I snapped my rear 6 bolt rotor clean off whilst riding. Damn!!!!!

[Neeko DeVinchi]

I'll take pics in the morning when I've got good light to show you all but flippin heck. I have never experienced that!!!

Basically, I decided to hit some dirt after work before heading home and I'm blasting down Coombs Wood when all of a sudden, I hear a 'ding!!!' followed by scraping sound.

I wont bore you with how I discovered that the rotor had completely snapped off all 6 bolts of the hub (and I don't have no gopro footage anyway ). But damn. THAT HAS NEVER HAPPENED TO ME BEFORE!!!!

Yes, I can confirm that the 6 T25 bolts were torqued up correctly. But still, this is a ggenuine mystery.

A pic is required I'm sure but to describe what I'm looking at, imagine all 6 points of the hub where the rotor attaches sheared off 'Disintegrated' would be the word. The rotor however seems fine along with the bolt holes (don't ask me where the 6 bolts are even with a 3000 lumin light, you ain't finding rotor bolts in the dark).

Anywho, just thought I'd share. Front brakes fine FYI

 

[levity]

That’s why I use center-lock brake discs

Glad you weren’t hurt! I’ve heard of frames failing (seatstays) on sudden extreme braking, but not disc attachment. Sadly, the hub is likely toast because it will be tough to get the remaining screws out. Look forward to the pics and what brand/model of rotor and screws.

BTW, did you rotate the disc clockwise a bit to remove residual play before tightening the screws? If not, a bit of slippage could lead to a sharp shear force and cut the screws.

 

[2WheelsNot4]

Pics required for sure. But it sounds like the fault is in the bolts and those might just be down to generic cheapies

did you rotate the disc clockwise a bit to remove residual play before tightening the screws?

Such a scenario would only be an issue if it was newly fitted, and no braking had been undertaken prior to this braking any play, if any at all, i dont think would be enough to suddenly shear every bolt at the same time, rather the bolts are at fault.

 

[RustyIron]

Yes, I can confirm that the 6 T25 bolts were torqued up correctly.

Dude! You sure those weren't aluminum bolts intended for your bottle cage?

 

[lightning]

Sounds almost impossible with the amount of braking force you can put on an mtb disc brake.

My money is on the wrong type of bolts fitted, as suggested above. But even then, it's surprising.

 

[DJ57UMP]

Sounds almost impossible with the amount of braking force you can put on an mtb disc brake.

My money is on the wrong type of bolts fitted, as suggested above. But even then, it's surprising.

Erm, you can use the wrong type of bolts... just asking for a friend is there an easy way to know???

 

[Mcharza]

Erm, you can use the wrong type of bolts... just asking for a friend is there an easy way to know???

I asked a friend and he answered.
- crappy chinese colored bolts
- aluminium bolts for weight weenies

 

[B1rdie]

The correct torque is important, but also thread lock is necessary to maintain the bolts in place.
I have seen one or two bolts get loose and have the head hitten by the rotor, but all six seems very unlikely.
By the way… center lock tighteners can also get loose, and the noise it makes souns like what Neeko describes.

 

[Rich-EMTB-UK]

Decent rotor bolts and buy decent rotors which come with good bolts, not eBay fakes, and check them every now and again as part of your routine checks.

 

[RustyMTB]

check them every now and again as part of your routine checks.

Whilst agreeing wholeheartedly, I'd bet practically no one ever does this.

 

[Mteam]

Have you (or someone else) recently bolted the rotor onto the hub? If so what changed when you did this.

The only obvious reason for the failure would be using the wrong type of bolts.

 

[Rich-EMTB-UK]

Whilst agreeing wholeheartedly, I'd bet practically no one ever does this.

I do every few years or if I am truing up my wheels or swopping tyres.

 

[StuE]

Didn't Steve Pete run his rotors with only 3 bolts back in the day ?

 

[Doomanic]

pic is required

It certainly is.

 

[aarfeldt]

It certainly is.

Way overdue....

 

[DrStupid]

Were the bolts too long in a blind hole?

 

[RustyMTB]

Didn't Steve Pete run his rotors with only 3 bolts back in the day ?

Peaty didn't need no damn brakes.

 

[slippery pete]

Yes, I can confirm that the 6 T25 bolts were torqued up correctly.

Tell us more. Six sheared bolts have filed a class action saying otherwise.

 

[Doomanic]

Yes, I can confirm that the 6 T25 bolts were over-torqued to fuck

Possibly?

