Luna X2 rear Axle almost failed!

[IOUZIP]

Doing my bike check I found the rear thru axle almost came out. The screw that holds the handle came loose and I almost lost the handle. Thread locker and reassembled. Crazy I never thought the quick release handle could come off. Add that to your next bike check. The small allen head screw check it.

 

[retiredNH]

Does this really count as an AXLE fail? Not in my book...

Interesting caution, though, about a different failure mode.

Thanks for posting.

 

[rarobo]

I had the same issue once, what I noticed is when you turn the quick release handle make sure it is seated in the cutout slot, otherwise it will unthread the axle

 

[tomjasz]

It falls on owners to learn how to safety check builder direct bikes. Tough for those not well versed in maintenance. Good on you for posting the warning. Might reach more owners on www.electricbike.com/forum the Luna site.

 

[Neverlost99]

It falls on owners to learn how to safety check builder direct bikes. Tough for those not well versed in maintenance. Good on you for posting the warning. Might reach more owners on www.electricbike.com/forum the Luna site.

And check lbs built as well

 

[IOUZIP]

New problem I caught just yesterday. Slight creek while pedaling. After several months the Chainring nut loosened up. Good thing I had the Bikehand tool YC-29BB-2AN to retighten the lock ring in my toolbox. Not that I cannot handle the bike maintenance I can. I am just passing along my experience and areas to watch on the X2.

 

[floid]

Twice now I've found the rear axel very loose and nearly ready to come undone. I noticed the problem both times due to shifting problems.

I've also had the same pedaling creaking noise. In my case, the pedal crank arms were loose, and the nut on the outside of the crank arms was not even finger tight. I don't think Luna does a great job at assembling these before shipping...gotta double check everything and apply thread-locker in several places.

 

[tomjasz]

Twice now I've found the rear axel very loose and nearly ready to come undone. I noticed the problem both times due to shifting problems.

I've also had the same pedaling creaking noise. In my case, the pedal crank arms were loose, and the nut on the outside of the crank arms was not even finger tight. I don't think Luna does a great job at assembling these before shipping...gotta double check everything and apply thread-locker in several places.

As we should with all builder direct bikes.

 

[IOUZIP]

$100 investment in tools would be enough to cover the average builder direct bike maintenance. Luna sells a ebike tool kit for $50 which is a great starter kit for someone new to bike maintenance.

 

[rtp]

$100 investment in tools would be enough to cover the average builder direct bike maintenance. Luna sells a ebike tool kit for $50 which is a great starter kit for someone new to bike maintenance.

Haven't had the chainring issue, or not to failure, or the axle issue. Chainring bolts loosened even though I had the chainring off and had loc-tited. Lost one of the crank arm 'caps' that can't easily source exact replacements for, and had one crank arm come off on a ride - which was also loc-tited and torqued...the latter being the most surprising, but now added into the list of things I check on every few rides.

 

[retiredNH]

Haven't had the chainring issue, or not to failure, or the axle issue. Chainring bolts loosened even though I had the chainring off and had loc-tited. Lost one of the crank arm 'caps' that can't easily source exact replacements for, and had one crank arm come off on a ride - which was also loc-tited and torqued...the latter being the most surprising, but now added into the list of things I check on every few rides.

What bike do you ride? These failures seem pretty remarkable?

 

[IOUZIP]

With many parts in short supply you cannot expect to get parts from Luna when needed. Almost lost a crank arm bolt when the cap screw started to back out. I noticed more aluminum showing between the motor and crank arm. I have now have enough blue loctite to keep the cap from moving. Pinch bolts were always tight. The X1 and X2 use many of the same parts.

 

[m@Robertson]

A thru axle coming loose is something that can happen with any bike. On my Bullitt, I have a DT Swiss 350 rear hub. Not too long ago I found the rear axle was a few turns undone. I had forgotten to check it for several months. The same has happened on my fat ti bike. That one is a DT 350 fat hub (190mm) with an axle that comes from the USA frame manufacturer (Chumba). Both of the thru axles did not use a lever, they were hex key only. So there was no way to visually see either of them coming loose.

