I’m not fully sure the circumstances this sign is elucidating, but I can tell you I won’t be riding my bike here, that’s for sure.
@superbetsy don't turn sharply because instead of just falling off your bike your front tire will catch in the grooves of the road and you will be launched head first into the pavement?... i'm guessing?? looks like thats supposed to be a tire that got turned into a groove almost..
how many times has it happened for it to become a sign?! +_+

@dumdumdelish @superbetsy It's for tram tracks. They are a hazard to bikes as the wheel gets stuck in the groove.

It's not a very good sign though. Looks like there is no front wheel on the bike, which does indeed make it a bit dangerous.

@veronica @dumdumdelish @superbetsy This design is from Portland, Oregon