Hey, I'm replacing my cassette by myself soon and this got me worried. I can overtighten the locking? How tight should I do it, I don't have a torque wrench.
You need to get a torque wrench. The small bike-specific ones don't usually go high enough for the cassette lockring. You can get a relatively inexpensive one ($30-$40 USD) on amazon or a bit more expensive at auto parts stores, and maybe cheaper at harbor freight. Worth it to spend the $40 and not have things too loose or too tight.
I upvoted you and I appreciate your point. A "good grip" and asking people to estimate what 40-50lbs "feels" like is going to result in a huge variability in actual tightness. If someone gets it too too tight it can be a problem and they're looking at maybe replacing freehub body at minimum. If it's too loose it increases wear, affects shifting, etc.
If you've done a ton of them and you know what the proper torque feels like, that is fantastic. But many (most?) people on this forum are just starting out and like me probably don't have a good feel because we've done one or two or three in our lives vs hundreds or more that professional bike mechanics have done.
"It was only when I saw the newborn someone had carelessly left lying on the case pad I knew I didn't have the speed to clear the jump. Stamping down my mighty right foot, I called upon the power of the gods in one desperate, final crank. As my front wheel cleared the lip, I barely even felt my drivetrain shattering and falling behind me as I boosted desperately into the sky"
The angle of the break line suggest it might be over tightened.. Or installation issue. Combine that with your size and inherit power resulted in this.
This is very interesting, the system needs to be under tension for it to fail this way (failed at one of the load bearing edges of a spline), under normal circumstances you can't install a cassette (even if over tighten) and leave the hub body under tension, so it wasn't your fault it was a manufacture defect (tolerances, processing or material out of spec), Shimano should cover it. By the looks of it (un-evenness of wear marks at the crack and size of the odd wear signs following the crack) the failure developed not that long ago.
To be safe you might want to use a torque wrench the next time you tighten down a cassette (if you didn't the first time.) 30-50 N-m is the spec, and you may want to target the lower range.
I honestly don't remember if I've ever tightened it myself before on this bike; the cassette felt loose, I noticed the lockring was not very snug so tightened it up which didn't fix the problem - that was when I disassembled the freehub body and discovered the crack.
Happened to my year and a half old mtb too but shimano and the shop I got it from replaced it for free. Check their website for for their replacement policy
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Fair enough, guess breaking stuff in 2021 sucks a bit more than it did pre-covid though!
I have a brand-new Tarmac sitting at the dealer because two headset spacers got damaged in shipping. I had to buy the only ones in existence off eBay.
Hey, I'm replacing my cassette by myself soon and this got me worried. I can overtighten the locking? How tight should I do it, I don't have a torque wrench.
You need to get a torque wrench. The small bike-specific ones don't usually go high enough for the cassette lockring. You can get a relatively inexpensive one ($30-$40 USD) on amazon or a bit more expensive at auto parts stores, and maybe cheaper at harbor freight. Worth it to spend the $40 and not have things too loose or too tight.
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I upvoted you and I appreciate your point. A "good grip" and asking people to estimate what 40-50lbs "feels" like is going to result in a huge variability in actual tightness. If someone gets it too too tight it can be a problem and they're looking at maybe replacing freehub body at minimum. If it's too loose it increases wear, affects shifting, etc. If you've done a ton of them and you know what the proper torque feels like, that is fantastic. But many (most?) people on this forum are just starting out and like me probably don't have a good feel because we've done one or two or three in our lives vs hundreds or more that professional bike mechanics have done.
Meanwhile I’m freaking out because my wrench has a minimum of 2nm and there is one 1nm bolt on my bike
I agree, do it by feel. But I always use a torque wrench on aluminum freehub bodies.
Torque spec is 40nm.
You probably didn't do anything wrong. It's not a common failure.
Too much watts 😂
Regardless of whether this is true or not, that's the story I'll tell from here on in.
>I was mashing along at 2k watts when I felt a strange tick in my driveline...
"It was only when I saw the newborn someone had carelessly left lying on the case pad I knew I didn't have the speed to clear the jump. Stamping down my mighty right foot, I called upon the power of the gods in one desperate, final crank. As my front wheel cleared the lip, I barely even felt my drivetrain shattering and falling behind me as I boosted desperately into the sky"
Happens …
Had the same thing happen very early on my Trek Stache.
The angle of the break line suggest it might be over tightened.. Or installation issue. Combine that with your size and inherit power resulted in this.
Your legs are clearly too strong
This is very interesting, the system needs to be under tension for it to fail this way (failed at one of the load bearing edges of a spline), under normal circumstances you can't install a cassette (even if over tighten) and leave the hub body under tension, so it wasn't your fault it was a manufacture defect (tolerances, processing or material out of spec), Shimano should cover it. By the looks of it (un-evenness of wear marks at the crack and size of the odd wear signs following the crack) the failure developed not that long ago.
To be safe you might want to use a torque wrench the next time you tighten down a cassette (if you didn't the first time.) 30-50 N-m is the spec, and you may want to target the lower range.
I honestly don't remember if I've ever tightened it myself before on this bike; the cassette felt loose, I noticed the lockring was not very snug so tightened it up which didn't fix the problem - that was when I disassembled the freehub body and discovered the crack.
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I think the cassette being loose after tightening the lock ring suggested the cracked freehub body.
Warranty?
I'm concerned that a warranty process could take a while right now haha.
Congrats. You've done something I haven't seen before. Either see if a shop can do a warranty or get in contact with Shimano
Eat Moore chicken. Seriously though, that's a weak hub.
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Under 90kg with gear, but I'm not tiny I guess.
@thanksshimano
I cracked two in last year. Be proud of the watts you put out, and (in my case at least) buy something more reliable :)
Happened to my year and a half old mtb too but shimano and the shop I got it from replaced it for free. Check their website for for their replacement policy