So I've got a GT Talera rigid mountain bike that I bought new back around 1990 when I was in college.

I pulled it down from the rafters and the old girl is in pretty respectable shape yet. I'd like to get her back in perfect running order as a second bike. My primary issue: the bottom bracket (crank) bearings are pretty much toast.

I've looked everywhere online to try and find out exactly what the heck I need to track down with no luck. Looks to be square taper, but that's all I know. Can anyone help?

TIA

Quote from: Speedbag on June 05, 2012, 05:38:07 PM
So I've got a GT Talera rigid mountain bike that I bought new back around 1990 when I was in college.

I pulled it down from the rafters and the old girl is in pretty respectable shape yet. I'd like to get her back in perfect running order as a second bike. My primary issue: the bottom bracket (crank) bearings are pretty much toast.

I've looked everywhere online to try and find out exactly what the heck I need to track down with no luck. Looks to be square taper, but that's all I know. Can anyone help?

TIA

This type of thing you mean?
http://www.chainreactioncycles.com/Models.aspx?ModelID=36419

Based on this site ( http://sheldonbrown.com/bbsize.html#200 ) and measurements off my bike, I have a 68x121mm unit.

Crankset is a Shimano 200GS.

1. Does it contain sealed bearings like in brimo's link above?
2. If so, which do I need?

Best just to pull it out and take the bearings to a bearing shop. cheaper than buying from a bicycle shop or online.
the bearings might just need a clean and regrease after many years of sitting, if you want to do it on the cheap.
And that can be done with sealed bearings.

Started cleaning the filth off the bottom bracket shell, and got the left crank side off.

It's not a cartridge type as originally thought. It's got a caged ball inside, which sits on the spindle, onto which the race threads into the shell and a jam nut on the OD of the race holds it into the frame.

Can't seem to get the right side crank off, looks to be a somewhat similar arrangement on that side.

If I can get it apart without destroying anything I might be able to fix it cheap..... 

Quite often that type of arrangement has a left hand thread on one side and a right hand thread on the other, may be why you can't get one side off.

Quote from: Speedbag on June 05, 2012, 07:23:02 PM
Can't seem to get the right side crank off, looks to be a somewhat similar arrangement on that side.

If I can get it apart without destroying anything I might be able to fix it cheap..... 

You're using a crank puller, correct?  AKA not banging the arms with a rubber mallet.

Just buy a new cartridge BB.  1990 isn't that old.  Just get a 68x121+ Shimano square taper.  You should be able to find one for $10 or so:
http://www.amazon.com/gp/product/B001IOW41U/ref=pd_lpo_k2_dp_sr_1?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B0052UDX20&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=1FHBV70ZSQKF0JW8K648

Quote from: stateprez on June 05, 2012, 07:46:11 PM
You're using a crank puller, correct?  AKA not banging the arms with a rubber mallet.

Yeah.....I need to get one of those. 

A trip to the local bike shop is in order today.....

What stateprez said. I've got all the specialty tools to replace, adjust and fiddle  with fussy old BBs, but these days just buy a new cartridge one, install it and forget about it. You'll need to buy or borrow a splined BB tool (when you get that crank puller) in order to install it.

So I take it the thread/OD of the BBs are pretty much standard, just the length differs....

For all practical purposes, yes. Also be aware that one of the cups (Left, IIRC) is left hand thread

Weird, the current race that threads on the left side is right hand thread.

For English BB's, which your's should be, the Drive Side is Left Hand thread.

http://www.parktool.com/blog/repair-help/bottom-bracket-tapping-and-facing-bts-bfs

Italian is Right Hand on both- applies to Pinarello's, Merckx's, etc European brands.

The bike shop didn't have squat, so I ordered a BB and crank puller from Amazon.

Thanks peeps! 

I always have to look at the BB to remember which is normal and which is left-hand thread. I tried to work it out logically when typing that previous note, so it's little surprise I got it wrong.