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Old 12-29-04, 02:12 PM   #1
55/Rad
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Compact Crank and Braze-On Front Der

I've been through this before and I'm frustrated.

Frame - Trek OCLV 5500. I want to put a compact crank on but the braze-on front derailleur won't go low enough for a 50 tooth big ring. It will only get to within a half inch or so.

Any suggestions? Can I modify the bracket in some way? Or is a clamp-on an option instead of the braze-on?

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Old 12-29-04, 02:42 PM   #2
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Originally Posted by 55/Rad
I've been through this before and I'm frustrated.

Frame - Trek OCLV 5500. I want to put a compact crank on but the braze-on front derailleur won't go low enough for a 50 tooth big ring. It will only get to within a half inch or so.

Any suggestions? Can I modify the bracket in some way? Or is a clamp-on an option instead of the braze-on?

55/Rad
There is something wrong with that picture. My 5200 has plennty of adjustment to get to a 50,with room to spare. There is only about 3/8" diameter diff between a 50 and a 53, meanig the derailer would only have to drop about 1/2 of that. you could file a bit more ajustment into the braze on slot,and if you hose it, I think it just bolts on. If yours bolts on like mine, it could be removd and maybe replaced with a clamp on if the diameter is 13/8" and assuming the tube has enough strength.
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Old 12-29-04, 02:54 PM   #3
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Sydney - I don't know why it is that way but it is. When I bought the bike used a year ago, I tried lowering the der to the proper height but couldn't get there. I even took it to the local Trek dealer and they scratched their heads for a half hour before I discovered that the big ring was a 50. I changed it to a 53 and the der got to where it needs to be. I don't mind going to a clamp-on if it makes sense and doesn't look weird - is the 1 3/8 the right size? I believe the tube measures in at 34 mm.

Thanks.

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Old 12-29-04, 03:39 PM   #4
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Originally Posted by 55/Rad
Sydney - I don't know why it is that way but it is. When I bought the bike used a year ago, I tried lowering the der to the proper height but couldn't get there. I even took it to the local Trek dealer and they scratched their heads for a half hour before I discovered that the big ring was a 50. I changed it to a 53 and the der got to where it needs to be. I don't mind going to a clamp-on if it makes sense and doesn't look weird - is the 1 3/8 the right size? I believe the tube measures in at 34 mm.

Thanks.

55/Rad
You might want to check with Trek and give them all this info. They may offer different hangers,and yours could have been switched out. I wouldn't trust LBS idiots to have the full story. There are plenty of folks running compacts on OCLV,and trek even offers one.
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Old 12-29-04, 04:33 PM   #5
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Originally Posted by sydney
You might want to check with Trek and give them all this info. They may offer different hangers,and yours could have been switched out. I wouldn't trust LBS idiots to have the full story. There are plenty of folks running compacts on OCLV,and trek even offers one.
Mine was originally switched out from a 7700 DA to a 6500 Ultegra by the previous owner.

Went to the local Trek dealer here in Portland and found out that the seat tube on the 5500 is 39 mm - too thick for a clamp-on. I was reminded that the tube has a flat indent where the der connects and thus would hinder a clamp from seating properly. I'll contact Trek directly and see what they can do. I'm wondering if this is specific only to the Ultegra 9 derailleur and if going to the new 6600 version or back to a 7700 (or 7800) DA would correct that. I was hoping not to have to buy a new der but....

The other options are to file the slot or have a hanger custom made.

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Old 12-29-04, 04:52 PM   #6
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Originally Posted by 55/Rad
Mine was originally switched out from a 7700 DA to a 6500 Ultegra by the previous owner.

Went to the local Trek dealer here in Portland and found out that the seat tube on the 5500 is 39 mm - too thick for a clamp-on. I was reminded that the tube has a flat indent where the der connects and thus would hinder a clamp from seating properly. I'll contact Trek directly and see what they can do. I'm wondering if this is specific only to the Ultegra 9 derailleur and if going to the new 6600 version or back to a 7700 (or 7800) DA would correct that. I was hoping not to have to buy a new der but....

The other options are to file the slot or have a hanger custom made.

