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View Full Version : mtb - changing bottom brackets



lph
04-08-2009, 05:28 AM
After trying to ignore the increasing wobble in my pedals for some time I finally caved and got a new bottom bracket. The old one was like 15 years old and looked like this (see below), so I guess it was about time :o

I tried to get a Shimano BB UN-73 as my techie savvy dh did all the googling and told me that was a good buy, but the closest I could get with the right dimensions was a BB UN-54. I was surprised that the locking ring/cup (the thingy you screw on last from the left side, after installing the bb from the right side) was made of plastic. Didn't seem very sturdy to me :confused: and I sure am gonna have to be careful about unscrewing it in the cold.

I've kept the old one in aluminium (UN-51) just in case, but was a bit curious to see if anyone knew if these plastic rings hold up.


Gee, we have a really messy entrance...

DebW
04-08-2009, 05:51 AM
I've seen the plastic ones break when overtorqued. But they generally hold up OK. It's really the right side threads that hold the bb tight. The left side ring only occupies the extra space between the frame and bb.

lph
04-08-2009, 09:26 AM
Thanks Deb, that eases my mind :)

mayanorange
04-08-2009, 09:47 AM
I've seen the plastic ones break when overtorqued.
Yeah, like when you hand the torque wrench to yours truly....;) (it was just a little crack)

fatbottomedgurl
04-08-2009, 11:30 AM
Nothing to say about the BB but just that my son is going to Oslo in August on his honeymoon. His fiance is on her third quarter of Norwegian in university. They are enamored with Norway!

lph
04-08-2009, 01:18 PM
They are enamored with Norway!

As well they should be :D