Crank tool threads for a BodyGuard R6X I need to replace a circuit board on my Bodyguard R6X exercycle. Bodyguard sent me the circuit board but little else with respect to information/instructions.
I need to pull a crank so I need to buy a crank tool. Are all cranks the same thread?
Pretty much yes.  Most exercycles or stationary bikes use a mixture of generic bolts/screws and some standard bicycle components.

A cheap crank tool will look like this, whereas the more expensive ones tend to integrate some kind of handle.  You just need a 150mm (6") adjustable spanner, or larger.



There is probably a cover of some sort which can be popped off, or unscrewed.  There will be a 14mm nut underneat.  Or a newer crankset might have a bolt instead the nut and cover.

Once that's off you should see threads inside the crank arm.  These mate up with the black threads on the pictured tool.  Grease and thread them in.  Then turn the silvery end to wind the pusher in and haul the crank off.

It will get hard, just let the pressure generated by the tool do the work.  You may worry that this feels like stripping the thread on the crank arm, and while its very similar sensation it is different.

One gotcha - look down inside the crank arm hole and see if you see a square interface, or a round one.  99% likely its a square meaning a square taper, but more modern bikes have a round interface called Octalink, and the tool for square taper tends to damage octalink.