# Advice needed... I heard a crackle sound while torquing my front derailleur clamp



## beston (Jul 4, 2008)

Argh..

I was swapping front derailleurs this weekend and got out the old torque wrench to clamp the front derailleur to the seat tube of my carbon frame. Most specs recommended the torque of the clamp to be between 5-7n•m (44-60in•lb). So I set my wrench to 5nm. I'm an idiot for not using common sense here, as I had thought that 5nm was awfully tight.

Sure enough, I heard a little crackle sound. I immediately stopped and backed off the torque. There is now a fine vertical line in the seat tube where the derailleur clamp was. The area doesn't feel like it is 'soft' or more bendable than any other area, but a line is clearly visible

I've put the clamp back on at 3n•m, which is more than enough for the job and the line doesn't seem to have gotten any bigger (I used a permanent marker to mark the top and bottom of the crack just to keep track).

So what do you guys think? Is my frame toast?


----------



## Dinosaur (Jan 29, 2004)

I hate to say this...I think it's toast. Bound just to get worse...


----------



## robdamanii (Feb 13, 2006)

That's not a good thing...

What kind of frame is/was it?


----------



## beston (Jul 4, 2008)

It was a Pedal Force RS2 frame. I had been really enjoying it so far too.


----------



## PlatyPius (Feb 1, 2009)

Not good, BUT you might be lucky and it just compressed it slightly and cracked the clearcoat. Keep an eye on it.


----------



## beston (Jul 4, 2008)

PlatyPius said:


> Not good, BUT you might be lucky and it just compressed it slightly and cracked the clearcoat. Keep an eye on it.


That's my hope too! I've made sure to mark out where the ends of the crack is. If it grows, I'll be sure the frame is done. 

I've done a couple of trainer rides on this bike since doing this and the break hasn't spread yet.


----------



## robdamanii (Feb 13, 2006)

beston said:


> It was a Pedal Force RS2 frame. I had been really enjoying it so far too.


Depending on how much you paid for it, you may consider sending it to Calfree for analysis and repair if it continues to get worse.


----------



## beston (Jul 4, 2008)

I bought the frame / fork and headset barely used for $300, but the retail on these frames is $750. It still might be worth it to send to calfree, but that is a minimum of $275 + shipping. 

... shoot. I'm pretty pissed at myself for this.


----------



## rx-79g (Sep 14, 2010)

Depending on how the frame is constructed, I could see inserting an epoxied internal reinforcement inside the affected area of the tube.


----------



## TomH (Oct 6, 2008)

whats the range of your torque wrench?


----------



## beston (Jul 4, 2008)

TomH said:


> whats the range of your torque wrench?


It's a 1/4" drive with a 20-200 in•lb (~2.2-22n•m) range.


----------



## mriddle (Nov 16, 2005)

*Calfee ~$200*

About 2 years ago a guy I ride with did this exact sale thing on his De Rosa. Never go with the Sram/Campy/Shimano spec on a carbon frame. Good news is that this is not a high stress point of the frame. He continued to ride the bike all summer and there was no additional issue. This guy was about 6 feet tall and approx. 180lbs. He did switch immediately to a Parlee carbon clamp that actually wrapped most of the cracked area. That winter he sent the bike to Calfee to be repaired for about $200. Good as new, your frame will be fine. When you buy a new frame look at steel.


----------



## robdamanii (Feb 13, 2006)

mriddle said:


> About 2 years ago a guy I ride with did this exact sale thing on his De Rosa. Never go with the Sram/Campy/Shimano spec on a carbon frame. Good news is that this is not a high stress point of the frame. He continued to ride the bike all summer and there was no additional issue. This guy was about 6 feet tall and approx. 180lbs. He did switch immediately to a Parlee carbon clamp that actually wrapped most of the cracked area. That winter he sent the bike to Calfee to be repaired for about $200. Good as new, your frame will be fine. When you buy a new frame look at steel.


Um, why steel? Just because of an overtightened clamp?


----------



## beston (Jul 4, 2008)

Thanks for the advice! I am tempted to ride it and see if the crack actually spreads.

I've seen that Parlee carbon clamp, but didn't buy it because it was around $100. In retrospect, that $100 would have saved me all of this grief.

I'm contemplating sending it to Calfee, but since I live in Canada, I also want to see if there are any more local options (I haven't yet found anything similar).


