Robert,
Good luck finding these Simplex ball bearing pulleys. I had a set that I acquired back in the 70s. They sat in my derailleur parts box for 35 years. Back in January I picked up an all original 1971 Gitane Tour de France with Simplex Criterium derailleurs.
I had the bike on my repair stand and noticed that it was shifting funny. The pulleys looked strange then I realized that the plastic on them had disintegrated. I finally put these NOS pulleys to good use.
You may have a problem finding the original Simplex ball bearing pulleys. The standard metal bushing plastic Simplex pulleys regularly show up on eBay.
Having used both styles on old Simplex derailleurs, I've never seen or felt any difference. In fact Simplex stopped supplying the ball bearing pulleys as standards on the Criterium derailleurs sometime during the US Bike Boom of the 70s.
You can probably substitute any standard set of pulleys that are close to the same width as the original Simplex ones. If need be, you can use a washer or two to correct the width.
For years I've been running Bullseye aluminum pulleys with ball bearings on a number of my bikes. I didn't use them for the claimed reduction in friction but because they ran quieter and smoother than many plastic pulleys. The Bullseye pulleys occasionally come up for auction on eBay but they go for exorbitant prices.
There are several brands of aluminum ball bearing pulleys plus some plastic ones I've seen offered on eBay. I have no idea about the quality.
Charles Colerich Oakland, CA
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