[grundy]

I finally dragged my 1x1 out of the shed where it's been living for far too long and took it out for a few rides.

I gave it a once-over before riding and found that both crankbolts were loose. I tightened them up, went out for my ride, and had them loosen up again during the ride.

I'm running lx (splined) cranks, with a relatively new bb. I pulled the bolts out, and found that the threads looked ok. The crankbolts were REALLY greasy, so I wiped the excessive grease off and reinstalled. One short ride later, the crank bolts are still tight. However, that short ride didn't involve much climbing, so I'm still concerned that they may loosen again.

My question is, what would make crankboolts loosen up? the crank arms, crank bolts, and bb are all in good shape. The spindle, crankarms, and chainring all appear true - I don't see any eccentric movement when I spin them. There was exessive grease on the bolts, but I don't really suspect that of causing problems... so why are they loosining up?

Any ideas?

 

[jh_on_the_cape]

I finally dragged my 1x1 out of the shed where it's been living for far too long and took it out for a few rides.

I gave it a once-over before riding and found that both crankbolts were loose. I tightened them up, went out for my ride, and had them loosen up again during the ride.

I'm running lx (splined) cranks, with a relatively new bb. I pulled the bolts out, and found that the threads looked ok. The crankbolts were REALLY greasy, so I wiped the excessive grease off and reinstalled. One short ride later, the crank bolts are still tight. However, that short ride didn't involve much climbing, so I'm still concerned that they may loosen again.

My question is, what would make crankboolts loosen up? the crank arms, crank bolts, and bb are all in good shape. The spindle, crankarms, and chainring all appear true - I don't see any eccentric movement when I spin them. There was exessive grease on the bolts, but I don't really suspect that of causing problems... so why are they loosining up?

Any ideas?

I have messed up some cranks by riding them with loose crank arm bolts, and then they never quite get tight again, but those were square taper.
When I installed my cranks, I tightened them down HARD. Like with an old seatpost for leverage on the allen wrench, but be sure it's in theere good so you dont round anything out.
Then I tighten after each ride for the first few rides. It somehow beds in there and needs to be tightened. about quarter turn or more, then when i cant tighten it anymore after maybe 3 rides, it's oK. but then a bastard to take off!
try that. if it doesnt work, your crank/bb interface might be bad from riding them slightly loose. and remove most of the grease. i just use a very little amount.
maybe you need a new titanium bike and then the crankbolt will stay tight??? ha!

 

[DiRt DeViL]

Use a torque wrench and tight the bolts at 40#/ft.

 

[grundy]

Use a torque wrench and tight the bolts at 40#/ft.

one a them things sure would come in handy!

 

[ernesto_from_Wisconsin]

when you're not looking....

I finally dragged my 1x1 out of the shed where it's been living for far too long and took it out for a few rides.

I gave it a once-over before riding and found that both crankbolts were loose. I tightened them up, went out for my ride, and had them loosen up again during the ride.

I'm running lx (splined) cranks, with a relatively new bb. I pulled the bolts out, and found that the threads looked ok. The crankbolts were REALLY greasy, so I wiped the excessive grease off and reinstalled. One short ride later, the crank bolts are still tight. However, that short ride didn't involve much climbing, so I'm still concerned that they may loosen again.

My question is, what would make crankboolts loosen up? the crank arms, crank bolts, and bb are all in good shape. The spindle, crankarms, and chainring all appear true - I don't see any eccentric movement when I spin them. There was exessive grease on the bolts, but I don't really suspect that of causing problems... so why are they loosining up?

Any ideas?

It is a well known loose fact that, when you're not looking, bastard smurfs loosen bolts. Why do you think the Titanic sank?

 

[dodjy]

Use a torque wrench and tight the bolts at 40#/ft.

Clean threads (inside and out). Apply Loc-tite. Torque to manufacturer's specifications. Let it sit for ~24hrs. Should be good as gold.

Always use manufacturer recommended torque specs or you could damage the taper on the crank (non-ISIS).

dd..''

