Shimano cranks breaking - You need to know !

[Music] [Music] hey [Music] [Music] [Music] oh i don't know maybe 800 cycles here today cheer ice oh tegra it's a different one 105 that's a good one you ride all the way from sterling yeah yeah real good but it was cold bear yeah seven degrees or something yeah see tegra [Music] out of all the bikes here by far the majority of the crank sets on the pikes are shimano ultegra actually shimano crank sets they're a very good crank set and they're the most populous on the market they're also very light but they're very strong and how they achieve those two factors together is instead of having this crank here being solid like it used to be in years gone past they hollow them out and the same with the bottom bracket axle it's hollow so they're actually done for a very reasonable price of course unless of course you're talking about due race or xeo they're top of the range model they're rather pricey but they're still a very good performing crank set there's a high chance that you've ridden or are still riding one of these four crank sets the shimano ultegra 6800 the shimano ultegra r8000 the shimano durace 9000 or its newer one the shimano durace r 90 100 which i haven't got here but here's the picture and i have one thing in common unfortunately they are breaking or failing at a much higher rate than any other crank set on the market whilst there are a few documented shimano holotec left hand crank failures and bottom bracket axle failures by far the majority of failures are on the right hand crank side now even though your crankset on your bike is not considered a critical safety component unlike the fork steerer on your frame here if that cracks you're going to go over your handlebars and if you're going any reasonable speed you're going to hurt yourself pretty badly so with these crank sets that are failing what you need to know and what you can do about it if you've got these crank sets on your bike now two of these crank sets here have failed this older duress one and a slightly older ultegra model one and they both belong to the same person so let's have a closer look at how they're cracked and why they might have cracked because i've broken 9000. i broke the 6800 i think it's six or seven years before cracked before craig but the 9800 one only had that for three years because i wanted to go you mean the 6800 at the 6800 sorry the sixth three years for three i think it's about three years twenty thousand kilometers it would have been around that yeah shimano you owe me two cranks now so you've got 105 on the moment no no hassles of 105. and and the wax chain and the wax chain having a closer inspection of the ultegra 6800 crankset we have it's cracked on the inside of the crank arm just above the pedal thread this is the most common failure point you can see the bonding has given away and the back face is lifting away from the front face this begs the question did the bond give way first causing a crack or did it crack first causing the bond to come unstuck what do you think on inspecting the front of the crank their front face and the large chainring line is flush and smooth on one of the arms but on one of the opposite arms you can feel your finger catching on the face plate which is lifting a closer view from the side you can see that the normal arm is flush which is how all the arms should be on your crank but the arm on the other side the face plate is lifting up and away so if you see this on any one of the four arms on your crank chances are the bonding has come unstuck the due race 9000 crank set again the back of the right hand crank arm two marks we'll have a close look at the upper mark and it looks more like a scratch and using a macro lens you can see the mark goes across both the inner and the outer plate not affecting the joint it's only superficial so it's only a scratch the bottom mark though it's in that suspicious place just above the pedal thread certainly looks like a crack and with the macro lens you can see it starts at the bonded joint and it goes across the inner plate and it's a secondary crack as well in fact this third mark there could even be another crack forming the front of this dura's crank set exactly the same scenario the front face plate is lifting up and away and a lower gap here between the large chainring and the face plate is indicative of a twisting force which is normal when we pedal our bike but the gap is not normal so our rider having experienced failures with these durace and ultegra cranks has gone for shimano 105 because it's extremely rare that you'll find a failure of a shimano 105 crank and it's the same with shimano claris tiagra and sauro crank sets they don't seem to be failing either you can see the difference looking at the back of this alternate right hand crank you can see the inner crank arm and the spider is glued yes this is glue here shimano call is bonding it is epoxy after all the spider or front face plate is where the chain rings are bolted onto and the glue or the bonding follows the join along the outside of the spider and down the crank arm so because there's a hollow between the back plate and the front plate shimano called this crank hollow bonded with 105 and the three other crank sets they are all one piece cast so no gluing at all and it's called hollow forged here's a hollow's forged crank sliced lengthways in half and as you can see it's one piece aluminium but hollow in the middle a different view you can see hollow bonded two pieces hollow forged one piece and the back of the right hand cranks you can see the hollow bonded one two pieces glued at the join of the front and the rear faces but the hollow forged no join because it's one piece now for common consensus the failure rate's pretty low so don't worry about it what's the chance of one person experiencing two failure rates and it doesn't take much looking on the interweb like forums to realize there's quite a few people out there that are experiencing multiple failures of these cranks another thing you might say is uh this guy he treats his bike like rubbish you should see how he goes over the bumps or he weighs too much the guy's a big guy or the weather we ride in is terrible no wonder the cranks failed what do you call normal use on a bicycle what about some of our pro riders sprinters putting out 1800 watts would you call that normal use how come they don't break their cranks or do they one of the best compilations of reasons why these cranks may be failing i saw is by peak talk on youtube have a look at him and he'll explain it for you much better than i can so one of the possible scenarios he said was moisture so that air cavity inside of your crank and the hollow crank contains moisture as all air usually does and that moisture when it gets cold it condenses onto the metal in the inside of that crank which is aluminium and then when the temperature rises it vaporizes again into that air cavity and