@Kenho : I wouldn't buy this type of locking tool because I would be afraid to split the part of the crankcase where the bolt goes in. There's only a single bolt which is loaded sideways and acting as a lever, while the small tool can also wedge itsef in between the wheel and the bolt in a nasty way.
I've got the type of tool that Baddi has. With this tool you have two bolts carrying the load and nothing will wedge itself in anywere. I've used this tool many, many, many times (I've found my perfect variator setup by A LOT (tm) of trial and error
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) and it works just perfect without putting too much stress on anything (e.g. like with an impact wrench...)
just my thoughts...