Dust46 Posted August 28, 2018 Share Good evening Hubbers, So I was working on my bike this evening when I saw my frame is cracked (read broken). It is pretty much broken through where the seat tube and top tube meet. Obviously there is already a weld there, my question is can this be repaired safely? If it can be, who would be the best to do such a job? Any suggestions are welcome. Edited August 28, 2018 by Dust46 Link to comment Share on other sites More sharing options...
Guest Ratchet road Posted August 28, 2018 Share What brand? And how? Usually warranty from producer depending on the scenario Link to comment Share on other sites More sharing options...
Dust46 Posted August 28, 2018 Share It is a Momsen but a 2014 model so I'm pretty sure it is out of any warranty. Im not sure how it happened, I did the Garmin MTB classic this past weekend and was changing my brake pads this evening when I noticed the damage. Link to comment Share on other sites More sharing options...
porqui Posted August 28, 2018 Share What is your location? You would need to take that to expert at alu welding.Would need heat treatment afterwards I think. Some warranties are lifetime if you are the original buyer.1st stop would be to go back to the dealer. Looks pretty terminal though. Dust46 1 Link to comment Share on other sites More sharing options...
Butterbean Posted August 28, 2018 Share If you bought it new, then try your luck with Momsen its only 4 years old so not that far gone... Other than that, it's probably not worth the cost and risk of repair. Aluminum welding repairs will be almost impossible to get right and normally, because of the heat associated and how it affects the structure of the metal, will jsit break right next to the weld... And as its in a high stress area you're just going to be waiting for the next crack... Used good considiton hardtail frames can be had for little money if you don't come right with Momsen, so that would be my recommendation, replace in both cases. Renier82, DJR and Dust46 3 Link to comment Share on other sites More sharing options...
Renier82 Posted August 28, 2018 Share yep looks fairly kaput! wonder how and why it went kaboom. Dust46 1 Link to comment Share on other sites More sharing options...
Ampandy Posted August 29, 2018 Share Yes it can be repaired and I have done many in a similar state, some worse. Dust46 and V12man 2 Link to comment Share on other sites More sharing options...
stefmeister Posted August 29, 2018 Share Are mountain bikers aerotucking as well now? Dust46, Danger Dassie, Andymann and 10 others 13 Link to comment Share on other sites More sharing options...
CAAD4 Posted August 29, 2018 Share How far out was your seat post? Dust46, ChunkyMonkey, fanievb and 1 other 4 Link to comment Share on other sites More sharing options...
Dust46 Posted August 29, 2018 Share yep looks fairly kaput! wonder how and why it went kaboom. I would love to know, the frame has served me well so it's strange how this happened. Link to comment Share on other sites More sharing options...
Dust46 Posted August 29, 2018 Share If you bought it new, then try your luck with Momsen its only 4 years old so not that far gone...Other than that, it's probably not worth the cost and risk of repair. Aluminum welding repairs will be almost impossible to get right and normally, because of the heat associated and how it affects the structure of the metal, will jsit break right next to the weld... And as its in a high stress area you're just going to be waiting for the next crack... Used good considiton hardtail frames can be had for little money if you don't come right with Momsen, so that would be my recommendation, replace in both cases.Unfortunately I bought it second hand, I have been looking in the classifieds for a frame and as you mentioned there are some fairly cheap replacement frames available. I will probably go that route. DJR 1 Link to comment Share on other sites More sharing options...
Dust46 Posted August 29, 2018 Share Yes it can be repaired and I have done many in a similar state, some worse.I will send you a pm to discuss, thank you. Link to comment Share on other sites More sharing options...
Dust46 Posted August 29, 2018 Share Are mountain bikers aerotucking as well now?Hahaha luckily this is not my 3rd replacement frame and it is fairly well used, there is absolutely nothing negative I can say about the Momsen brand. Is it Friday yet? eddy, PhilipV and DJR 3 Link to comment Share on other sites More sharing options...
Dust46 Posted August 29, 2018 Share How far out was your seat post?My seatpost is out 220mm with 200mm still inside the frame Link to comment Share on other sites More sharing options...
TyronLab Posted August 29, 2018 Share You'll need to find someone with the right equipment (read pre and post heating facilities) if you want to have that fixed. I highly doubt Momsen would have a custom Aluminium alloy made for their comparatively low volumes, so you should be able to get the alloy grade from them and related welding procedure. This should contain the recommended pre and post heating procedures, recommended electrodes etc. You should give that through to your chosen repairer as well. If he doesn't ask for it or show you that he already has the material spec I would stay away. All aluminum is not created equally. How often do you inspect your frame? A failure like that would be one of two things: 1. (Unlikely) there was a massive impact on your seatpost/saddle in the rearward direction and it fractured in one go. I'm pretty sure you would feel whatever body part it hit for a few days afterwards.2. There was a slight impact some time ago that caused the weld toe to crack, and due to not being picked up the crack propagated through to parent material. If this was picked up right after initiation the simplicity and robustness of the repair would be substantially better. But hey, what do I know, I'm just a Mechanical Engineer. Dust46 1 Link to comment Share on other sites More sharing options...
ChunkyMonkey Posted August 29, 2018 Share How far out was your seat post?How far out was your seat post? Yep... looks like the post was a bit far out...? Dust46 1 Link to comment Share on other sites More sharing options...
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