Wobbly Oval Concepts 730 crank arm - Non drive side.

[Trebz]

Hi All

This is 'Kind of' a double post as I made a post for a replacement non drive side crank arm in the 'Wanted' section. I thought this might be a good place for advice about how to bodge a wobbly Octalink crank arm so....

I'm working on a bike for a friend and it's wobbling on the spindle. I think it's been ridden whilst loose as when the retaining allen bold is fully tightened it wobbles on the spindle:

https://youtu.be/TxuRUypg8pg

If the crank arm is knackered surely I could fold up a sliver of a soft drinks can and tap it into place on the end of the spindle, then tighten it all up again and hey presto, it'll work.....right?

Forgive the stupid question from me, you'd think that after all these years I'd know all about Octalink style cranks etc. Gimme a square taper any day of the week hehe.

Thanks in advance

Trebz (Not a racist).

 

[Trebz]

Re:

I now think that there's a spacer missing from inside the non drive side crank arm. The Octalink spindle sticks out about 1mm and when the locking nut it tightened it rightly tightens up against the end of the spindle, leaving 1mm play for the spindle to rattle around in. If you get my meaning.

Surely there's an Octalink shaped spacer missing:

 

[FluffyChicken]

Re:

you need yhe bottom bracket fitted and then you tension the arm against the it, it should not hit the bottom of the spline.
you then clamp it.

I think,.it looks like HT2 but isn't ?

but given it has gone on that far, the spline is probably knackered.


That's my guess as not a actually used that style. (I have use Octalink (square taper) ISIS and HT2 that then clamps like a aheadset stem.

 

[Trebz]

I'm convinced there's a spacer missing. The spline is perfect, as are the internal crank arm teeth. When I offer them up together off the bike there's no play at all, until of course I bolt it together. The bolt isn't clamping it together fully due to that little 1mm gap.

 

[mdvineng]

Hi All

This is 'Kind of' a double post as I made a post for a replacement non drive side crank arm in the 'Wanted' section. I thought this might be a good place for advice about how to bodge a wobbly Octalink crank arm so....

I'm working on a bike for a friend and it's wobbling on the spindle. I think it's been ridden whilst loose as when the retaining allen bold is fully tightened it wobbles on the spindle:

https://youtu.be/TxuRUypg8pg

If the crank arm is knackered surely I could fold up a sliver of a soft drinks can and tap it into place on the end of the spindle, then tighten it all up again and hey presto, it'll work.....right?

Forgive the stupid question from me, you'd think that after all these years I'd know all about Octalink style cranks etc. Gimme a square taper any day of the week hehe.

Thanks in advance

Trebz (Not a racist).

If it has been ridden whilst loose, the steel axle will have chewed away the alloy of the crank arm.
Lower pictures don't seem correct either as the axle isn't protruding enough from memory.

 

[Trebz]

I'd though of that myself but iv'e checked the crank arm and the teeth are Ok, when the two components are offered up to each other without the bolt they fit perfectly and there's no play at all.

I'm not sure about the spindle length myself but what I can say is that it's the factory fitted unit. The bike is completely standard and the previous owner was not an enthusiast or even a tinkerer. It's been sat in a shed for over three years unused.

 

[FluffyChicken]

Re:

I think that's an ISIS spline by the way, just used in a HT2 bottom bracket setup.

But it works similar to a square taper in that the further you crank it on, the more it splits the spline apart.
So if the crank can go all the way on now with 1mm showing through, it should be loose if it's 1mm spaces out so it can bolt down.
i.e. the spline is tapered.

you could try find a bolt ring/spacer.
or another crank.

 

[ishaw]

Re:

I have a few cranks that require a spacer and/or wavy washer to space out the arm and also preload the bearing. I'd say you are missing one and/or the other depending on what was specced by the manufacturer.

 

[FluffyChicken]

Re:

also just noticed,
I assume that's a 73mm shell?
The spacer in the BB would usually go on the drive side.

 

[ishaw]

Re:

A bit of Google fu suggests the cranks are gxp so a standard shimano bb won't work due to gxp axles being 22mm one side and 24mm the other. That is probably the source of your play if this is correct:

https://forums.thepaceline.net/showthread.php?t=155578