55/Rad
To my knowledge, there is no functional difference between the ultegra and DA double derailers.They are both designed to operate with the same cahinset and folks routinely switch them. You are right about the settube diameter tho. I had a 2100 with a CF seartube and it took a 34.9 clamp on.
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Old 12-29-04, 05:39 PM   #7
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Originally Posted by sydney
You are right about the settube diameter tho. I had a 2100 with a CF seartube and it took a 34.9 clamp on.
It's funny you mentioned this because the other reason I went to the dealer was to get an exact clamp-on size for the Campy front der I'm putting on the project bike - the Lemond TdC. It has the carbon seat tube also and measured to exactly 34.9. I assume this translates to 1.37 or 1 3/8.

Should have asked you first and saved the trip. Thanks.

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Old 12-29-04, 07:32 PM   #8
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Just curious if anyone knows whether the bolt-on version of the Campy Record and Chorus Compact Drive-specific front derailleurs it introduced earlier this year has been modified in any way to provide for a lower net cage height vs standard front derailleurs?

Their literature and press releases go to great lengths in describing how the inner and outer cage plates have been modified for the smaller chain rings, but I found nothing to address vertical adjustments.
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Old 12-29-04, 07:37 PM   #9
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Originally Posted by livngood
Just curious if anyone knows whether the bolt-on version of the Campy Record and Chorus Compact Drive-specific front derailleurs it introduced earlier this year has been modified in any way to provide for a lower net cage height vs standard front derailleurs?

Their literature and press releases go to great lengths in describing how the inner and outer cage plates have been modified for the smaller chain rings, but I found nothing to address vertical adjustments.
If they are bolt-on or clamp-on, can't they be adjusted to whatever height you'd need?

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Old 12-29-04, 08:15 PM   #10
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Originally Posted by 55/Rad
If they are bolt-on or clamp-on, can't they be adjusted to whatever height you'd need?
I wasn't clear....

Bolt-on = bolt-on to the bracket that was brazed-on (or bonded, as the case may be) to your seat tube, aka. braze-on derailleur.

Braze-on derailleur is one of those terms that just doesn't compute in my head. After all, water bottle cages aren't usually referred to as 'braze-ons' nor are any other components that attached to 'brazed-on' frame fittings. Don't get me started on clipless pedals; you know, the ones you clip in to and out of.
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Old 12-30-04, 12:15 AM   #11
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http://www.nashbar.com/profile.cfm?c...eid=&pagename=


Hay I’m no mechanic so this may be white noise, but I had a bz on that I put on a bike using the nashbar gizmo….

28.6mm, 31.8mm, or 34.9mm size options

or take a look….

http://aebike.com/site/page.cfm?Page...and=367&type=T
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Old 12-30-04, 02:52 PM   #12
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Originally Posted by 55/Rad
Frame - Trek OCLV 5500. I want to put a compact crank on but the braze-on front derailleur won't go low enough for a 50 tooth big ring. It will only get to within a half inch or so.
That doesn't sound right to me. I have an OCLV. I run 39/53 and the FD is about in the middle of the bracket and has room to lower the 5 or 6mm required for a 50T big ring. What is your front derailer?
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Old 12-30-04, 04:23 PM   #13
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That doesn't sound right to me. I have an OCLV. I run 39/53 and the FD is about in the middle of the bracket and has room to lower the 5 or 6mm required for a 50T big ring. What is your front derailer?
I run a standard Ultegra double. I found the whole situation to be pretty silly myself until I was informed on another forum that Trek has come out with a "compact drive" front derailleur bracket to specifically address this issue and that it can be ordered through Trek dealers.

Apparently, it's a standard bracket where the slot gap has been machined to travel a wider distance and range.

Theoretically, problem solved.

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Old 02-26-05, 11:33 PM   #14
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Hey this is very good to know. I have a 2005 SL 5.2 56cm that I built with the FSA SLK compact crank and Campy Record CT front derailleur. I have been adjusting the front derailleur for the last 2 hours and found that it was impossible to get it to shift from the 34 to the 50 chainring.

I am very glad to hear that Trek has a compact crank braze-on bracket for the compact cranks.

Have you had any other issues with the compact cranks?
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Old 02-27-05, 08:56 AM   #15
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Hey this is very good to know. I have a 2005 SL 5.2 56cm that I built with the FSA SLK compact crank and Campy Record CT front derailleur. I have been adjusting the front derailleur for the last 2 hours and found that it was impossible to get it to shift from the 34 to the 50 chainring.

I am very glad to hear that Trek has a compact crank braze-on bracket for the compact cranks.

