A bad set of knicks can all of a sudden turn into a bearable set of knicks if you just add a bit of chamois cream. Even if you own a set of $400 Assos FI.13_S5 intergalactic space knicks, putting a bit of butt butter in there will make your long rides a lot more enjoyable. I can’t say that I put the stuff on if it’s anything less than 100km, but I’ll take the effort to lather up my chamois on long rides that last more than 3 hours. It prevents chaffing and keeps bacteria and infection away. This is how saddle soars are prevented.
The stuff that I use is the Assos Chamois Crème which costs about $25 AUD for a 140ml jar. It lasts a few months with the frequency that I use it. I just lather up the chamois fairly generously (I use about a 2 fingers blob of it) and wipe it into all the chafe-prone areas. I also take care to rub it into all the areas where there is stitching in the chamois.
A cheaper option that I’ve heard very good things about is Bepanthen Nappy Rash creme. You can get a tube of the stuff for $10 at your pharmacy. It has the antiseptic you need and is very breathable. I suppose any diaper rash cream will do and it’ll costs you a lot less than the good Assos creme de la creme will.
What you don’t want to do is use Vaseline. It’s hard to rinse out of the chamois and difficult to wash off your backside. Also, don’t get the chamois creme mixed up with the hot leg balm. You won’t make that mistake twice.