Non-Standard BB Shell?
03-13-23, 11:20 AM
#1
Senior Member
Thread Starter
Join Date: Jul 2018
Posts: 603
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 167 Post(s)
Likes: 0
Liked 252 Times
in
146 Posts
Non-Standard BB Shell?
I recently picked up an '85 (I think) Rocky Mountain Giro road bike which I've taken apart. When I went to install a different BB, I found that the diameter of this shell was slightly bigger than normal. I've never seen this before. Has anyone had a similar experience?
03-13-23, 11:24 AM
#2
Senior Member
Join Date: Jun 2002
Location: Montreal, Quebec
Posts: 5,925
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1819 Post(s)
Liked 1,693 Times
in
974 Posts
If by some chance that the frame was built in Italy it might have an Italian threaded bottom bracket shell. What is the width of the bottom bracket shell? If it is 70 mm that would be a clue
Likes For alcjphil:
03-13-23, 01:26 PM
#3
I'm good to go!
Join Date: Jul 2017
Location: Mississippi
Posts: 14,986
Bikes: Tarmac Disc Comp Di2 - 2020
Mentioned: 51 Post(s)
Tagged: 0 Thread(s)
Quoted: 6193 Post(s)
Liked 4,809 Times
in
3,317 Posts
Maybe it had a Ashtabula one piece crank in it originally. Those are way bigger shells IIRC. But it's been over a dozen years since I had anything with a Ashtabula crank?
What did you take out of it? Or was it with no cranks?
What did you take out of it? Or was it with no cranks?
03-13-23, 04:53 PM
#4
Senior Member
Thread Starter
Join Date: Jul 2018
Posts: 603
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 167 Post(s)
Likes: 0
Liked 252 Times
in
146 Posts
Looks like it's an Italian BB shell on a Canadian frame, and the dropouts are Campy, guess I just got confused. That happens a lot.
03-14-23, 05:52 AM
#5
I’m a little Surly
Join Date: Jan 2010
Location: Near the district
Posts: 2,422
Bikes: Two Cross Checks, a Karate Monkey, a Disc Trucker, and a VO Randonneur
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 699 Post(s)
Liked 1,294 Times
in
647 Posts
Some mountain bike BB shells are 73mm vs the 70mm IT or 68mm BSA
03-14-23, 09:42 AM
#6
Old fart
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,784
Bikes: Several, mostly not name brands.
Mentioned: 153 Post(s)
Tagged: 0 Thread(s)
Quoted: 3587 Post(s)
Liked 3,400 Times
in
1,934 Posts
I recently picked up an '85 (I think) Rocky Mountain Giro road bike which I've taken apart. When I went to install a different BB, I found that the diameter of this shell was slightly bigger than normal. I've never seen this before. Has anyone had a similar experience?
03-14-23, 09:45 AM
#7
Old fart
Join Date: Nov 2004
Location: Appleton WI
Posts: 24,784
Bikes: Several, mostly not name brands.
Mentioned: 153 Post(s)
Tagged: 0 Thread(s)
Quoted: 3587 Post(s)
Liked 3,400 Times
in
1,934 Posts
03-15-23, 09:39 AM
#9
Senior Member
Join Date: Jun 2002
Location: Montreal, Quebec
Posts: 5,925
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1819 Post(s)
Liked 1,693 Times
in
974 Posts
I recently picked up an '85 (I think) Rocky Mountain Giro road bike which I've taken apart. When I went to install a different BB, I found that the diameter of this shell was slightly bigger than normal. I've never seen this before. Has anyone had a similar experience?
Last edited by alcjphil; 03-15-23 at 05:03 PM.
03-15-23, 02:45 PM
#10
Senior Member
Join Date: Dec 2010
Location: northern Deep South
Posts: 8,903
Bikes: Fuji Touring, Novara Randonee
Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 2604 Post(s)
Liked 1,932 Times
in
1,213 Posts
The cynic in me says there can't be any non-standard BBs. If you took a bear's claw and stuck it through a piece of metal, it would surely be within tolerance for at least one of the many BB standards!
