Bicycle Mechanics - Braze on front derailleur

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View Full Version : Braze on front derailleur


critking
09-02-10, 05:54 PM
I have a Carbon Fiber frame with a Braze on front der. My problem is that the braze on clamp has some play on it and my LBS is telling me there is no way to fix it since it is connected to my frame with rivets and not screws. Does anyone know any bike manufuctoring company or a GOOD bike shop in the US that may able to fix this? I bought it second hand and the frame is brand new so I don't know where the Original owner bought it from or if there's a warranty.

I have attached a pic of the braze on. please help. returning it to original manufactorer is not an option.


FBinNY
09-02-10, 06:08 PM
You have a number of choices. First of all there are any number of skilled shops through the country that can fix this, even though your LBS doesn't know how. If you prefer to have a shop do the work, PM me & I'll give you a referral.

If you want to DIY you can carefully drill out the head of the rivet, remove the braze on, push the rivet through and drop it out the seat tube, and use two pop-rivets to put it back together.

If you'd rather try something less drastic, you can wick some glue between the braze on and the frame then hold it tight and steady with a clamp or winding multiple turns of string and let it set for as long as the glue requires. If the gap is very small, Loctite makes a number of retaining products (not the familiar thread grades) including one that expands as it cures,which might solve your problem.

Shadow7874
09-02-10, 06:23 PM
If it were me (i dont know much...) id drill out the rivets and put in two new pop rivets then get some 1-2" carbon fiber tape and epoxy it over the mount to make sure its pretty much permanent


CACycling
09-02-10, 06:35 PM
Is the seat tube round (hard to tell for sure from the pics)? If it is, I'd see if you can finsd a braze-on adapter clamp the right size and eliminate the bracket completely.

Bianchigirll
09-02-10, 07:03 PM
we don't normally have issues like this on good old fashioned steel bikes :) I would do as the first two suggest but also use some epoxy too

HillRider
09-02-10, 07:11 PM
If you want it done professionally, contact FBinNY for his recommendations. Also Craig Calfee (www.calfeedesign.com) specializes in repairing damaged carbon frames and they are one of the best known companies for this type of work. They are also in California and could be relatively convenient to you. Here is their contact info:

Calfee Designs
783 San Andreas Road
La Selva Beach, CA 95076
Toll Free: 1-800-965-2171

cbfight
09-02-10, 09:42 PM
If it were me (i dont know much...) id drill out the rivets and put in two new pop rivets then get some 1-2" carbon fiber tape and epoxy it over the mount to make sure its pretty much permanent

This is what I'd do if it was my bike, but then again I don't mind if my bikes look "personalized".

Actually, I forgot how much I hate braze-on derailleur mounts. I'd probably just drill it out, reinforce the area with a bit of carbon tape and epoxy, then replace the whole thing with a clamp-on.

critking
09-03-10, 07:44 AM
Thanks for all of your comments. I will definitely look into a CF manufacturer. I have no clue on how to drill a wall much less a CF bike. The seatpost is not round so a clamp on will not work.

wunderkind
09-03-10, 10:14 AM
The last thing you want is over drill it and cause fracture to the plastic.... err I meant CF. The seat tube after all do carry alot of your body weight.

HillRider
09-03-10, 10:30 AM
The seatpost is not round so a clamp on will not work.
This is the usual reason manufactures use braze-on tabs for the front derailleurs these days and, unfortunately, there is no easy alternative.

Al1943
09-03-10, 02:04 PM
Looks to me as if it needs to go back to the factory for warranty work.

JohnDThompson
09-03-10, 03:30 PM
we don't normally have issues like this on good old fashioned steel bikes :) I would do as the first two suggest but also use some epoxy too
I had a customer insist on having a braze-on mount on his 753 frame. I told him Reynolds did not recommend this, but he was insistent. So it went on. A few month later the frame came back: he had jammed his chain in the front derailleur and the mount tore the seat tube open like a can opener. That was the end of that frame.

Oh, and +1 on the epoxy, as long as it is compatible with the CF tubing.

critking
09-03-10, 09:48 PM
Well I'm glad I found a bicycle company near me that specializes in Carbon Fiber. CYCLART.COM will have my bike back in a week, Won't have to deal with taking my bike apart and mailing! Thanks for all your post! See you guys @ a crit near you!