----------



## rx-79g (Sep 14, 2010)

beston said:


> Thanks for the advice! I am tempted to ride it and see if the crack actually spreads.
> 
> I've seen that Parlee carbon clamp, but didn't buy it because it was around $100. In retrospect, that $100 would have saved me all of this grief.
> 
> I'm contemplating sending it to Calfee, but since I live in Canada, I also want to see if there are any more local options (I haven't yet found anything similar).


Aside from the internal reinforcement I mentioned, another thing you could do is switch to an adapter that moves the pinch spot to a different section of tubing. Shifting is going to cause the clamp to flex against the tube, but that would move the sharp edges away from the damage.


----------



## beston (Jul 4, 2008)

rx-79g said:


> Aside from the internal reinforcement I mentioned, another thing you could do is switch to an adapter that moves the pinch spot to a different section of tubing. Shifting is going to cause the clamp to flex against the tube, but that would move the sharp edges away from the damage.


Good idea! Another poster had also mentioned I should go with a Parlee carbon clamp. They tend to be quite expensive, but I have found a similar product on ebay that should do the trick.

http://cgi.ebay.ca/NEW-CROSS-Full-C..._Accessories&hash=item4aa7da05d2#ht_914wt_907


----------



## rx-79g (Sep 14, 2010)

beston said:


> Good idea! Another poster had also mentioned I should go with a Parlee carbon clamp. They tend to be quite expensive, but I have found a similar product on ebay that should do the trick.
> 
> http://cgi.ebay.ca/NEW-CROSS-Full-C..._Accessories&hash=item4aa7da05d2#ht_914wt_907


That's pretty cool - especially the price.

Even with a mild adhesive under it (waterproof wood glue, loctite) that wide band is going to effectively reinforce the damaged area as if it had been repaired. Do it!


----------



## beston (Jul 4, 2008)

rx-79g said:


> That's pretty cool - especially the price.
> 
> Even with a mild adhesive under it (waterproof wood glue, loctite) that wide band is going to effectively reinforce the damaged area as if it had been repaired. Do it!


Yep, I went ahead and bought it.

...I'm not so sure about the glue idea though. How would it provide any advantage over the mechanical binding (or tightening) of the band?


----------



## Weav (Jun 21, 2009)

I know someone whose been riding a frame with the exact same problem for about 800 miles and no issues. Same fine vertical line coming out of the clamp area, line has not grown. The LBS swears that it's not structural and nothing to worry about, but he'd be on the hook for a new frame so who knows what to believe.


----------



## ewitz (Sep 11, 2002)

skip the glue won't help the cause


----------



## beston (Jul 4, 2008)

Weav said:


> I know someone whose been riding a frame with the exact same problem for about 800 miles and no issues. Same fine vertical line coming out of the clamp area, line has not grown. The LBS swears that it's not structural and nothing to worry about, but he'd be on the hook for a new frame so who knows what to believe.


That's good to know. I imagine that this problem is more common that we think, but goes un-noticed by many. 

From what I've read, the seat tube is does not bear much of the load of a bike, so a fine crack there is not _likely_ to cause an issue. However, if my LBS did that to my frame, I would definitely want the problem to be corrected.


----------



## rx-79g (Sep 14, 2010)

beston said:


> Yep, I went ahead and bought it.
> 
> ...I'm not so sure about the glue idea though. How would it provide any advantage over the mechanical binding (or tightening) of the band?


Putting something tacky between the two will make them flex together rather than in opposition. No different than the lamination principle that makes carbon fiber into tubing.

Probably completely unnecessary, but it wouldn't hurt, either.


----------



## frdfandc (Nov 27, 2007)

You could do the quarter test. Its not 100% scientific, but works well in a pinch to determine structural damage. The only real way would be to have someone either X-ray the bike or have someplace like Calfee or RRVelo look at it.

Take a quarter and tap on the seat tube in an undamaged area. Then tap the seat tube where the "crack" is. If the sound changes to a deadened sound, then the carbon has been compromised where you clamped the FD to. If it doesn't change, then the carbon is ok, and its more than likely just a clear coat issue.


----------



## Vee (Jun 17, 2010)

Post up when you put that clamp on there. I am curious to see how it comes out.


----------



## Mel Erickson (Feb 3, 2004)

A light sanding could reveal if the crack is just in the clear coat or into the weave. Might be worth a try.


