Bicycle Mechanics - bottom bracket size on an 84 Ross Gran Tour II

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osiris419
11-04-09, 09:34 AM
Hey. I'm in the process of converting an 84 Ross Gran Tour II into a fixed gear. This is my first build. I got the frame bare (and free) so there is no older parts to compare but I need to know what size the BB is. I know I need it to be 107mm in length but what I don't know is the thread size. I went to Sheldon Brown and I think I need a 63mm but I'm not sure. Any help would be great.
Thanks
Steve

DMF
11-09-09, 11:57 AM
Try measuring it. I guarantee it's not 63mm.

Ross was made here in the states so it's most likely English. If you can lay hands on a standard BB, try screwing it in. If it goes you've found what you need to know.

Alex Ross, grandson of the founder, occasionally posts on the Classic forum.
old and new
11-09-09, 12:28 PM
Sure it's 107 length ? OK I suppose. It IS English in any case, even if it was a slightly later Asian built. A VERY slight chance of 73. Odds are overwhelmingly.. 68mm.

osiris419
11-09-09, 02:50 PM
ok thanks I'll figure it out.