Bicycle Mechanics - Bike creaks only when I sit on it

OK I am 170lbs. That said, I noticed that lately my bike creaks (rear part of the bike) when I am on it riding around. When i push it around, it is quiet. Spin the wheels. it's fine. What could it be? Something that is caused by being under load? Am I that fat... but I lost a few pounds since I started riding to work? It was quiet all these times. :cry:

You may find the following links helpful in tracking it down:

http://sheldonbrown.com/creaks.html

AND

http://www.parktool.com/repair/readhowto.asp?id=123

It's usually just a matter of patiently removing, cleaning,
re-lubing, and re-torquing fasteners until it quiets down.

Seat post?

Seat post?
Seat post or saddle rails/saddle clamp. Remove and thoroughly grease (assuming it's aluminum) or assembly paste cover (for carbon) the seatpost before reinstalling. Tighten the saddle clamp bolt(s) too.

Seat post or saddle rails/saddle clamp.
Yes, the saddle rails in their clamp. Or maybe the rails where they plug into the saddle. A bit of WD-40 dribbled in while the bike is upside down would work.

seat post? how can it be? It makes noise only when I am on it and the bike is in motion.

seat post? how can it be? It makes noise only when I am on it and the bike is in motion.

Is that sarcasm?

seat post? how can it be? It makes noise only when I am on it and the bike is in motion.

Do you sit on the seat when you are on the bike and the bike is in motion?:rolleyes:

seat post? how can it be? It makes noise only when I am on it and the bike is in motion.

Huh... when else would a seat post creak? When you stand on the pedals it stops creaking... yes?

I've had many creaks in the past. Could be pedals, cranks, bottom brackets, seats, chain rings, chains, handlebars. etc. The worst: I just found some cracks in my swing arm. :(

OK found the culprit. It is the rims! For those that suggested the seat post, I think it is due to my poor and incomplete explanation. The creak shows up even if I am standing on the pedals. Basically when there is weight put on the bike and in motion the bike emits the creaking sound.
Anyhow I have discovered that it is the rims by swapping out the rear rims from my wife's bike into mine. My bike was quiet using her rims and hers was creaking using mine. :notamused:

So my next task is to figure out what is wrong with the rims. The spokes seems straight. I spun the wheel around and didn't notice any significant wobble. Maybe I wasn't holding right... it was hard to tell. Any thoughts?

The spokes being straight is only part of it. Feel each spoke to make sure none are noticeably loose, and that they all have about the same tension.

I get creaks from my old Dawes Galaxy, on and off, usually for about a week at a time, then none for months. It seems to vary with the weather, I fancy. Sometimes I've thought a certain act of tightening or lubrication has chased the creaking away, but it hasn't really. I've no idea what does it.

Believe it or not, I get a creak in humid conditions between the hub and the steel dropouts on my front wheels. Since it's steel on steel there . . . I squirt a touch of Boeshield on the dropout ends and the creak is gone.

This may or may not pertain to your situation . . .but it may be worth a shot.

Every creak has it's own sound frequency. Learning to listen is another story :)

Did you rule out the QR? If not, try using your wheels but change out the QRs.

OK found the culprit. It is the rims! For those that suggested the seat post, I think it is due to my poor and incomplete explanation.
No, it was due to your VERY explicit tltle for this thread. You wrote; "Bike creaks only when I sit on it." :rolleyes:

The spokes being straight is only part of it. Feel each spoke to make sure none are noticeably loose, and that they all have about the same tension.

Hmm... I did notice some spokes seem to wobble a bit when I flick my fingers at them. As if the part where spoke meets the rim has some play to it. Does it need to be trued? I think this is beyond me and will likely take it to the shop. How much does it cost? Or is it a matter of just re tightening the spokes which i doubt. I might over tension them right?

I recently figured out a similar problem. It turned out to be a couple of my rim eyelets. It only made the noise when weight was on the wheel (i.e. I was sitting on the bike, or equivalent), but then I found I could induce the noise by firmly moving the affected spoke in/out. It was not the nipple or spoke threading, which I lubed, but the actual eyelet where it is formed into the rim.

This vintage Mavic (Open4CD) is on my commuter, which gets dirty and wet. I found the eyelets are actually rusting a bit inside, under the rim strip. Probably the next rain would've stopped the noise, but I put a tiny bit of silicone lube on the eyelet. I hope it doesn't seep onto the braking surface.

Logic would say, it is a seat or seat post related problem.

However, noise is a funny thing on bikes. I must have taken apart and regressed those silly parts 10 times and still could not get rid of the squeak that only occurred while sitting.

Then, for the hell of it, I redid my bottom bracket with Teflon tape and lo and behold, the creek was gone and has not come back.

You sure it's the bike?

I recently figured out a similar problem. It turned out to be a couple of my rim eyelets. It only made the noise when weight was on the wheel (i.e. I was sitting on the bike, or equivalent), but then I found I could induce the noise by firmly moving the affected spoke in/out. It was not the nipple or spoke threading, which I lubed, but the actual eyelet where it is formed into the rim.

This vintage Mavic (Open4CD) is on my commuter, which gets dirty and wet. I found the eyelets are actually rusting a bit inside, under the rim strip. Probably the next rain would've stopped the noise, but I put a tiny bit of silicone lube on the eyelet. I hope it doesn't seep onto the braking surface.

What do you mean by rim eyelets? You mean the part where the spokes are connected to the rim hub?

Don't say hub - hubs are in the center. I'm referring to a small metal cup built into each place in the rim where a spoke nipple holds the spoke to the rim. If you take the tire and rim strip off, you see the cup aspect. Not all rims are constructed with the same style of eyelet/cup, but something is inserted into the rim itself to reinforce the hole where the spoke nipple will hold the spoke through.

In my case, I was suspecting the spoke nipple itself, but turning it back and forth did not change the noise pattern.

I had the same type of noise. On a ride, a co-worker thought I should try a dripping a little dry lube over the nipple of each spoke. Basically, the noise at least for me went away and hasn't come back.

^ ok worth a try....