FBOATSB

Un uomo duro.

Erzulis Boat 

The reason JB Weld is totally ubiquitous is not because it's "cheap", it is because it works.

I have used Marine-Tex, West Systems, vinyl esters, fiberglass, and JB Weld. For repairs that call for a tough and permanent bond, JB does a great job.

One of the great things about JB, is that you can get a small and fresh quantity. Fresh? Yep, once epoxy "sugars" (gets gritty and isn't smooth flowing when wet) it's done. JB Weld is used in industrial applications all the time.

fender1

First off I am glad you are ok and this didn't cause any kind of accident or injury.

I would adhere the frame to the saddle with carbon specific tape and then encase the area in PC7 epoxy.

As aothers have mentioned, given the amont of flex in the design and the fact that it has already failed once, I would not go too far in investing in a repair. See if you can get it stable and take it for a ride.

If I were faced with this decison, I would get a new saddle. Failures of this type when repaired, give me the heebe jeebees. Be safe!

I

dedhed

How old is it?

https://www.selleitalia.com/en/warranty-2/

squirtdad

Mad Honk has small piece carbon fiber experience, IIRC thoughts?

Drillium Dude 

Further detailed analysis of the saddle components and manufacture process has made me realize I need to share some additional photos - plus some observations.

First of all, the anchoring piece is made of some sort of PVC or polycarbonate. It has two holes drilled into it from the top, and a plate - also of polycarbonate, with two countersunk holes - carries two screws which screw down into the anchor. This plate covers the front U-bend of the rail and holds it in place. Details in the following photos:







The carbon layer covers the entirety of the underside of the shell, and before the failure it simply wrapped over and around the entire nose anchor piece. Pretty sure the anchor piece was also held in place by some epoxy, but it must have been a very, very thin layer as the only evidence of epoxy is in the backside of the two drilled holes:



From the evidence, the failure occurred when the hit exceeded the load the carbon layer was designed to take - first at the rear of the anchor (the force transferred forward by the saddle rail U-bend). The carbon layer doesn't seem to have been well-formed to the base of the anchor, and curves upwards as can be seen from these next couple shots - for orientation purposes, that tiny bit of white paint is towards the rear of the saddle:





At the rear, the saddle rails were held in place in their anchors by interference fit along with a small amount of silicone. I assume these anchors are also polycarbonate, bonded with epoxy, and covered by the main carbon layer. Luckily, that layer didn't fail as well. I cleaned out the dried-up silicone and will replace. Some pics to show details:





Last but certainly not least is a close-up look at the forward anchor - separated from the shell. From the evidence, it appears this piece would have been epoxied to the shell, then covered over completely by the final carbon layer. This layer is a simple 90 degree weave, and comes apart by hand, suggesting it was not pre-impregnated with resin. I've had one other version of this saddle, and the underside had been coated with a shiny epoxy or resin - probably for added strength. This layer is extremely thin, so I have to wonder: was it really doing much in the way of strengthening the forward anchor point, or would the epoxy affixing the anchor have been doing the job? This anchor is very tight when placed back into the shell - in fact, I have to give it a massive tug to get it back out, and it even stayed in place when I did a test re-fit of the saddle rails. Anyway, this is what it looks like now I've prepped it for re-installation; note I've removed most of the remaining carbon layer except at the front and the triangular bit that will go back in last to shore up the inner flank:





I left the remaining bit of the carbon layer on the front of the anchor to help with lining it up and for aesthetic purposes.

So, what's the solution? Honestly, I'm gonna go with what I know: JB Weld. After all, it's epoxy - right? Just recently used it to repair a metal light fixture outside the house and it's holding up fine. In this application, the forces will mainly be vertical; the hit it took was a shearing load, but in all honesty that was me not paying attention!

I have reviewed the other posts (still need to make some responses) and I was very interested in the one with the carbon weave availability at McMaster-Carr. For now, I'm gonna try this with epoxy only, but may revisit with a small layer of carbon weave, too. Have to check on availability and do a little research into how to properly place/attach the stuff.

So, off to Wal-Mart for the JB Weld and some liquid silicone. I'll update the thread with pics of the process soon.

DD

Drillium Dude 

Ha ha

What surprised me: what hurt the most when I got home was my feet - specifically both big toes. Prolonged forward pressure against the toebox (I like my shoes on the tight size); almost felt as though I had ingrown toenails on both of them. Not fun.

DD

fordbailey

I bought a carbon repair kit on eBay after I crashed and my frame cracked. It came with two part epoxy and a small sheet of unidirectional.carbon. It cost maybe $20 and I was able to fix my frame one day and do a long grueling ride the next. Your saddle looks pretty easy to fix.

