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 10-20-10, 12:05 PM   #1
|3iker
Alfredo Contador
Thread Starter
 
|3iker's Avatar
 
Join Date: Jan 2010
Location: Where everybody knows my name
Bikes:
Posts: 431
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
FD cage travel - Road vs MTB

I'm trying to use my road FD on a 48/38/28t chainring. However the FD cage can't seem to travel far enough to the largest ring.
Does road FD move less than mtb FD?
|3iker is offline   Reply With Quote
Old 10-20-10, 12:06 PM   #2
gitarzan
Lost Again
 
gitarzan's Avatar
 
Join Date: Jul 2009
Location: Columbus, Oh!
Bikes: Soma Saga, 1991 Sirrus, Specialized Secteur Elite, Miele Umbria Elite.
Posts: 1,041
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Is it built for two rings?
gitarzan is offline   Reply With Quote
Old 10-20-10, 12:22 PM   #3
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 18,766
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 207 Post(s)
There lies the question: triple road versus triple mountain a valid comparison.

Throw of the parallelogram can me measured, but not on a working bike,
as you have to back off both limit screws, and the chain is in the way.

Do a Berto, buy the parts and set up a measuring fixture.
fietsbob is offline   Reply With Quote
Old 10-20-10, 12:56 PM   #4
wunderkind
Pro Paper Plane Pilot
 
wunderkind's Avatar
 
Join Date: May 2009
Bikes:
Posts: 1,645
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
see bicycletutor.com videos.

Last edited by wunderkind; 10-20-10 at 04:07 PM.
wunderkind is offline   Reply With Quote
Old 10-20-10, 01:44 PM   #5
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Bikes: Trek 5500, Colnago C-50
Posts: 9,433
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Was the shifter in its lowest position when the cable was attached? It should have been, with all of the slack pulled out of the cable.
Is the chainline correct for the crankset?
Al1943 is offline   Reply With Quote
Old 10-20-10, 05:05 PM   #6
|3iker
Alfredo Contador
Thread Starter
 
|3iker's Avatar
 
Join Date: Jan 2010
Location: Where everybody knows my name
Bikes:
Posts: 431
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It's a triple FD.

Al1943, that was the first thing I checked about I dunno..... 1000x!
Apart from the road FD the crankset and chain are original.
|3iker is offline   Reply With Quote
Old 10-20-10, 05:16 PM   #7
surreal
Senior Member
 
surreal's Avatar
 
Join Date: Mar 2002
Location: NJ
Bikes:
Posts: 3,084
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The "throw" of road and mtb triple FDs are quite similar, but the little arm that the parallelogram sits on will be further out on the mtb FD, meaning that the parallelogram of the mtb FD will not swing as far inboard, and the parallelogram of the road FD will not swing as far outboard. If you have a mtn crank and a road FD, i wouldn't be surprised if the thing won't swing out far enough. Fixes? Get an appropriate mtb FD; one with the pull and swing you need, that'll handle a 48t large chainring. Or, if you have a square taper crank, you may be able to use a BB with a shorter spindle, depending on the requirements of your crank. Grabbing a dual-pull, high-clamp XT with the 48t large-ring capacity would probably solve your problem most easily, but it's hard to say with the available information.

-rob
surreal is offline   Reply With Quote
Old 10-20-10, 05:25 PM   #8
Bezalel
Senior Member
 
Join Date: Mar 2010
Location: City of Brotherly Love
Bikes: Raleigh Companion, Nashbar Touring, Novara DiVano, Trek FX 7.1, Giant Upland
Posts: 1,507
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by |3iker View Post
I'm trying to use my road FD on a 48/38/28t chainring. However the FD cage can't seem to travel far enough to the largest ring.
Does road FD move less than mtb FD?
They move the same amount but the road chainline is shorter that a MTB chainline so you might need a shorter bottom bracket. Also keep im mind that road amd MTB FDs have different cable pull ratios co you can't mix index shifters and FDs.
Bezalel is offline   Reply With Quote
Old 10-20-10, 09:28 PM   #9
Cyclesafe
Senior Member
 
Join Date: May 2006
Location: San Diego
Bikes: IF steel deluxe 29er tourer
Posts: 1,435
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Not all road FD are the same. For example, "improvements" from the Ultegra 6503 to subsequent 10 speed Ultegra FD's made them no longer work well with a 48T big chainring. The IRD Alpina-d FD has been described as a clone of the 6503.

http://www.interlocracing.com/cdfrtder.html
http://sheldonbrown.com/harris/derailers-front.html

If friction shifting, an XT FD works fine.
Cyclesafe is offline   Reply With Quote
Old 10-20-10, 09:51 PM   #10
surreal
Senior Member
 
surreal's Avatar
 
Join Date: Mar 2002
Location: NJ
Bikes:
Posts: 3,084
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
holy crap, i'd forgotten about the likelihood that he's got an indexed front shifter. that'd complicate the mtb FD recommendation a bit. OP, let us know what cranks and shifts you're using. That info'd decide whether you want a different BB or a different FD.

-rob
surreal 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 04:23 PM.