Chamois BUTT'r can be purchased in small packets, light, easy to carry, use it if you need it.

Vaseline does work very well, but is greasy and a bit messy. Easy to put into a small container and take along.

You can also use ChapStick, which is mostly Vaseline, just get the unscented kind. Or Aquaphor, which is a reformulated (and pricier) Vasoline. I was able to score a handful of free half-ounce doctor's samples a couple of years back. These were perfect for hiking and biking.

Body Glide is probably the very best, as it isn't absorbed. It was designed to be an on-skin lubricant. Even after 12 hours you've got to wash it off to get it off.

Many other lotions & cremes work okay. Almost most of those sold as moisterizers are formulated to soak in and once they do, they no longer do much lubricating. So you might need to reapply every now & then.