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-   -   What size bottom bracket do I need? (https://www.bikeforums.net/bicycle-mechanics/866683-what-size-bottom-bracket-do-i-need.html)

tdsherman325 01-09-13 07:44 PM

What size bottom bracket do I need?
 
It's for an Open Road 3000GT, a 90's? Taiwanese 10 speed I'm fixing up for my sister in law. Here's what's got me stumped:

The axle has "5S" stamped on it and according to Sheldon Brown's site at http://sheldonbrown.com/bbsize.html 5 series axles fit 70mm Italian style bottom brackets. The bottom bracket shell measures 70mm in width. So far, so good.

However, according to Wikipedia at http://en.wikipedia.org/wiki/Bottom_bracket Italian style bottom brackets have an internal diameter of 34.6-34.9 mm and right-hand threads on both sides. This particular bottom bracket measures 33.5-34mm internal diameter and has left-hand threads on the drive side, matching Wikipedia's specs for an English style bracket.

So, which is it? Since I'm replacing the crankset as well I gather that I should select a bottom bracket matching the length recommended for that crankset, in this case 118mm. But I don't know if I need a 68x118 or a 70x118

Thanks,
Terry

Ex Pres 01-09-13 07:47 PM

68x118


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