----------



## wim (Feb 28, 2005)

Mel Erickson said:


> A light sanding could reveal if the crack is just in the clear coat or into the weave. Might be worth a try.


Agree. And just because, I'd also pull the seat post and shine a strong light down into the seat tube, hoping to not see anything "irregular." Carbon-fiber reinforced stuff doesn't always crack from the outside in.


----------



## Zipp0 (Aug 19, 2008)

A good case for braze-on front derailleurs on all carbon frames?

I currently have 2 steel frames and an aluminum frame, and every story like this that I hear makes me think the next frame will be nice titanium. Maybe a Moots CR.

Imagine if that crack happened on your brand new $5,000 high-zoot frame. I'd lose my fricken mind.


----------



## beston (Jul 4, 2008)

Mel Erickson said:


> A light sanding could reveal if the crack is just in the clear coat or into the weave. Might be worth a try.


I agree and I've been contemplating this too. This would be a sure way to see how deep the crack is. If it is cracked, it should be repaired. In this case, it doesn't matter if I've taken off some clear coat. If it's not cracked, the derailleur band I'm getting should cover up the exposed part

I'm going to run this by a really nice guy in my area who has a lot of experience as a mechanic. I believe he has been a 'wrench' for national teams (maybe pro teams too). He's close enough to Gerard & Vroomen (aka. Cervelo), that they let him borrow bikes from their museum to hang in his coffee shop. It's really neat to see;
-Cancellara's Paris Roubaix winning R3 
-DZ's world record P3C, 
-One of Satre's stage victory bikes - the time that he put the pacifier in his mouth

As an aside, if anyone's ever in the Hamilton region, I highly suggest you visit his shop, Cafe Domestique. I'm hooked on their Americano coffee.
http://www.cafedomestique.com/


----------



## beston (Jul 4, 2008)

Zipp0 said:


> A good case for braze-on front derailleurs on all carbon frames?
> 
> Imagine if that crack happened on your brand new $5,000 high-zoot frame. I'd lose my fricken mind.


Well, the lesson learned is that I should have used common sense and eased off earlier. I'd love to blame the design of the clamp, but in the end, it was user error.

...My motto is, if you can't afford it, don't touch it. I don't go for the $$$ frames because the cost of making a mistake is just too high! I too, would be in tears if this was an uber expensive frame.


----------



## Zipp0 (Aug 19, 2008)

beston said:


> Well, the lesson learned is that I should have used common sense and eased off earlier. I'd love to blame the design of the clamp, but in the end, it was user error.
> 
> ...My motto is, if you can't afford it, don't touch it. I don't go for the $$$ frames because the cost of making a mistake is just too high! I too, would be in tears if this was an uber expensive frame.


Even wealthy people (perhaps especially wealthy people) don't like wasting money.


----------



## olr1 (Apr 2, 2005)

Meh.

It's a crack in a tube which has a big reinforcing ring tightened ( maybe a leetle too tight..) around it. 

Therefore..... the only way it can collapse is inwards, which is highly unlikely.

I'd ride it like I stole it and stop worrying; exactly how many down tubes have you ever seen break at that point?


----------



## rx-79g (Sep 14, 2010)

olr1 said:


> Meh.
> 
> It's a crack in a tube which has a big reinforcing ring tightened ( maybe a leetle too tight..) around it.
> 
> ...


The problem here is that the front derailleur puts more than a little strain on the tube, especially shifting up to the big ring. Changing to a different clamp point is at least going to stop the crack from getting bigger.


----------



## olr1 (Apr 2, 2005)

_The problem here is that the front derailleur puts more than a little strain on the tube, especially shifting up to the big ring. Changing to a different clamp point is at least going to stop the crack from getting bigger._

*Meh* is still the strongest emotion I feel; the forces from the front derailleur are from the side, and I suspect (although I don't actually know, and may therefore cause the death of an innocent man) that the strength of said tube at said point is not significantly reduced by a vertical crack.

As I said, I'd ride it, probably even harder than before, after all it's broken now, right?


----------



## rx-79g (Sep 14, 2010)

olr1 said:


> _The problem here is that the front derailleur puts more than a little strain on the tube, especially shifting up to the big ring. Changing to a different clamp point is at least going to stop the crack from getting bigger._
> 
> *Meh* is still the strongest emotion I feel; the forces from the front derailleur are from the side, and I suspect (although I don't actually know, and may therefore cause the death of an innocent man) that the strength of said tube at said point is not significantly reduced by a vertical crack.
> 
> As I said, I'd ride it, probably even harder than before, after all it's broken now, right?


