Creaking from cranks/spindle. How to fix? Recently the cranks on my bike started to creak.
I checked with my usual "bike-bible" Park Tool. They recommended dis-assemble, lubricate, re-assemble.

So I did that.

Remove cranks.
Remove spindle.
Clean.
Lubricate.
Reassemble.

No, the creak is still there.

(To find out the source-area of the sound I had a friend riding the bike slowly while I ran alongside listening. And the sound where coming from the area of the bottom bracket/cranks. I am happy no neighbor saw me...) 

For each revelation of the cranks there are two creak-noises. 
If I, when on the bike, push down with both feet I hear a noise. Turn 180 degrees without pressure, push down again and there is the noise again.
If I am "too soft", low pressure there are no sound.
Since I have clips I have tried to only work with one foot to keep a constant load during a revelation, there where no detectable sound then.

Anyone have any idea what is wrong on the bike?
And how I should fix it?

/Leif
There are many possible causes of creaking. But Deemar has the most likely reason in this case - the cranks are loose on the axle. Think about how a creak is produced. It's one item sliding over another. But instead of sliding it's repeatedly sticking then jumping. The amount of movement might only be a fraction of a millimetre. The OP would have noticed if the cranks were really loose. But in this case the looseness may be at the microscopic scale. 

You can easily test this without having to run alongside the bike. Get on the bike with the brakes on and your shoulder against a wall. Rotate the pedals so the cranks are horizontal and bounce up and down with your weight equally on both pedals. This twists the cranks and axle as far as possible in one direction. Then rotate the pedals to a position 180 degrees from that (the other foot forward) and do the same. This twists the assembly as far as possible the other way. Repeat the procedure listening all the while for creaks. Testing in this way avoids many other sources of noise such as wheels, chain, seat, etc. Take care. If something breaks or your foot slips off the pedal you'll hurt yourself. 

When new the cranks have a square tapered hole which fits exactly onto the tapered square on the axle. As Deemar says, if it has been wobbling for a while the hole will be damaged and you may never get a satisfactory fit. On my bike I fixed it (at least for now) by carefully reshaping the inside of the square holes with a file and cleaning the square shaft on the axle. Then I assembled it with grease. To get the parts to bed in together I applied the following procedure repeatedly. Bash the crank a few times with a soft hammer. Bounce up and down on the pedals as above. Retighten the bolt. Eventually the soft aluminium crank took up the shape of the hard axle and the creaking was completely eliminated. You will probably need to do this for both cranks. 

Remember that the amount of movement between the crank and axle may be so small it's imperceptible. You may not see it moving. But you will be hear the result when you do the pedal bouncing test. On my bike the noise was really loud and infuriating and now it's completely silent. I will re-tighten the bolt periodically. If it loosens again I may have to replace the cranks and bottom bracket.