Rear axle fell out during downhill run ???

[Kiwi Phil]

Has anyone had this happen before????

My rear axle somehow unwound itself as I was doing a downhill run last night. It was extremely lucky it happened where it did.....it locked up the rear as a spoke became wedged in the lower cog on the hanger, the axle became wedged on the angle, and the rear tire hit the frame!! The rear brake rotor was also wedged and now warped ???

The bike is not long back (4 rides)from having the sensor and cable replaced after that failed.

 

[levity]

Yikes, you're lucky the only damage was to the bike and not to you!

Did you remount and tighten the wheel after the sensor and cable replacement, or did a shop? If it was a shop then they should be responsible for any repairs.

It's possible to leave it too loose if you just snug it to check alignment and then forget to fully tighten it. I grease my rear axle and threads every time I remove and replace the wheel, no need for any loctite. You just need to be mindful to fully tighten it before taking it off the rack. It should not come loose unless the threads on the axle and/or frame are stripped or damaged. You'll need to carefully check both before riding the bike again!

 

[DaveMatthews]

Holy crap!
I know what I'm checking ASAP!!!
Glad you're OK!

 

[Kiwi Phil]

All done by the shop Levity.
I’m going to do a full check this morning to see what the extent of the damage is.

 

[bbred]

All done by the shop Levity.
I’m going to do a full check this morning to see what the extent of the damage is.

Having just changed the rear tyre on the Levo it was easy to remove the rear axle but you had to have immense patience to get it back in. The thread does not want to line up easily and you have to keep trying to get it started. I would guess the bike shop might want to look at this

 

[Gary]

I've had 12mm axles work loose on DH, SS and Enduro bikes infact I had one 12mm axle loosen from catching on a seatbelt when pulling the bike out the car before even riding.. If you're riding DH regularly you need to periodically do full bolt checks on the bike. it only takes a minute or so with a multitool. Any bolt that you find yourself having to frequently re-tighten needs examining and sorting out (cleaning threads and threadlocking if needed - not wheel axles though)
The type of 12mm axle that threads in by simply twisting the lever on the other end can become loosened by catching on an object or your foot while riding and once loose it is free to continue to loosen as you ride.
it's unlikely your rear wheel coming loose will result in injury unless it happens at a very unlucky moment but it can ruin the drop out or bend the rear triangle. A single pivot bolt falling out can ruin a frame too. sounds like you were lucky it only damaged your disc.

 

[Jimi]

Not the first, neither the last? People, check that bolt frequently!

Has happen to several people, something weird that get's it loose. Check also that the bearing is ok - when that happened to me the back bearing got loosen and now is a constant issues. After every 200km needs to be tighten.

Check e.g. Roval wheel issue - EMTB Forums

 

[Al Boneta]

I check it every time I ride

 

[jwrx]

yup. Happened to 2 levos in my group. After it happened to me as well...i blue loctite it in.

 

[Tim69]

Has anyone had this happen before????

My rear axle somehow unwound itself as I was doing a downhill run last night. It was extremely lucky it happened where it did.....it locked up the rear as a spoke became wedged in the lower cog on the hanger, the axle became wedged on the angle, and the rear tire hit the frame!! The rear brake rotor was also wedged and now warped ???

The bike is not long back (4 rides)from having the sensor and cable replaced after that failed.
View attachment 6473 View attachment 6474 View attachment 6475 View attachment 6476

Yes.. this is verry common... Search the forum, it's been writen about many times.
Happened to me so many times that I felt the wheel loose on a run and had to stop and tighten it, that now I'm totally religious about checking it before every ride!
It has to be ridiculously tight! To not loosen up..much more than the torque that is listed for it.
I believe it is caused by the sideways torsion on the rear triangle arms, moving parallel to each other. Even when tight you can grab the top of the wheel and pull it side to side and feel the flex in the suspension..
This is what loosens it.
IMHO it should have a locking mechanism on the axle.
Tim

 

[Mikerb]

Mine has never come loose and I always tighten to the recommended 15nm torque. A couple of things that would prevent the correct torque being applied are dirty threads with no grease on them and applying the torque with the weight of the bike on the ground. The correct torque is determined by the axle material and thread pitch so applying too much torque is likely to damage the thread and that will lead to it coming loose again. The through axle pulls the 2 chainstay arms together which is why no locking or spring washer type device is needed. If you have gone well beyond recommended torque I recommend you get a replacement through axle.

 

[Tim1023]

Happened not long ago on my Stumpy. Fortunately I was only riding up a small curb in town, so a big surprise, but no damage.
I check it often now!!

 

[Rosemount]

I check it every time I ride

W check before every ride .
Has saved my ass more than once .

 

[MrSimmo]

Yup check every ride. I've had axles come loose on pretty much all of my bikes. My mechanic back in the day used to swear by it; then once we didn't and the wheel fell out during a race ?