I don't think it's going to make the frame break in half, but there is something to be said for a bike that continues to shift well without making crackling noises.


----------



## beston (Jul 4, 2008)

rx-79g said:


> I don't think it's going to make the frame break in half, but there is something to be said for a bike that continues to shift well without making crackling noises.


Well, I don't hear crackling noises (yet) when I shift.

I spoke with Krys Hines at Cafe Domestique. He took a look at the pics and said that I shouldn't really worry about it. He re-iterated that the area is not prone to causing catastrophic failures and he is used to seeing cracks like this form on the crown junction of Carbon/Aluminum forks. He did tell me to keep an eye on it and see if it grows, but not to fret too much.

So, at this point, I'm going to put on the carbon braze-on adapter clamp and monitor the crack to see if it grows. 

I'll post pics of of the adapter on the bike when it comes in.

thanks for the advice so far!


----------



## olr1 (Apr 2, 2005)

_I don't think it's going to make the frame break in half, but there is something to be said for a bike that continues to shift well without making crackling noises_.

I would agree with this, but in the absence of noise I (..and I'm only suggesting what I would do to avoid any litigation or other vendetta style revenge..) ...I would not hesistate to ride it.


----------



## rx-79g (Sep 14, 2010)

olr1 said:


> I would agree with this, but in the absence of noise I (..and I'm only suggesting what I would do to avoid any litigation or other vendetta style revenge..) ...I would not hesistate to ride it.


Neither would I. I think the solution Beston has found will not only stop the problem from getting worse but make it a complete non-issue, since this new clamp is going to reinforce the area. I'd feel pretty good about it if it was my bike.


----------



## olr1 (Apr 2, 2005)

_ I'd feel pretty good about it if it was my bike._

I agree 100%.

(I would be less keen to have the entire western world know I was a ham-fisted spanner monkey though..... JOKE!!!!)


----------



## beston (Jul 4, 2008)

olr1 said:


> _
> (I would be less keen to have the entire western world know I was a ham-fisted spanner monkey though..... JOKE!!!!)_


_

Well, if I learn from my mistake and get some good guidance in the process, I'm o.k. with being outed for being the ham-fisted monkey that I am!

Funny thing is, if I didn't have a torque wrench (which is supposed to protect me from doing stupid stuff like this), there is no way in hell that I would have tried to tighten the clamp as much as I did._


----------



## olr1 (Apr 2, 2005)

It was a joke, and I am glad that you took it well. 

As rx-79g and myself have said, I would be a bit disappointed that it had a crack, but I would feel quite happy riding that frame, especially with the new adaptor. 

Hope it goes well!


----------



## shinewheel (Jan 14, 2011)

*an afterthought*

You could have a tube machined up the ID to match your seat tube and OD to match the next size up standard clamp band. Split longitudinally to fit around the tube. Done right it wouldn't look too cludgy and if long enough would distribute the load over a sufficient area. Just a thought.


----------



## beston (Jul 4, 2008)

shinewheel said:


> You could have a tube machined up the ID to match your seat tube and OD to match the next size up standard clamp band. Split longitudinally to fit around the tube. Done right it wouldn't look too cludgy and if long enough would distribute the load over a sufficient area. Just a thought.


Yes. My hope is that the Carbon clamp that I just bought from ebay achieves this. It should eliminate any major stress points on the tube, particularly in the area that was stressed by the standard clamp. Hopefully, it will also provide some reinforcement along the crack.

Here's a pic of what I bought.


----------



## rx-79g (Sep 14, 2010)

beston said:


> Yes. My hope is that the Carbon clamp that I just bought from ebay achieves this. It should eliminate any major stress points on the tube, particularly in the area that was stressed by the standard clamp. Hopefully, it will also provide some reinforcement along the crack.
> 
> Here's a pic of what I bought.


Where'd you find one that doesn't say "Cross" on it?


----------



## beston (Jul 4, 2008)

mine will say cross on it, this is just the first picture that I could find on the internet to show what it looks like. My decision was all about price...

