I did this in the middle of the road, in versum hills. if you circle the grind rail in the center of the road just outside the train station its pretty easy to do. I do not recommend this location though, you need to dodge cars and there are 100% easier locations to do this

Go to versum hill where you battle the franks and you can literally just go in circles for infinite manual and no effort

For another ez method go to versum hill. The immediate area of the van under the billboards is a nice open space. You can carve back and forth or go in small circles.

Patch notes released today mentioned that the achievement will be available for Bike and Skates when it drops. Right now it *is* only for skateboard.

I assume the achievement is meant for skateboard only, hence the achievement icon. I will add this to the guide though, I did not consider trying this on bike!

When I tried this on a bike it didn't work, but I switched to skateboard and it worked first time, I believe the achievement is bugged on bike. So for anyone that's trying this, switch to skateboard

Thanks mate.