Moped Gearing Calculator

May 20, 2014

So I made a gearing calculator for mopeds a few weeks ago. I put a link to it in the menu on the site and you can also find it at

I’ve calculated out some of the internal gear ratios of various moped engines. Just pick your bike and your engine then you can mess around with different sprockets and tire sizes and ┬ásee what you end up with for a final gear ratio. It’ll display what RPMs you’re hitting at different MPH and vice versa.

It’s helpful to know what you’re maxing out at for RPMs and then you can gear your bike for different situations. Also if you start hitting you powerband at X miles an hour you can use the calculator and see what RPM that translates to.

I’ve chased down most of the bugs in it and have a bunch of different engines in there, still quite a few more to do, but it’s all setup so I can just plop them in as I find them.

I’m already working on version 2 of it and I have a lot of other features that I plan on adding to it.

If you can help me out supplying me with gearing for engines that I’m missing I’d be most grateful. At present here are the major peds I’m missing. For some of these I’ll also need the rear wheel hub gear ratio.

  • Tomos A3,A35,A55
  • Honda PA50,PA50II,etc.
  • Vespa Engines
  • Morini Engines
  • Derbi Engines