# 1990 (?) Gary Fisher Mt. Tam with odd BB



## JaquesN (Sep 14, 2009)

I have just been given this Gary Fisher frame with a strange BB.

Gary Fisher Mt. Tam BB Shell by jimn, on Flickr


Gary Fisher Mt. Tam BB Shell by jimn, on Flickr

The shell measures about 87mm wide, and the ID of the shell is about 35mm. Does anyone know what kind of bottom bracket this is, or where you can get a new one? Has anyone tried cutting down and threading one of these for a standard English 68mm BB?

Thanks!
Jim


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## anthonyk (Feb 15, 2012)

Not sure about current sources, but when I had to replace mine ~15 years ago on a similar-era Fisher AL1, it was a proprietary Fisher bottom bracket.

If yours is in pretty bad shape, you're welcome to my old one (if I can get it out of the broken frame). It still spins, though the bearings feel like they could use some grease for sure.


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## TheMachinist (Feb 24, 2007)

You just need to remove the clip ring and press/pound the spindle out. It is a straight spindle riding on cartridge bearings. You should be able to find replacement bearings without too much trouble. Pull them out and measure the ID, OD and width. I would look on McMaster.com for replacement bearings. Motion Industries would probably have them too.


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## unicrown junkie (Nov 12, 2009)

It helps to have the "slug" tool to drive these in/out, but as Icantdrive says, they are easy enough to work on. In fact, this is my favorite BB system, love this style and it works FANTASTIC in my opinion.


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## theMeat (Jan 5, 2010)

Do you have a crankset that works/fits? Before you go throu the trouble of changing the bb, I'd recommend finding one suitable. Pretty sure that year fisher had an odd ball 88mm bb shell width, and the spindle is prolly 127 but not 100% sure.
If the bb and spindle are as suspect, do a google search for "gary fisher prometheus bb" should get you onto some info.


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## muddybuddy (Jan 31, 2007)

Just pull the clips, tap out the bearings and take them to a bearing store as suggested. or if i'm reading the number off your bearings correctly (6003DU):

NSK 6003DU Bearing 17 mm Bore 35 mm OD 9.96 mm Wide NEW | eBay

Just checked my 91 Super Caliber that has that style bottom bracket and the spindle is 127mm, which would be pretty typical for that time frame. It should work with a Shimano m730, Deore DX, Suntour XC or Sugino AT crank plus probably a bunch of the boutique cranks that were available around that time.


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## BAndy (Oct 17, 2011)

although they look pretty rusty and dirty - you might could clean them up and re-grease, if that grime and rust is just on the outside and the inside still has grease and isn't too bad or just plain worn out.. yes new bearings are preferable but hey, it's just a suggestion!..
(fyi - carefully pry the plastic seals from the bearing and clean with solvent, blast with carb cleaner, dry and re-grease) 
I have the same thing and did that although mine was a lot cleaner to start with!
have fun!


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## JaquesN (Sep 14, 2009)

icantdrive65 said:


> You just need to remove the clip ring and press/pound the spindle out. It is a straight spindle riding on cartridge bearings. You should be able to find replacement bearings without too much trouble. Pull them out and measure the ID, OD and width. I would look on McMaster.com for replacement bearings. Motion Industries would probably have them too.


That is the ticket.

I pulled out the clip on one side, tapped the spindle out, and presto, it's just a standard bb spindle meant to be used with the loose bearings of a typical BB. It's actually a Specialized brand spindle, though it might have been replaced at some point.

I still don't know if I'll use this frame, though, as it takes the inch-and-a-quarter threaded fork which I remember from this era with horror.

Thanks to all for the suggestions and info.


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## -Anomie- (Jan 16, 2005)

FYI on the headset, you can get reducers for about twenty bucks that will allow you to use a 1 1/8" head set and fork with that frame, so don't let that keep you from building it up. Also, if you replace the BB bearings, keep the old ones to use for tapping the new ones into the BB shell. The races will line up perfectly and it's better to hammer on crappy old bearings that you're going to throw away than directly on the new ones.


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## theMeat (Jan 5, 2010)

muddybuddy said:


> Just pull the clips, tap out the bearings and take them to a bearing store as suggested. or if i'm reading the number off your bearings correctly (6003DU):
> 
> NSK 6003DU Bearing 17 mm Bore 35 mm OD 9.96 mm Wide NEW | eBay
> 
> Just checked my 91 Super Caliber that has that style bottom bracket and the spindle is 127mm, which would be pretty typical for that time frame. It should work with a Shimano m730, Deore DX, Suntour XC or Sugino AT crank plus probably a bunch of the boutique cranks that were available around that time.


I actually built up an old 1990 Prometheus which I think had the same bb and shell size. My bb measured 127.5 and all those cranks except for Sugino touched the chainstays slightly. I also tried time correct topline and cook bros and they too touched slightly.


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## muddybuddy (Jan 31, 2007)

Odd. I've had both m730 and FX on mine with plenty of clearance.


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