 

[grundy]

gotta bump this old thread... situation is still the same, which is:

LX splined cranks, Shimano BB. Threads are greased, no loc-tite, and are torqued properly. Yet, the crank arms have a way of working loose. I have heard of this with tapered cranks, where the crank arm becomes deformed, impairing crank-BB spindle fit, and causing them to loosen up... but I haven't heard of this with splined cranks.

Anybody have any idea what could be wrong here? I'm just about at the point of dumping the crank arms and BB and starting over... which I hate to do as they are in nice condition and I'm on a bit of a budget...

any thoughts?

 

[jdub347]

gotta bump this old thread... situation is still the same, which is:

LX splined cranks, Shimano BB. Threads are greased, no loc-tite, and are torqued properly. Yet, the crank arms have a way of working loose. I have heard of this with tapered cranks, where the crank arm becomes deformed, impairing crank-BB spindle fit, and causing them to loosen up... but I haven't heard of this with splined cranks.

Anybody have any idea what could be wrong here? I'm just about at the point of dumping the crank arms and BB and starting over... which I hate to do as they are in nice condition and I'm on a bit of a budget...

any thoughts?

I've got a set of Octalink Ultegras on my fixie that have/had that problem. The reason is because the splines on the crank arm (left side) are screwed up because the previous owner let the crank arm bolt loosen and still rode. My remedy was to use a new BB and tighten the piss outta the crank arm bolt. Figure if the crank splines are already screwed up, it doesn't matter if I screw them up more and I know the spindle is waaaay tougher than the crank. Plus the cranks were free....so....

 

[Tukson Rider]

I have that problem with LX splined (M570) cranks. Problem is that there is too much play when the splines interlock. This is due to damage most likely cause when the crank bolts were not tight enough when first ridden.

When you place the crank arm on the spindle, there should be NO play whatsoever. The slightest play will loosen the crank bolts. RED loctite is really a common fix. I've used blue loctite, but it's worked its way loose.

Other than that, replace the carnkarm.

gotta bump this old thread... situation is still the same, which is:

LX splined cranks, Shimano BB. Threads are greased, no loc-tite, and are torqued properly. Yet, the crank arms have a way of working loose. I have heard of this with tapered cranks, where the crank arm becomes deformed, impairing crank-BB spindle fit, and causing them to loosen up... but I haven't heard of this with splined cranks.

Anybody have any idea what could be wrong here? I'm just about at the point of dumping the crank arms and BB and starting over... which I hate to do as they are in nice condition and I'm on a bit of a budget...

any thoughts?

 

[32seventeen]

I have heard of this with tapered cranks, where the crank arm becomes deformed, impairing crank-BB spindle fit, and causing them to loosen up... but I haven't heard of this with splined cranks.

This can happen with splined cranks.....veelz, want to chime in here? What else "could" be wrong?
LX crank and what BB?
btw, I didn't know that the Titanic sunk because smurfs loosened the crank bolts? wow, you learn somethnig new every day...Thanks ErNestO!

 

[grundy]

LX crank and what BB?

BB is a Shimano, I think an ES-71.

 

[Tukson Rider]

BB is a Shimano, I think an ES-71.

Those are the older splined cranks (m570?). The M572 have deeper splines which help prevent the problem (thus going from a 113mm to a 121mm).

 

[grundy]

Those are the older splined cranks (m570?). The M572 have deeper splines which help prevent the problem (thus going from a 113mm to a 121mm).

so is this a common problem? any solution, other than replacement?

 

[32seventeen]

so is this a common problem? any solution, other than replacement?

There are two shimano spline lengths. XTR and Road cranks have the short splines. All other mountain cranks have the long splines. Check to be sure your BB and crank are compatible.
TR was suggesting that the M-57x came in two different spline lengths. I don't think that is true. Unless TR was talking about overall spindle length, which would have no effect on the splines.
I hope that helps.

 

[Rockin]

Like 32seventeen said, there are two spline lengths for the bottom brackets. Shimano refers to them as V1 and V2. The V2 ones are the deeper ones. V1 bottom brackets should definitely not be used for singlespeeds - too much torque on the arms.