Difference in Dia between 32T, 34T and 36T chainrings ?

Home Forum Bike Forum Difference in Dia between 32T, 34T and 36T chainrings ?

Viewing 9 posts - 1 through 9 (of 9 total)
  • Difference in Dia between 32T, 34T and 36T chainrings ?
  • thomthumb
    Member

    chain is 1/2″ pitch.

    so 2t will add 1″ (25.4 mm) circumference

    diameter of 32t = 128 mm
    diameter of 34t = 137 mm
    diameter of 36t = 144 mm

    * guessing

    allthegear
    Member

    The number of teeth defines the circumference of the chainring so the difference in diameter will be the difference in circumference measured in teeth divided by ?

    So, ((32/36)/?)*100 for percentage difference = about 28%

    Wow – more than I thought!!

    Rachel

    Premier Icon gofasterstripes
    Subscriber

    My 40t Surly measures approx. 175mm Dia.

    If we allow 10mm for the height of the teeth, we get: 165

    165*Pi = 518

    518/(25.4/2) = 40ish [it has 40T]
    So (518-25.4)/Pi = 38T = 157mm ish
    and (518-50.8)/Pi = 148mm….ish

    ie for each 2T less than 40, you remove 25.4mm from the Circumference and then divide by Pi

    I think

    clubber
    Member

    No need for pi in the calc rachel – it cancels out for both sizes. It’s a straight percentage difference.

    (32/36) x 100 = 89%

    chillidave
    Member

    Think that may be a little off, I believe the diameter is directly proportional to the circumference. So a 36t would have 12.5% larger diameter than a 32 which I think is what Thom said up there.

    And that’s the most I can remember from my degree. 🙂

    Premier Icon cr500dom
    Subscriber

    Cheers everyone,
    I shall have a measure up tonight but I suspect if I want to maintain a decent chainline then I shall have to go down on the rear sprocket instead

    Premier Icon woody2000
    Subscriber
    Premier Icon jameso
    Subscriber

    Easy.

    32-34-36 are ~134mm, 142mm and 150mm

    (I’m not great at maths but I do have the shimano tech book..)

    Premier Icon cr500dom
    Subscriber

    Nearly finished the commuter build and rode it in for the first time today (Rides nicely on 2.3 Supermotos)
    It has an Alfine 8speed hub with an 18t sprocket fitted

    I have just put a new 32T stainless front chain ring on and I could do with it being a bit taller geared.
    I am limited for chainring clearance so was wondering if anyone knew the difference in Diameters of a 32T 34T 36t chain ring ?

    Cheers
    Dom

Viewing 9 posts - 1 through 9 (of 9 total)

The topic ‘Difference in Dia between 32T, 34T and 36T chainrings ?’ is closed to new replies.