I have a Super Maxy triple off of a Miyata 1000 I want to use for my "daily driver" steel road bike. It is a 52-47-34. The 47 tooth is badly worn and I would like to replace it if possible. The BCD seem to be all over the map for SR cranks. The distance center-to-center between adjacent bolt holes is 50.7 mm. I have not been able to find a chart that works for that, or any luck finding new chain rings that would have a BCD corresponding to that center-to-center dimension. Chainrings is something I am reluctant to buy on Ebay. Any sources on those old SR rings would be much appreciated.
Thanks,
Gyro Gearloose

Super Maxy was Sugino, not SR, right? Got any pictures of the crankset?

I assume it's a five-arm crank. If so, Sir Sheldon says it's 86BCD, based on your measurement.

https://www.sheldonbrown.com/cribsheet-bcd.html

Sheldon shows 50.5 for 86 bcd rings. Pretty close.

I am sorry I was confused looking at the various cranks around here. The Super Maxy was on a Super Le Tour. The crank from the Miyata is a SR Apex which is pictured. So I guess I am looking for an 86 BCD ring. Thanks also to smontanaro and due ruote for finding that for me.

So any ideas where I could get a new ring or two?

86BCD is/was a Stronglight size. SR produced the Apex crank in various BCDs, so you have to be careful if you find something online, but there's always eBay:

47T 86BCD | eBay

No worries, I often ask for pictures even if I'm not sure they'll help.

Hilary Stone has some 86 BCD rings, and Stronglight apparently still makes them:
https://www.hilarystone.com/chainrings86BCD.html
STRONGLIGHT :: Spa Cycles, Harrogate - The touring cyclists specialist.

Thanks for the help. I think you have solved it for me...again!!

St. John St. Cycles in the UK seem to stock a modest selection of new 86 BCD rings:


https://www.sjscycles.co.uk/86-bcd-5-arm/?geoc=US


I bought a few from them years ago. They don't seem to be specifically set up to sell to customers in the US, but we figured it our via email. Shipping was not too costly. Pleasant folks to deal with, as I recall.


I also have a few used 86 rings in a box somewhere, but not sure I have the size you're looking for. PM me if you get stuck. I'm going to be out of email range for the next week or so, though, so you if you're in a big rush that might not work for you.

After learning a bit more about finding older style chain rings, I hope to stay with the old Zeus crankset and just try to find a ring smaller than 44t for the small ring. The Zeus is kind of an odd size, and the adjacent bolt holes are 69.7 mm as close as I can come with my Harbor Freight digital caliper. According to Sheldon's chart the closest is 69.4mm, that corresponds to a 118 BCD ring. His chart does not mention Zeus, but only SR and Ofmega. I was wondering if anyone has an idea if Zeus in fact did use a 118mm BCD. I was surprised to find a 39 tooth SR on Ebay which looks very good. I'm just a little leery about buying it, if it does not fit I'm stuck.

^ Now that is an odd sized BCD. Us guys with 86's should feel lucky. (I've got the same Apex as the OP, and Stronglight, too.)

ISTR that Zeus is actually 119BCD. Google for "Zeus crank bcd." I'm sure there are people on the Classic Rendezvous list with some Zeus chainrings. You might also set up an eBay search for them.

If your crank still has the original 16mm bold, I think you might find that to be more of an issue. You'll need a thin wall socket to remove them. Probably a good idea to pull them (and stash them in your parts bin), then replace them with 15mm bolts.

The Zeus cranksets and chainrings are often listed as 120 mm BCD, so the OP may want to search using that sizing too.

Zeus used a unique 120mm BCD (apparently, there was also a 120mm BCD Takagi BMX crank, but I've never seen one). People have reported that a 118mm BCD ring can be modified to fit on a Zeus crank, but I've not tried it myself.

For the Original Question . There was also 110 Bolt circle cranks made by the same company

You can build up a 52-47-34, using Most any 110 pcd crankset with 5_ 3 chainring long Bolts..

Sounds like I would be better off keeping my 44 tooth and getting a larger cog in the rear. That would mean taking off the old Zeus Criterium derailleur, which is badly worn anyway and depends on a brass bushing I made out of a .38 caliber casing. I hate to do that but I need to ride this bike and not let it hang in the garage. I am giving my daily rider Motobecane to my son for his birthday. I just needed a little lower gearing for the old joints I am stuck with! Where I ride, most will not denounce me if I put an SLX derailleur on to get me the gearing I need. Thanks to you all.