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 05-25-11, 09:02 PM   #1
Dan The Man
Senior Member
Thread Starter
 
Join Date: May 2008
Bikes:
Posts: 1,215
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Help, broken front derailleur tab

I was adjusting the deraileur on my mom's 2003 Giant OCR 2 and somehow broke off that tab that attaches the front derailleur to the seat tube. It's a piece of aluminum which is bolted onto the frame and also bolted onto the derailleur. It has a slot in it for the derailleur to move up and down. I have no idea what this is called or where to find a new one. Are they particular to the bicycle or is it a generic part? Tomorrow I will try phoning some bike shops.
Dan The Man is offline   Reply With Quote
Old 05-25-11, 09:27 PM   #2
FastJake
Constant tinkerer
 
FastJake's Avatar
 
Join Date: May 2010
Location: Madison, Wisconsin
Bikes:
Posts: 7,577
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I believe that's called the braze-on tab. Since it's bolted on, there's a good chance you'll be able to find a replacement and just bolt it on. When you start snapping the actual FD braze-ons off the frame you run into real trouble.

Post a picture of it, maybe someone on here can identify it.
FastJake is offline   Reply With Quote
Old 05-25-11, 09:46 PM   #3
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,824
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 858 Post(s)
+1 "braze-on" is a name that carries forward from the days when these were brazed on to steel frames. Nowadays it's used for all attached front derailleur mounts, brazed of bolted on. If the screws aren't damaged or stripped you should be able to scrape up a new one.

BTW- when's the last time anyone dialed a phone.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline   Reply With Quote
Old 05-25-11, 10:00 PM   #4
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 22,043
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1097 Post(s)
if the front derailleur tab is pop-riveted on, the pop rivets
can be drilled out and re done,
if not, you have a single chainring bike from now on..

shut off the computer and go down to the dealer that
sold you the bike.

Last edited by fietsbob; 05-25-11 at 11:09 PM.
fietsbob is offline   Reply With Quote
Old 05-25-11, 10:47 PM   #5
jeepr
Senior Member
 
jeepr's Avatar
 
Join Date: Mar 2011
Location: Detroit, MI
Bikes:
Posts: 552
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by fietsbob View Post
aluminum frames that don't have replaceable
dropout dérailleur tabs are scrap metal.
Working on converting one to a replaceable rear hanger now. We will see.
jeepr is offline   Reply With Quote
Old 05-25-11, 11:15 PM   #6
Dan The Man
Senior Member
Thread Starter
 
Join Date: May 2008
Bikes:
Posts: 1,215
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by fietsbob View Post
if the front derailleur tab is pop-riveted on, the pop rivets
can be drilled out and re done,
if not, you have a single chainring bike from now on..

shut off the computer and go down to the dealer that
sold you the bike.
The tab was attached to the bike with two flathead hex screws. I removed the screws and the broken half of the tab so now there are just the braze-on threaded holes in the frame. There were no rivets.

Also, on a somewhat unrelated note, when I was adjusting the rear derailleur (9 speed Tiagra), I could either get every up-shift to work consistently or get every downshift to work, but I could not get both at the same time. Is this more likely due to gunked housing or gunked shifters or something else? Should I fiddle with the B-tensioner?

Last edited by Dan The Man; 05-25-11 at 11:20 PM.
Dan The Man is offline   Reply With Quote
Old 05-25-11, 11:28 PM   #7
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Bikes: velospace.org/viewcluster?c=873
Posts: 7,115
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
I'd call that 'tab' a front derailleur hanger.

As for your shifting, b-screw adjustment might help, but it's most likely caused by excessive cable friction; clean and re-lube.
Kimmo is offline   Reply With Quote
Old 05-26-11, 12:04 AM   #8
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 22,043
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1097 Post(s)
Dealer have the replacement part?
did you ask a Giant brand bike dealer??
that's not a question to get that answer here.

Last edited by fietsbob; 05-26-11 at 12:08 AM.
fietsbob is offline   Reply With Quote
Old 05-26-11, 01:10 AM   #9
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Bikes: velospace.org/viewcluster?c=873
Posts: 7,115
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
If you can't get one from Giant, you should be able to carve one from a lump of ally.
Kimmo is offline   Reply With Quote
Old 05-26-11, 01:27 AM   #10
igknighted
Senior Member
 
igknighted's Avatar
 
Join Date: Sep 2008
Location: Somerville, MA
Bikes:
Posts: 414
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Or... file away the excess and just use a clamp-type front derailleur instead (or even better... they make an adapter that clamps onto the seat tube to allow you to use a braze-on front derailleur on a bike without such a tab, so you wouldn't even have to buy a new front derailleur)
igknighted is offline   Reply With Quote
Old 05-26-11, 07:48 AM   #11
Dan The Man
Senior Member
Thread Starter
 
