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  1. #1
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    20 T Granny Gear

    Need some help. I want to replace the 22 T granny gear on my Shimano SLX cranks with a 20 T. I can get a 20 T titanium ring but I was looking for one that is stainless steel. Does anyone know where I can get one?

    Thanks

  2. #2
    pedal pusher
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    Edit: nevermind

    Yeah, those are pretty hard to find.

  3. #3
    29 some of the time...
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    The Actiontec Ti is about the easiest 20t to come by. I had no problem with mine. I rode it all last year and am heavily into clydesdale territory
    Quote Originally Posted by saturnine
    that's the stupidest idea this side of pinkbike.

  4. #4
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    Middleburn offers a 20t granny, although I'm not sure if it would be compatable with your current setup.

  5. #5
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    I'm guessing you want something like this-


    You can find that one at http://www.universalcycles.com/shopp...s.php?id=16024

    Whats so hard to find about these? QPB carries them, so any shop in the USA can get one, most likely. Google turns up PLENTY of them. http://www.google.com/search?q=20t+chainring

    For a Shimano SLX crank, any of the ones with 4 bolt holes should do the trick, unless it is a VERY old crank. Kinda obvious; if your crank has 4 bolts, get the one with 4 holes. If it's an older version that has 5, get the one with 5, although you probably should check with a shop first; they will be happy to confirm it will work and order one from QPB.

  6. #6
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    Fungazi, while it kinda surprised me to see the number of 4 bolt 58bcd 20t steel rings out there, on an SLX you need a 64bcd...that's why it's harder to find...
    "...the people get the government they deserve..."
    suum quique

  7. #7
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    Thanks for everyone input. I can get a Ti 20T, but want to use stainless steel for reasons of price and my fear (maybe unjustified) of the durability of Ti.

  8. #8
    ballbuster
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    All 4 bolt cranks are 64mm bcd...

    Quote Originally Posted by Bikinfoolferlife
    Fungazi, while it kinda surprised me to see the number of 4 bolt 58bcd 20t steel rings out there, on an SLX you need a 64bcd...that's why it's harder to find...
    ... with the possible exception of last generation XTR, which is prolly some other wonky XTR only size. If there is a 4 arm 58mm bcd, I have never seen it... and I am a pretty s1utty gear s1ut.

    I have an ActionTec 4 bolt 20t on my XT cranks on my 29er. Honestly, I don't know it its stainless steel or ti. I got it in trade from a bud, and he told me it was steel, but he might be wrong. I had to take a hacksaw to the crank arm and file to make tiny notches around the bolt mounts to let the chain plates drop down all the way, or the chain will ride on the plates, not the rollers... which is not good. It's easy to do yourself, but you are getting into warranty voiding territory. I shoulda taken pictures. Maybe I will next time I have it apart for whatever reason.

    THe next setup is to get an older 5 arm crank with 58mm bcd. There are 20t rings for those that are pretty common.

  9. #9
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    Quote Originally Posted by pimpbot
    ... with the possible exception of last generation XTR, which is prolly some other wonky XTR only size. If there is a 4 arm 58mm bcd, I have never seen it... and I am a pretty s1utty gear s1ut.

    I have an ActionTec 4 bolt 20t on my XT cranks on my 29er. Honestly, I don't know it its stainless steel or ti. I got it in trade from a bud, and he told me it was steel, but he might be wrong. I had to take a hacksaw to the crank arm and file to make tiny notches around the bolt mounts to let the chain plates drop down all the way, or the chain will ride on the plates, not the rollers... which is not good. It's easy to do yourself, but you are getting into warranty voiding territory. I shoulda taken pictures. Maybe I will next time I have it apart for whatever reason.

    THe next setup is to get an older 5 arm crank with 58mm bcd. There are 20t rings for those that are pretty common.
    I was thinking there were just a few obscure cranks that came out in 4 bolt 58/94 but I don't know what they are nor can I find one now....but take a look at both the Universal and google links from Fungazi...
    "...the people get the government they deserve..."
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  10. #10
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    Huh, I thought there was only 2 common 4 bolt "standards" for MTB - the one you see on LX and XT every year for the past decade, and then the wierdo ones they use for XTR. Gotta admit, I don't replace a lot of chainrings (or cranks), but its worth knowing I can't assume all 4 bolt grannies (and larger rings) are the same.

    Here's some 64 bcd's - those titanium action tec's AL29er mentioned. Kinda spendy...
    http://www.comcycle-usa.com/ProductInfo.aspx?id=1157698

  11. #11
    NMBP
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    Quote Originally Posted by sxmatt
    Thanks for everyone input. I can get a Ti 20T, but want to use stainless steel for reasons of price and my fear (maybe unjustified) of the durability of Ti.
    I have been using an ActionTec ti 20 tooth for 3 years and it has held up just fine. I probably don't have many miles on it because I'm not using all that often. It sure is nice when you need it though.
    Riding Fat and still just as fast as I never was.

