@bgood420 There are TONS of posts about nosedives happening for various reasons. If you truly are going anywhere near or over 20 mph, you are courting disaster. The max speed is dependent on a lot of factors including rider weight, battery charge level, incline, etc. A few years back, I saw a youtube video of kid (I think he was 90 lbs) breaking 30 mph on an XR! Anyway, there is no warning of a nosedive, except pushback (look it up or read the card that came with the board). For me, I can't feel it at those speeds. I (as well as a TON of other people) have been asking for an update to the app that will do a notification (sound and vibrate) at a user set speed, but alas, @Future-Motion insists on adding social features, like leaderboard updates and such, instead of this one highly requested safety feature.
Anyway, as a long time rider and one who hasn't crashed since the 600 mile mark (doing 21 mph and, like you, road rash everywhere), my solution was to get a smart watch (Wear OS or Apple) and run the OneWheel app on the watch. This way, I can tell my battery level and speed at a glance. Since my crash I am now coming up on 7000 OW miles and I keep my speed at or below 17 mph. This is plenty fast for me and for my weight of 175, the board never fails me.