shelbyfv

On my first TA bike the front wheel axle entered from the non-drive side. I was careful to get it good and tight because I'd read about some coming loose. On my current bike the front TA enters from the drive side, righty tighty. It has a max torque of 12 Nm but when I get back from a ride it has tightened noticeably. Is this something to do with precession? If I initially tighten it to say 8 Nm+/- can I count on it becoming more tight rather than loose? I have to remove the wheel for transport and sometimes I've had to whack the Allen wrench with my shoe. I'd like to avoid that. Thanks.

FBinNY 

ANY torque spec is for as tightened condition. Otherwise it would depend on the user to be psychic, and somehow predict what is not in their control.

As for why it tightened, the first thing to consider is that it didn't. Static, friction is always greater than sliding friction. This is why you torque by steadily turning until the torque spec is met, rather than getting close and giving a final tug.

By the same token, if you tighten a part to X, then stop, count to three, and reapply the same torque wrench it will require X+ to move either way. This is what I think is happening here, which is analogous to why car wheel lug nuts always seem harder to get off than they were to get on.

FWIW, the only way you'd believe the torque increased is by using a torque wrench to loosen it, and drawing an improper conclusion form the result.

So, not precession, and nothing to try to "correct"

shelbyfv

Thanks! I'll just get a little extension for the Allen wrench. FWIW, I'd have bet money that it was tighter after a ride. So much for my "sounds good to me" physics.

Bill Kapaun

I think a simple test might be to torque it about 20% below spec.
Go for a ride.
Torque to spec.
I expect you'd see the same phenomena. Break away friction is higher than sliding (rotating) friction.

Barry2 

Captain Obvious reporting for duty.

I do hope this is a joke.

Nothing touching the Thru-Axle should be moving.
The Thru-Axle shouldn’t tighten or loosen.
Unless you’re using tubulars. Tubulars were never intended to be paired with Thru-Axles.
And don’t even get me started on Thru- skewers!

Barry

FBinNY 

Sometimes you have to read beyond the words to get the picture. From the context, it's clear that the OP was turning something to tighten it.

I hate to bring it up and get you started (please don't) but it sounds like we're talking about a (shudder) thru skewer.

shelbyfv

Yep, I'm the moron here. I got so caught up trying to figure how the thing was getting tighter (it isn't) that the obvious escaped me. At 75 I'm apparently having to come to grips with mental as well as physical decline.

Barry2 

Well at least it’s not Thru-Skewers.
Like we needed another propitiatory standard to hold wheels on a bike.
I had to hunt a NOS Trek FX4 for the wife, just to avoid Thru-Skrewups.

I’ve got thru-axles. (including RATs, don’t get me started on RATs)
I’ve got skewers
I’ve even got nuts

……..deep breath, hold it, let it out,

OK, I’m fine now.

What were we talking about?

Barry

(yes, obvious pun intended)

t2p

do you apply a small amount of grease to the thru axle threads ?

bboy314

Thru-skewers don’t require anything proprietary.

I agree RATs can go to hell.

shelbyfv

Google popped up this thread from 5 years back where I was schooled on the red herring of precession. Duh. Good thing there is not a third side to the fork or I might be back again...