I'm assuming it was indented for whatever reason, but the knee indent shape obviously strays from the CR750 tank design. It still looks nice, and the outer shape and vent, fuel cap, etc gives it the CR 970 tank style. I wonder why they went for the knee dents. It's actually harder to make the that way.
Perhaps they didn't want it to look TOO much like a CR tank. I get that.
Cafe racer fan,
Yup, that exactly what I expected from Denis. Single sheet bottom, bent with a sheet metal brake. It makes a solid base that way to form and weld the sides and top to with minimal/no jigging forms required if done right. If you compare that underside with the CR 970 tank, you'll notice what extreme measures they went to construction wise so they can get that extra maybe 1/2 gallon into it. A very convincing CR replica tank (extrnally) could be built using a CMR style bottom pan along with accurate dimension top and side panels. You can easily put in any baffle design one wished before the sides and top were welded on.
For an alloy CR style tank to go racing with, that makes sense.
George