Weird ol' bottom bracket
07-20-15 | 06:37 AM
#1
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Joined: Jun 2015
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From: Norway
Bikes: Fuji Roubaix 1.3 LE 2014
Weird ol' bottom bracket
I got this cheap steel frame bicycle off craigslist, but the bottom bracket is knackered so I need a replacement. The spindle is square tapered, so it fits a standard square tapered crank. The BB shell doesn't have any threads, but the ball bearings roll directly against the BB shell, as indicated in the below photo. The shell width is 68 mm. I saw some BB's online that looked sort of similar but not quite. Help much appreciated! 
Last edited by krfarstad; 07-20-15 at 06:56 AM.
07-20-15 | 06:51 AM
#2
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Joined: May 2003
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From: Mountain Brook. AL
Unless the races are truly horrible, you may end up cleaning it up, maybe replacing the balls, using an abrasive pad to clean up the races
and reassembling. The bearing cages are not needed, just convenient to assembly. There are replacement BB for threadless BB housing
that rely on compression, but these assume a certain diameter in the housing, so spacers maybe needed to make them work.
Just a brief google shows this example of such a BB: Mavic Bottom Bracket - Bicycle Parts at discount prices / the Buyer's Guide / Bicycle Parts at their finest! / Professional Bicycle Source / Bike Pro
Availability is another matter, but such do exist.
and reassembling. The bearing cages are not needed, just convenient to assembly. There are replacement BB for threadless BB housing
that rely on compression, but these assume a certain diameter in the housing, so spacers maybe needed to make them work.
Just a brief google shows this example of such a BB: Mavic Bottom Bracket - Bicycle Parts at discount prices / the Buyer's Guide / Bicycle Parts at their finest! / Professional Bicycle Source / Bike Pro
Availability is another matter, but such do exist.
07-20-15 | 07:00 AM
#3
Thread Starter
Junior Member
Joined: Jun 2015
Posts: 11
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From: Norway
Bikes: Fuji Roubaix 1.3 LE 2014
Unless the races are truly horrible, you may end up cleaning it up, maybe replacing the balls, using an abrasive pad to clean up the races
and reassembling. The bearing cages are not needed, just convenient to assembly. There are replacement BB for threadless BB housing
that rely on compression, but these assume a certain diameter in the housing, so spacers maybe needed to make them work.
Just a brief google shows this example of such a BB: Mavic Bottom Bracket - Bicycle Parts at discount prices / the Buyer's Guide / Bicycle Parts at their finest! / Professional Bicycle Source / Bike Pro
Availability is another matter, but such do exist.
and reassembling. The bearing cages are not needed, just convenient to assembly. There are replacement BB for threadless BB housing
that rely on compression, but these assume a certain diameter in the housing, so spacers maybe needed to make them work.
Just a brief google shows this example of such a BB: Mavic Bottom Bracket - Bicycle Parts at discount prices / the Buyer's Guide / Bicycle Parts at their finest! / Professional Bicycle Source / Bike Pro
Availability is another matter, but such do exist.
07-20-15 | 08:15 AM
#4
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Joined: Apr 2007
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From: Syracuse, NY
Bikes: 2008 Novara Randonee - love it. Previous bikes:Motobecane Mirage, 1972 Moto Grand Jubilee (my fave), Jackson Rake 16, 1983 C'dale ST500.
No, the photo above is of a bearing cage/retainer.The retainer can be straightened - it's only there to ease assembly - but is best replaced anyway. The races are more commonly called BB cups, and are what the balls are sitting on in your 3rd photo. The cups are not part of the BB shell but rather are a press fit - easily removed and installed. The BB shown is a variation of a Thompson/Thun BB. What you need to do is to inspect the cups as well as the cones (name should allow you to identify them) for pitting, especially as it appears the right cup may be pitted.
If they are indeed damaged your best option if the bike is worth it is to get a full replacement. See if a local shop can order a replacement (take in the old parts) or Google "Thompson BB set" or similar (add . You need to make sure it is for square taper and the correct BB width, especially as many of the sources are from overseas.
If they are indeed damaged your best option if the bike is worth it is to get a full replacement. See if a local shop can order a replacement (take in the old parts) or Google "Thompson BB set" or similar (add . You need to make sure it is for square taper and the correct BB width, especially as many of the sources are from overseas.
Last edited by cny-bikeman; 07-20-15 at 09:02 AM.
07-20-15 | 08:35 AM
#5
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From: Ffld Cnty Connecticut
Bikes: Old Steelies I made, Old Cannondales
Also called bearing retainer. You can find new ones, or just use loose bearings instead. Use the grease to hold them in place while you assemble it. You'll need 2-3 more bearings without the retainer. Something like "tight fit minus 1" to calculate how many loose bearings.
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Last edited by Homebrew01; 07-20-15 at 08:43 AM.
07-20-15 | 09:16 AM
#6
Thread Starter
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Joined: Jun 2015
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From: Norway
Bikes: Fuji Roubaix 1.3 LE 2014
No, the photo above is of a bearing cage/retainer.The retainer can be straightened - it's only there to ease assembly - but is best replaced anyway. The races are more commonly called BB cups, and are what the balls are sitting on in your 3rd photo. The cups are not part of the BB shell but rather are a press fit - easily removed and installed. The BB shown is a variation of a Thompson/Thun BB. What you need to do is to inspect the cups as well as the cones (name should allow you to identify them) for pitting, especially as it appears the right cup may be pitted.
If they are indeed damaged your best option if the bike is worth it is to get a full replacement. See if a local shop can order a replacement (take in the old parts) or Google "Thompson BB set" or similar (add . You need to make sure it is for square taper and the correct BB width, especially as many of the sources are from overseas.
If they are indeed damaged your best option if the bike is worth it is to get a full replacement. See if a local shop can order a replacement (take in the old parts) or Google "Thompson BB set" or similar (add . You need to make sure it is for square taper and the correct BB width, especially as many of the sources are from overseas.
07-20-15 | 09:21 AM
#7
Mechanic/Tourist
Joined: Apr 2007
Posts: 7,522
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From: Syracuse, NY
Bikes: 2008 Novara Randonee - love it. Previous bikes:Motobecane Mirage, 1972 Moto Grand Jubilee (my fave), Jackson Rake 16, 1983 C'dale ST500.
"Might get away with it" yes, but if the cups are badly pitted you will quickly wear out the balls and will have a hard time adjusting the BB. Considering you are in Europe a local shop may have the complete bb or can order it for you. Punch out the cups and take the whole shot in for advice.
Last edited by cny-bikeman; 07-20-15 at 11:59 AM.
07-20-15 | 10:32 AM
#8
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From: NW,Oregon Coast
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walk into your friendly local bike shop with all those parts in a bag, they will match the retainer and ball size an hand you new parts .
Thun BB's considering where you write from they are not weird at all ..
Thun BB's considering where you write from they are not weird at all ..