 

[ebsocalmtb]

Same thing happened to me on my DIY chameleon mk7 ebike build. It was a novatec rear hub, which I should have known better because novatec hubs are total crap. that being said, I expected to the free-hub to explode, and i was not expecting to have the rear end explode with a bang in the middle of a descent and end up with only a front brake to slow myself down from about 25mph. Made for quite the interesting 15 mile ride home after that with only a front brake and a lot of elevation to deal with.

I am an incredibly meticulous bike mechanic, I always use loctite, I am keenly aware of the how tight the bolts need to be without being over tightened.

 

[Zimmerframe]

Same thing happened to me on my DIY chameleon mk7 ebike build. It was a novatec rear hub, which I should have known better because novatec hubs are total crap. that being said, I expected to the free-hub to explode, and i was not expecting to have the rear end explode with a bang in the middle of a descent and end up with only a front brake to slow myself down from about 25mph. Made for quite the interesting 15 mile ride home after that with only a front brake and a lot of elevation to deal with.

I am an incredibly meticulous bike mechanic, I always use loctite, I am keenly aware of the how tight the bolts need to be without being over tightened.

Tis but a scratch !

 

[Neeko DeVinchi]

Oh crap!!!
Apologies, I need to upload a pic of the broken wheel.

Sorry, sorry, sorry!!!! Work commitments.

Bare with me everyone, I'll make it a top priority to take pics tomorrow morning before shooting out and shooting a vid

 

[apac]

I reckon...
bolts had no threadlock on them and they've came loose and then sheered off after a time of being loose with repeated braking.

 

[Mikerb]

The only scenario I can think of that would...maybe....generate sufficient force to shear either the bolts or the portions of hub the bolts screw into, is if the wheel is "locked" with the brake fully on, the bike takes air, and the rear wheel finds a lot of grip on landing. Given the amount of flex most frames have, especially the chainstays and seat stays, that scenario would generate force at an angle to the normal orientation of the brake disc if the landing was not straight ( e.g like a whip) . That would apply an angled force to the mounting points such that only 2 or 3 of the bolts/hub flanges were taking the strain.

 

[Gary]

Didn't Steve Pete run his rotors with only 3 bolts back in the day ?

Nah. That was Nico
Nico also sent back the frame decals to be re-done when riding the V-Process as when they arrived they were heavier than he'd spec'd
Stuff like that would often get trotted out at World Champs but it was more of a head game between teams than any actual gains in performance. nowadays most just get custom paint jobs and get on with racing.

When I've seen 6 bolt hubs fail in the way Neko's described (and the rotor is still intact) it's almost always been because of loose rotor bolts. Seen it happen a few times. Including to Hope and Shimano hubs so I wouldn't be so quick to point the finger at beands (eg. novatec) Plus Novatec make hubs for many other brands You may not be aware of. Threadlock does not assure bolts won't loosen. it's just a little more insurance.
Over torqued rotor bolts can stress/damage the alu threads in the hub and the head of the rotor bolts. Weakening both. But the former would generally show before having all 6 fail catastrophically and the latter the head would normalls break leaving the bolt still threaded in the hub.
Centre lock is IMO a pretty terrible way to attach a rotor to a hub and if the lockring EVER comes loose it'll generally damage the splines. meaning it will either keep coming loose again OR it will have rotational play even when correctly torqued.

Glad you're OK Neko and we all hope and pary no (more) golfers were hurt (even mentally)

 

[Gary]

Actually Steve Pete might be Stu's mate and a bit of a Nico Fan.

Steve Peat definitely less so

 

[Neeko DeVinchi]

Lol, I'm cool @Gary, and thanks for all your suggestions about unearthing the potential problem.

Again, I'll take pics in the morning to show but I'm in the market for a new rear wheel so I'll check out other threads to see what testimonials and suggestions others have outlined.

It is probable that the bolts came loose but I've never not torqued up the rotor bolts correctly. If anything, I make sure to thread them in perfectly to avoid cross-threading with bit of threadlock.

Still, @Mikerb could be onto something but I'd have to play it out and re-attempt the same stretch of trail (In daylight and with the Gopro ).

Nevertheless, pics in the morning. Top priority

 

[2WheelsNot4]

I see the problem.

It's not a Hope hub

 

[urastus]

I wonder if increasing rotor diameter is getting too great for the 6 bolt design? Also take into account aggressive tyre design and width?

 

[apac]

imagine all 6 points of the hub where the rotor attaches sheared off 'Disintegrated' would be the word.

so it was the hub that failed... not the bolts?