Without going into details, go to any of the sports stores and you will find compression clothing. You can also get different brands at Wal-Mart, Target, K-Mart, Shopco, etc........
The best I have found is actual Under Armor for more insulation value, but the others are very good for a minimal base layer. I have some Nike, and blank-Mart brands that I have had for a few years and they get worn about three times a week. So they are holding up very well.
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2007 Jamis Ventura Comp
2006 Jamis Explorer 2.0
2000 Specialized Hardrock (bought used)
Swim, Bike, Run and sounds like fun