Oh, that's what that noise is
 

At about 20 miles into 50 mile ride today I am aware of a creaking sound with each pedal stroke coming from what I think is the bottom bracket. It's a carbon frame and cranks, so I figure it's just the frame amplifying whatever it is, and make a note to check it out after my ride.

Then I get a little lost 5 miles later, and stop at the only garage I've seen for a long time to ask for directions. While I'm there I take a look and find that my left crank is coming loose. Yikes! I don't have a wrench large enough to deal with it. I ask the mechanic if he had a wrench I could borrow for 30 seconds. He was really nice about it, and loaned me his wrench set. I tightened it about 1 1/2 turns, got my directions, thanked him kindly and was on my way.

But, wow, that could have ended so much worse. Today I got lucky.

FSA cranks?

This happened to my brother last summer, except that his crank actually did come off at around 35 mph.... He did come off fine, but almost crashed since his foot was still attached to the left crank (imagine the surprise at first.... then the oddness of trying to stop while stepping on your crank). Yes, dangerous stuff, but user error - having built up the bike himself. Glad you found the problem first before it found you.

Aren't cranks reverse threaded so when you're pedaling forward, you're torquing the threads tighter?

Indeed.

You're thinking of pedals. Cranks are splined, the bolt holds it in snug, but has little to do with rotational force.

It's probably still pretty loose. Crank fixing bolts are put on pretty damn tight. It's pretty difficult to reach recommended torque with a little T-handled allen wrench set. FSA crank bolts, for instance, are supposed to be tightened to around 400 inch pounds.

I'll have to take a note of this as I notice the same issue with mine. Thanks for the heads-up

Had the same issue happen to me while on a ride just 2 weeks ago. At first i thought it was my cleat that was coming loose then when i looked down to unclip it the whole crank moved. had to ask some guy that was working on a tractor if he had a allen i could use. lucky for me he did and I was on my way.

Damn I'm good.

Yes... but, did you give him a couple of bucks ?

.
.
.

No, but I did ask the right way. I grew up in a garage from a family of auto mechanics, so I know my way around that area.

Okay, give it up.

I didn't grow up in a mechanics family. I have no idea what is the right way to ask. I didn't even know there was a right way.

Now I'm all paranoid I'm gonna be stuck on the road right next to a perfectly stocked service station, and not know the code to get the tool I need.

Let us in. Let us in. ;););)

Tag

I've been hearing some pretty serious creaking sounds from the BB on my commuter bike, after I put in a new BB and FSA Vero crankset... I'll definitely be looking more into this now. Thanks for posting!

I'm also feeling inclined to double check the FSA Gossamer cranks on my main road bike :eek:

Happened to me. I was hearing a creak, and I swore my BB was going bad. Then I washed my bike and decided to check ALL bolts for tightness and sure enough my left crank arm was loose.

Tightened it up and I'm all good now.

Torque wrench.

/thread.

Getting a little lost turned out to be a fortunate thing this time. I'm going to pay more attention to this from now on, as opposed to once a year. And I think it's reason enough to invest in a nice torque wrench instead of the old, slightly bent one I inherited years ago.

And come on Tagged... the "right way" to ask is simply showing you respect that a working man's tools are his livelihood, and that you really appreciate that. No payment will be necessary or probably accepted in that case.

In addition to the previously posted torque wrench advice . . .some FSA cranks require the use of Loctite 641 installation compound (not to be confused with Loctite threadlocking compounds) on the left splines. Might check the latest installation instructions on FSA's website in case it applies to your particular crankset.