Re-installing crankset

[Moodyman]

I had a loud grinding noise coming from the bottom bracket area and after the usual checks – pedals threads, cleats - it was determined that my bottom bracket had packed in. It was a cheap unserviceable type so shop suggested I replace it. I did, with a Shimano UN54.

Now the grinding noise is gone, but I still get a creaking noise when I’m putting the power in – i.e. from stationary.

Now that I’ve got the right tools, I took off the crank last night. I turned the BB by hand and it’s nice and tight and turns smoothly.

But I noticed there was no grease between the square taper and the square hole in the crank. So I greased it up and re-fitted the crank.

Not ridden bike yet, but appears marginally quieter when turning pedals by hand.

This morning, spoke to bike mechanic about the non-existing grease and he said that one shouldn’t put grease on the sq. taper as it can slide off when laying down the power – especially in warmer weather.

Is this true? Should I go back and remove the grease and re-fit crank.

 

[Tim Bennet.]

Don't worry about it; the world divides neatly between those who think greasing a crank taper is worse than necrophilia and those who think it really doesn't matter.

I'm a greaser and ten family bikes over thirty years have come to no harm.

 

[ianrauk]

When I had a square taper bb I also greased it lightly with no problems what so ever.

 

[brockers]

But then you don't yet know if the problem's gone away in real world conditions, do you? Am pretty sure the grease/non grease issue depends on the alloys which the crank and axle are made from. With some combinations, it's meant to be ok, but with others it's not.

The creak could also be one of the bb cup flanges rubbing against the frame under load.

 

[Moodyman]

But then you don't yet know if the problem's gone away in real world conditions, do you? Am pretty sure the grease/non grease issue depends on the alloys which the crank and axle are made from. With some combinations, it's meant to be ok, but with others it's not.

The creak could also be one of the bb cup flanges rubbing against the frame under load.

No I don't. I think I'll leave as is and see what the next ride is like. If it still creaks, will have to re-visit.

What should be done to fix the BB cup flanges rubbing against the frame? They're well greased already.

 

[corshamjim]

I do grease the taper on the axle. Anything for a quiet life!

 

[betty swollocks]

Highpath Engineering, experts in cycle transmissions, maintain that you should grease the taper.
Look under 'Cycle Information' > 'Bottom Brackets'.
For creaking, check the tightness of the chainring bolts.

 

[henshaw11]

Bearing in mind the two ends of the argument, I've always wiped the taper over with wd40/gt85 to stop it galling when it goes on, which then dries out. Seems to work ok.

 

[mickle]

My personal opinion? Do not grease. Grease will stop it creaking if the crank comes loose. You want it to creak if it comes loose.



I was trained by a pro mechanic to the stars never to grease square tapers.

Shi**no cranks come with a dab of grease already installed.

You decide...

 

[brockers]

What should be done to fix the BB cup flanges rubbing against the frame? They're well greased already.

loosen the cup off by a tiny amount, if that's what's causing the creak.