Best of luck-

Ford
Ghent, NY
USA

Chombi1 

I guess the trick might come down to how you'll get the repair resin to penetrate the CF weave on the saddle shell and the rail receiver piece.
Maybe you can use one of those counter top food packaging vacuum bag system over the repair area to "push in" the resin into the surrounding structure?

Drillium Dude 

Found this stuff:



Carbon fiber was called out specifically in the compatibility list. Dries tan, not clear, but what the hey - the repair site is on the underside of the saddle so I don't really care.

Finishing up the prep work with a little more sanding of the mating surfaces. I figure as the interference fit is pretty tight, I'm going to get a goodly amount of epoxy squeezing out. With that in mind, I have wet paper towels and Q-tips standing by

The fix will be completed tonight and I'll wait until tomorrow to road test. Feeling pretty confident, however, now that I've found a bonding agent specifically for plastic to CF.

DD

Drillium Dude 

Apparently that wasn't the process used in the initial manufacture, so I'm not concerned about it. From the evidence the top outer shell is the only CF that has pre-preg resin; the polycarbonate anchors were apparently epoxied to the shell, then covered with a finishing, non-pre-preg layer of CF. Not sure how it was attached - but I'm assuming a light film of epoxy over the entire underside of the shell.

This photo shows the strands loose from the the one large piece I removed from the front anchor point; I was able to undo them by hand, which suggests more than ever to me that this layer served in an aesthetic capacity rather than structural:



DD

Drillium Dude 

All done. Gonna give it 24 hours before I whip out some 120 grit, do some cleanup of excess epoxy, and put everything back together.

I used a goodly amount of epoxy in the shell, then pressed in the anchor. A goodly amount of epoxy squeegeed out around the edges - which gave me an idea: why not add a bead/fillet of epoxy to both the front and rear of the anchor? Figured they'd serve as strengthening fillets in the absence of the original CF layer. A little ugly, but strength is the important factor:





Should be able to put it back together tomorrow morning and - fingers crossed - have a successful apres-ride report in the afternoon.

DD

gugie 

Just run bolts through the saddle to clamp that bit on.

And keep in the rivets while riding.

droppedandlost 

How many grams did that add?

TPL

Must be that the mechanic who takes care of the equipment for the professional team that pays you to ride should be able to just put a new replacement saddle on your bicycle

Drillium Dude 

Thanks! When the front anchor cracked the saddle hardly moved. It was only when I came off the saddle and coasted to a stop that the top popped off! Also happy that the crack(s) didn't extend to the main shell - or I'd have probably suffered some sort of trauma.

I've wanted to keep the monetary outlay low for the reasons you've pointed out (plus I'm cheap!); giving a fix a go makes monetary sense, and I'll be sensible with the test run as well. Hoping my extra strengthening with the epoxy makes this at least as reliable as it was before - or perhaps even more so.

DD

Drillium Dude 

Probably too old - early 90s? In any case, I'm not the original purchaser, so...

DD

Drillium Dude 

I think I need to stay off the rivet to extend the life of this saddle now

It'll take some time to feel comfortable that this fix has worked, but for now it sure seems solid enough. Tomorrow's test run will tell the tale.

DD

Drillium Dude 

Dunno, but if the extra stuff translates into extra strength I don't care in the slightest!

DD

Drillium Dude 

Ha ha - I'm just an old hack trying to feel as young as I can for as long as I can

DD

repechage

Resin starved.

Drillium Dude 

Re-assembly complete:









Saddle is back on the bike, ready to go for tomorrow. I have high hopes - hopefully they aren't misplaced.

Flexibility has been retained by using silicone in the rear anchors and leaving the front U-bend floating. Both are per original spec. I think the additional epoxy will result in a stronger bond between the forward anchor and the shell, so perhaps I've made this a touch stronger in this area than the original. Fingers crossed; again, finding CF repair specific JB Weld has my confidence level up higher than it might have been.

DD

Drillium Dude 

Yes, it works - but it was inexpensive, too. The JB Weld was $6.99 and the silicone was $4.99. If this repair lasts, the outlay was $11.98 - only ten bucks more than the cost of a late 70s Beauty Queen

Thanks for the suggestion; I figured on getting some negative feedback about using JB Weld, but I totally agree: it works. That's enough for me.

DD

Millstone

How does it look on the top? The part that you sit on?
Nice repair btw.

Drillium Dude 

Thank you!

The top wasn't affected at all:



DD