Wibbly wobbly....

gtvlusso

mudcow007 wrote:

UndercoverElephant wrote:

gtvlusso wrote:

I tightened them to a fair amount of torque - like 10Nm. Will check them though.

We have a winner, I seem to recall when I installed mine it required nearer 45 Nm.

Mr Lusso have you just openly admitted on this here forum that you have the arms of the snowman an arnt able to tighten more than 10Nm

*giggles*

I have shame on my shoulders, my mincey wincey shoulders.....

itboffin

I've had the same problem twice on two different bikes, first one was a loose cassette the second one was a missing spacer from cassette which allowed just the tinniest bit of wobble until you put the power down esp uphill.

rjsterry

UndercoverElephant wrote:

gtvlusso wrote:

gtvlusso wrote:

UndercoverElephant wrote:

gtvlusso wrote:

I tightened them to a fair amount of torque - like 10Nm. Will check them though.

We have a winner, I seem to recall when I installed mine it required nearer 45 Nm.

45Nm is huge!! My last crankset (FSA) was only rated to 20Nm - I did 10Nm as it did not say anything in the instructions for the UN55 (and I have stripped BB crank threads many years ago), safe rather than strip the threads.

I will re-tighten though.

A quick google suggest about 34Nm upwards to 50Nm. I'd best dig out the 'big' torque wrench!

http://www.shimano.com/publish/content/ ... 0Specs.pdf

Thanks dude.

Yes it's huge. For that very reason I ditched the Allen-bolts and used the supplied ones with a socket instead. I would suggest that at those torques, either your Allen keys or the bolt will round off nicely.

On the plus-side, the regular bolts won't need adjusting much once they're on.

I seem to remember my brother (a mechanical engineer) telling me that having the flats of any nut or bolt narrower than the threaded part (like allen bolts and pedal axles) is always asking for trouble if you need to apply significant torque. I'll let someone else explain why.

ETA: Actually, the one I always have problems with are the tiny allen bolts that secure cartridge type brake pads. The tiniest amount of seizure - as is usually the case as they get so wet and sprayed with cack - and the head rounds off.

gtvlusso

So, it's not the crank bolts!

Done up to 40Nm - still a wobble on the spider. I think it is the chainring that is warped or maybe even split, but I did not get time to inspect it.....

Any other ideas - BB still looks solid!

UndercoverElephant

Yup, I've had to throw brake block holders for that very reason.

Torx bolts would work much better than allen bolts, never understood why they aren't used more.

tgotb

Kieran_Burns wrote:

Real men used:

Ugh. I never got on with the bl**dy things (though they did teach me a lot about stripped threads and appropriate torque). Even now I have traumatic memories of the feel of the cranks moving with every stroke as the next cotter pin deforms.

Were these thing intentionally made of plasticene to avoid damaging the cranks and spindle, or did I just buy cr*p ones?

rjsterry

UndercoverElephant wrote:

Yup, I've had to throw brake block holders for that very reason.

Torx bolts would work much better than allen bolts, never understood why they aren't used more.

Torx keys that small are a bit tricky to find. Even quite decent tool kits only come with larger sizes.

Kieran_Burns

TGOTB wrote:

Ugh. I never got on with the bl**dy things (though they did teach me a lot about stripped threads and appropriate torque). Even now I have traumatic memories of the feel of the cranks moving with every stroke as the next cotter pin deforms.

Were these thing intentionally made of plasticene to avoid damaging the cranks and spindle, or did I just buy cr*p ones?

I thought that image would bring back nightmares for a few 'round here.

Some of the younger ones will be asking "WTF is THAT????" :shock:

tgotb

Kieran_Burns wrote:

I thought that image would bring back nightmares for a few 'round here.

If we still had to use those things, I genuinely think I'd have given up cycling by now...

gtvlusso

Kieran_Burns wrote:

UndercoverElephant wrote:

Kieran_Burns wrote:

My method is to tighten as much as is comfortable and then a 1/4 turn more. Quick and dirty I know but I've not stripped a thread yet and never had a crank come loose.

Torque wrenches are cool and make you feel like a proper bike-mechanic: Accept no substitute.

Ha.

Real men used:

Mmmmm - cotter pin.....The pinnacle of 1940's technology.

gtvlusso

gtvlusso wrote:

So, it's not the crank bolts!

Done up to 40Nm - still a wobble on the spider. I think it is the chainring that is warped or maybe even split, but I did not get time to inspect it.....

Any other ideas - BB still looks solid!

Just asking, again!

Sharkyssurfers

checked the pedals? loose cleat? or it could be your legs!!

gtvlusso

Sharkyssurfers wrote:

checked the pedals? loose cleat? or it could be your legs!!

Nope - I can see the actual chainring/chainset is malformed - when rotating. But cannot identify if it is crank spider, chainring, crank bolts loose or BB loose......

There will always be some flex in the chainring, but not to this degree.

rjsterry

I think some disassembly is needed. Remove the chainring and lay it on a flat surface - that'll show up if it's bent. It'll also let you get a good look at the bolts. If neither of those then that leaves the crank/spider. You'd need a manufacturing fault or a really big knock to bend those, but if you've eliminated other options...

One other thought: when you first assembled the whole thing, is there a chance that something got between the square taper of the BB and the socket of the crank? That could give you the tightness on the crank bolt, but still some flex.