Busted Carbon - Help Please?
 

Today this happened:

https://cimg5.ibsrv.net/gimg/bikefor...ef4e95e75f.png

https://cimg1.ibsrv.net/gimg/bikefor...495961b8b0.png

https://cimg7.ibsrv.net/gimg/bikefor...cdba3d2bd6.png

I was sitting "heavy" when I hit a substantial bump at substantial speed. Crack! I stuck the shell under my jersey, the anchor in a jersey pocket, and rode standing up the remaining 15 miles. Yes, my legs were damned tired at the finish :)

The failure seems pretty localized. The shredded bit looks to be a single layer that butted up against the base of the forward anchoring point; doesn't even look as though it was structural. Is it possible to clean that up with an X-Acto, then use epoxy to re-attach the anchor piece? Note there doesn't appear to have been any epoxy holding the anchor in the original configuration; doesn't appear to have been any at the rear attachment points, either.

I'd really like to save this saddle. Carbon repair experts are encouraged to weigh in with their suggestions; if suggesting products, please provide name brands so I can find them if/when I go lookin'

Thanks!

DD

Good thing you didn't get a vasectomy or something more drastic :eek:

A seat is extraordinarily dynamic. So, I'm not surprised that it wasn't glued in the back, with the expectation that the rods would float a bit as weight shifted, perhaps on both ends.

That is an odd two layer construction on the nose, but probably with the concept of not putting a hard lump at the nose end of the saddle. That is a unique hanging cradle design.

I've broken a direct Chinese import saddle once, a few years ago.

Mine failed because it had a glob of non-reinforced, but brittle goop holding the end on. No fiber reinforcing at the critical point. I think the rails at the rear were still fixed to the saddle, and I was able to carefully ride mine home about 5 to 10 miles.

https://www.bikeforums.net/attachmen...hmentid=529914

In your case, I'd probably reinforce that cradle area a bit. Then slide everything together and expoxy the nose piece onto the cradle. Perhaps even wrap around the nose piece a few times (tubular/sock carbon fiber?)

Carbon is brittle.
the secondary bond nose collar? Cave?
is not held in with much surface area.

I am not excited about the aft ends of the Ti frame, there be flexing there and one side looks sharper than the other.

my wife would suggest I buy a new one.

It's trashed. Really, it is ready for the bin. Buy a new saddle.

It could be rebuilt as a hobby project but it would be a lot of work.

I use West System epoxy and carbon fiber to repair lots of stuff that I have, I have not done a seat, however, it would be simple enough I believe. West System sells carbon fiber unidirectional ribbon that is on a roll rather than a woven mat. This is what I would get for this repair. I would mix up the epoxy, thicken it a bit with colodial silica and brush it over the damage rail and seat. Then apply lengths of the carbon fiber over the repaired area first going in one direction, then the other. You may want to have more layers going across the rail and fewer in the direction of the rail.

If you want to make the rails float, you could try coating them were they will be covered by the epoxy with Vaseline or something similar to prevent the epoxy sticking to it.

Alternatively, if you like the seat enough you could make a mold of the seat and start off making a new seat. You will still have to attach the seat rails to the seat though.

I find that epoxy is easy to work with and I like using carbon fiber for the repair because the I can control where the strength is based on the direction that I apply the fibers.

I haven't ordered from West Systems in a long time. I don't see their carbon fiber ribbon on their website.

You might be in the wrong sub forum for this topic :lol:

There is a small plate (not carbon) screwed into the lower portion of the anchor; the anchor separated from the shell due to the hit. When the screws are removed, the plate comes off and allows you to remove the rails from the saddle. It's actually a pretty interesting design, and I think it'll allow me to affect a simple repair. Since the lower portion seems to only have been fixed in place by a single carbon layer, I think a liberal application of epoxy might just lock the anchor back in enough to provide continued support. Heck, it only broke because I was firmly planted too far forward on the saddle when I hit really hard - and I normally "ride light".

For additional info, once home I stuck the anchor back into the saddle and it fits really tightly on it's own - I really had to yank to pull it back out. Add some industrial-strength epoxy when re-fitting and I'm betting it will last for many more years. However, I'll not be adding epoxy to the three points where the rail connects to the shell - agreed, it should "float" a bit to relieve stress.

Would like to add some carbon fabric, but don't know where to find that stuff.

DD

The slot in front which locates the front of the rail is actually plenty deep, so that's not a problem; I just over-stressed the design load.

The ends of the Ti frame are okay, tho I may round them a bit when I put this back together. But no, I'm not really ready to toss this saddle just yet. For one, it's damn comfortable (tho it probably doesn't look like it), and two, they're uncommon and extremely expensive to replace.

DD

Tell that to the guy in a recent thread (you may even have posted in it) that was repairing a broken fork blade!

Pretty sure this can be saved - and I'm gonna give it a go.

DD

Thanks for the West Systems call-out; I looked and didn't see any carbon materials for sale, either :(

While I'd love to add carbon ribbon to the epoxy solution, I may have to pass if I cannot find the material. As far as making a new seat, no way. Waaaaaaaay out of my paygrade, plus much more work than simply re-attaching the anchor point and beefing it up with epoxy.

