Figuring out if a trail is a good fit can be pretty subjective. For example—I ride a CRF250L in Chiang Mai, and I find this specific one trail easy, even when it's wet. Most trails get tougher when it's rainy season, so it's not that helpful for folks. Just imagine if most tracks got tagged this way; the map would be a total puzzle! :)

In general, description tag is the right place to warn users, and name is intended only for official purposes. FYI, It's considered poor practice to use the wrong tags with the intention of making them appear on renderers: https://wiki.openstreetmap.org/wiki/Tagging_for_the_renderer
