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  1. #1
    tastes like chicken mostro's Avatar
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    Vintage bottom bracket dilemma

    I have a 1985 Bianchi Stelvio with a worn bottom bracket. The shell width measures 68mm, but the threading appears to be Italian? Both left and right sides are right threaded, and when I tried an English bottom bracket I had lying around (on the drive side) it was a bit too small.

    Does this mean I have a French threaded bottom bracket, as Sheldon Brown's site might suggest? The cranks are ostensibly Ofmega Brilliante, according to a period review of the bike. Neither the cranks nor the bottom bracket are marked in any way. Zilch. I've read that Ofmega spindles are not compatible with other makes so I've considered buying a vintage Campy crankset to go with a vintage bottom bracket, but I'm not sure what would work.

    I suppose I could also go modern with a cartridge BB, but my preference is to keep the bike period if possible.

    Any suggestions?

    TIA

  2. #2
    cyclist/gearhead/cycli... moxfyre's Avatar
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    What is worn about the bottom bracket? If the spindle isn't *TOO* bad, then new bearing balls and grease will do wonders for it.

    Sheldon's site says that nothing but Ofmega spindles will work with Ofmega Brilliante cranks... bummer. Why anyone thought it was a good idea to have more than one square taper shape is beyond me.

    It does sound like a French thread to me, 68 mm and right-hand threaded on both sides. I would troll ebay for matching bottom bracket spindles if you can't make the current one work.
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  3. #3
    tastes like chicken mostro's Avatar
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    moxfyre, thanks. Both the spindle and cups are worn. I'm beginning to think that the bottom bracket is French threaded. I don't have any way to check other than taking measurements, but the thread *appears* to be 35mm. Note that I am measuring with a ruler, not calipers. A guy at my LBS is working on a fixie project using an early 80's Tomasini frame which has French threads. So it's not unheard of, I guess, amongst Italian steel frames of that era. Is there any way to confirm this short of actually trying either a French or Italian BB? Neither of my LBS have them in stock.

    Maybe Bianchi decided to "French thread" these frames because they had a supply of French thread BBs and cranks from Ofmega. I've read that Ofmega also made Avocet parts...

    I also wonder how this fits with the idea that you can determine a mid-80's Bianchi frame by the BB shell width. I've heard that 68mm = Japanese fab'd frame and 70mm = Italian made frame, but what if the BB has French threads? Japanese or Italian? I'm crossposting this to the vintage thread.

    At any rate, what I really need is a way to figure out which threading it DOES have so I can get the right BB and get it back on the road.

  4. #4
    cyclist/gearhead/cycli... moxfyre's Avatar
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    Good luck! Definitely take some calipers to that thing to get a precise measurement. You can measure the thread pitch fairly well by PRECISELY measuring the length of, say, 10 threads and then dividing by 10.

    If the cups are more worn than the spindle, you may be able to get away with JUST replacing the cups, in which case you could keep your current cranks. Otherwise, it sounds like you'll have to part with those classic cranks... they might fetch a decent sum on ebay at least
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  5. #5
    Sometimes knows stuff. rmfnla's Avatar
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    BB width isn't an accurate indicator, anyhow; one good pass with a facing tool (remember those?) on each side and suddenly 70mm is now 68 (or even less).

    Have a decent shop check it with gauges (or known BB cups).

    My guess is it's Italian (vintage Bianchi... ya think?).
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  6. #6
    cyclist/gearhead/cycli... moxfyre's Avatar
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    Quote Originally Posted by rmfnla
    BB width isn't an accurate indicator, anyhow; one good pass with a facing tool (remember those?) on each side and suddenly 70mm is now 68 (or even less).

    Have a decent shop check it with gauges (or known BB cups).

    My guess is it's Italian (vintage Bianchi... ya think?).
    If you measure thread pitch AND diameter precisely, you'll know whether it's Italian or French. The good news is, if it's an Italian BB there's one on eBay. http://cgi.ebay.com/OFMEGA-COMPETIZI...QQcmdZViewItem
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  7. #7
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    "Both the spindle and cups are worn."

    Worn is not really a problem if the surfaces are smooth, pitted is a problem.
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