Classic & Vintage - Are all Regina cogs created equal? Doesn't look that way...

How does one distinguish regina cogs. In other words, can I take any regina cog from a 7 speed freewheel and use it on a 5 or 6 speed? I've noticed some cogs have 3 notches, some have 6. Some are threaded, some double threaded. They also have letter designations like A1, A3, B3, etc. What do these mean? I came to cycling long after the use of freewheels, so I'm pretty green when it comes to these old parts.

For a long period, Regina cogs were quite interchangeable. EXCEPT, there are two body configurations, one that has a single land for the largest cog is the close ratio body, The other more common body where the last two land cogs share a common land or step. With these two body configurations a close ratio 5 speed can assist in making a 6 speed "regular" body. One of the old Sutherland's Manuals shows the position guide for each and how the cog positions overlap. So to partly answer your question most but not all cogs are interchangeable. Brass plated Oro cogs have the same dimensions, as do many Atom freewheel cogs, also branded as Milremo.

There were some "odd" cog positions to acheive freewheels with a 15 or 16 tooth small cog.

While this is interesting, finding the correct loose cogs to make that "prefect" freewheel today is like winning in Vegas.

For the later designs, such as the CX, BX, America, you are on your own.

Does the body with the single land for the large cog accept cogs with 3 notches or 6? Same question for the double land body? What are the "perfect" cog combinations?

Does the body with the single land for the large cog accept cogs with 3 notches or 6? Same question for the double land body? What are the "perfect" cog combinations?

I do not fully understand your comment regarding notches.

For all the freewheels I have described the cog scheme, all the cogs screw onto the body and/or each other. Nothing slides on.

For all the freewheels I have described the cog scheme, all the cogs screw onto the body and/or each other. Nothing slides on.

Well, the Regina cogs I'm dealing with are intended for 7 speed, I think, hence the question of whether or not they're compatible with 5 and 6 speed freewheels. The freewheels I have are both splined and threaded. So the freewheel body is splined and the cogs have notches to stack them onto the spline, however some of the cogs thread on. A typical setup goes something like this...

Let's call Position 1 the largest cog and Position 7 the smallest. The spacers mentioned are around 2.5mm in thickness.

Position 1 - Cog fits onto a spline of diameter A
Insert a spacer
Position 2 - Cog fits onto the spline of diameter A
Position 3 - Cog threads onto the end of the spline of diameter A. Note the absence of a spacer. The threaded body of the cog automatically spaces it.
Position 4 - Cog fits onto another spline of diameter B. There is enough of the diameter A spline sticking out to space this cog away from the cog in Position 3, so no spacer is necessary.
Insert another spacer
Position 5 - Cog fits onto the spline with diameter B
Position 6 - Cog threads onto the end of the spline with diameter B. No spacer necessary.
Position 7 - Cog threads on inside the cog in Position 6.

You have one of the later designs, if some of the cogs fit it is just a tooling reuse, but the cog spacing will be off. Yours probably dates from the 80's. There was a Regina freewheel that had a version that came in a kit to allow reasonably easy reworing of the ratios, possibly based on the America design, other than that, not alot of good probability that you will locate replacement cogs and or different cogs to rework a ratio series.

Thank you for the help. I actually have about 60 old cogs from this era with just about any tooth count you can imagine. I wonder what some popular cog ranges are.

Depends on your legs and what rings are being used up front, 53/42 was Campagnolo, later they adopted 53/39 that was being pushed by Shimano.

13-14-15-17-19-21-23 would be a stock assemblage for roadracing. Some guys would start with a 12 and have a downhill gear.