I had a bottom bracket failure yesterday on my '85 Mongoose All Terrain. I was hoping to order a replacement today. Does anyone know the specs I need?

I can measure when I get home today, but I was hopeful someone might know the specs or be able to locate it. My googling has come up dry! (I've even gone back to the catalog, which is a hoot: https://www.vintagemongoose.com/pdfs/mongoose_cat85.pdf)

I did find that the '85 Stumpjumper had a 120 x 68, so I'm guessing the the ATB has similar.

Cheers!

My Mongoose thanks you!

Does that have the BiPlane fork?

700C?

Nice bike, looks sharp. The 68 is the diameter of the BB shell which would be the same. The 120 is the spindle length..

How did your BB fail? Do you just need a new spindle? Did it snap? The spindle length is usually depending on the crank being used so it's probably best to measure whatcha got. It is possible someone on here knows though..the knowledge 'round here is great

Thanks! I'm familiar. Are those the right specs, though? I'll post once I measure everything.

120 seems short for a MTB of that vintage. I would think you would need in the 127 range. Measure the existing one.

It does have a biplane fork. The wheels are 26"
It originally had the MTS slingshot stem and matching bars.

So COOL!!!

Chrome and a biplane fork!

Cool, cool bike.

I believe that 68 is the width of the BB shell and 120 is the OLD.

OLD? Do you mean spindle length?

Posts like this one drive me nuts- You have the all parts to measure right at your fingertips, go buy some $10 calipers at harbor freight and contribute to the knowledge base instead of taking the lazy way out. Take the extra day to measure a tangible object instead of making a wild guess based on another bike of the era. The new BB will get here soon enough, I promise.

Remember: The information on the internet didn't get there by itself.

Over locknut dimension (rear dropout spacing).

Dude...DUDE!

I have the calipers.

And I said that I'd post when I measure.

I'm innocently asking if the know-ledge is out there.

And I posted a picture of a really sweet bike (Golden Boy, for one, is super jazzed to see my Mongoose).

And I helped all of us bike nerds have something to talk about instead of feeling alienated at work by all the non-cyclists (or the crabon cyclists).

What does the rear dropout spacing have to do with a bottom bracket?

Love those chrome mongooses, I have one myself, though without the biplane and in far worse condition. Got it for $20 at a campus police auction.


Never mind the setup, I'd launched the stem and saddle for a friend to borrow.

Come on guys, everyone knows those chrome Mongeese look better without the stickers.

Look at the markings on this 127mm bottom bracket spindle. I'm not the one to ask why they were marked that way, but they were.

https://velobase.com/ViewComponent.as...9-3776e73dfeae

So, as promised (it only took 2 months), I measured the bb. It's a 68mm shell and a 130mm spindle.

That's very cool. Learn something new every day.