would do a tour of south american on.

I can't speak for myself, but reading other's travelogues you find that the 26" rubber you can come across is so crappy that it's almost worth nothing (well, maybe a day's ride). So I wonder if it wouldn't be better to carry as many Marathon's XR with you as you can? I don't want to sound pesimistic, just want to know what more experienced expeditionists feel about this.

13/15/14 triple butted DT spokes and an 18mm inside width rim
36 spoke front. Most likely a 36 rear, though I would like a 40 rear, new 40 hole hubs are almost non-existant outside of 140mm+ tandem or $300+ fancy pants brands, either way I'd "like" a high low flange rear hub.
I plan on doing a half radial rear and a 3x front.

I'm still a little floaty on the 700c vs 26" thing.
Maybe 26" but pack a few tires of my own and still have the crappy-rubber tires as an option/backup. Or pack all of my own tires/arange some shipping/stumble across a good shop and enjoy the much wider 700c range of touring tires.

Why triple butted? Double butted should give you high strength with good fatigue resistance. I would go with 36 hole rim, 3x pattern. 4x usually crosses over spoke heads causing additional stress and making roadside spoke repair difficult. If you are planning on panniers instead of trailer, you might consider higher spoke count. But, if you have a rim failure you may have a hard time finding a replacement (not that any replacement may be easy!).

Why triple butted?(the long answer)
"Since spokes use rolled, not cut threads, the outside diameter of the threads is larger than the base diameter of the spoke wire. Since the holes in the hub flanges must be large enough to fit the threads through, the holes, in turn are larger than the wire requires. This is undesirable, because a tight match between the spoke diameter at the elbow and the diameter of the flange hole is crucial to resisting fatigue-related breakage.

triple-butted spokes are thicker at the head end than at the thread end, they may be used with hubs that have holes just large enough to pass the thick wire at the head end."

Starting at the head/hub end a triple butted spoke would start 13 guage, go to 15, then go to 14, then the threads. So it's just like double butted but thicker at the hub end so it fills the hole.

When you say 4X crosses spoke heads, please clarify. My old road bike uses 36 4x and it doesn't appear to have any near-head lacing. The reason I might consider 4x is that the spokes are more tangent to the wheel and hub which reduces stress from torque, either from driving force or disk brakes(if ya use 'em) this is also a big reason for utilizing high flange hubs, high flange also create a slightly wider side to side spoke triangle(veiwed from front or back of bike), for a given lacing pattern, which reduces lateral(side to side) flex.

The reason I'd consider a higher spoke count wheel is not for the spokes sake (can always step up a spoke size), it would be to reduce the stress on the rim and the rim holes. Yes the possibility of needing a repacement rim (and initial cost) is my main hold up on the 40 or 44 hole rear. Than again a 36 spoke wheel stresses the individual spokes and rim holes 11% more than a 40 spoke wheel or 22% more than a 44 spoke an 33.3% more than the same load spread over 48 spokes, so a higher spoke count is less likely to fail and thus replacement sould become an afterthought.
40 spoke rears were the standard on Brit. bikes for many years, of course I'm not going to go to England, but tandems use higher count wheels though too, so they shouldn't be totaly unheard of. Besides lots of people bicycle in poorer countries, why is it assumed that hardly anything is availible there?


I go with the high count rim, if in the unlikely event that my burly high count wheel gets so screwed that it can't be fixed than it's trash anyway, so if it's trash I will buy a new wheel, toss the trashed rim and put the high count hub in my gear for use at a later time, hubs are compact, spokes are too (when bundled in the seat tube[with a touch of foam rubber to prevent rattling]). The front wheel will be 36 from the start as there is less stress on front wheels in general.
Can any one see anything wrong with this?