Bicycle Mechanics - Question: Shimano bottom bracket with fixed flange on non-drive side

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robert schlatte
08-25-11, 07:31 AM
I recently acquired a used Shimano BB-UN72 bottom bracket 68x110 from a used parts bin at a bike co-op. Interestingly, the fixed flange is on the non-drive (left) side as opposed to the the drive side which is the norm in my experience. Unfortunately, I do not have the removable sleeve for the drive side with left-hand threading but would like to acquire one so I can use the BB. Is anyone familiar with this type BB? The only reference to such a BB that I could find is on the Park tool website. Further, are removable sleeves with left-hand threading available anywhere? Thanks.
mechBgon
08-25-11, 09:17 AM
I recently acquired a used Shimano BB-UN72 bottom bracket 68x110 from a used parts bin at a bike co-op. Interestingly, the fixed flange is on the non-drive (left) side as opposed to the the drive side which is the norm in my experience. Unfortunately, I do not have the removable sleeve for the drive side with left-hand threading but would like to acquire one so I can use the BB. Is anyone familiar with this type BB? The only reference to such a BB that I could find is on the Park tool website. Further, are removable sleeves with left-hand threading available anywhere? Thanks.
You can use it as-is if it fits your BB width.
robert schlatte
08-25-11, 09:57 AM
Okay. I figured it out. What I thought was the fixed flange was actually the removable sleeve that was just jammed on. Somehow the fixed flange came off this BB. Now my issue is getting and then attaching a fixed flange to the right side. I have a UN 26 BB. I am thinking of removing its fixed flange and putting it on the UN72. Anyone know is it possible to do that?
Ex Pres
08-25-11, 10:02 AM
UN-72 (and earlier) had removeable cups, which made them great for adapting to French threaded BB and the like. In true Shimano style, they took that adaptability away with the 73 series. Phil Wood makes cups that [I've read, not tried] will fit.
mechBgon
08-25-11, 10:10 AM
Okay. I figured it out. What I thought was the fixed flange was actually the removable sleeve that was just jammed on. Somehow the fixed flange came off this BB. Now my issue is getting and then attaching a fixed flange to the right side. I have a UN 26 BB. I am thinking of removing its fixed flange and putting it on the UN72. Anyone know is it possible to do that?
I'd just head to a local bike shop, the older the better, and tell them what you need. They probably have a bin of them. Note whether you have a 68mm or 73mm bottom-bracket shell, since there are specific cups for each.
robert schlatte
08-25-11, 10:16 AM
Thanks. I just read on Sheldon Brown what you said about UN-72. I think I will go back to the co-op and look through the parts bin for the piece that I missed the first time.
robert schlatte
08-25-11, 10:20 AM
Thanks. The BB is a 68mm shell which is what I am replacing. The spindle is 110mm. I am trying to move my chain rings in a little closer to get better chain alignment with my rear cogs. The spindle I am replacing is 113mm which place the rings to far to the right.
HillRider
08-25-11, 11:06 AM
UN-72 (and earlier) had removeable cups, which made them great for adapting to French threaded BB and the like. In true Shimano style, they took that adaptability away with the 73 series.
I believe one of the reasons for the redesign between the 72 and 73 series bottom brackets was the chronic creaking problem between the cartridge shell and the inside of the cup with the loose driveside cup on the 72's. The plastic nds cup on some of their bb's was also there to quiet them down.
fietsbob
08-25-11, 11:28 AM
New UN BBs are cheap, just get a new one..
and put it the right way in..
your 110 + spacer behind the right flange of, say, 1, 1.5 or 2mm?
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