Have you had any other issues with the compact cranks?
If you can get the outer cage close enough to the big ring(2mm cleace will do it), the problem is somewhere else.
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Old 02-27-05, 09:17 AM   #16
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Originally Posted by sydney
I wouldn't trust LBS idiots to have the full story.
It's always prudent to trust annonymous people on the web as opposed to the people that work on these bikes for a living and are in direct contact with the manufacturer.
It's so refreshing to see you make yet another generalization about LBS.

"To generalize is to be an idiot."
William Blake, English poet and artist
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Old 02-27-05, 09:21 AM   #17
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Originally Posted by 55/Rad
It has the carbon seat tube also and measured to exactly 34.9. I assume this translates to 1.37 or 1 3/8.
For future reference, size in millimeters divided by 25.4 results in a sufficiently accurate approximation in inches. 34.9 mm equates to 1.375"
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Old 02-27-05, 09:26 AM   #18
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It's always prudent to trust annonymous people on the web as opposed to the people that work on these bikes for a living and are in direct contact with the manufacturer.
It's so refreshing to see you make yet another generalization about LBS.

"To generalize is to be an idiot."
William Blake, English poet and artist
I have vast experience with nose pickers 'working on bikes', and masquarading 'bike experts'.Just cuz you hear it it a bike shop doesn't mean the idiot actually has a clue. Said with all due respect to the seemingly small number that actually know what they are doing.
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Old 02-27-05, 09:30 AM   #19
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You keep saying "all due respect," yet you give us absolutely none by making these generalizations.
Don't get me wrong, I've seen, and worked with, a few guys that had no business being in the business. It's unfortunate, as it gives us all a bad name.

Last edited by Waldo; 02-28-05 at 06:07 AM.
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Old 02-27-05, 09:39 AM   #20
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Originally Posted by Waldo
You keep saying "all due respect," yet you give us absolutely none by making these generalizations.
Don't get me wrong, I've seen, and worked with, plenty of guys that had no business being in the business. It's unfortunate, as it gives us all a bad name.
Well, there ya go. You just confirmed what I said wasn't exactly an obtuse observation,and there are plenty of them that are certainly a less reliable source than some 'anonymous internet poster'. Alto there are plenty of the latter that shouldn't be dishing up barnyard waste either. Ya just gotta know how to sort road apples from the good ones.
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Old 02-27-05, 04:00 PM   #21
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"To generalize is to be an idiot."
William Blake, English poet and artist
Sounds like poor Willie was a self-described idiot...
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Old 02-28-05, 06:06 AM   #22
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Sounds like poor Willie was a self-described idiot...
That's why I picked that one. I thought it was better than the rash of "All generalizations are wrong except this one," type stuff.
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Old 02-28-05, 06:12 AM   #23
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Quote:
Originally Posted by sydney
Well, there ya go. You just confirmed what I said wasn't exactly an obtuse observation,and there are plenty of them that are certainly a less reliable source than some 'anonymous internet poster'. Alto there are plenty of the latter that shouldn't be dishing up barnyard waste either. Ya just gotta know how to sort road apples from the good ones.
I don't know how my orignal post with "a few" ended up with "plenty," but I've got it back to what I originally said.
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Old 02-28-05, 07:55 AM   #24
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I don't know how my orignal post with "a few" ended up with "plenty," but I've got it back to what I originally said.
Maybe I know more of then you do, so plenty seemed more appropriate. Sorry for the confusion.
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Old 04-13-09, 12:13 PM   #25
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Originally Posted by 55/Rad View Post
I run a standard Ultegra double. I found the whole situation to be pretty silly myself until I was informed on another forum that Trek has come out with a "compact drive" front derailleur bracket to specifically address this issue and that it can be ordered through Trek dealers.

Apparently, it's a standard bracket where the slot gap has been machined to travel a wider distance and range.

Theoretically, problem solved.

55/Rad
I'm resurrecting this old thread because I recently ordered a new FD bracket from Trek for my '07 Madone 5.0 based on this info. I was also trying to lower my FD so that it lined up with the top of a smaller-than-normal large chainring. I had already filed down my current bracket to allow a few more millimeters adjustment downwards, but this was not enough, so I was hoping that the new FD bracket would solve the problem.

Unfortunately, the new bracket is identical to the modification I had done to the bracket that I already had - it is just the standard bracket with the hole filed down lower. Therefore, I wouldn't recommend that anyone purchases one of these - just file down your current bracket yourself. When it comes time for me to buy another frame, it will have a standard-sized seat tube designed for a clamp-on front derailleur so that I can run whatever chainring sizes I want to.
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