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 07-29-09, 08:43 PM   #1
sjs731
Strob
Thread Starter
 
sjs731's Avatar
 
Join Date: Jul 2007
Location: Wisconsin
Bikes: Trek 4300 and Redline D460 29er
Posts: 77
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Bottom Bracket Length

I ride a Redline Mono 9 and the original spec says the bottom bracket is 68mm x 108mm. Will a 68mm x 113mm make that much difference in chainline? 113mm seems to be the most common ISIS length.
sjs731 is offline   Reply With Quote
Old 07-29-09, 08:50 PM   #2
AnthonyG
Senior Member
 
AnthonyG's Avatar
 
Join Date: May 2005
Location: Queanbeyan, Australia.
Bikes:
Posts: 3,710
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 231 Post(s)
Yes it will make a difference but one of the catches is that the chainline often isn't what the specs say it is so a different axle length is called for. Now the problem is that the most common error is that the chainline is WIDER than spec so the last thing you need to do is to deliberately make it wider still.

Measure it to see where your at. Measure from the centre of the seat tube or down tube to the chainring. I'm assuming it has a single ring on front? If its a double you measure to halfway between the two rings and if its a triple you measure to the middle ring.

Anthony
AnthonyG is offline   Reply With Quote
Old 07-30-09, 09:09 AM   #3
Retro Grouch 
Senior Member
 
Retro Grouch's Avatar
 
Join Date: Feb 2004
Location: St Peters, Missouri
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Posts: 26,908
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 207 Post(s)
Are you changing cranks? The crankset is the most significant single factor in determining the proper BB spindle length.
Retro Grouch is offline   Reply With Quote
Old 07-30-09, 09:20 AM   #4
DaveSSS
Senior Member
 
Join Date: Sep 2008
Location: Loveland, CO
Bikes: Two LOOK 585s, one KG461
Posts: 4,987
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I've figured out why manufacturers use that stupid 43.5mm to a point in between the chainrings, that can't be measured. It's far easier to check to the tip of a tooth on the little ring when the FD is in place. That should be very close to 40mm. The big ring would be in the 47-48mm range. Measure from the side of the seat tube and add half the diameter.
DaveSSS is offline   Reply With Quote
Old 07-30-09, 11:54 AM   #5
sjs731
Strob
Thread Starter
 
sjs731's Avatar
 
Join Date: Jul 2007
Location: Wisconsin
Bikes: Trek 4300 and Redline D460 29er
Posts: 77
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I'm not changing cranksets and yes it just has a single ring in the front. I think I can figure it out from here. Thanks for the help.
sjs731 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 02:22 AM.