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

Dura Ace FC-7402: which BB?

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.

Dura Ace FC-7402: which BB?

Old 11-19-07, 07:09 PM
  #1  
digitalbicycle
Senior Member
Thread Starter
 
Join Date: Aug 2007
Location: Western North Carolina
Posts: 437
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Dura Ace FC-7402: which BB?

I just bought an 80s ***gin frameset (pics at http://bikeforums.net/showthread.php?t=363421) and am going to put a new Shimano 10 speed drivetrain on it. I have a set of Dura Ace FC-7402 cranks, which are 9 speed, but Sheldon Brown's site says there's no difference in the spiders b/w 9 and 10 speed, so if I get 10 speed chainrings I should be good to go.

I found on the internet somewhere that this crankset takes a 113mmx70mm Italian BB. Will a BB w/these dimensions give me a good chainline for a Shimano 10 speed cassette? I know that Shimano's BB-UN54 comes Italian threaded in a 113mmx70mm square taper, but I don't know how it stacks up to other BBs. Have other people had good experiences w/the UN54? If not, any other suggestions? Thanks.
digitalbicycle is offline  
Old 11-19-07, 07:18 PM
  #2  
vasracer
vasracer
 
Join Date: Oct 2007
Location: NYC!!!!
Posts: 247

Bikes: Leader LD-735TR, Mercier Kilo tt, 3Rensho pursuit(not complete)

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
You mean the frame takes a 113x70mm Italian Bottom bracket. Usually 113mm bottom brackets are for triple cranksets. If you have a triple crankset then your good but if you have a double the crank might sit out just a bit too far and you run the risk of derailing you chain.

If you have a double chainring crank try finding a 109mm x 70mm Italian bottom bracket. This will bring your chainline closer to your frame. This will eliminate extreme chainline angles and reduce the risk of derailment.
vasracer is offline  
Old 11-19-07, 07:26 PM
  #3  
digitalbicycle
Senior Member
Thread Starter
 
Join Date: Aug 2007
Location: Western North Carolina
Posts: 437
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by vasracer View Post
You mean the frame takes a 113x70mm Italian Bottom bracket. Usually 113mm bottom brackets are for triple cranksets. If you have a triple crankset then your good but if you have a double the crank might sit out just a bit too far and you run the risk of derailing you chain.

If you have a double chainring crank try finding a 109mm x 70mm Italian bottom bracket. This will bring your chainline closer to your frame. This will eliminate extreme chainline angles and reduce the risk of derailment.
Thanks for the reply. I found the measurements for the BB here:
http://www.bikepro.com/products/bott...omptable.shtml

I assumed this meant that the crankset was only compatible with this size BB. If this is not the case, and spindle length will vary w/frame, what's the point of that compatibility table?

Also, the crank is a double.
digitalbicycle is offline  
Old 11-19-07, 07:44 PM
  #4  
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Posts: 28,349

Bikes: 1987 Bianchi Campione

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 31 Post(s)
Likes: 0
Liked 6 Times in 6 Posts
Originally Posted by digitalbicycle View Post
If this is not the case, and spindle length will vary w/frame,
Uh. Why would this be true. Spindle length 'x' gives chainline 'y'. That doesn't change on any bike. Unless the crankset hits the chainstay and you have to get a longer bb.
operator is offline  
Old 11-19-07, 07:50 PM
  #5  
Soil_Sampler
A little North of Hell
 
Join Date: Mar 2006
Posts: 4,892
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Likes: 0
Liked 1 Time in 1 Post
7402

7402 should be 8spd

112-113 bb

http://www.sheldonbrown.com/bbsize.html#dura
Soil_Sampler is offline  
Old 11-19-07, 08:06 PM
  #6  
digitalbicycle
Senior Member
Thread Starter
 
Join Date: Aug 2007
Location: Western North Carolina
Posts: 437
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Soil_Sampler View Post
7402 should be 8spd

112-113 bb

http://www.sheldonbrown.com/bbsize.html#dura
Damn, I don't know where I got the idea that 7400 was 9 speed. Are there going to be any compatibility problems using the 7402 crankset with a newer 10 speed drivetrain, provided I buy new chainrings?
digitalbicycle is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
jetjock
Road Cycling
1
09-20-12 05:59 AM
Kenal0
Road Cycling
7
09-01-05 10:44 AM

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


Thread Tools
Search this Thread

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

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.