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  1. #1
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    my diy 30 tooth 104bdc chainring

    Made mine own 30 tooth steel chainring for my XXIX dingle.

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    kind of steam punk looking but works great.

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    30t #40 ansi blank

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  2. #2
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    Run it on my dingle setup 26/22 low 30/18 high,same chain length. when I get to the top of a climb flip the bike over, open the quick release, raise up the wheel (vertical dropouts) and drop the chain to the 30-18 rings and ride on.

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  3. #3
    The need for singlespeed
    Reputation: zaskaranddriver's Avatar
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    Holymoly those are low gears. Sounds like some serious climbing. Nice work there!

  4. #4
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    sweet, nice work!

    where did you source the blank?

  5. #5
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    Quote Originally Posted by cdn-dave View Post
    sweet, nice work!

    where did you source the blank?
    McMaster Carr, $26

    Its over 1/4" thick, after i found the center I bored a .750" hole in it and mounted it in the lathe on a 3/4" bolt with a center drilled in the end for support.
    (note the live center in one of the pics).
    I then shaved it down on both sides.
    The holes are threaded 5/16 fine thread.
    The bolts have a little .388"x.05" shoulder cut on them with a part-off tool
    You have to file a bevel on the crank spider for chain side-plate roller clearance.

    let me know if you need some dimensions because it not cut from the center line of the sprocket.

  6. #6
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    Quote Originally Posted by zaskaranddriver View Post
    Holymoly those are low gears. Sounds like some serious climbing. Nice work there!
    Yes there are some grinder climbs around the San Fernando Valley.
    Some are 14-26 percenters. You have to learn to say "shut up legs".

  7. #7
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    Sorry for offtopic but I've been looking for something like this but why don't any companies make 30t x 104mm chainrings readily available?

  8. #8
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    Quote Originally Posted by AnonymouseTech View Post
    Sorry for offtopic but I've been looking for something like this but why don't any companies make 30t x 104mm chainrings readily available?
    In general, i think its a clearance issue. The spider for 104bcd is usually wide enough to interfere with the chain on the smaller chainrings. I think the groove/low point of teeth on my e.13 32t ring is right where my spider mounts on my Sram AKA. This is why spiderless rings will allow a smaller ring.

    Moving the chainring away from the spider will adjust the chainline. Generally this is fine on a SS setup, but, geared may mess up the ring spacing. There are possibly too many factors to get the spider clearance on all cranks/spiders to make it worth the supply for the minimal demand.

  9. #9
    meatier showers
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    Quote Originally Posted by jetboy23 View Post
    In general, i think its a clearance issue. The spider for 104bcd is usually wide enough to interfere with the chain on the smaller chainrings. I think the groove/low point of teeth on my e.13 32t ring is right where my spider mounts on my Sram AKA. This is why spiderless rings will allow a smaller ring.

    Moving the chainring away from the spider will adjust the chainline. Generally this is fine on a SS setup, but, geared may mess up the ring spacing. There are possibly too many factors to get the spider clearance on all cranks/spiders to make it worth the supply for the minimal demand.
    This is spot on. Good explanation.

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  10. #10
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    it moved the chanline over about 1mm, granny gear is still in the same place and i dont have any problems running 8 speed chain. there is a guy here on mtbr that makes a geared verison 30t with ramps out of aluminum google anderson 30t chainring.

  11. #11
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    Quote Originally Posted by AnonymouseTech View Post
    Sorry for offtopic but I've been looking for something like this but why don't any companies make 30t x 104mm chainrings readily available?
    here a link to the tread

    30 tooth 104 bcd

  12. #12
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    Quote Originally Posted by ovwok View Post
    McMaster Carr, $26
    Thanks for the info! I think the last time I looked at McMaster Carr, was for an M10x1.0 bolt to mount my DIY chain tensioner onto the derailleur hanger

  13. #13
    Bicycle Addict
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    Really nice! But don't try and go all homebrewed on us
    The unexamined life is not worth living - Socrates
    Bearded Women Racing

  14. #14
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    Tension?

    How do you keep chain tension? I dont see a movable dropout or chain tensioner

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