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  1. #1
    The bike plague MightyLegnano's Avatar
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    Replacing ofmega 70 x 118.5 Bottome Bracket

    Hello!

    I have been dealing with issue some time now and although I have a look though the forum I didn't get any answers. Is there anybody who had Ofmega Competizione BB and had to replace it? Mine works fine but I hate this Italian threading that gets unscrewed (I don't have the proper tools) all the time, so I'm looking for a Sealed Cartridge Bottom Bracket. Is there a not expensive alternative? Like shimano's squared taper 70x115 maybe? Is there anyone who had success replacing it with a shorter JIS?

    By the way the cranks are the Ofmega 'Legnano' 42/52 .

    Thanks a lot!
    Last edited by MightyLegnano; 07-11-14 at 11:47 AM.
    Nature is my mentor

  2. #2
    Senior Member squirtdad's Avatar
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    Replacing the bottom bracket will not change the italian threading. the unthreading may be less of an issue with a cartridge..but you will need the right tools to install the cartridge

    Lot's of people (me included) have italian bb and don't have a problem with unthreading

    The simplest option might be finding some one or a shop with the right tool or buying one....they are like $18 to $20 https://www.benscycle.com/p-3064-par...Fabm7Aod-z4AWA

    the ofmega bottom bracket for a cometizione is asymmetrical with iso taper.

    my previous research is that the only option for an exact fitment replacement cartridge is going to be a Phil Wood which is expensive

    any option i found with a iso taper (like the miche for used for track and fixie bikes) did not have the length on the right to provide proper clearance and chainline.

    I chose not to deal with the Iso crank on a JIS taper as I am a big guy and put some a fair amount of pressure on the crank.

    If I recall right using an iso on a jis move the crank out 4mm (check sheldon brown) so if you are ok with the not fully seated crank then a 70/115 with jis taper would be about right.

    have fun
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  3. #3
    Bianchi Goddess Bianchigirll's Avatar
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    A lot of these Ofmega BB/cranks had a unique taper. Again check Sheldons website.

    Some one makes adaptor rings for changing a Italian thread BB shell to English but without the correct tools and locktite I wouldn't try it.
    Bianchis '87 Sport SX, '90 Proto, '90 Campione del Fausto Giamondi Specialisma Italiano Mundo, '91 Boarala 'cross, '93 Project 3, '86 Volpe, '97 Ti Megatube, , '90 something Vento 603,

    Others but still loved,; '80 RIGI, '80 Batavus Professional, '87 Cornelo, '09 Motobecane SS, '?? Jane Doe (still on the drawing board), '90ish Haro Escape

  4. #4
    Retro Grouch onespeedbiker's Avatar
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    Quote Originally Posted by Bianchigirll View Post
    A lot of these Ofmega BB/cranks had a unique taper. Again check Sheldons website.
    "Ofmega cranks, including those branded "Avocet" use a non-standard spindle, thinner than either J.I.S. or ISO spindles. As far as I know, nothing else works". Sheldon Brown's Bottom Bracket Size Database

    I believe all the Ofmega cranks/BB have the Ofmega propitiatory square taper, (I will update velobase). As mentioned earlier there is no point switching to a different BB as it will still need to be Italian. As mentioned the only way to properly tighten the fixed cup of an Italian BB is with a BB tool bb.jpg Amazon.com : Park Tool HCW-4 Box End and Pin Spanner Crank Wrench (36mm) : Bike Cranksets And Accessories : Sports & Outdoors and $17.40 would certainly be a good investment.

    If you must get a cartridge style BB you will need to switch the crankset also..
    Last edited by onespeedbiker; 07-11-14 at 02:22 PM.
    Chiunque tenti di scappare a queste regole dovrÓ mangiare un piatto largo di polenta vecchia di tre settimane e sarÓ schernito per questo, soprattutto se Ŕ straniero

  5. #5
    Senior Member squirtdad's Avatar
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    Quote Originally Posted by Bianchigirll View Post
    A lot of these Ofmega BB/cranks had a unique taper. Again check Sheldons website.

    Some one makes adaptor rings for changing a Italian thread BB shell to English but without the correct tools and locktite I wouldn't try it.
    Quote Originally Posted by onespeedbiker View Post
    "Ofmega cranks, including those branded "Avocet" use a non-standard spindle, thinner than either J.I.S. or ISO spindles. As far as I know, nothing else works". Sheldon Brown's Bottom Bracket Size Database

    I believe all the Ofmega cranks/BB have the Ofmega propitiatory square taper, (I will update velobase). As mentioned earlier there is no point switching to a different BB as it will still need to be Italian. As mentioned the only way to properly tighten the fixed cup of an Italian BB is with a BB tool bb.jpg Amazon.com : Park Tool HCW-4 Box End and Pin Spanner Crank Wrench (36mm) : Bike Cranksets And Accessories : Sports & Outdoors and $17.40 would certainly be a good investment.