The one in the picture is likely a Parlee carbon clamp - They tend to run for $70 - $100
http://fairwheelbikes.com/parlee-front-derailleur-clamp-p-1301.html

Velocite also sells one with a cool design for $60
http://shop.velocite-bikes.com/velocite-elemental-carbon-front-derailleur-clamp.html

The one I 'actually' bought was the cheapest at $36, but does come with the lame X Cross label. 
http://cgi.ebay.ca/NEW-CROSS-Full-C..._Accessories&hash=item3364fd937e#ht_914wt_907


----------



## rx-79g (Sep 14, 2010)

beston said:


> mine will say cross on it, this is just the first picture that I could find on the internet to show what it looks like. My decision was all about price...
> 
> The one in the picture is likely a Parlee carbon clamp - They tend to run for $70 - $100
> http://fairwheelbikes.com/parlee-front-derailleur-clamp-p-1301.html
> ...


I found the Parlee for $60. But I'll probably get one of these instead. It isn't hard to get the logos off.


----------



## beston (Jul 4, 2008)

rx-79g said:


> I found the Parlee for $60. But I'll probably get one of these instead. It isn't hard to get the logos off.


I've seen the Parlee clamp for <$60, got interested, and then realized that it was only for a 31.8mm tube. The 34.9mm clamps tend to sell for more.

I hope that the x cross is removable too!


----------



## mriddle (Nov 16, 2005)

robdamanii said:


> Um, why steel? Just because of an overtightened clamp?


Um, yes.


----------



## purplecu22 (Sep 25, 2005)

*damage is done.*

The damage is done. When selecting a FD clamp. Shamino's are not round. If you take the clamp off and close it you see it makes a oval. This is bad for carbon seat tubes. I install a orion on my frame. its more round and does not pinch the seat tube. A parlee clamp is almost a perfect circle. I used carbonfiber paste and 35 in pounds. Its never moved. Always go up in torque never down. 

A Shamino will work but you see what happens it to much clamping pressure is used. I have 3 of them.


----------



## beston (Jul 4, 2008)

Update: 
I ordered the carbon clamp on the 11th and it arrived today (17th). Why is it that international shipping is faster than shipping within N.A.?

The installation was dead simple. I used some Tacx carbon assembly paste to reduce the chance of carbon-on-carbon slippage and used a torque wrench to tighten the clamp to just under 3nm. The clamp feels secure, and time will tell if the clamp slips during real riding.

I've used a permanent marker to identify the edges of the crack and keep track of it. If the line starts to grow, it will be time to get a new frame.

Unfortunately, the label 'x cross' is under the epoxy clear coat. At this point I'm just going to leave it alone.

Here are some pics of the installation. Thanks for your help guys.


----------



## LOUISSSSS (Dec 14, 2009)

^^ that clamp looks REALLY GOOD. it blends in with your frame perfectly and the labeling doesn't make it look bad. I'd ride it, but take it slow for the first 100 miles or so...


----------



## Vee (Jun 17, 2010)

Not only does that clamp look nice on your frame, it looks like the ideal clamp for a clamp-on derailleur on a carbon frame. If you got a new carbon frame I would still look into using that same clamp. Just looks too good.


----------



## beston (Jul 4, 2008)

I absolutely agree. The clamp really blends in with the frame. In all honesty, I didn't even know these things existed when I got my frame. But now that I know, I would certainly use it again in the future (assuming it doesn't slip). 

I'm not out to build the lightest bike, but the clamp is 20-30 grams lighter than the shimano alloy clamp it replaced ($20-$30 more expensive though). Add that to the fact that it would be nearly impossible to damage the seat tube with this clamp and you've got a clear winner for carbon tubes!


----------



## Tommasini (Apr 24, 2002)

*Whoa*



LOUISSSSS said:


> ^^ that clamp looks REALLY GOOD. it blends in with your frame perfectly and the labeling doesn't make it look bad. I'd ride it, but take it slow for the first 100 miles or so...


Whoa.......are you trying to run Shimano shifters with a SRAM rear der?


----------



## beston (Jul 4, 2008)

Tommasini said:


> Whoa.......are you trying to run Shimano shifters with a SRAM rear der?


Nope. I've got D/A 7800 shifters and Ultegra 6700 derailleurs, cassette and chain. The only SRAM part is the crank


----------



## rx-79g (Sep 14, 2010)

Tommasini said:


> Whoa.......are you trying to run Shimano shifters with a SRAM rear der?


That's clearly NOT a SRAM derailleur.


That looks pretty sharp, Beston. Has the front shifting changed any?


