aviatoreb Posted August 27, 2019 Report Share Posted August 27, 2019 Here’s a picture I took today on my bicycle during bicycle “preflight”. yikes! That’s my stem. If the stem breaks st 35mph down a hill - forgetabout it. That’s a break a shoulder break a nose loose some teeth get a concussion wake up in a helicopter crack. its aluminum. It’s a top of the line al stem. Glad I caught that one... 3 Quote Link to comment Share on other sites More sharing options...
EricJ Posted August 27, 2019 Report Share Posted August 27, 2019 JB Weld? 1 1 1 Quote Link to comment Share on other sites More sharing options...
Air pirate Posted August 27, 2019 Report Share Posted August 27, 2019 (edited) Good thing you caught it when you did. I ride an Indian Motorcycle, I had an aluminum tool tube (like a tennis ball can). bolted to the front of my frame with two aluminum brackets, been there for 10 years . A few weeks ago I'm riding down the hwy at about 55 mph and all of sudden I hear a clank and the bike (all 750 lbs of it , plus my 225) hops into the air from the back, I hear more metal clanking and a quick glance in the mirror reveal parts behind me (some very large). I kept her upright and straight and didn't hit the brakes not sure what the hell happened. After I coasted down to a slower speed, I gently tried the brakes and the bike stopped, I though the engine fell out or the trans. The bike was still running well. I shut it down and put down the kick stand, looked back and noticed the large piece I saw was one of my saddlebags that departed to the violent jolt of the rear end hopping 3 feet in the air and coming down, fortunately I was able to get to it before some dope ran it over, it was then I noticed the tool tube scuffed up and with rubber marks from the rear when n the road and the broken aluminum brackets. The brackets were pretty thick (two of them) and they cracked, makes wonder about the integrity of my front end now. I gave the bracket (stamped Indian) to my mechanic, I think we was going to make it into a bong. Edited August 27, 2019 by Air pirate 2 Quote Link to comment Share on other sites More sharing options...
RLCarter Posted August 28, 2019 Report Share Posted August 28, 2019 1 hour ago, aviatoreb said: It’s a top of the line al stem. Glad I caught that one... When you replace it, tighten the pinch bolts evenly, and don't over torque...I've seen this numerous times in the Motorcyle industry 2 Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted August 28, 2019 Report Share Posted August 28, 2019 The other side looks like it has a crack forming too. Quote Link to comment Share on other sites More sharing options...
carusoam Posted August 28, 2019 Report Share Posted August 28, 2019 Erik... There seems to be a bit of road rash on the part. A great source of stress-multipliers... enough to form and propagate a crack. as are the machine marks left over from the manufacture of the part... Maybe somebody thought the machine marks looked nice? Grinding and polishing probably costs a bit extra... PP thoughts only, not a materials scientist... Holy Cow, Pirate! Got a checklist/pre-flight procedure for the two wheeler? Best regards, -a- Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted August 28, 2019 Author Report Share Posted August 28, 2019 26 minutes ago, N201MKTurbo said: The other side looks like it has a crack forming too. Yes there are cracks on the other piece. That stem is one good bump from a catastrophic failure. Goose bumps on the back of my neck when I saw it. Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted August 28, 2019 Author Report Share Posted August 28, 2019 (edited) 5 minutes ago, carusoam said: Erik... There seems to be a bit of road rash on the part. A great source of stress-multipliers... enough to form and propagate a crack. as are the machine marks left over from the manufacture of the part... Maybe somebody thought the machine marks looked nice? Grinding and polishing probably costs a bit extra... PP thoughts only, not a materials scientist... Holy Cow, Pirate! Got a checklist/pre-flight procedure for the two wheeler? Best regards, -a- I was kidding check list but yes in 15 seconds you can look over the bike. Tires and parts. Glad I did! dont laugh but I’ve snapped in two four different cranksets, one pedal, one frame and lots of spokes over the years. Edited August 28, 2019 by aviatoreb 1 Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted August 28, 2019 Report Share Posted August 28, 2019 35 minutes ago, carusoam said: Erik... There seems to be a bit of road rash on the part. A great source of stress-multipliers... enough to form and propagate a crack. as are the machine marks left over from the manufacture of the part... Maybe somebody thought the machine marks looked nice? Grinding and polishing probably costs a bit extra... PP thoughts only, not a materials scientist... Holy Cow, Pirate! Got a checklist/pre-flight procedure for the two wheeler? Best regards, -a- I’m thinking that road rash came from setting the bike upside down to change a tire. 1 Quote Link to comment Share on other sites More sharing options...