    If you must get a cartridge style BB you will need to switch the crankset also..
    fwiw

    I spent a lot of time on Ofmega crankset and bottom bracket research and experimentation when I was given a 'free" torpado super stradaa couple of years ago.

    At best there is a lot of mystery and uncertainty including on velobase.

    this is my understanding (which again is based on research of a voodoo subject and some personal experience)

    Early Ofmega cranksets used a proprietary taper. The problem is no one can define exactly what early/old means. to quote sheldon "(Note: Old Ofmega/Avocet spindles were quite a bit skinnier/longer even than ISO. There are no modern bottom brackets that work with old Ofmega/Avocet cranks.)"

    The ofmega cranksets from the 80's (again not precise) think competizone and CX (at least I hope CX as I just ordered a set on ebay) were essentially campy clones with ISO taper and they used the asymmetrical bottom bracket (118.5 mm spindle) like campy records did. The Mistral may be different
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  6. #6
    Retro Grouch onespeedbiker's Avatar
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    Quote Originally Posted by squirtdad View Post
    fwiw

    I spent a lot of time on Ofmega crankset and bottom bracket research and experimentation when I was given a 'free" torpado super stradaa couple of years ago.

    At best there is a lot of mystery and uncertainty including on velobase.

    this is my understanding (which again is based on research of a voodoo subject and some personal experience)

    Early Ofmega cranksets used a proprietary taper. The problem is no one can define exactly what early/old means. to quote sheldon "(Note: Old Ofmega/Avocet spindles were quite a bit skinnier/longer even than ISO. There are no modern bottom brackets that work with old Ofmega/Avocet cranks.)"

    The ofmega cranksets from the 80's (again not precise) think competizone and CX (at least I hope CX as I just ordered a set on ebay) were essentially campy clones with ISO taper and they used the asymmetrical bottom bracket (118.5 mm spindle) like campy records did. The Mistral may be different
    Let me throw another monkey wrench into the machinery, and that is Campy did not officially use ISO until 1994, prior to that you will see Campagnolo taper (described as being between ISO and JIS; closer to JIS).
    Last edited by onespeedbiker; 07-11-14 at 10:06 PM.
    Chiunque tenti di scappare a queste regole dovrÓ mangiare un piatto largo di polenta vecchia di tre settimane e sarÓ schernito per questo, soprattutto se Ŕ straniero

  7. #7
    feros ferio John E's Avatar
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    Have you tried Loctite blue on the fixed cup? I used to have problems with French and Italian bikes, but this cured it for me.
    "Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
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  8. #8
    The bike plague MightyLegnano's Avatar
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    Quote Originally Posted by John E View Post
    Have you tried Loctite blue on the fixed cup? I used to have problems with French and Italian bikes, but this cured it for me.
    Hmm, I haven't thought about that. But, doesn't it make the cup stuck forever there?
    Nature is my mentor

  9. #9
    Senior Member squirtdad's Avatar
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    Quote Originally Posted by onespeedbiker View Post
    Let me throw another monkey wrench into the machinery, and that is Campy did not officially use ISO until 1996, prior to that you will see Campagnolo taper (described as being between ISO and JIS; closer to JIS.
    Just when I was thinking i sort of had it figured out..... typically italian machinery: beauty, history, intrigue, vagueness and magic
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  10. #10
    The bike plague MightyLegnano's Avatar
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    Yes, Sheldon says that Ofmega need unique spindle width, but I have read about experiences from people who had success using standard spindles. Maybe this issue is about old Ofmegas? Mine is very different from what Velobase has. Only the spindle has some markings (ofmega text along with a bird logo). I couldn't match it online.
    Nature is my mentor

  11. #11
    The bike plague MightyLegnano's Avatar
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    Quote Originally Posted by squirtdad View Post
    Replacing the bottom bracket will not change the italian threading. the unthreading may be less of an issue with a cartridge..but you will need the right tools to install the cartridge

    Lot's of people (me included) have italian bb and don't have a problem with unthreading

    The simplest option might be finding some one or a shop with the right tool or buying one....they are like $18 to $20 https://www.benscycle.com/p-3064-par...Fabm7Aod-z4AWA

    the ofmega bottom bracket for a cometizione is asymmetrical with iso taper.

    my previous research is that the only option for an exact fitment replacement cartridge is going to be a Phil Wood which is expensive

    any option i found with a iso taper (like the miche for used for track and fixie bikes) did not have the length on the right to provide proper clearance and chainline.