----------



## robdamanii (Feb 13, 2006)

mriddle said:


> Um, yes.


Here's an amazing concept...don't tighten the clamp so much? :idea:


----------



## beston (Jul 4, 2008)

rx-79g said:


> That's clearly NOT a SRAM derailleur.
> 
> 
> That looks pretty sharp, Beston. Has the front shifting changed any?


Thanks.

I just finished my first interval session on the trainer this evening. The shifting is just as good as it was with the alloy clamp. There was not any movement, or any give / flex that I could notice.


----------



## vladvm (May 4, 2010)

Take it easy with the frame. Same thing happened with my carbon seat post, heard a crack. Eased it off, then retightened. Crack did not get bigger but when I was riding and hit a pot hole, saddle loosened and seatpost broke. I did not crash but you should take it easy and still be careful.


----------



## Genshammer (Mar 24, 2011)

*Damage*

You should be okay for a while, but just keep in mind that many times you can't see the full extent of damage from the outside. Most often, carbon frame damage is more evident inside the tube. If possible, get a flashlight and look down inside the seat tube and check to see if you can notice any inconsistencies near the outer crack. Just keep an eye on it. If it gets worse, it's easily repairable.

Feel free to contact us if you have any questions. That carbon derailleur clamp is pretty tight looking!

Sincerely,


----------



## Vee (Jun 17, 2010)

How is this working out?


----------



## Pirx (Aug 9, 2009)

beston said:


> I'm an idiot for not using common sense here, as I had thought that 5nm was awfully tight.


Hmm, nobody has commented on this yet, but 5Nm is nothing. For example, that's how I torque my stem, on both the carbon handlebar and the carbon steerer tube. 5Nm should not have damaged that seat tube either.


----------



## beston (Jul 4, 2008)

So far, The carbon derailleur clamp has worked well. I did have some very slight slippage of the clamp when I torqued it to about 2.5Nm. I've since adjusted the torque to the Max that the clamp specifies (3 Nm) and it has held very well. 

As for the comments by Pirx. I somewhat agree with that statement. 5Nm is actually pretty tight, but still around the norm of the torquing range for most carbon pieces. On this occasion though, I forgot to also rely on feel. As I was tightening the bolt, I thought to myself that this was feeling very tight, but I continued on anyway because some guideline said that the max torque was 5Nm! From now on, when I use the torque wrench, I usually start the wrench with a torque setting of 3Nm, just to get a feel of how much I'm tightening the bolt and to give me some indication on my progress and then I increase the torque 1 or 2 more times until I get to my desired tightness. It helps keep me in check of the 'feel' of torquing.


----------



## winstonw (Apr 27, 2011)

beston, appreciate your thread here. I recently broke an ultegra chain on a 2010 Trek Madone 4.7. The broken outer plate then snagged on the front derailleur outer plate, and tore it apart. 











Fortunately the FD (Ultegra 6700 34.9mm clamp on) didn't transmit all the force to the seat tube. 

Anyways, I just got a new FD, same type. Some shops tried to sell me a braze on, and after reading this thread, wished I had. For some reason, Trek don't do Braze on, on 4 and 3 series Madone, only 5 and 6 I believe.....and I was biased towards getting the original part. Thought Trek must have a good reason for it. (but maybe it is nothing other than Trek helping Shimano clear redundant clamp on stock). 

Why do I say redundant? Well, I suspect Shimano realize clamp ons are damaging too many CR frames. And the braze ons allow for after market clamps, which would help dilute liability for damages.

I don't mean to rub your nose in it, but did you read this part of the Ultegra 6700 FD installation manual? 











The comment about CR frames is lawyer speak for :
- we accept no responsibility for damaging CR at 5-7Nm, or sub 5Nm. 
- we don't know what torque is safe for affixing this FD to CR frames.


----------



## beston (Jul 4, 2008)

... I hadn't actually read that. I wish I had!

When trying to determine the clamping torque, I looked at a few different sources which mentioned torque ranges from 5 to 7Nm. Of course, now I realize that all I really needed was 3Nm to hold the clamp in place.

I now officially hate clamping anything carbon. I'm even switching to an aluminum handlebar for this reason (and the shape suits me better).

Your derailleur looks insane! I hope no one / nothing else was hurt as a result of the chain snap. I've seen lots of chains break on MTB's, but none that have caused this kind of damage.


