Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

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.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 12-14-09, 05:07 PM   #1
takingcontrol
Mass Mover
Thread Starter
 
takingcontrol's Avatar
 
Join Date: Apr 2009
Location: Independence OR
Bikes: KHS XXL
Posts: 303
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
drive side crank

Thanks in advance for any advice. I have recently rebuilt an ~84 Bianchi (Japanese) and replaced the bottom bracket with a square tapered cartridge. My issue is the driver side has come loose a couple of times with minimal mileage (around 10). The socket has no visible deformity but I don't have a tool to measure or Mic the inside. The cranks are the original Sugino and I am wondering if they need to be torqued to a minimum ftlb or if I need to replace the cranks.
takingcontrol is offline   Reply With Quote
Old 12-14-09, 07:54 PM   #2
CCrew
Older than dirt
 
CCrew's Avatar
 
Join Date: May 2008
Location: Winchester, VA
Bikes: Too darn many.. latest count is 11
Posts: 5,343
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Most square taper are 40ft/lbs for the torque spec. And yeah, torquing to the correct spec is highly adviseable, or they come loose and egg the holes in the cranks. Sugino should have torque specs somewhere on the web I'm sure. I'd find what they call for rather than blindly following the 40lb, although that should be close.
CCrew is offline   Reply With Quote
Old 12-14-09, 08:51 PM   #3
tonski 
Senior Member
 
Join Date: Jun 2009
Bikes: Ritte 8055, Felt TK3, Cervelo S2 & P3, Giant TCR
Posts: 255
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by CCrew View Post
Most square taper are 40ft/lbs for the torque spec. And yeah, torquing to the correct spec is highly adviseable, or they come loose and egg the holes in the cranks. Sugino should have torque specs somewhere on the web I'm sure. I'd find what they call for rather than blindly following the 40lb, although that should be close.
40 Nm or 40 lb/ft? I really don't know but 40 lb/ft seems pretty damn tight (40Nm is 29.5 lb/ft).
tonski is offline   Reply With Quote
Old 12-14-09, 08:56 PM   #4
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Bikes: 1987 Bianchi Campione
Posts: 28,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by tonski View Post
40 Nm or 40 lb/ft? I really don't know but 40 lb/ft seems pretty damn tight (40Nm is 29.5 lb/ft).
Square taper cranks generally take 35ft/lb+
operator is offline   Reply With Quote
Old 12-14-09, 08:56 PM   #5
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Bikes: 1987 Bianchi Campione
Posts: 28,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by takingcontrol View Post
Thanks in advance for any advice. I have recently rebuilt an ~84 Bianchi (Japanese) and replaced the bottom bracket with a square tapered cartridge. My issue is the driver side has come loose a couple of times with minimal mileage (around 10). The socket has no visible deformity but I don't have a tool to measure or Mic the inside. The cranks are the original Sugino and I am wondering if they need to be torqued to a minimum ftlb or if I need to replace the cranks.
You don't need to guess. If the cranks come loose after apply appropriate tightening torque they're hosed. You have nothing to lose, really by trying.
operator is offline   Reply With Quote
Old 12-15-09, 12:11 AM   #6
noglider 
aka Tom Reingold
 
noglider's Avatar
 
Join Date: Jan 2009
Location: West Village, New York City
Bikes: too many
Posts: 27,142
Mentioned: 25 Post(s)
Tagged: 0 Thread(s)
Quoted: 246 Post(s)
How do you determine that it's loose? This is not a trick question. Does it wobble? Or are you testing the tightness of the bolt?
__________________
Tom Reingold, noglider@pobox.com
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog

Please email me rather than PM'ing me. Thanks.
noglider is offline   Reply With Quote
Old 12-15-09, 09:28 AM   #7
Bianchigirll 
Bianchi Goddess
 
Bianchigirll's Avatar
 
Join Date: Apr 2009
Location: Camp Hill, PA
Bikes: Too many to list here check my signature.
Posts: 22,462
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
you did use the correct taper cartridge BB yes? JIS I think right gentlemen? if you used a Campi or some other Italian designed to fit pre 95ish Campi cranks the different taper may be adding to your woes
__________________
Bianchis '87 Sport SX, '90 Proto, '90 Campione del Fausto Giamondi Specialisma Italiano Mundo, '91 Boarala 'cross, '93 Project 3, '86 Volpe, '97 Ti Megatube, , '90 something Vento 603,

Others but still loved,; '80 RIGI, '80 Batavus Professional, '87 Cornelo, '09 Motobecane SOLD, '?? Jane Doe (still on the drawing board), '90ish Haro Escape
Bianchigirll is online now   Reply With Quote
Old 12-15-09, 09:47 AM   #8
davidad
Senior Member
 
Join Date: Feb 2009
Bikes:
Posts: 4,863
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
25 to 32 ft pounds of torque. http://www.parktool.com/repair/readhowto.asp?id=88
Do not retorque. The arms will try to move away from the bolts and the torque will go down slightly. http://www.sheldonbrown.com/brandt/i...ng-cranks.html
davidad is offline   Reply With Quote
Old 12-15-09, 09:53 AM   #9
Homebrew01
Super Moderator
 
Homebrew01's Avatar
 
Join Date: Jul 2004
Location: Ffld Cnty Connecticut
Bikes: Old Steelies I made, Old Cannondales
Posts: 19,727
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 117 Post(s)
Quote:
Originally Posted by Bianchigirll View Post
you did use the correct taper cartridge BB yes? JIS I think right gentlemen? if you used a Campi or some other Italian designed to fit pre 95ish Campi cranks the different taper may be adding to your woes
To follow on to this, if you have a mis-match, then the crank might go on too far, so that the BB is flush with the crank opening. Thus the bolt cannot press the crank tighter, because the bolt is now pressing against the BB and crank at the same time. You could remove the bolt and verify that the bb axle is still recessed, not flush with the crank.
__________________
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike
Homebrew01 is offline   Reply With Quote
Old 12-15-09, 12:29 PM   #10
takingcontrol
Mass Mover
Thread Starter
 
takingcontrol's Avatar
 
Join Date: Apr 2009
Location: Independence OR
Bikes: KHS XXL
Posts: 303
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by noglider View Post
How do you determine that it's loose? This is not a trick question. Does it wobble? Or are you testing the tightness of the bolt?
A very noticeable wobble.
Quote:
Originally Posted by Bianchigirll View Post
you did use the correct taper cartridge BB yes? JIS I think right gentlemen? if you used a Campi or some other Italian designed to fit pre 95ish Campi cranks the different taper may be adding to your woes
I think so, I am using an English threaded Shimano BB that I was recommended by my LBS.
takingcontrol is offline   Reply With Quote
Old 12-15-09, 03:42 PM   #11
DMF 
Elitist Troglodyte
 
DMF's Avatar
 
Join Date: Jun 2006
Location: Dallas
Bikes: 03 Raleigh Professional (steel)
Posts: 6,924
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
40 Nm or 30 ft-lb. (ft-lb = Nm * 0.75).

Sugino probably uses a JIS taper (vice ISO). But taper isn't necessarily a problem - both use the same taper angle. The issue is more a matter of where the crank sits on the taper.

What did you do to correct the wobble? Retighten the bolt? If so you're probably hosed as riding a loose (wobbly) crank arm distorts the hole and ruins the arm. Replace the arm and this time tighten the bolt correctly.
__________________
Stupidity got us into this mess - why can't it get us out?

- Will Rogers
DMF is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -6. The time now is 03:50 PM.