    I chose not to deal with the Iso crank on a JIS taper as I am a big guy and put some a fair amount of pressure on the crank.

    If I recall right using an iso on a jis move the crank out 4mm (check sheldon brown) so if you are ok with the not fully seated crank then a 70/115 with jis taper would be about right.

    have fun

    This tool is much cheaper than some tools I've found on ebay. I might get it and forget about buying a new BB. Damn, it's so complex. It seems there is not an easy way out. Stupid Ofmega
    Nature is my mentor

  12. #12
    Retro Grouch onespeedbiker's Avatar
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    Quote Originally Posted by MightyLegnano View Post
    Hello!

    Is there anybody who had Ofmega Competizione BB and had to replace it?
    By the way the cranks are the Ofmega 'Legnano' 42/52 .
    FYI, your Legnano cranks are actually Ofmega Competizione or Strada; they were rebranded "Legnano" for bicycles made by the company of the same name..
    Last edited by onespeedbiker; 07-11-14 at 11:08 PM.
    Chiunque tenti di scappare a queste regole dovrÓ mangiare un piatto largo di polenta vecchia di tre settimane e sarÓ schernito per questo, soprattutto se Ŕ straniero

  13. #13
    Ride, Wrench, Swap, Race dddd's Avatar
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    I'll chime in, since I have measured hundreds of spindle tapers for comparative purposes.

    Squirtdad's first post is solid info in my opinion.

    These Ofmega spindle tapers are fairly close to ISO tapers, just a tiny bit smaller, so can be substituted imo.
    Just as pre-cartridge Campagnolo spindles are pretty close to ISO dimensions. And, as onespeedbiker mentioned, the pre-cartridge Campag spindle tapers are a bit bigger than ISO tapers yet a good bit smaller than JIS to the tune of about 2mm in spindle/crankarm overlap.

    I personally would try a 115mm symmetric JIS cartridge, as the missing "spindle offset" and thicker JIS taper should cancel each other out.
    The new cartridge will act like a 120mm spindle but with a bit less offset, making the pedal stance more symmetrical in the process.
    A splined tool will be needed to seat the cartridge's cups, but these cartridges can go without maintenance for many years in my experience.
    Any deficiency in the "chainline" measurement of the seated right crankarm can be easily dealt with using a fixed cup spacer of perhaps 1-3mm, but you only need a millimeter or two of clearance between the small chainring and the right chainstay and there is probably already much more than that now.
    Last edited by dddd; 07-12-14 at 06:11 PM.

  14. #14
    The bike plague MightyLegnano's Avatar
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    Quote Originally Posted by dddd View Post
    I'll chime in, since I have measured hundreds of spindle tapers for comparative purposes.

    Squirtdad's first post is solid info in my opinion.

    These Ofmega spindle tapers are fairly close to ISO tapers, just a tiny bit smaller, so can be substituted imo.
    Just as pre-cartridge Campagnolo spindles are pretty close to ISO dimensions. And, as onespeedbiker mentioned, the pre-cartridge Campag spindle tapers are a bit bigger than ISO tapers yet a good bit smaller than JIS to the tune of about 2mm in spindle/crankarm overlap.

    I personally would try a 115mm symmetric JIS cartridge, as the missing "spindle offset" and thicker JIS taper should cancel each other out.
    The new cartridge will act like a 120mm spindle but with a bit less offset, making the pedal stance more symmetrical in the process.
    A splined tool will be needed to seat the cartridge's cups, but these cartridges can go without maintenance for many years in my experience.
    Any deficiency in the "chainline" measurement of the seated right crankarm can be easily dealt with using a fixed cup spacer of perhaps 1-3mm, but you only need a millimeter or two of clearance between the small chainring and the right chainstay and there is probably already much more than that now.
    Thanks for your valuable suggestions. I, as well believe that the 115 symmetric JIS catridge would work. I have decided to to order the wrench mentioned by squirtdad earlier and go with the old ofmega BB. I think it's safer that way. And I hope with that tool I can generate enough torque so the cup won't get unscrewed (100km from home).

    By the way, whats the splined tool?
    Nature is my mentor

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