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  1. #1
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    Shimano 730 cranks w/SG rings question

    I just recently picked-up a set of shimano 730 cranks in pretty decent shape. The cranks have SG rings mounted on them and based on what I can determine from doing some homework the early SG rings came out in late 89-90 time frame. These cranks/rings came off of a 1990 Serotta built Off-Road Pro-flex frame which confirms this timeframe assumption I think. The rings don't have any ramps or such, but do say they are for a narrow chain. I have them mounted on my 89 Ritchey Timber Comp w/XT 7spd, and the current Shimano chain I am using (which is supposed to be for 7/8 speeds iirc) works/shifts fine but is a bit short and I am getting ready to replace it.Any thoughts on the proper chain for those SG rings?

    Alternatively perhaps I should just swap-off my non-SG chain-rings from my other 730 crankset. The newer nicer 730 cranks are the right vintage, but I doubt the SG rings ever made it onto an 89 Ritchey so maybe that would make the most sense. I have been slowly trying to procure the right vintage parts and pieces for the bike and was just interested in others thoughts on this.

  2. #2
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    You just need a 7/8 speed chain, nothing fancy. Any decent bike shop will have one. Something like a Shimano HG91 will work, or you could get a chain from SRAM or even KMC. Good luck.

  3. #3
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    What little shifting on the front rings I have done with the "too-short" 7/8 spd chain, seemed to be fine, so I was hoping that was the simple answer. Thanks for confirming!!

  4. #4
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    I just use a cheaper Sram chain on all my 7 and 8spd drive trains, including M730 cranks with period correct rings. Works fine.



    -eric-

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  5. #5
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    Thanks for the visuals and confirmation Eric, my crankset/rings look exactly like that.

  6. #6
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    Yup...Sram PC-58 chains. Cheap, work. Or...are they PC-830's now? Something like that.
    -eric-

    http://www.rumpfy.com

    Wanted: Syncros 27.2 x 425 seatpost, 26.8 x 400 IRD seatpost

  7. #7
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    What? no vintage correct chain?

    That from you Eric??? Not possible...from the one that usually points out everything that's not correct?

    N10S...you need an old chain with some life left thats period correct (before SRAM was ever though of) send me a PM and let me know how long.
    Needed: 26.8mm XTR seatpost, blue GT/Grundig Jersey.

  8. #8
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    Quote Originally Posted by gm1230126
    What? no vintage correct chain?

    That from you Eric??? Not possible...from the one that usually points out everything that's not correct?

    N10S...you need an old chain with some life left thats period correct (before SRAM was ever though of) send me a PM and let me know how long.

    I know. Pretty shameful.

    But keeping a fleet of rider vintage MTB's running gets expensive. Cables/housing, tubes, chains...had to cut some corners. I've personally never been the best at the intricate details for my own bikes.
    -eric-

    http://www.rumpfy.com

    Wanted: Syncros 27.2 x 425 seatpost, 26.8 x 400 IRD seatpost

  9. #9
    PCC
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    Wouldn't an '89 have those Bio-Pace rings? I can take a picture of the cranks on my son's bike. 730s in 170mm, 46, 36, 26T Bio-Pace chainrings. When he outgrows them I'll probably put these cranks onto my old '89 Stumpie, though they're 5mm shorter than the cranks that bike originally came with.

  10. #10
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    cough... suginos look much better...cough.. cough.
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  11. #11
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    Looks like 1990 might have been the first SG year?
    http://mombat.org/Shimano.htm#1990

  12. #12
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    Quote Originally Posted by PCC
    Wouldn't an '89 have those Bio-Pace rings? I can take a picture of the cranks on my son's bike. 730s in 170mm, 46, 36, 26T Bio-Pace chainrings. When he outgrows them I'll probably put these cranks onto my old '89 Stumpie, though they're 5mm shorter than the cranks that bike originally came with.

    Yeah, I'm not going to run Bio-Pace anywhere.
    -eric-

    http://www.rumpfy.com

    Wanted: Syncros 27.2 x 425 seatpost, 26.8 x 400 IRD seatpost

  13. #13
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    Jeff, thanks for confirming on the rings. Since the crankset came off of a 1990 Pro-flex that makes sense. At this point I have tried to build my Timber Comp up with the right vintage parts, but since it is never going to be a cream puff restoration, the SG rings being within a year of correct works for me. More than anything I just wanted to make sure the rings would work ok with a normal 7/8 speed chain, and I appreciate the confirmation to that question.

    Thanks again!

    Jeff

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