I need a small 28 tooth c
09-06-20, 06:42 PM
#1
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I need a small 28 tooth c
chain ring for sg 200 crank.
This is an old biopace crank. Can I use a round ring? Will a shimano 105 5703-l work? The bcd is 74mm.
This is an old biopace crank. Can I use a round ring? Will a shimano 105 5703-l work? The bcd is 74mm.
09-06-20, 06:47 PM
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There should be 28T rings in 74mm but be certain the old ones bolt on and are not riveted in place. 28T round will probably be more plentiful than Biopace by now.
09-06-20, 06:59 PM
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I forgot to mention that it is a 8 speed. The existing chain ring is bolted to the crank and the chain ring is flat with no offsets.
09-06-20, 08:15 PM
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That was the common design a few years ago with the granny chainring having its own bolt circle on the crank spider. Also, granny rings just about never have any shifting enhancements or shaped teeth.
09-06-20, 09:05 PM
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Look for a Sugino or Salsa 75 BCD for 5,6-speed, 7,8-speed. I'm pretty sure a 9-speed would also work. There are a lot of them out there. Probably a few no-name ones too. I'm using a no-name 24 on a 9-speed and it does the job just fine. (It did much better than its rider today on a 3000' 60 miler today.) If you find a steel one it will last near forever.
Ben
Ben
09-07-20, 10:38 AM
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*5,6,7,8 speed chains are for up to 3/32" wide cogs.. 9+ speeds the chains have to be thinner..
..
09-07-20, 12:57 PM
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I ordered a 30 tooth chainring. I think this will be the ideal size for my current fitness level and the places where I ride.
