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Replacing chainrings widths & ratios

  • 03-03-2011 12:06am
    #1
    Fiachra cork
    Closed Accounts Posts: 76 ✭✭


    Hi all - Im using an old suntour superb pro chainset and need to replace the big ring. I don't have a load of dosh and was looking at the Shimano sora (fc3300) on chain reactions but it says that its for 7/8 speed. Im running a 9 speed. Does anyone know if they're really specific to 7/8 speed and are totally incompatable? The other option is a specialites zephyr (110mm). This one doesn't say, but can anyone shed some light on the 110mm bit? Finally - any opinions on the compact set up - Im a born again so the original set up was a 42/52 - I have a 38 as a small ring (which I find great) and it has been suggested to me to use a 50 on the big ring. I don't really see any advantage but opinions would be good. Im planning on doing some A4 racing this year if that makes any difference!


Comments

  • #2
    kumate_champ07
    Closed Accounts Posts: 7,150 ✭✭✭kumate_champ07


    Is it 1980s or 1990s? Its either 144bcd (which is now just used for track chainrings) or 130mm bcd is Shimano standard,
    110mm is for compact cranks and defintely wont fit

    if you have a 38T on the inside its probably 130mm bcd crankset, if you have a pic I could probably identify the model, suntour superbe pro was as good as dura ace, some say better


  • #3
    kumate_champ07
    Closed Accounts Posts: 7,150 ✭✭✭kumate_champ07


    this explains the BCD measurements

    http://sheldonbrown.com/gloss_bo-z.html#bcd


  • #4
    blorg
    Registered Users, Registered Users 2 Posts: 15,995 ✭✭✭✭blorg


    AFAIK speeds doesnt matter for the front chainrings; the inside pitch of all derailleur chains is the same (3/32")


  • #5
    Fiachra cork
    Closed Accounts Posts: 76 ✭✭Fiachra cork


    Hi Kumat - I could and will google it but what does bcd stand for. It was originaly a 42/52 set up but I changed the small ring to a 38 a few years ago without any bother. Yep - the chainset was close to top of the range at the time and was really a matter of taste in for riders to pick this over the dura ace - knowing me though they were probably slightly cheaper. Its a 1980's model. around 87 - the bikes a rapparee.


  • #6
    kumate_champ07
    Closed Accounts Posts: 7,150 ✭✭✭kumate_champ07


    Fiachra cork wrote: »
    Hi Kumat - I could and will google it but what does bcd stand for. It was originaly a 42/52 set up but I changed the small ring to a 38 a few years ago without any bother. Yep - the chainset was close to top of the range at the time and was really a matter of taste in for riders to pick this over the dura ace - knowing me though they were probably slightly cheaper. Its a 1980's model. around 87 - the bikes a rapparee.
    it's 130mm bcd so

    the Suntour Superbe group was actually a mixture of manufacturers, Dia Compe made the brake calipers, and I could be mistake but I think Sugino made the cranks. Suntour failed when they were too slow to come up with their own version of integrated gear/brake levers like Shimano STI


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  • #7
    Fiachra cork
    Closed Accounts Posts: 76 ✭✭Fiachra cork


    Interesting - in the meanwhile ive done my homeword on BCD and yes - it is a 130mm. Ordered a new one through chain reactions - should work ok but won't make me faster!!:rolleyes:


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