Join Date: May 2008
Bikes:
Posts: 1,215
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by igknighted View Post
Or... file away the excess and just use a clamp-type front derailleur instead (or even better... they make an adapter that clamps onto the seat tube to allow you to use a braze-on front derailleur on a bike without such a tab, so you wouldn't even have to buy a new front derailleur)
There is no excess to file off, why do people keep implying that this thing was somehow welded onto the frame?
Dan The Man is offline   Reply With Quote
Old 05-26-11, 07:54 AM   #12
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 30,824
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 858 Post(s)
One other possibility if you can't find a replacement "braze-on". If you remove it completely there shouldn't be any reason you can't use a clamp-on mount front derailleur. So you're in good shape either way.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline   Reply With Quote
Old 05-26-11, 08:00 AM   #13
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: 29,108
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 174 Post(s)
Quote:
Originally Posted by Dan The Man View Post
There is no excess to file off, why do people keep implying that this thing was somehow welded onto the frame?
The "excess" can the female threaded fittings that the tab bolts thread into and they may not be flush with the seat tube.

If the seattube is round and of a standard diameter (1-1/8", 1-1/4" or 1-3/8"; 28.6, 31.8 or 34.9 mm respectively) a front derailleur clamp adapter is the way to go. If the seat tube is not round or of an non-standard diameter, you will have to replace the factory tab or fabricate a replacement.
HillRider is offline   Reply With Quote
Old 05-26-11, 08:00 AM   #14
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Bikes: velospace.org/viewcluster?c=873
Posts: 7,115
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
There are a couple of thread inserts in the tube; it'd be a crying shame to employ a clamp-on rather than use them IMO.

Also, they may foul the clamp if they're not flush.
Kimmo is offline   Reply With Quote
Old 05-26-11, 08:02 AM   #15
igknighted
Senior Member
 
igknighted's Avatar
 
Join Date: Sep 2008
Location: Somerville, MA
Bikes:
Posts: 414
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Dan The Man View Post
There is no excess to file off, why do people keep implying that this thing was somehow welded onto the frame?
Easy, because if I assume there is nothing left and you try my suggestion (and there was something still there), it wont turn out well. If I assume that there might be something there and you simply skip that step if there isn't, then everything works out. You weren't specific in your OP, so I tried to cover as many bases as possible.
igknighted is offline   Reply With Quote
Old 05-26-11, 08:11 AM   #16
Dan The Man
Senior Member
Thread Starter
 
Join Date: May 2008
Bikes:
Posts: 1,215
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
The Giant dealer in town told me they could order one for around $20. I don't know if any of the other shops will have it. I found a picture of it from the Giant website:
Dan The Man is offline   Reply With Quote
Old 05-26-11, 08:14 AM   #17
Kimmo
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Bikes: velospace.org/viewcluster?c=873
Posts: 7,115
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Shwing!

The one on my CFR1 was stainless plate; I always thought it was dumb how it wasn't ally.
Kimmo is offline   Reply With Quote
Old 05-26-11, 08:16 AM   #18
Dan The Man
Senior Member
Thread Starter
 
Join Date: May 2008
Bikes:
Posts: 1,215
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by igknighted View Post
Easy, because if I assume there is nothing left and you try my suggestion (and there was something still there), it wont turn out well. If I assume that there might be something there and you simply skip that step if there isn't, then everything works out. You weren't specific in your OP, so I tried to cover as many bases as possible.
I said in the original post and in a later post that it was bolted onto the frame (not welded). I am guessing that the confusion is that there are other types of derailleur mounts which are integral to the frame judging from comments about the frame being toast without rivets and having to file things.
Dan The Man is offline   Reply With Quote
Old 05-26-11, 10:43 AM   #19
JohnDThompson 
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Bikes: Several, mostly not name brands.
Posts: 16,759
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 206 Post(s)
Quote:
Originally Posted by FBinNY View Post
One other possibility if you can't find a replacement "braze-on". If you remove it completely there shouldn't be any reason you can't use a clamp-on mount front derailleur. So you're in good shape either way.
Unless you have some odd-shape (i.e. non-round) seat tube.
JohnDThompson is offline   Reply With Quote
Old 05-26-11, 10:16 PM   #20
Dan The Man
Senior Member
Thread Starter
 
Join Date: May 2008
Bikes:
Posts: 1,215
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
There is some kind of dent in the seat tube right where the derailleur goes. It looks like it's there to give the derailleur clearance. The paint is all shiny on it, so it's not frame damage, but the result is that the seat tube is not round.
Dan The Man is offline   Reply With Quote
Old 05-26-11, 10:59 PM   #21
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)
Sigh.

That 'dent' is meant to be there. Your bike has a replaceable front derailleur hanger. You have a source for one, buy it, install it and end thread.
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 08:04 AM.