One pair of underwear.....5 days.

Smartwool are nice and I have a few of their shirts that I love, but I've found Darn Tough to be much, much more durable for socks. If they're primarily riding socks, it's probably not a big deal, but when walking a lot, my Darn Tough socks have lasted at least 3X longer than Smartwools.

+1 for the darn tough socks. I am very hard on socks and generally blow through them very quickly (14 hour days with heavy boots walking on concrete). The smartwool are generally more comfortable but for the difference in how long they last I will stick with darntough. This is based off trying tons if different socks and brands. If there is one think I enjoy spending money, its quality socks.

As for the underwear, I wear both the exofficio and under armor everyday alternating throughout the week. Basically the only underwear I own. Multiple of each. All day comfort I love my boxer shorts from under armor and will choose them for day trips anytime. As for extended wearing periods the exofficio wins hands down for staying fresher, and more comfortable longer. Both great underwear and excellent quality but depends on what I'm doing for when I wear them.

Washed every day, I have not had problems. I have issues wearing clothes more than once without washing them my whole life.
I guess an early life of presumed colonial ease and sensibilities living in southern Africa must have developed that....
Or maybe just living and traveling in hot climates...

The material is different to the shirts I have. They do cling a bit more, but that is part of the comfort / support thing, as they are not cut to fit slightly loose like the ExOfficios are.

I bought a pair of these...

http://www.duluthtrading.com/store/...f-socks-86014.aspx?kw=socks&processor=content

IT won't be my last pair. high enough for my MX boots and all day comfortable at work.

socks from Mario at LDComfort. He has them in tall boot length and in shorter, more like a normal sock length.

They're the best sock I've worn for riding, I wear them with Sidi boots and they stop the chafing of the boot on my legs that exists if I'm not wearing a pair of his LDComfort tights.

I also wear the shorter version at work with a pair of Eco boots, they also work great, keep the feet dry and comfortable.

He also offers an inmate discount, find him in the Vendors area.

His LDComfort underwear is the best thing since sliced bread to wear under your riding gear too.

For some reason a few years back my feet would smell super bad even with fresh socks every day, smelled like cat pi$$. Tried powders, absorbine Jr, and other foot odor remedies to no avail.

Just using my head, and knowing rubbing alcohol kills bacteria, I got some of the mint scented stuff and put in a spray bottle. Every morning I sprayed my feet, for about a week, smell gone! And it has never returned.

took two pairs of Exofficio boxer briefs on a 5 day backpacking trip through yosemite last summer. I'll say they are good for 3-4 days on a bike, but if we are talking about backpacking, they are good for 2 days max! =)

They are super comfortable and worth the couple of extra bucks (i normally wear gap boxers)

Try Lamisil cream or equivalent, the bad odor is caused by fungi and not by bacteria. You need to use it as in the instructions and you will probably want to repeat after 6 months. Fungi are quite resistant to regular washing, higher temperature washing is needed for all your socks and also a spray for your all your boots and shoes - or else you will get reinfected.

How do you think the real deal, tough as nails Iron Butt riders do it? Probably more like 10 days. It builds character.

Ha ha, posted exactly the same time by a fellow Brit.

REI is having a sale on Ex Officio and Smartwool. Just bought 3 pair of Smartwool ultra light hiking socks and another pair of Ex Officio boxer briefs.

one vendor on amazon has exofficio boxer briefs for less than 20 bux, black is cheapest. wool would be better, but $$$ Also, patagonia and rei brands are close to the exes.
wash them in the shower if you travel, just keep them out of hot water or the elastic will give up. wash in the cold water that comes first while you're waiting for the hot water. bar soap works fine.

Wool ones on BF sale at EMS for $30...http://www.ems.com/product/index.jsp?productId=12513546

Merino wool socks are now the only socks I wear. The very odd time I will toss on an old pair of cotton socks to sit around the house in, but work\going out\riding it is always merino such a great material.

Coconut socks by Roadgear.
http://roadgear.com/coconut-silver-socks-c-22_63.html

An update to the above. I've just spent a week, swapping between 1 set of ExOfficios and the Under Armor shorts.
Washed either one every day. Towards the end, I washed both pants on the same day, hung both up to dry, and after applying the sniff test, the Under Armor shorts were noticeably better smelling (as in no smell).
Not sure why, I would have expected the ExOfficios to do better.

The Under Armors are made from a stretchier material, that sits tighter and clings more, except for the crotch area which is a much more absorbent material.
For the $9 I paid for them, IMHO a real bargain compared to the ExOfficios.

This real life testing is great. I can't wait to start sniffing my underpants

I'm telling you guys - you'll be surprised with bamboo underwear then as well... but based on that test I'll eventually try the UnderArmor as well.

Ditto on the merino socks for riding. I've tried a lot of sox and underwear combos, and the SmartWool Merino sock liners are great. They are a bit thinner than regular socks but noticeably cooler in Texas weather and MUCH less smelly after use.

I've used the nylon/spandex type shorts for underwear when riding and they've worked really well at staying comfortable far longer than other types. Look for brands that don't have seams across the butt area. Pack small and wash/dry easy.

Recently I've tried the Ex Officio's and they are really comfortable. I think I'll carry a couple pairs of those and couple pairs of the spandex on long trips.

Nothing like chatting about underwear amongst friends