67tony 

I'm restoring a Miyata Two-Ten mixte for my wife, and the middle front chain ring is pretty boogered up. (I'm guessing it was used about 95% of the time by the previous owner!)

The setup is a Sugino VP 50/44/28, and the closest I can find in my modest parts bin to replace it is a Sugino 40. Can I call this close enough, or am I messing with some elaborately-researched Miyata gearing formula?
(The freewheel is a 6-speed Shimano SIS, MF-Z012, made in Singapore.)

icepick_trotsky 

I would think it's fine. You can use an online gear calculator to see what the actual difference would be, but a 44t ring wouldn't be hard to find at the local co-op, either.

gugie 

The 50/44 combo is odd. Google "half-step gearing", I'm not going to go into the theory, but suffice it to say those that tout it use spreadsheets to design their gearing, then memorize shifting patterns or tape a piece of paper on their handlebars like an NFL quarterback with the playbook on their forearm.

What many advocate (I'm in this herd) is about 10 tooth difference from high to mid, then whatever granny gear you need. So for your 50 - X - 28, substitute X=40, which exactly equals the zero cost replacement you have on hand. It'll also make shifting from the 40 to the 28 a bit easier than 44 to 28, with little degradation in high to mid shift up front.

Just my 2 cents.

67tony 

Thanks for the replies...that's exactly the advice I was hoping for.
It is re-assembled with the 50/40/28 combo, at my preferred price range of $0!