----------



## DaveVelo (Jul 17, 2011)

Recently replaced my clamp-on record 10 derailleur with a record 11 clamp-on. Without my knowledge, the builder had overtightened the the 10 which caused a slight indentation on the tube. When I removed it to install the 11, I noticed a slight cracking noise when cinching the bolt. It so happens that the 11 is made different than the 10 causing it's clamp to be placed in a slightly different position. This agravated the damage the builder had caused and hence, further cracked the tube. I've scraped the area clean and applied PC7 Epoxy into the wound. Wound electrical tape (adhesive side out) to tighten the bond while it sets. Ordered X Cross clamp for $39. Will see how it goes. For guys who want to remove corny x cross logo, remove top-coat and polish carbon to high luster with crocus and buffing compound... beautiful! Ciao


----------



## oldcannondale (Jul 23, 2011)

Nice looking frame and that clamp looks like it grew on there.


----------



## oldcannondale (Jul 23, 2011)

Just wondered how your frame was holding up after 6 months.


----------



## DrFragnasty (Nov 12, 2009)

The carbon sleeve looks good and should prove reliable. 

FYI
With any tube, the "hoop strength" is key. With carbon weaves 2x2 etc without any angle bias, 50% of the fabric contributes to hoop strength. 

If I hadn't know about the sleeve and it was my bike I'd repair it. 

Here's how I'd do it:
Mask off above below crack, sand to reach the fabric then run a few wraps of tow (the 1/4" wide carbon ribbon) over the area followed by a 4oz plain weave (no bias) maybe 2 wraps for finish. On top of that use wide clear tape to provide compression until it cures.

Peel the tape off and you should have a neat glossy fabric finish. By increasing the diameter the strength increases too.

Be wary of thickness added since it offests the DR by the amount you add.

The other option is filling internally. Bung a lightweight snug plug down the seat tube to just below the strap mark, add a mix of resin filler/ finely cut carbon fabric (for strength) just enough to exced the height of the clamp and let cure in the vertical position. Adds a bit of weight though.

I've never done this personally but repair compsites all the time.

Chris.


----------



## beston (Jul 4, 2008)

oldcannondale said:


> Just wondered how your frame was holding up after 6 months.


Sorry for the delay. Just noticed the post. 

In any case, the frame is great. Not a single problem since the incident. I did have a creaking noise pop up about a month ago and thought the crack might be starting to grow. However, the noise was due to some creaky front wheel spokes. The crack hasn't grown at all.

I'm not babying the bike either. I do a weekly group ride that is all about pushing ourselves to the limit of what we can do. There are a few sprints and hill climbs mixed in there. The frame hasn't let me down at all.

I have to say that I'm really happy with the bike! I'll keep an eye on it, but I really think that I got lucky here.


----------



## beston (Jul 4, 2008)

DrFragnasty said:


> If I hadn't know about the sleeve and it was my bike I'd repair it.
> 
> Here's how I'd do it:
> Mask off above below crack, sand to reach the fabric then run a few wraps of tow (the 1/4" wide carbon ribbon) over the area followed by a 4oz plain weave (no bias) maybe 2 wraps for finish. On top of that use wide clear tape to provide compression until it cures.
> ...


Thanks for the insight. As you noted, any repairs would probably change the outer diameter of the tube, and would make it tough to fit the derailleur clamp around it.

... Just a question though. What epoxy resin would you use with the carbon ribbon?

thanks again.


----------



## DrFragnasty (Nov 12, 2009)

*west systems epoxy (slow cure hardener)*

Just 24 hr epoxy; West Systems (boat builder supplier) would do. Available off the shelf in small quantities (150ml smallest from memory).

Cures in 24 at room temp., full strength after 2-4 days depending on temp.

I've used aerospace resins but West is fine I reckon.


Chris.


----------



## alfredwenzl (Oct 27, 2011)

beston said:


> That's my hope too! I've made sure to mark out where the ends of the crack is. If it grows, I'll be sure the frame is done.
> 
> I've done a couple of trainer rides on this bike since doing this and the break hasn't spread yet.


Ok, back to chromoly! 
Just kidding, I love CF.


----------



## beston (Jul 4, 2008)

Nah, I'm done with steel. The ride qualities and performance is just too good.

In any case, the line never grew this summer and i just may have gotten lucky here!


---
I am here: http://maps.google.com/maps?ll=43.250814,-79.887686


----------