I like the hex-key-only for low profile but realized after the fact that you lose visual indication of shifting when using them. My last two bikes use the lever versions of a thru axle: Use an axle with a lever on the end so you can see it if it starts shifting. Then you just tighten it a little when doing your daily preflight check and fuggedaboudit.

Don't use loctite on a thru axle. Thats a band aid that takes the place of proper care and attention.

 

[m@Robertson]

I've also had the same pedaling creaking noise. In my case, the pedal crank arms were loose, and the nut on the outside of the crank arms was not even finger tight.
<snip>
...gotta double check everything and apply thread-locker in several places.

If its a square-taper bottom bracket spindle (axle) then them coming loose on their own is just something they do. Riding any bike with square-taper or JIS cranks requires irregular maintenance... once every 6 months or so for an infrequent ride, and every 3-4 weeks for one that is pedaled daily. Its a normal thing to have a bike properly torqued to about 30 ft lbs, then come back a couple months later after daily commutes and its down to 20. Creaking is a sign that something is loose down there. Usually its the crankarms creaking in their mounts, moving just a tad when they shouldn't. Threaded 'english' style bottom brackets are also known to creak even though they may be perfectly tight.

You really REALLY need to use a torque wrench on this, and never ever use loctite on crankarms. In fact if you do some looking at maintenance videos you will find that the shop-recommended procedure is to grease the threads of your crankarm bolt. The torque wrench is a requirement because 30 ft lbs is more than humans can figure out how to do on their own - especially given the tapered spindle that smooshes the alloy crankarm against the hard steel spindle. Undertighten and it rounds and never can be repaired. Overtighten and you spread it and thats also never going to go back to how it is supposed to be.

Here is the Park instructional vid on installing cranks. I have queue'd it up to the part where you begin installation and grease the crankarm bolt.

 

[floid]

If its a square-taper bottom bracket spindle (axle) then them coming loose on their own is just something they do. Riding any bike with square-taper or JIS cranks requires irregular maintenance... once every 6 months or so for an infrequent ride, and every 3-4 weeks for one that is pedaled daily. Its a normal thing to have a bike properly torqued to about 30 ft lbs, then come back a couple months later after daily commutes and its down to 20. Creaking is a sign that something is loose down there. Usually its the crankarms creaking in their mounts, moving just a tad when they shouldn't. Threaded 'english' style bottom brackets are also known to creak even though they may be perfectly tight.

You really REALLY need to use a torque wrench on this, and never ever use loctite on crankarms. In fact if you do some looking at maintenance videos you will find that the shop-recommended procedure is to grease the threads of your crankarm bolt. The torque wrench is a requirement because 30 ft lbs is more than humans can figure out how to do on their own - especially given the tapered spindle that smooshes the alloy crankarm against the hard steel spindle. Undertighten and it rounds and never can be repaired. Overtighten and you spread it and thats also never going to go back to how it is supposed to be.

Here is the Park instructional vid on installing cranks. I have queue'd it up to the part where you begin installation and grease the crankarm bolt.

Good info - thanks. The bikes we are discussing are X1/X2/Z1 from Luna, which are all e-bikes with Bafang mid-drive motors. I don't think these are standard crank attachments.

 

[m@Robertson]

Good info - thanks. The bikes we are discussing are X1/X2/Z1 from Luna, which are all e-bikes with Bafang mid-drive motors. I don't think these are standard crank attachments.

Ah. My bad. From what I understand the Ultra on the Z1 and others is standard ISIS spline (Lekkie's buzz bars for the Ultra are ISIS crankarms), but the M600's use a proprietary almost-ISIS config. Same procedures apply though, although if your arms use little opposing M6 bolts you need to dial down the torque to whatever the max is for an M6 is taking into account it is threaded into a softer alloy (Lasco quality level) arm. 8Nm? thats probably too much.

 

[IOUZIP]

The M600 lock ring has teeth on the side facing the aluminum chainring. Tighten down the ring to 35nm or 25 ft lb.

 

[rtp]

What bike do you ride? These failures seem pretty remarkable?

X2. Not a huge deal, just expanded the preventative maintenance list a bit.