Joined: Feb 2016
Posts: 1,860
Likes: 821
From: SE Wisconsin
Bikes: Lemond '01 Maillot Jaune, Lemond '02 Victoire, Lemond '03 Poprad, Lemond '03 Wayzata DB conv(Poprad), '79 AcerMex Windsor Carrera Professional(pur new), '88 GT Tequesta(pur new), '01 Bianchi Grizzly, 1993 Trek 970 DB conv, Trek 8900 DB conv
Bottom bracket BB UN50 replacement
I've torn down and rebuilt a number of bikes, but in the cases where I needed to service/replace the bottom bracket and/or headset, I've had my local bike shop do it for me.
I recently rode a bike I have at a vacation home and heard some noises that I'm reasonably sure are coming from the bottom bracket. I'd like to replace the BB as I'm sure it's original. The bike is a 1992 Trek 8900 MTB. It has a M900 series XTR 8-speed groupset on it. Crank is the original XTR triple (46/36/26). Per the spec manual the BB is "39/52/40.5, 3UT Shimano BB-UN50" with a 68mm shell. The spindle length isn't known..the tech manual doesn't indicate it and I haven't taken it apart yet.
What more modern (or at least available) replacement BB will fit the bike? I assume whatever replacement is available will have stock spindle lengths available once I get it apart.
thx..