then of course when it cools down again it grips back onto the aluminium surface on the inside so it's going through a cycle and that cycle causes corrosion on the inside of the aluminium so that's a very possible scenario another good explanation he presents is if you turn the crank over and have a look at the back you'll see where the two shelves are joined and glued there's a gap so that gap even though it's very very small could still allow some moisture to get in there and of course it's going to start that cyclic effect again of damaging the aluminium so that's a good possible scenario of why they come apart up near the spider another slightly less technical reason why it might be happening is sheer force going through the crank now i'm not talking about leg power talk about the weight of the rider for instance in this rider who's broken these two cranks weighs slightly over 100 kilos and if he's going over the bumps like we all do you take your weight off your seat a bit don't you and so more weight goes not so much on your hands but on your feet on your pedals through the axle through the cranks so when you go over the bumps you see saw over the bumps so you can imagine a lot more force going through the crank like this and when you weigh a fair bit that's a fair bit of force which could do the damage another reason it could be is when you unclip say at the light or at a cafe or wherever you are whenever you stop you unclip and which foot you unclip it's usually the left one so the weight goes on to the right pedal maybe not all your weight but it's certainly a difference because instead of balancing the weight between your two legs you've now got considerably more force on the right hand side so what will shimano do about this has there been a recall of these crank sets no has there ever been a recall by shimano of cranksets yes it has it was in 1997 in the us and it was for the cranksets fc-c79 fcm 290 and fcmc12 and that affected 49 different brand names using those cranks on those bikes in the us and shimano recognize that as a recall and here's something interesting if you have a look at your instructions for your crank set read on there and i'll quote it for you here's the instructions from the crankset and you'll see under important safety information warning check that there are no cracks in the crank arms before riding the bicycle if there are any cracks the crank arm may break and you may fall off the bicycle be careful not to let the cuffs of your clothes etc so there you go cracks in the crank like all products they have designers and the designers have three very important things in mind and that is make sure the cranks are strong but light but also fairly cheap to manufacture so manufacturing and also the materials that it's made from so you need to balance it all up so that it makes a consumable product so for like these crates you could say a certain percentage of these cranks need to remain trouble free for a certain life span let's just pull some figures out of the air and say 95 percent of this product must be still functioning after 40 000 kilometers now those decisions are called a safety margin so these designers or engineers have to make sure that the product makes money for the company profit which is fair enough but also means like in the old days when products used to last a long long time imagine a crank set you pass it on from one frame to another from one bike to another maybe well that doesn't happen these days the park is designed for a certain amount of life and then what do you do it's disposable you throw it out and buy a new one so it probably gets recycled so what can you do if you've got one of these crank sets on your bike first of all be aware of any signs to failure and they can be very easy to miss for instance you might have small amounts of clicking or some creaking going on in your shoes or the pedals or the cranks maybe as you're pedaling around the shoe or the pedal axle feels like it's on an angle slightly skewed well they're definitely early signs of maybe possible crank fracture so on the power stroke at the bottom of the the bottom of the stroke the the foot pushed out you could feel it pushing out i like the pedal was slightly coming yeah it felt like the pedal was was um power down and it felt like you were throwing your foot every now and then maybe when you're cleaning your bike feel for any cracks or lifting behind the crank arm especially just above the pedal thread and then also where the four arms join the large chainring and then don't forget to check the left hand crank as well then do a visual inspection viewing at different angles helps the light bring out any hairline cracks that you can't always feel with your fingers if you find any of the signs we've discussed or any other it will be wise not to ride your bike with that crank set for safety reasons if you have the original receipt for the crank set whether it's a hard copy or electronic contact a seller and inquire about a warranty claim now if your crankset fails on you while you're riding and you don't have an accident that's a good thing however if your crank sets out a warranty then it's still going to cost you money to buy another crankset anyhow if you need to replace a faulty crank but the warranty doesn't stand you will need to purchase a new crank so you can either purchase a compatible crankset without chainrings or a complete crankset with chainrings be very wary of buying a secondhand crankset of which shimano models have these faults you may just be buying someone else's faulty crank set whether the seller knows it or not you might be thinking what you could do is just buy the later model of the durace or ultegra right hand crank only without chainrings then transfer over the chainrings from your faulty crankset which are probably in good condition anyhow onto that newer model well great thinking but unfortunately shimano have made it the inner ones probably compatible but the outer one and one of the arms have a little chamfer so they make it that it doesn't quite fit on the newer model crank set so there you go if anyone has an idea how you can actually modify that maybe file a little bit off of that chainring then maybe you can transfer it over let us know in the comments that would be really handy for so many of us so i hope this video has been helpful for you in determining whether you're riding with a 40 shimano crank set and what to do about it and let's hope that shimano have addressed this crank issue in their neutral speed group sets remember the old shimano 600 ultegra they didn't break did they no but the new ones do actually right go on it's gone no no no one thing i learned today apparently it's okay and perfectly healthy to smoke if you've got a fantabulous bike [Music] yes

Channel: oz cycle

Views: 61,976

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Id: FkEkQV-zK0s

Length: 17min 0sec (1020 seconds)

Published: Sun Mar 14 2021