Can U Diagnose This Problem? Funny Noise



NJAgent020

Member
Apr 3, 2015
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I have a Trek 7.3 fx hybrid. A lot ofm iles but well maintained. When sitting on the bike and riding, I hear a metallic "tong" sound.

The sound repeats faster the faster I go. The sound continues whether I'm pedaling or not. If the crank arms are still, I still hear it. The sound is absent when I put it on a bike stand. It only makes the noise when I'm sitting on the bike.

I doubt my safety is at stake as I have had a professional tune up and maintenance on the bike recently but the sound is so ****ing annoying. I just want it to stop.

My wife can hear it riding like 5 feet behind me. It appears to come from the middle or back of bike not front. It almost sounds like a loose spoke, but I check them all. No such luck.

So, amateur wrenches, what could it be??? Help me!!!

I'm dropping it off at a pro shop tomorrow and I'd like to give him an idea of what it could be.
 
The first thought that came into my head was a loose spoke, too, but you checked them. I had a mystery metallic noise once, too. Turned out that my cassette lock ring had somehow worked itself loose.
 
"The sound repeats faster the faster I go. The sound continues whether I'm pedaling or not" - means it has to be related to the wheels going round.
If all spokes are healthy and there's nothing touching the wheels as they rotate, the only thing I can think of is a damaged bearing or a busted axle.

At slow speeds, mystery sounds CAN be caused by something loose either inside the hub or inside the rim, a ball bearing gone astray or a nipple dropped into the rim at build etc. But at higher speeds, rotational forces tend to stick these in position, making the noise disappear.
 
nice information
thanks
happyemo.jpg
 
Thank you folks.. I directed the professional mechanic who did my recent tune up to the the rear hub. To add insult to injury I got a flat on the way home (my second in two days) so I am upgrading my Bontrager 700x 32 stock tires to Gator Skins 700X32. Should help with the flats.

It should be ready by Thursday night!
 
My guess is that it's coming from a rear spoke. Even if the spokes seem tight enough, a slight bit of corrosion or dirt at the X crossing (mid-spoke) could cause the "tong" noise you describe as a spoke goes round under load. Your mechanic should check the spokes by squeezing each crossed pair together. If that's it, a drop of oil on the spoke junction will usually silence it.
 
OK I got the bike back. He repacked the rear hub and tightened the spokes as well. Noise gone!!! Wahoo