Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Install Bottom Bracket backwards?

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Install Bottom Bracket backwards?

Old 07-13-05, 09:50 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Mar 2005
Posts: 1,442
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Install Bottom Bracket backwards?

Any reason I can't install a cartridge BB backwards? Why, you ask?

Hehe- I want a compact crank on my homebuilt recumbent. The present "boom" is from an old ten-speed with an old-style BB. It accomadates an aged full-size triple crank, but that makes my overall gear ratios just a tad too high. I have a nice Alivio compact crank, but it won't work on the present BB and spindle, it won't seat deep enough, and the front DR wont adjust to accomodate it.

So, I have an old Cro-mo Trek frame that was trashed by the frat boys. Seattube and BB still OK, but this would mean reversing the BB to have the "long" end of the spindle (where the crank mounts) on the proper side of the bike. (the downtube is bent.)

(This is one ugly critter, BTW, but functional. It's a test-bed for version 2.0)
Bikewer is offline  
Old 07-13-05, 10:45 AM
  #2  
Senior Member
 
DiegoFrogs's Avatar
 
Join Date: Feb 2005
Location: Scranton, PA, USA
Posts: 2,570

Bikes: '77 Centurion "Pro Tour"; '67 Carlton "The Flyer"; 1984 Ross MTB (stored at parents' house)

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 169 Post(s)
Liked 93 Times in 61 Posts
If it's a cup and cone bottom bracket, you could just flip the spindle. Whether or not this helps is a different matter... Sometimes this is an effective tool for getting fixed-gear chainline pretty close on the cheap, sometimes not. You'll have to measure your spindle to see how this affects things...
DiegoFrogs is offline  
Old 07-13-05, 10:57 AM
  #3  
Senior Member
 
juicemouse's Avatar
 
Join Date: Mar 2005
Location: Happy Valley
Posts: 813
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Bikewer
Any reason I can't install a cartridge BB backwards? Why, you ask?

Hehe- I want a compact crank on my homebuilt recumbent. The present "boom" is from an old ten-speed with an old-style BB. It accomadates an aged full-size triple crank, but that makes my overall gear ratios just a tad too high. I have a nice Alivio compact crank, but it won't work on the present BB and spindle, it won't seat deep enough, and the front DR wont adjust to accomodate it.

So, I have an old Cro-mo Trek frame that was trashed by the frat boys. Seattube and BB still OK, but this would mean reversing the BB to have the "long" end of the spindle (where the crank mounts) on the proper side of the bike. (the downtube is bent.)

(This is one ugly critter, BTW, but functional. It's a test-bed for version 2.0)
Most every modern bottom bracket, including the one that's meant to work with your Alivio compact crank, uses a symmetrical spindle. There ain't no "long end" on these units. The cranks might go on the bottom bracket that's in the Trek, but the offset was designed for a symmetrical spindle. They're cheap. Take the plunge.
__________________
It is my belief that every person in this world has something to teach, and everything to learn.

In memory of Jim Price (aka. sydney) ...
juicemouse is offline  
Old 07-13-05, 07:16 PM
  #4  
Senior Member
Thread Starter
 
Join Date: Mar 2005
Posts: 1,442
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 1 Time in 1 Post
I'm actually embarrassed. I had already cut the frame segment away and was simply looking at it wrong. The "short" side of the spindle takes the crank, and the long side goes on the left. I was holding it wrong...

This bit of cro-mo frame should give me a slightly-lighter boom, and the compact crank should lower my overall gear ratios to the point I want 'em. The only fly in the ointment will be mounting the front DR on the rather bent portion of the frame. I think it will go right under the damaged part, though.
Bikewer is offline  
Old 07-13-05, 07:35 PM
  #5  
Perineal Pressurized
 
dobber's Avatar
 
Join Date: Oct 2003
Location: In Ebritated
Posts: 6,555
Mentioned: 0 Post(s)
Tagged: 1 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by juicemouse
Most every modern bottom bracket, including the one that's meant to work with your Alivio compact crank, uses a symmetrical spindle. There ain't no "long end" on these units.
Some of the Shimano brackets are non-symmetrical. A 107 and a 110 extend equal length on the drive side but the 110 is 3 mm longer on the non-drive side. This lets you fiddle a bit with the chainline if need be.

Campy has asymmetrical cartridges. Phil Wood has a plethora of em
__________________
This is Africa, 1943. War spits out its violence overhead and the sandy graveyard swallows it up. Her name is King Nine, B-25, medium bomber, Twelfth Air Force. On a hot, still morning she took off from Tunisia to bomb the southern tip of Italy. An errant piece of flak tore a hole in a wing tank and, like a wounded bird, this is where she landed, not to return on this day, or any other day.
dobber is offline  
Old 07-13-05, 07:47 PM
  #6  
Senior Member
 
sydney's Avatar
 
Join Date: Jan 2004
Posts: 9,428
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by dobber
Some of the Shimano brackets are non-symmetrical. A 107 and a 110 extend equal length on the drive side but the 110 is 3 mm longer on the non-drive side. This lets you fiddle a bit with the chainline if need be.
With shimano cartridge type,No workee in english threaded BB unless you have the specific ones where both cups can be separated from the cartridge,allowing the carridge to be flipped.
sydney is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.