Hey all,

I'm currently doing a few upgrades / cleaning up my (new-to-me) old Trek 1400 (possibly an '89? Blue with white decals).

I decided to take the bottom bracket off so I could clean the inside up so it doesn't get jammed in the future (it took a some overnight soaking and leverage to get the drive side off) and the non-drive cup is totally thrashed (not my doing).

I'm wondering what my best route is for replacing the cup. Current BB is a UN52 68 113 (1.37 x 24 - Don't think this is necessary but more info is better I suppose).

Should I just buy a new cup (UN54 cup) like this for about $14:

Amazon.com : Shimano UN54 Left Bottom Bracket Cup (68-mm BSA) : Bottom Bike Brackets And Accessories : Sports & Outdoors

Or am I better off spending $24 for a brand new UN55 for $24:

https://www.amazon.com/Shimano-Tapere...bottom+bracket

At the moment, I'm unsure the differences between a UN52 and UN55 (55 has metal cup and better internals?) as I haven't found much info on the UN52. I'm going to do some more research, but I was hoping you guys might know the answers to my more "specific" question on whether to upgrade or go for the cup. As far as I can tell, there is no damage to the UN52 other than the cup.

Thanks,

Alex

(Apologies for a double post, I put this in the Road Cycling forum initially but realized this is probably a better place)

So...... why did you take it apart again?
It's a sealed unit, and won't get jammed up.
Buy a new one:
QB-55 Quad Bottom Bracket

Does the bottom bracket turn smoothly, or is it rough?

As long as you get the type (square taper, Octalink, etc) and the threads (English, Italian, etc), and the length (double, triple) correct, then replacement should be straight forward. I'd probably start with all new parts.

BTW, your hyperlinks are all messed up with the repost.

Hard to tell exactly what you are asking, especially with the busted link.

It APPEARS the question is-
You have a BB with removable cups/spindle. (old style)
You want to use an aluminum NDS cup for a CARTRIDGE BB?
It's NOT the same thing.

I would just buy a whole new crankset you can get a external hollowtech for $100 that would be better and have an easy replacement. I am still of the school that the external BB are the best things invented.

If the bb you removed is a BB-UN52 than just replace it with a similar one or a BB-UN55 in the same spindle length. BTW, the UN52 is not original to those bikes. They came with Tange cup-and-cone bbs so somewhere along the line the OEM was replaced.

Remember that frame is aluminum so use LOTS of grease or, better, anti-seize on the bb cup threads.

Edit: I just saw Deacon Mark's recommendation and it has merit. A Tiagra crank, either double or triple, plus a Tiagra or 105 level external bearing bottom bracket can be had for $100 or so if you look around.

Thanks for the replies, sorry for the broken link. I just copied and pasted from my previous post. Here are the links in working order:

https://www.amazon.com/Shimano-UN54-B...om+bracket+cup

https://www.amazon.com/Shimano-Tapere...bottom+bracket

I took the BB out for two reasons. Firstly, the cup was broken and I wanted it out before it got any worse (and more jammed) so I could replace it. Secondly, it's a 2nd hand (probably 8th hand by now - ha ha) bike and I wanted to make sure it would come out and was properly greased so I could replace it in the future if anything broke.

I don't think I'm going to upgrade the crankset at the moment because this is going to be my around-the-towner and I'd like to keep it relatively low-key (for the moment).

However, I did briefly look at some cranks and from my understanding a 9/10 speed crank will work with a 7 speed cassette, correct?

I'm sure I will find more information online, busy working at the moment.

-Alex

Yes, 9/10-speed cranks will work with a 7-speed cassette but the 7/8-speed chain might be a bit too wide to shift between the chainrings well and might rub on the big ring when you are in the small ring. However, a 9 or 10-speed chain will work with a 7-speed cassette.