Yetti Posted August 28, 2019 Report Share Posted August 28, 2019 Meh the bottom would hold for awhile. I believe there was a recall on some of the Thompson Stems. Might want to check CPSC. Myself and only one other guy are the only ones I know who have broken a Thomspson Seat post. 1 Quote Link to comment Share on other sites More sharing options...
MB65E Posted August 28, 2019 Report Share Posted August 28, 2019 Wow! Two broken Tompson parts in one thread. I’ve never heard of that! I have them on my Waltworks 29” -Matt 1 Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted August 28, 2019 Author Report Share Posted August 28, 2019 8 hours ago, N201MKTurbo said: I’m thinking that road rash came from setting the bike upside down to change a tire. I'm not seeing the road rash- where? Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted August 28, 2019 Report Share Posted August 28, 2019 2 hours ago, aviatoreb said: I'm not seeing the road rash- where? The little grey chips on the top of the stem. Quote Link to comment Share on other sites More sharing options...
RLCarter Posted August 28, 2019 Report Share Posted August 28, 2019 2 hours ago, aviatoreb said: I'm not seeing the road rash- where? Looks more like pitting than road rash.... Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted August 28, 2019 Author Report Share Posted August 28, 2019 (edited) 10 minutes ago, RLCarter said: Looks more like pitting than road rash.... I don't think that is road rash but I suspect corrosion. Actually bicycles live in an extra ordinarily corrosive environment. Besides road grime, and road salt...there is sweat rolling off your nose. No kidding. Sweat is amazingly corrosive. And the stem gets the worse of it. Most of my bike(s) are titanium which is beautifully non corrosive but the Al stem not so much. P.S. I wish my Mooney were made of Titanium. Edited August 28, 2019 by aviatoreb Quote Link to comment Share on other sites More sharing options...
RLCarter Posted August 28, 2019 Report Share Posted August 28, 2019 16 minutes ago, aviatoreb said: I don't think that is road rash but I suspect corrosion........... Sweat is amazingly corrosive. I suspect corrosion as well. I machined a set of extended forward controls (foot pegs) for a guy's Harley and sent them out for chrome, less than a year later the chrome was peeling and pitting, while looking at it I noticed corrosion/rust was starting pretty much everywhere. Short story long he had a pool installed and the pool chemicals (chlorine) was stored less than 1ft from the bike. I've also seen the same with water softners which use rock salt 1 Quote Link to comment Share on other sites More sharing options...
Yetti Posted August 28, 2019 Report Share Posted August 28, 2019 I am going to say not corrosion, but a stress riser caused this one. and probably too tight. Thompsons have pretty good coating. Even though I coat in bearing grease prior to putting the seatpost on, I still have had to dig one out because of lack maintenance. Note there is a nick on the bottom band and a nick on the Headset bearing race. Oh and the last cracking issue was faceplates. Oh and the OP has kind of used the wrong tool to tighten the stem. And there is an alum to carbon galvanic thing. I would guess that bike has tumped over a couple of times. never had a stem crack, but I buy parts based on design durability and would not use that stem for the reason the OP posted. https://forums.mtbr.com/components/thomson-admitting-their-products-not-meant-last-1091681.html Quote Link to comment Share on other sites More sharing options...
Yetti Posted August 28, 2019 Report Share Posted August 28, 2019 Oh and I don't run carbon bars on anything. 1 Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted August 28, 2019 Author Report Share Posted August 28, 2019 1 hour ago, Yetti said: Oh and I don't run carbon bars on anything. Me neither - I have known several people to have failures. Despite torque wrenches. It is so common these days carbon forksets with carbon steerer tubes that are easy to over torque your stem onto and cause a crack that will eventually make a fork failure. To prevent that I do the standard "clysdale trick" (which I am even at my meanest leanest at 6'4''), which is you get a metal tube liner to put inside of the carbon steerer tube, which you epoxy in place. That makes a laminate and thicker tube that is far less likely to fail. Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted August 28, 2019 Author Report Share Posted August 28, 2019 1 hour ago, Yetti said: I am going to say not corrosion, but a stress riser caused this one. and probably too tight. Thompsons have pretty good coating. Even though I coat in bearing grease prior to putting the seatpost on, I still have had to dig one out because of lack maintenance. Note there is a nick on the bottom band and a nick on the Headset bearing race. Oh and the last cracking issue was faceplates. Oh and the OP has kind of used the wrong tool to tighten the stem. And there is an alum to carbon galvanic thing. I would guess that bike has tumped over a couple of times. never had a stem crack, but I buy parts based on design durability and would not use that stem for the reason the OP posted. https://forums.mtbr.com/components/thomson-admitting-their-products-not-meant-last-1091681.html I doubt it was over torqued as I always use torque wrenches there. But bike stuff does get beat up over time. Eeeeh ghad what a horrible record and policy for a company selling high priced crap to declare that its not supposed to last. Thomson is a proper high priced company presumably. Well I ain't buying anything from them again. Quote Link to comment Share on other sites More sharing options...