  12. #12
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    Just out of curiosity is this 20T being combined with a 32 or 34T cassette? In either case can you really use such a low gear without looping out? My lowest gear is a 22-28 and I can't imagine being able to go much lower, maybe 22-30.
    Keep the Country country.

  13. #13
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    Quote Originally Posted by Lelandjt
    Just out of curiosity is this 20T being combined with a 32 or 34T cassette? In either case can you really use such a low gear without looping out? My lowest gear is a 22-28 and I can't imagine being able to go much lower, maybe 22-30.
    My lowest gear is 18t front and 34t rear. My bike also has fairly short chainstays for a 29er: 17.7". Looping out? As in flipping over backward? No, not a problem for a skilled rider. But really low gears do take getting used to. When climbing very steep stuff I get low over the bars and push down on the bars with a force vector that is aimed at the front of the contact patch of the rear tire. Works for me.
    Abandoned the 26" wheel in May '03

  14. #14
    pedal pusher
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    When I have all my gears on--which I don't at the moment--I have an 11-34 cassette and a (94/58mm 5-arm) 46/32/20 chainring combo. I've been running it like this for a decade with an XTR derailleur, and I've never had an issue.

    I'd really like to find an affordable 64mm BCD 20T for my wife's bike. I'm about to upgrade her to an 11-34 cassette (up from 11-32), and a 20T, instead of 22T, would help out even more. I feel bad easily climbing a hill with gearing to spare, while she's stuck at 22-32 and powering through it.

  15. #15
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    Ah, 29ers, that's why. On a 26" wheel bike an 18-34 combo would be insanely low. Before you ran out of torque you'd run out of traction. Just out of curiosity, how much does the larger wheel affect gearing? Is a 29er with 22-34 equal to a 26er with 22-28? Someone care to do the math so we can talk apples to apples?
    Keep the Country country.

  16. #16
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    A 29er wheel is about 11.5% bigger than a 26er wheel.

    Here is a handy gear inch calculator: http://www.hostelshoppe.com/tech_gearcalc.php
    Abandoned the 26" wheel in May '03

  17. #17
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    Quote Originally Posted by Lelandjt
    Just out of curiosity is this 20T being combined with a 32 or 34T cassette? In either case can you really use such a low gear without looping out? My lowest gear is a 22-28 and I can't imagine being able to go much lower, maybe 22-30.
    Depends where you ride. 22-34 is often usable for me with no problems. On a 26er or 650B, no experience with 29ers there.
    "...the people get the government they deserve..."
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  18. #18
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    That gearing calculator requires that I know the outside diameter of a 29er tire. Can someone who owns one please post this measurement along with the width of your tire for some reference.
    Keep the Country country.

  19. #19
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    29 x 3.14. Not 100% accurate, but it'll get you in the ball park.

  20. #20
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    Quote Originally Posted by Lelandjt
    That gearing calculator requires that I know the outside diameter of a 29er tire. Can someone who owns one please post this measurement along with the width of your tire for some reference.

    The outside diameter of a 29er tire is 29 inches.
    Abandoned the 26" wheel in May '03

  21. #21
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    Quote Originally Posted by f3rg
    29 x 3.14. Not 100% accurate, but it'll get you in the ball park.
    That would give you the circumference.
    Abandoned the 26" wheel in May '03

  22. #22
    pedal pusher
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    Der, misread his post.

  23. #23
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    Quote Originally Posted by 29erchico
    The outside diameter of a 29er tire is 29 inches.
    That doesn't sound right. Isn't the bead diameter about 29"? Can someone who owns a 29er just measure how tall their tire is from the ground to the top of the tire? If you then include the width of your tire it will give some idea of whether your's is on the large or small side since tires run from 2"-2.35".
    Keep the Country country.

  24. #24
    pedal pusher
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    A typical 2.3(ish)" 29er tire will be right about 29" tall. The wheel's rim is not what the 29 inches is a reference to.

  25. #25
    rider
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    Quote Originally Posted by Lelandjt
    That doesn't sound right. Isn't the bead diameter about 29"? Can someone who owns a 29er just measure how tall their tire is from the ground to the top of the tire? If you then include the width of your tire it will give some idea of whether your's is on the large or small side since tires run from 2"-2.35".
    The bead seat diameter of a 700c rim, that is what 29er's run, is 622mm. 622mm is about 24.5 inches. I don't need to measure my 29er tires again to tell you that they are 29 inches in diameter.
    Abandoned the 26" wheel in May '03

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