Bottom Bracket Identification help for old Road Bike

kbajaj

Well-Known Member
So I started a an old road bike restoration project while this crazy snow/ice is keeping me away from the trails.
The frame is an old (likely late 80s early 90s) Specialized Allez - carbon fiber tubes with aluminum lugs. Its got Shimano 105 rim brakes, Campagnolo Athena rear hub and Campagnolo 8 speed cassette paired to a Shimano RX100 RD. The rear Brifter is 7 speed and front is 3 speed. The crankset is a 3 piece square taper Propulsion 8 with pedals stuck in it (probably corrosion welded) with front derailleur being Shimano Deore XT. So a lot of mix and match going on here but this all worked together nicely before I decided to take it all apart to paint the frame.

When I took the BB out, some rubber seals fell out crumbled and a couple of ball bearings also fell out so pretty sure I can't reuse it. I can't figure out the type of replacement BB to order.
Here's what I know:
The BB (photo 1) says Shimano BC 1.37 on it
The shell width I measured is about 68.4 mm (one side of the BB rings has 70 etched on it - is this shell width?)
The shell dia. I measured is 34 mm
BB is threaded (photo 2 of the shell)
There is a rubbery sleeve inside the shell - not sure if this is a part of the frame and is supposed to stay but it is stuck. Do I rip it out?
From internet research, this could be a BSA threaded.

Can you experts guide me on what BB to order as a replacement to use with the same spindle and crankset? and if I decide to get a new crankset - is there an alternate option for BB and crankset?


IMG_4697.JPG

Photo Feb 08, 6 11 28 PM.jpg
 

GSTim

Formerly M3Tim
Pretty sure this a standard ISO BB. I think if you thread out that inner race, you should be able to put a standard threaded or cartridge BB in there (Shimano, Chris King).
 

Karate Monkey

Well-Known Member
Measure the spindle length and order a Shimano UN55 or the like. The stock cranks will work.

This. Don't bother futzing with the original, not worth it. The bit still in the shell is the center cover for the original bottom bracket--it comes out (sometimes with a good yank). If it's a Shimano spindle, it will have a 3 character code on it (ie: DN-L) which will tell you length/whether it's symmetric or not (but it probably is, and as @jimvreeland pointed out, just replace it anyway). that "70" is really "OL", and is a date code.

btw: don't paint a frame without plugging holes (including the head tube/bottom bracket shell). It's bad juju, and only serves to increase the amount of time you need to spend cleaning it prior to reassembly.
 

kbajaj

Well-Known Member
Measure the spindle length and order a Shimano UN55 or the like. The stock cranks will work.
Thanks @jimvreeland. This is probably the best option for my skillset and tool level!
Now I gotta figure out whether I can get the pedals unstuck from the cranks or I may need to get new cranks too.
Can you get these 3 piece cranks now or should I go with is it GXP standard?

The pedals I have now are so stuck that the pedal wrench just notches the spindle and the Allen key side is stripped.
D38F718B-5CDC-4CA2-BE31-DC0798426168.jpeg
 

kbajaj

Well-Known Member
This. Don't bother futzing with the original, not worth it. The bit still in the shell is the center cover for the original bottom bracket--it comes out (sometimes with a good yank). If it's a Shimano spindle, it will have a 3 character code on it (ie: DN-L) which will tell you length/whether it's symmetric or not (but it probably is, and as @jimvreeland pointed out, just replace it anyway). that "70" is really "OL", and is a date code.

btw: don't paint a frame without plugging holes (including the head tube/bottom bracket shell). It's bad juju, and only serves to increase the amount of time you need to spend cleaning it prior to reassembly.
Yeah I agree with all you said. I am going to get a cartridge type BB.

And too late for plugging holes - already did the deed this past summer. Head tube didn’t give any issues, the steerer spins nicely. Hope the BB doesn’t give any issues. I bet the sleeve still in the shell is stuck because I painted over it.
 

Patrick

Overthinking the draft from the basement already
Staff member
Thanks @jimvreeland. This is probably the best option for my skillset and tool level!
Now I gotta figure out whether I can get the pedals unstuck from the cranks or I may need to get new cranks too.
Can you get these 3 piece cranks now or should I go with is it GXP standard?

The pedals I have now are so stuck that the pedal wrench just notches the spindle and the Allen key side is stripped. View attachment 151463

take the pedal off the spindle and use a pipe wrench.
 

mtbiker87

Well-Known Member
Did a similar resteration on my U-08, but since it was French, and I was to cheap to buy a French threaded cartridge BB from Velo Orange, I rebuilt it with new individual ball bearings...yay !!. So take everyone's advice and buy a new cartridge one..lol. Those look like Origin 8 cranks. Nothing special there. I'd forget trying to remove the pedals and find something better.
 
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kbajaj

Well-Known Member
Did a similar resteration on my U-08, but since it was French, and I was to cheap to buy a French threaded cartridge BB from Velo Orange, I rebuilt it with new individual ball bearings...yay !!. So take everyone's advice and buy a new cartridge one..lol. Those look like Origin 8 cranks. Nothing special there. I'd forget trying to remove the pedals and find something better.
U-08? That sounds like a submarine.
 
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