Yetti Posted August 28, 2019 Report Share Posted August 28, 2019 Yetti trumps Clydesdale... just saying. Which is how I became the Yetti. Someone was drafting behind me and said it is like drafting behind a Sasquatch..... I responded with "I am a Yetti we are the northern tribe and don''t associate with the southern yehaws" and it stuck. both my bikes have really long steer tubes so I have found that Wound up and Whitebrothers will put an extra length steer tube on their forks. Only Wound up is carbon, and yes they use an insert. Quote Link to comment Share on other sites More sharing options...
Yetti Posted August 28, 2019 Report Share Posted August 28, 2019 2 minutes ago, aviatoreb said: I doubt it was over torqued as I always use torque wrenches there. But bike stuff does get beat up over time. Eeeeh ghad what a horrible record and policy for a company selling high priced crap to declare that its not supposed to last. Thomson is a proper high priced company presumably. Well I ain't buying anything from them again. I have Thompson posts from the last decade. I think they have to say that for the lawyers. I have broken way more Ti rail saddles that thompson posts. Selle Itallia will rerail your saddles if you send them in. Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted August 28, 2019 Author Report Share Posted August 28, 2019 2 minutes ago, Yetti said: Yetti trumps Clydesdale... just saying. Which is how I became the Yetti. Someone was drafting behind me and said it is like drafting behind a Sasquatch..... I responded with "I am a Yetti we are the northern tribe and don''t associate with the southern yehaws" and it stuck. both my bikes have really long steer tubes so I have found that Wound up and Whitebrothers will put an extra length steer tube on their forks. Only Wound up is carbon, and yes they use an insert. I think in a fight - a Yetti will definitely stomp a Clydesdale. But maybe a Clydesdale is better in a race?..... But Clydesdale is generally the phrase for a bike rider larger than 200lbs - which in my leanest meanest days of road and track racing even when I was a cat 2 back 20 years ago... Today I am 15...20lbs more. My bike is built by the oversized-rider guru Lenard Zinn, and the fork is a custom job he has made by Alpha Q for oversized over weight riders with extra thick carbon and that metal sleeve. The 200mm cranks are also extra beefy. And I have all my wheels built with extra spokes, even though they are fancy aero wheels. Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted August 28, 2019 Author Report Share Posted August 28, 2019 5 minutes ago, Yetti said: I have Thompson posts from the last decade. I think they have to say that for the lawyers. I have broken way more Ti rail saddles that thompson posts. Selle Itallia will rerail your saddles if you send them in. Ti is DEFINITELY a better material for bicycle applications than any of the other metals (but lets not discuss carbon as it has both its own good and bad properties). Ti is lighter, stronger, less corrosive. But any metal can fatigue and crack. I think usually if a Ti part breaks like the seat rails you are describing the metal was over worked and improperly worked when it was shaped at the factory. And generally not beefy enough. Also Ti can fail at the weld joints if the welds were done improperly which is a trick since the process requires welding in an O2 free environment. But a properly built (welded and not over shaped/worked metal) Ti bike will last forever. My road bike is Ti and about 15 years old and seems the same as when I bought it. It is an extra beefy Clyde-build. Meaning emphasis on thick tubes, extra thick welds, etc. But being Ti it is still very a reasonable weight. No paint or anything needed on a Ti build since it doesn't corrode. ...I wish my Mooney were Ti. Quote Link to comment Share on other sites More sharing options...
steingar Posted August 28, 2019 Report Share Posted August 28, 2019 (edited) Sounds hinky. Both my Super Sport motorcycles have aluminum frames, as do a lot of the adventure bikes. These bike all go through hell without cracks in the frame or anything else. Edited August 28, 2019 by steingar 1 Quote Link to comment Share on other sites More sharing options...
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