Okay, at the expense of getting dumb answers, let me try one I have not found an answer to.
I have two half IM’s and one Full IM this season. Since I do not ride my bike for lots and lots of miles at one time, I am trying to be proactive and figure out what is the best things to wear, use, one these long bike rides. I have things that work for my shorter tris, but, trying to get everything ready for these longer bike rides.
The short answer is nothing under the bike shorts.
In a half or shorter you won’t likely want to change between the swim and bike which is shy tri suits have a thin, faster drying chamois/pad. If you have decent padding on your saddle this isn’t an issue. I found my SLR saddle a little harsh when wearing a regular tri suit. Didn’t notice it on a long course though.
For IM this year I am going to change into shorts with the thickest pad I can find. I’ve worn bike shorts and knickers running and don’t have a problem with the thick chamois.
And as has been mentioned, chamois butter is great. I wouldn’t want to ride back-to-back days without it.
I agree - wear nothing under the shorts.
I would add to always wear clean shorts - do not wear shorts without washing after each use. The idea is to keep bacteria down to a minimum. Some of the chamois creams are also antibacterial.
Maybe I’m just lucky (or well worn) but all I ever wear for IMs (or any race) are my DeSoto tir shorts - all day - swim, bike run - don’t chang and never have any problems.
Well the excessively popular answer seems to be nothing. I’ll offer that I wear a pair of poly-lycra UnderArmour sport boxer briefs that are very comfortable, don’t chafe, and don’t ride up. Admittedly I don’t really enjoy going commando (too free, a little unsanitary too imo). But then again I also don’t urinate all over myself as some bikers do so I guess I’m a prude. Anyway, poly-lycra boxer briefs work well as an alternative to freestyle.