I've made some small improvements on your great gears-dev extension.
Please have a look at https://github.com/jnweiger/inkscape-gears-dev
- one can now switch from cyclic pitch to metric module, which is more common in europe.
- one can now lower the nodes count per tooth, which is helpful with large numbers of teeth.
- raised the limit on the number of teeth above 1000
- added an option to define some clearance at the inner tooth diameter
- fixed the rotation center.
I've also taken the liberty to send it upstream to be eventually included in official inkscape releases.