Bicycle Mechanics - Creaking crank

I know this has been done to death, but I've looked at the old threads and can't find the answer.

My new crank creaks particularly when pushing hard on the left pedal, but the noise sometime disappears when it is extremely cold (November in Scotland). Everything seems tight, as I tightened the crank every 25 miles when first installed (got about 2 or 300 miles on now), and the BB is a sealed Stronglight one, again new. I have checked frame and seatpost (steel frame)

Could it just be the way the alloy and steel react to changes in temperature.?

has anyone used PTFE tape over the BB taper ends to help fit crankarms?

Originally posted by chewa
I know this has been done to death, but I've looked at the old threads and can't find the answer.

My new crank creaks particularly when pushing hard on the left pedal, but the noise sometime disappears when it is extremely cold (November in Scotland). Everything seems tight, as I tightened the crank every 25 miles when first installed (got about 2 or 300 miles on now), and the BB is a sealed Stronglight one, again new. I have checked frame and seatpost (steel frame)

Could it just be the way the alloy and steel react to changes in temperature.?

has anyone used PTFE tape over the BB taper ends to help fit crankarms? Tape works on BB threads to help prevent creak, as does grease..Crank arms should be properly torqued,ridden a bit rechecked for tightness and THEN LEFT ALONE.

Pokey. I had read the other threads which mention this my BB cups were greased), and if you read mine again you'll see that I fitted, retightened etc.


I've 25 years plus experieence of cotterless cranks but this one won't stop creaking (except when it's very cold)

Originally posted by chewa
Pokey. if you read mine again you'll see that I fitted, retightened etc. Checking tightness once is enough. Are the crank and spindle tapers compatible? ISO? JIS? I once heard of using white glue on a tapered Ti spindle to stop a creak at that junction. A bit of grease on the spindle is another option that is sure to generate alot of howls from the pundits.but my tapered spindles on new BB atually came pre greased from Shimano.

Chewa,
Could it be your pedal? I have had a squeaking in one of my pedals for a couple of weeks. I knew what it was but had to await a new bushing to replace a cracked one. Two or three times I have had new noises crop up right after replacing a part and gone crazy trying to get the new part properly installed/adjusted only to eventually figure out that the noise was totally unrelated. I just happened to show up, or I noticed it, after the new part was installed.
FWIW,
Raymond

Could parts of the bottom bracket itself be creaking on eachother, or have you greased all the parts where they make contact, in addition to the threads? For instance, where the left cup supports the cartridge...

Might also be a good idea to pull out the seatpost and grease it if it hasn't been done recently... creaks can travel, and when the frame flexes, a dry post could creak in the seat tube.

Originally posted by pokey
Checking tightness once is enough. Are the crank and spindle tapers compatible? ISO? JIS? I once heard of using white glue on a tapered Ti spindle to stop a creak at that junction. A bit of grease on the spindle is another option that is sure to generate alot of howls from the pundits.but my tapered spindles on new BB atually came pre greased from Shimano.

I followed the instructions on the Stronglight BB package, to check tightness every 25 miles initially (every day for me) and all seems fine. Its a Stronglight Chainset and BB so assume would be compatible.

Anyhow, this weekend the whole thing is coming out, getting reinstalled with PTFE on the threads, grease in the supporting cups, 3 Hail Marys and all.

You raise an interesting point about greasing the tapers, I've always thought a wee bit did no harm but I know others don't think so.

From Barnett’s Bicycle Mechanics Manual; Chapter 20 Tapered Crank Arms: “…never lubricate the spindle flats! If there is a concern about preventing corrosion or about contaminants getting in the gaps between the spindle flats and the hole flats in the arm, then treat the mating surfaces with Loctite 222 or 242 (bearing-supply or automotive-supply stores). The Loctite will seal the surfaces from moisture or dirt, reduce creaking problems, will not cause the arms to be less secure, and will allow arm removal with normal effort.”

Surface prep for taper crank arm installation seems to be a subject that abounds with varying ideologies. It has become the first subject I now check in any tome on bicycle maintenance in hopes to find a pearl of wisdom. Barnett’s approach appears to be the most logical so far... I believe Shimano’s spline-fit crank arms may have been introduced owing to a high “incident” rate with this component. I am wondering if any riders with spline-fit crank arms have experience “creaking”?

Best wishes, for your ultimate success with the issue.

After 12 years as a mechanic, I'm inclined to use the methods that work, and a light film of quality grease on the tapers is what I've found to work most consistently.

I don't know what Barnett means by "less secure," since I've done this with cranks that are ridden 10,000mi+ per year, year after year, and they certainly don't go falling off between overhauls! ;) And as pokey said, Shimano pre-greases theirs as of late. I think Barnett's viewpoint has been carried over from when it did apply due to lower-quality alloys and manufacturing techniques.

Just my own 2c worth! :)

Chewa Iv'e had this problem too. It drove me crazy for weeks.
In the end I cleaned the crank arms really well and looked inside the tapered holes and lo and behold found my problem.
The casting on the cheap end Shimano crank arm was so bad that the crank was only making contact on the axle for about a quarter of the flats. It was clear to see because the aluminium surface had been peened real shiny where good contact had been made. The situation had been made worse by my riding it with the squeak which had ovaled the crank flats

I had a choice to chuck the cranks and possibly the axle or try a crude salvage so I very carefully dressed the inside taper of the crank arm with a high quality square edge file. (this is definitely only a very last resort as you could easily ruin the crank arm )
In my case a perfect solution and the cranks are still in use.

Worth a look maybe

Thanks for the advice guys. i stripped it down at the weekend and greased the sealed cartridge to cup facings, then used PTFE tape on the threads on the cups.

Then, and some of you may see this as heresy, I put a single layer of PTFE round the tapers before tightening.

Rode in this morning in silence, but I'll let you know if anything develops.(as the actress said to the photographer)

Yea ptfe tape is amazin.
Apparently it occasionally gets used for plumbing purposes too I hear:rolleyes:

Just an update, but I've now done about a hundred miles, and everything is still tight and not creaking!!

Excellent well done:thumbup:

At my age any creaking I hear is likely to be my bones!:D