Btw, the rails already float. I was originally thinking to add epoxy to all three points where they attach to the shell, but a member has suggested it's better to have some give, tho I might put a touch of silicone sealant in the rear sockets.

DD

Seems like the same people who do carbon fiber frame repair would handle that. Calfee is well known but plenty of these places have popped up in the last few years. Send it to a professional!

If this is the saddle, I can understand you wanting to try to fix it. $550 on fleabay https://www.ebay.com/itm/23438124719...xoCdZsQAvD_BwE

check out surfboard supplies these I think are in you neck of the woods

https://www.theshapingshack.com/

https://foamez.com/product-category/...einforcements/

https://fiberglasssupply.com/surf/

Yup - that's the one :)

I wonder if I can affix this thing with JB Weld? Half seriously thinking about it.

Any ideas of a specific name brand for an epoxy designed for use with carbon? And thanks for the links; assuming I find the correct epoxy, I would be open to using fiberglass reinforcement in lieu of carbon.

DD

While I'm sure they would, I doubt it would be cost-effective - and I'm fairly certain they wouldn't guarantee their work on a vintage bike product originally manufactured by a different company - outside the US, even. I want to effect this repair - if possible - myself.

DD

something like this might work, West Marine would likely have it. thick enough to add some filet reinforcing https://www.westsystem.com/specialty...-flex-syringe/

$550!, Ouch!

I have no idea of your level of experience designing and using fiber laminates and epoxy resins. These are my thoughts on the matter.

1. Don't forget to put doublers (plies of material over the break) on the outside, too. Without those, IMO, the saddle will likely break again. Weight on the "nose" will show up as a tensile load in the outer doubler plies (which is what you want). Without external doublers, the crack will just open up again and all your work underneath will be for naught. Fibers work best in tension, not compression.

2. Fabric is nice (easier) because you get fibers in two directions built into it. Unidirectional tape is more work but will also work well. Uni tape is thinner but much more directional in its properties (strong longitudinally, very weak tranverse).

3. If you are unfamiliar with layup, get a resin/hardener system with a long working time, a long pot life. They may be slower to cure but give you the time you need to get it right.

4. In designing your fiber plies and overall layup, be sure to maintain symmetry (same plies on both side) to keep it straight and true. Also, maintain balance or it may twist.

5. That fitting appears to be a stress riser, a sharp edge - little or no "fairing in" to the bottom of the seat, no extra plies (doublers) to spread the loads.

I hope some of this helps in some way.

You can do this repair for less than $550 but it will have to be a labor of love (don't factor in your cost of labor).

You have nothing to loose by trying to repair it. I wouldn't use JB weld even though it is strong. It doesn't have the fibers that will be crossing over the rails to give it enough strength. If you do go with JB Weld or Marine-tex (both are similar), and it fails or cracks, you could grind away the repair epoxy and try again with carbon fiber and epoxy.

To do the repair I would grind/file down the bumps where the rails go in and apply layers of carbon fiber with epoxy over the rails.

The carbon fiber I use looks like straight human hair in jet black. There is something sold by Wick's Supply that is West System unidirectional carbon fiber with a part number of 702. West may have put some fibers that run across the straight fiber to keep it neater. Keeping these fibers in place was a problem on version of the carbon fiber that I have.

Wick's Aircraft Supply

This look more like the stuff that I use: JL Smith

By the way, I think that even though this a carbon fiber component and some C & V'ers have an aversion to carbon fiber, many C & V'ers may have the knowledge and motivation to repair a components rather than buy another one. I originally bought this carbon fiber to strengthen a wooden sailboat.

Mcmaster-Carr has some CF options. They likely sell the correct epoxy, too.

McMaster CF

I order tools and materials from them regularly and they've been outstanding.

Drillium Dude , rhm can make you a new C&V appropriate cover for those rails... :innocent: ...jus' sayin'.

Another recommendation for WEST system stuff. I've been using their stuff for 40 years and have never had a failure. They will have all you need and I understand that they are good about giving advice about particular applications.

Though I’ve never worked with carbon, I’ve done more than my share of fiberglass work. I’d have no qualms about cleaning, sanding and reattaching that then reinforcing it with laid up pieces of fiberglass. I’d get the smallest container of west system epoxy I could find. You won’t need much. Like someone else mentioned, mix in some colloidal silica until it’s a peanut butter consistency, that’s your glue. Then reinforce it with some fiberglass. If you’ve never worked with these materials, do a practice run on some scrap. It’s hard to tell from the pics, but it seems like an easy repair. I guess you could use JB weld, but for some reason I just don’t trust it as much. I don’t really have a reason why, I’ve just had much more experience with west system epoxy. Much like painting, good prep work is essential. Clean with acetone, lightly scuff mating surfaces with medium grit sandpaper clean again with acetone then have at it. You may need to figure out how to clamp hold everything in place to keep it from sliding out of position as the epoxy sets.

the resin- hardener system by West is good but even the smallest qtys will set you back $50+
you do not need the pumps but would need a good gram scale. Plus cups, stir stick and brushes, gloves...

becomes an uneconomical repair.

I just bought some for a job.

the problem I see here is under engineered and not a good match for flex, ( the frame) and the rigid nature of carbon.

this is why I am suggesting this https://www.westsystem.com/specialty...-flex-syringe/ what do you think