A coworker has brought me a 1983 Diamond Back Ridge Runner to go through, so he can use it for a commuter. First off I wasn't expecting the bike to be so nice, from his original description. The bike is completely original, minus the saddle. The frame is constructed of Champion 5 tubing with very ornate lugs that are pin striped, Suntour chrome drop-outs and really nice cable routing. It has Suntour Superbe Tech dérailleurs and shifters, brakes are Dia-compe with monster motorcycle style levers mounted to a one piece bar and stem set up. The wheels are nice Arrayas on wide flange sealed bearing hubs, they even have stainless spokes.
The paint is really bad and I have convinced him to have it stripped and powder coated. The bottom bracket gave me a lot of resistance coming out, it was totally rusted in. I ultimately had to ruin the cups to remove it, because it was breaking all my BB tools trying to salvage it. The original bb is a Sugino sealed unit, actually still turns quite nicely, but the cups are now toast. It is a 68mm with a 129mm spindle. I have found a 127.5 Shimano UN54 sealed bb, that has the recessed cups, that I'm considering for use. Will this be a suitable replacement, mounted to a set of Sugino AX triple cranks? I'm wondering if the clearance will be ok, since the spindle is about 2mm shorter and I'm not going to have the cups stacked on the outsides of the bb. Any help will be appreciated, or if any one has a set of the cups. Thanks

Measure the frames BB but I suspect it is a 73 mm not a more common 68 mm. Make sure you get a 73 BB. Roger

I don't think there were many super fat tires around in 1983 so the chainstay clearance may not be much of an issue but I'd say it's trial and error time for this one. The UN54 has a shoulder on the drive side but you may be able to space it out a mm or 2 if needed. Have you considered converting to a double crankset?

I think the 127.5 will fit fine. With good clearance.

1+ although I agree with rhenning I would verify it isn't a 73.

description sounds alot like a Miyata Ridge Runner I serviced a while back (and about the same year I think) and I too was impressed with how *nice* it was once I got into it...I wonder if the early DBs were Miyata products? Anyhow, my guess it it's definitely a 68mm shell (given the year) and that the 127.5 unit will work fine, I believe that's what I used, but it depends on the crankset. You may need to add a spacer to the fixed side, and I *might* have a pair of cups but try the sealed unit first. good luck.

Thanks for the input. Yes Unworthy1, it does have a 68mm bottom bracket. I will probably go with the 127.5. When I asked the ? I didn't have the old cranks with me, now I do and I will do a quick rebuild to check clearances before I order the new bb. As far as the frame being a Miyata product, from what I found they were built by Centurian. Thanks again.

I believe that Centurion was made by Diamond Back.

technically it's the other way 'round: first came Centurion, then Diamond Back (or Diamondback, one word) but BOTH those were just the importer's brand names, not manufacturers. I don't know (but T-Mar would) except that Miyata may have been employed as a contractor for some DB products, especially since these model names (Ridge Runner) are the same. Lawyers would have become involved...

I did not know it was the other way around.
Thank You for the info.

IF your spindle is still good, you can get new cups at Loosescrews-
https://www.loosescrews.com/index.cgi...d=905897332680

Thanks Bill, the bottom bracket is a sealed unit. It's corroded on the exterior housing, but it turns very smoothly. The Sugino cups, in your link, look like they may work. Thanks for the input.