Damn, cracked seat tube.

[FHS]

Just got my daughter's bike together and I noticed this. Tideace fm-001 26er. Pretty sure I cracked it trying to fit the seat post. I knew I was going to have to cut it down to size but I pushed it in too deep trying to mark a cut point. Honestly not sure if it cracked going in, or twisting it out. I think it's repairable. Just hoping I don't have to trash the frame.

Any thoughts are welcome, I'll even take a tongue lashing because I know better

[carbonazza]

This should not happen by just putting the seatpost in.
Did you apply a lot of force?
Not sure this can be repaired unfortunately.
Maybe if you have a carbon repair shop around, ask them, but this could quickly become the price of a new frame.

Ask Tideace opinion, if they think this a defect?
Or if you're sure you caused it , delay your own bike I'm afraid, and get another frame for her.

[FHS]

I emailed Eddy, but I'm not all that optimistic honestly. Even if there is a replacement or something in line, even shipping costs would probably make it not worth the effort.
 
We have a pretty good carbon repair place locally, but yeah, that's probably not worth it either. Just the cost of admission of going this route.

Mostly just wondering about the stresses in that area of a frame. She's 60 lbs soaking wet, riding around the neighborhood. I mostly concerned about propagation into the seat stay.

[Zomb1e]

This should be a fairly simple repair and it can be done at home. All you need is sand paper, carbon fiber fabric and epoxy. Wet sanding should be preferred over dry (and if it is not possible, wear a respirator). Wrap upper part of seat tube with 3-4 layers of carbon fiber fabric (applying epoxy on each layer) after removing the paint, and this will be enough.

Also it will be a good idea to drill a small hole in the end of crack (you'll see where exactly it is located after sanding) to prevent further crack growth.

[Kirkspants]

^If you have a dremel, preference is to grind a hole at the end of the crack; less damage by grinding/sanding carbon.

Was the seatpost super tight/loose when you installed it? Like the other reply, were you really reefing on it when you shoved it down?

Sorry for the bad luck!

[FHS]

^If you have a dremel, preference is to grind a hole at the end of the crack; less damage by grinding/sanding carbon.

Was the seatpost super tight/loose when you installed it? Like the other reply, were you really reefing on it when you shoved it down?

Sorry for the bad luck!

Yeah, it's suuuuper tight. I don't even have to clamp it. I was as careful as I could be with it but it took more force than I've ever experienced on a new frame to try to seat it and then try to extract it. How big a hole would I have to grind/drill? I've been watching plenty of Youtube videos on carbon repair and feel like it's something I could do. I've read where people have drilled, or suggested drilling to stop propagation, but I haven't actually seen it done on CF.

The only thing that really concerns me about this crack is it's proximity to the seat stay. Otherwise, the seat post is so low, I can't see there being much leverage to do too much more damage given the length of the seat post below the crack and how much my daughter weighs.

[FHS]

This should be a fairly simple repair and it can be done at home. All you need is sand paper, carbon fiber fabric and epoxy. Wet sanding should be preferred over dry (and if it is not possible, wear a respirator). Wrap upper part of seat tube with 3-4 layers of carbon fiber fabric (applying epoxy on each layer) after removing the paint, and this will be enough.

Also it will be a good idea to drill a small hole in the end of crack (you'll see where exactly it is located after sanding) to prevent further crack growth.

Thanks Zomb1e. I've seen where people have used progressively smaller pieces of carbon fiber and progressively larger pieces to cover the damaged area. What do you think?

My thought was to do progressively larger pieces starting with a cut that just covers the crack by a couple centimeters to each side, then ending with a full wrap around the seat tube. I was then going to do a layering over the area near the seat stay by just laying the CF over the area rather than trying to wrap any CF around that portion. If I can blend it well enough, it'll look mostly like the CF seat post just goes all the way to the frame with some CF fourish at the seat stay. I'd rather clear coat bare CF rather than trying to match paint.

Thanks again!

[FHS]

Here's the whole build btw...

[Kirkspants]

I realize this is a non answer to you question of “how big of a hole do I drill” but it should not be small. Too small and you just have a good starting point for a new crack. Recall your metal frames of way back when- you’d often see a slit at the seatpost clamp, and the hole below it would be larger than the width of the slit.

Hope that at least helps?

Say, less than 1 cm diameter more than 3 mm diameter? I say go for 5??

[Kirkspants]

Yeah, it's suuuuper tight. I don't even have to clamp it. I was as careful as I could be with it but it took more force than I've ever experienced on a new frame to try to seat it and then try to extract it. How big a hole would I have to grind/drill? I've been watching plenty of Youtube videos on carbon repair and feel like it's something I could do. I've read where people have drilled, or suggested drilling to stop propagation, but I haven't actually seen it done on CF.

The only thing that really concerns me about this crack is it's proximity to the seat stay. Otherwise, the seat post is so low, I can't see there being much leverage to do too much more damage given the length of the seat post below the crack and how much my daughter weighs.

If you want to nerd out get a few good measurements of ID from a good set of calipers and see what the seat tube measures out at. I had a lower headset bearing on a Workswell frame that I once had to sand/hammer into place… one of those things, I guess…(The frame was not the right dimension not the bearing!)

If you go to China Freight and pick up the right size flex hone, that could work too. Just be careful and test fit often!!

[Zomb1e]

Thanks Zomb1e. I've seen where people have used progressively smaller pieces of carbon fiber and progressively larger pieces to cover the damaged area. What do you think?

This is good idea in terms of saving weight and cleaner look. But I think that after applying small pieces of CF you should do at least two full wraps over seat tube.

[FHS]

If you want to nerd out get a few good measurements of ID from a good set of calipers and see what the seat tube measures out at. I had a lower headset bearing on a Workswell frame that I once had to sand/hammer into place… one of those things, I guess…(The frame was not the right dimension not the bearing!)

If you go to China Freight and pick up the right size flex hone, that could work too. Just be careful and test fit often!!

Yeah, I've been wondering about fitment since the crack appeared. I didn't think about it while shoving the post in because I bought both the frame and seat post from the same vendor, specifically so I wouldn't have to worry about fitment. On my cheapie calipers, the post definitely falls between 31 and 32, and it definitely goes into the seat tube, it just starts to hit resistance about an inch or so in.

If drilling a hole in the frame is a scary thought, using a flex hone on the seat tube is terrifying. 

[carbonazza]

Did you get any response from Tideace?

I repaired a few frames already, but failed once around the seattube, as it was not easy to wrap it well because of the other tubes around.
As it is a quite solicited zone, it cracked again.
Good luck in trying, and send us pics !

[FHS]

Did you get any response from Tideace?

I repaired a few frames already, but failed once around the seattube, as it was not easy to wrap it well because of the other tubes around.
As it is a quite solicited zone, it cracked again.
Good luck in trying, and send us pics !

Yeah, Eddy has been responsive but guarded. He wants me to pay for shipping to send the frame back so they can inspect it to see if it'ds actually cracked. I told him I would rather spend the money on getting it repaired. He asked me how much that would cost. My local carbon repair shop says $350 minimum. Waiting for Eddy to respond back.

Like I said, not optimistic. It really looks like a crack from the outward pressure of the seat post. And it is at an awkward angle to completely wrap. Worth a try though if there is no recourse from Tideace. It's a bummer, but I'll do what I can do.

[Sitar_Ned]

Oh man, what a bummer.

It's not much and it may not help, but if you want, you can tell Eddy that I'll give him free 30 days of a banner advertisement if he'll replace the frame for you. That might help it make more financial sense for him.