Chinertown
Chinese Carbon MTB => 26er & 27.5 (650b) => Topic started by: FHS on May 22, 2022, 03:24:08 PM
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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
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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.
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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.
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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.
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^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!
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^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.
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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!
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Here's the whole build btw...
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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??
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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!!
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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.
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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. :-[
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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 !
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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.
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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.
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If drilling a hole in the frame is a scary thought, using a flex hone on the seat tube is terrifying. :-[
Yup! I have never ever done a flex honing of a carbon frame- I could see how it might be approached but I agree- terrifying!
Ooh! Track down your local Campy Guy Who Has All Of The Campy Tools And Will Die With Them and see if he also collected a seat tube ream and just get medieval with it :P
THAT would be a terrific page-turner of a post to see how that works out! Mad bike scientist!
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FHS, on a serious and hopefully actually helpful note, I highly highly recommend hopping on ebamazon and picking up a digital caliper. The Park tool ones are just fine. (Or get some swanky Mitutoyos like I use at work!)
For its utility, the Park Tool calipers are wonderfully useful for the money.
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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.
Oh man, I don't even know what to say except a heartfelt thank you and it's definitely worth a try. I certainly don't fault and hold no ill will towards Eddy. He's been great with communication, the transaction was smooth, shipping fast, and communication great. But yeah, bad luck. Thanks again!
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It's clearly cracked, not sure why eddy needs the frame to see that.
He would want the frame to see if it's poor machining though or hadn't been through QC at that finishing stage.
Otherwise, wrong size seatpost or the easy out of saying it was ridden/tested with insufficient insertion.
The way you said installed to mark a cut point reminded me of a friend who put his seatpost in to mark for the cut. Set his height, marked it, added the "minimum insertion depth" measurement as printed on the bottom of the post. Cut it, reinstalled it, sat on it and snapped the seat tube. Proper brain fart on his part.
Fortunately it was the relative early days of carbon and a 34.9mm seat tube. We epoxied in a shim and he ran a 31.6 post successfully.
With a fixed post, I'd insert it to its bottom out position, figure how much lower I need it to be which equals how much I want to take off, remove the post then measure up from the end of the post.
I personally would repair that crack at home, but I have all the materials to do it.
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...I personally would repair that crack at home, but I have all the materials to do it.
Are you using shrink tape or do you have something more sophisticated ?
On top of carbon sheets and epoxy, do you have some must have materials usually overlooked ?
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It's clearly cracked, not sure why eddy needs the frame to see that.
He would want the frame to see if it's poor machining though or hadn't been through QC at that finishing stage.
Otherwise, wrong size seatpost or the easy out of saying it was ridden/tested with insufficient insertion.
The way you said installed to mark a cut point reminded me of a friend who put his seatpost in to mark for the cut. Set his height, marked it, added the "minimum insertion depth" measurement as printed on the bottom of the post. Cut it, reinstalled it, sat on it and snapped the seat tube. Proper brain fart on his part.
Fortunately it was the relative early days of carbon and a 34.9mm seat tube. We epoxied in a shim and he ran a 31.6 post successfully.
With a fixed post, I'd insert it to its bottom out position, figure how much lower I need it to be which equals how much I want to take off, remove the post then measure up from the end of the post.
I personally would repair that crack at home, but I have all the materials to do it.
I had issues even inserting deep enough to get to the minimum insertion mark. I ordered a set of digital calipers, as suggested. Just hoping it's the seat post, not the seat tube.
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Are you using shrink tape or do you have something more sophisticated ?
On top of carbon sheets and epoxy, do you have some must have materials usually overlooked ?
Looking forward to his reply.
With the irregular surface around the crack, I don't see shrink tape working too well. I won't be able to get a sheet completely wrapped around the area of the crack, like I could on a tube, either way. I think laying sheets will work, and I think I can make a mold that I can wrap shrink tape around to put some good pressure on the layers. I've also seen a video where a guy just wrapped the whole area in foam and tape. I've just never worked with epoxy that has to be squeezed away. If I wrapped everything up tight under foam, or molds, I'm just not sure where the excess epoxy is supposed to go.
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Just various thicknesses and types of weaves, epoxy and shrink tape.
I'll make basic forms where necessary like with the carbon skeleton of the Nordic skate ski boots I fixed last.
I've done some complex repairs at home, chainstay bridges, BB/main pivot area etc..all with shrink tape and electrical tape. The excess epoxy comes out theought the wrap laps with heat under the low amount of tape pressure.
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Hi again,
Had a couple of follow up exchanges with Eddie, including the possibility of a new frame. But, in the end, it sounded like everything was going to involve sending the frame back. I decided to just do the repair myself, in stages. My daughter didn't have to be without her bike for any amount of time, and I got the chance to work on new skills.
Here's the repair. Need to clean it up a bit and buff out the new clear coat. Just an Ebay CF repair kit, some sand paper, some mold making clay from Michael's, electrical tape, and some rattle can paint and clear coat.
Edit: Just an fyi... I was able to measure the inner diameter of the seat tube and the outer diameter of the seat post with a set of digital calipers. The inner diameter actually measures slightly larger than the 31.6 mm standard. However, the seat post also measured larger than the 31.6 mm standard, maybe .1 mm smaller than the tube. I only have the one round seat poss and the one round seat tube, but, I'm guessing the seat post is more of an issue than the seat tube.
Does anybody have actual measurements for comparison?