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-   -   Bridgestone 400 Bottom Bracket (https://www.bikeforums.net/bicycle-mechanics/901897-bridgestone-400-bottom-bracket.html)

eusebio 07-16-13 08:28 PM

Bridgestone 400 Bottom Bracket
 
After searching Bikeforums.net and Sheldon Brown's website I have concluded that my Bridgestone 400 has a cup-and-cone bottom bracket with an English threading (1.375" x 24 tpi), shell width 68 mm. I do not know the exact make of the bottom bracket that was originally installed in my 400. The etchings read "Bo 3S" and "MTBS409." I believe the "Bo 3S" to be a size code. According to Sheldon Brown the "'3' series spindles normally fit 68 mm ISO/British/French bottom brackets" (http://sheldonbrown.com/bbsize.html#japan). Therefore I have two questions:

What cup-and-cone brand is this pictured? Sugino 75? I cannot tell if it is J.I.S. or I.S.O tapers.

http://i92.photobucket.com/albums/l3...ps7040a127.jpg

Is this the proper bottom bracket for my bike? I will learn the exact spindle length tomorrow.

http://www.jensonusa.com/Bottom-Brac...Bottom-Bracket

Thank you.

Andrew R Stewart 07-16-13 08:35 PM

Proper BB axle length is a result. The right chain stay clearance, good chainline agreement with the rear cogs, acceptible "Q' factor. When changing BB units some fudge and find out is the usual manor. Don't expect exact numbers. Andy.

Bill Kapaun 07-16-13 10:24 PM

3S is your spindle size- JIS

http://sheldonbrown.com/bbsize.html

Scroll down just a bit.

HillRider 07-17-13 07:20 AM

The '85 Bridgestone 400 I had came with an SR triple bottom bracket and an SR crank predrilled for a granny ring. It is certainly a JIS taper and English threaded.

What is the reason for replacing it? I really can't be sure but from the photos the spindle and cup appear to be in decent shape.

eusebio 07-17-13 10:36 AM


Originally Posted by Andrew R Stewart (Post 15858748)
Proper BB axle length is a result. The right chain stay clearance, good chainline agreement with the rear cogs, acceptible "Q' factor. When changing BB units some fudge and find out is the usual manor. Don't expect exact numbers. Andy.

I am keeping the original crank and pedals, so the Q factor (which is a bit out of my league) should not be noticeably affected. Also I switched from a double to a single (no front derailleur) so I have experienced a slight variation with chainstay clearance and chainline agreement. Nothing noticeable. I thought I would shave one or two millimeters off the spindle length to compensate for my change to single. Thanks for reminding me of these factors Andy.


Originally Posted by HillRider (Post 15859833)
The '85 Bridgestone 400 I had came with an SR triple bottom bracket and an SR crank predrilled for a granny ring. It is certainly a JIS taper and English threaded.

What is the reason for replacing it? I really can't be sure but from the photos the spindle and cup appear to be in decent shape.

The Bottom Bracket had not been maintenanced since its manufacture, so the entire drive side was totaled when I was muscling it off. Plus I was too busy to change the bottom bracket back in the winter, there has been audible grinding for several months now which I think also damaged the BB. I plan to keep the axle though. Maybe some day I will re-use it.

Finally, since the BB is Sakae - I am S.O.L. for knowing exactly which BB to get? This is considering (taken from a different forum thread):


Originally Posted by tellyho (Post 6830060)
You either search the hell out of the internet and hope you can trust the answers you get, or start buying bottom brackets and experimenting. Go to a forgiving bike shop and they might let you try a couple. I was going to point you to Sheldon's BB size database, but he doesn't have anything for Sakae.

Thanks for your help!

HillRider 07-17-13 01:02 PM


Originally Posted by eusebio (Post 15860463)
Finally, since the BB is Sakae - I am S.O.L. for knowing exactly which BB to get? This is considering (taken from a different forum thread)

As long as the spindle is a suitable length, JIS tapered and the English threaded, you can use any cup-and-cone bb from SR, Tange, Suguino, Shimano, etc. In fact you can often mix-and-match cups and spindles since they all require the same 1/4" bearing balls.

An alternative is to buy a sealed cartridge bottom bracket such as a Shimano UN 24 or UN 54 or similar of the proper spindle length.

Bill Kapaun 07-17-13 01:08 PM

Just pop in a 122mm cartridge and call it good.

eusebio 07-17-13 09:02 PM

Okay I just made the order:

http://i92.photobucket.com/albums/l3...psfe447eef.jpg

Thanks for the help!


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