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 05-04-08, 09:55 AM   #1
d2create
Senior Member
Thread Starter
 
d2create's Avatar
 
Join Date: Apr 2003
Location: Houston we have a problem
Bikes:
Posts: 2,914
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Best way to figure out best bb length?

I did a search and couldn't figure out the best way to calculate what bb length is needed for good chain line.
I'm starting a new build and i have the frame measurements. Will have the rear hub (sram i-motion 9) soon. Have not yet decided on a crank but it will be a single chain ring.
d2create is offline   Reply With Quote
Old 05-04-08, 10:19 AM   #2
bikeman715
Senior Member
 
bikeman715's Avatar
 
Join Date: Mar 2008
Location: Salinas , Ca.
Bikes: Bike Nashbar AL-1 ,Raligh M50 , Schwinn Traveler , and others
Posts: 2,404
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
the chain ring need to clear the chain stay by 5 mm at it closes point.
bikeman715 is offline   Reply With Quote
Old 05-04-08, 10:29 AM   #3
HillRider 
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Posts: 28,776
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 36 Post(s)
Actually, the crank defines the required bottom bracket length. Once you have chosen a crank, the bb should be based on what the crank manufacturer says.
HillRider is offline   Reply With Quote
Old 05-04-08, 01:04 PM   #4
d2create
Senior Member
Thread Starter
 
d2create's Avatar
 
Join Date: Apr 2003
Location: Houston we have a problem
Bikes:
Posts: 2,914
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by HillRider View Post
Actually, the crank defines the required bottom bracket length. Once you have chosen a crank, the bb should be based on what the crank manufacturer says.
But wouldn't rear hub spacing also factor in?
d2create is offline   Reply With Quote
Old 05-04-08, 01:57 PM   #5
roadfix
hello
 
roadfix's Avatar
 
Join Date: May 2003
Location: Los Angeles
Bikes:
Posts: 18,557
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Quote:
Originally Posted by d2create View Post
But wouldn't rear hub spacing also factor in?
In most cases, no. I think you're over-thinking this too much. Just go with the recommended BB for your crankset and you should be fine.
roadfix is offline   Reply With Quote
Old 05-04-08, 02:48 PM   #6
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 d2create View Post
But wouldn't rear hub spacing also factor in?
Not unless the hub was deliberately dished over and respaced. The chainline is listed as 48,9 mm in the technical docs. All you need is a crankset and a bb that will give you that chaInline and you're ready to go.

Manufacturers usually will state what length bb with $CRANK_MODEL will give $CHAINLINE_VALUE.
operator 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 07:06 AM.