Also be weary of over tightening; I've seen the threads shredded before with minimal extra torque (literally +10% max) which has caused the axle to have play in it.

A mate of mine just bought a new Levo, one ride he was complaining of the gears not working properly. Checked the bike and found the rear axle was loose. The slightly loose wheel messed up the gearing and warped the disc under heavy braking. Much further and the axle would have fallen out.

 

[Tim1023]

Happened not long ago on my Stumpy. Fortunately I was only riding up a small curb in town, so a big surprise, but no damage.
I check it often now!!

Out of interest, I should have spotted the clue that I was really struggling to index my gears correctly. The wheel must have already been a bit out of position and I just didn't notice. Once the axel was tightened up, the gears worked like a dream again!

 

[HGmtb]

There's an axle loosening problem with some Specialized rear hubs (and a few other brand hubs as well), which is because these hubs have an internal left-handed thread that hold the 2 halves of the axle "sleeve" together. I have seen this same thing happen on at least 4 bikes recently (fortunately no one was hurt - although one guy lost all his freewheel internals halfway along a big ride).

The threaded connection holding the 2 axle sleeves together becomes loose over time (they should be tightened better in the factory), but you can't tell, and so when you tighten the axle it feels tight. During the ride the axle sleeve threads tighten up a little due to the forces around the rear wheel, and so the axle becomes looser. As you ride the axle now unwinds itself, and the bad stuff happens. Even if you re-tighten the axle, and you think it must be OK, the axle sleeve thread just moves again, and the axle comes loose - almost every ride !

On all 4 bikes I found the axle sleeves were loose, and when they were tightened properly (anti-clockwise, because the threads are left-handed) the axles never loosened again.

 

[Mikerb]

I think there is a risk of some confusion here. Some are referring to the through axle rather than the hub axle.
I have no idea what you are referring to as "sleeves" as far as the Formula hubs in a Levo are concerned.

 

[HGmtb]

Apologies for any confusion - I am referring to the actual Axle, and not the "through-axle" (which is not really an axle - it just holds the wheel onto the bike).

This is a Specialized / Formula type Axle, and the thread on the freehub end (which is a left-handed thread) is the one that can loosen, making the through-axle impossible to tighten properly.

 

[Mikerb]

So we need to be clear what is coming loose or breaking. The main hub axle runs on 2 bearings and is secured with an adjuster nut and locking nut on the non drive side. The axle can only come loose if the lock nut moves or a bearing collapses. The silver left hand threaded nut on the drive side merely holds the free hub onto the axle that extends beyond the hub by applying minimal preload against 2 further cartridge bearings.
On the horst linkage type rear triangle the pivot in front of the through axle does the angulating so I cannot see any cause and effect that would loosen the through axle and certainly not the main axle.
I can only assume that any failure is due to incorrect assembly and/or poor maintenance.
If indeed it is the through axle coming loose that most are experiencing the most likely cause is using the incorrect torque when replacing it. The correct torque can only be achieved on any bolt if the threads are clean and lubricated...and given the length and passage of the through axle, its shaft also needs a smear of grease.

 

[HGmtb]

Theoretically Mikerb you are correct - nevertheless on all 4 bikes that had repeatedly loosening through-axles I found that the left-handed nut on the drive side of the main axle was loose (and one nut had come fully unscrewed), and tightening this nut completely solved the problem.

As to the cause, it could be that as the through axle is screwed in, friction between the through-axle and the inside of the main axle causes the main axle to turn relative to the frame. If the drive side nut was insufficiently tightened by the manufacturer, and it resists turning because it is being lightly pressed against the frame, the nut may loosen slightly (as the main axle is turning clockwise and the nut is stationary). Even though the through-axle is then tightened correctly, if the drive side nut re-tightens itself slightly during the ride, the through-axle will become loose - and unless the drive side nut is properly tightened, the problem will just repeat itself.

Apologies if these technical explanations are somewhat tedious - but it might just be worth checking that nut anyway.

 

[Mikerb]

In terms of assembling the rear axle I have serviced the freehub a few times and removed the cassette quite often to clean it ( far quicker than trying to clean it on the bike) and stripped the rear axle completely to replace the bearings. The through axle has never come loose for me in 1000 miles. If the through axle is rotating the main axle then it is either bent, dirty or not smeared with grease...or all 3!
My procedure is to insert the axle and then adjust the adjuster nut on the non drive side until I can just start to feel a little drag when rotating it. I then back it off a quarter turn making sure there is no sideways play at that setting. Then tighten the locknut against it. On the drive side, once the hub and cassette are replaced I tighten the silver nut finger tight...plus a quarter turn. With the through axle I make sure it is clean, including the threads, and also make sure the threads on the chain stay are clean and smeared with grease. Then tighten to 15nm with the wheel suspended off the ground.