Drive train creaks in low gear

weaponsgrade · #1 10-03-2019, 03:37 PM

I'm getting a very loud creaking sound when I'm in my lowest gear and cranking up a steep grade. This is on my mtn bike and part of my route has a steep 20% section and that's when the creaking happens. The drive train is otherwise silent including when I'm in the lowest gear on other sections that aren't so steep. Shifting is fine, no wobbles in the rear wheel, RD dropout looks straight and bolted down tight.

Does this sound like a problem with the chain? I'm using a waxed chain. I've got about 180 miles on it. I had maybe two or three rides where some sections of the trail were muddy. It wasn't like I was splashing through puddles, but the bike was dirty enough that I washed it. I took care to try and avoid the chain during the wash. Molten Speedwax states 300 miles between waxings. They do say to rewax after wet or muddy conditions, but again I don't think the chain got too mucked up and the creaking is only that lowest gear while on that 20% section. Still, I'm wondering whether I need to rewax.

I have another bike with 260 dry miles on a waxed chain and everything is quiet.

joosttx · #2 10-03-2019, 03:46 PM

I had a similar problem. And I fixed it when I realized my quick link was installed upside down.

muz · #3 10-03-2019, 03:52 PM

I also had a similar problem. Turned out to be rear hub bearings going bad. See if you can reproduce with another rear wheel.

jr59 · #4 10-03-2019, 04:02 PM

I would try changing shoes, and then pedals first.

bikinchris · #5 10-03-2019, 04:46 PM

We tracked down a noise this week to the last two cogs on a Dura Ace cassette. Swapped wheels, no noise. Put the original wheel back on and swapped out to a 105 cassette the same size and it was silent.
There is another bike making a noise only in low gear and I suspect it to have the same problem.

NHAero · #6 10-03-2019, 04:49 PM

Would you please say more about the brand of chain and quicklink? I didn't know there was a right side up!

Quote:

Originally Posted by joosttx

I had a similar problem. And I fixed it when I realized my quick link was installed upside down.

Dave · #7 10-03-2019, 05:13 PM

When I have that sort of problem, it usually means the rear skewer is not tight enough. Some ultra-light skewers apparently won't tighten enough, due to the skewer stretch under tension.

weaponsgrade · #8 10-03-2019, 06:02 PM

Thanks for the responses. I'm pretty sure the quick link was installed with the arrow pointing in the chain direction travel, but I'll check again. The rear axle is a thru-axle (which is secured). I did have a few different creaking sounds over the summer which I traced to the bottom bracket and the rear hub bearing on the drive side. I replaced the bottom bracket and also that single rear hub bearing. I didn't touch any of the other hub bearings since they felt smooth.

The creaks related to that hub bearing and bb were very quiet compared to the creaking sound I'm hearing now. The creak I'm getting now is loud, but it only happens on that little stretch of a 20% grade. It sounds more like something is under a lot of tension. I do have another wheel to swap in. It takes a different cassette/freehub though (Shimano vs Sram).

muz · #9 10-03-2019, 06:11 PM

Anything that moves can creak, and there is really no way to find other than by trial and error. I was sure mine was coming from the cassette or the BB, so I ignored it. Like yours, only made noise in the lowest 2 gears up steep grades. By the time I opened up the rear hub, the cone and the cup was shot

John H. · #10 10-03-2019, 06:43 PM

Check the rear hub, make sure cassette is tight, thru axle tight and greased.
But your interval between wax jobs may be too long for the conditions that you ride in.
Sometimes when it is really dusty I find that I need to wax more often.
I particularly notice this on the smallest gear on my mountain bike- the 51 tooth cog (XTR).
I also bring a paste type wax in my saddle bag. I can apply this on the road if noise is too loud

Ralph · #11 10-03-2019, 08:18 PM

Quote:

Originally Posted by Dave

When I have that sort of problem, it usually means the rear skewer is not tight enough. Some ultra-light skewers apparently won't tighten enough, due to the skewer stretch under tension.

Check this first. it's a common problem.

fmradio516 · #12 10-03-2019, 09:07 PM

Oof, i didnt realize re-waxing was needed so often. Makes me re-think my recent purchase of moulten and teeny crock pot

unterhausen · #13 10-03-2019, 11:35 PM

Is it a shimano hub? Your cassette body is cracked.

David Kirk · #14 10-04-2019, 09:32 AM

I doubt it's related to your choice of chainlube. A creak is almost always one part shifting relative to another. In your case it only happens when you apply a large torque load which speaks to things like the cassette hub to frame interface.

I'd start by pulling the cassette and greasing the freehub body. This is a very common source of high-torque creaking.

A number of years ago I had some DT MTB wheels that had a super annoying creak but only in low gears on steep grades. I for the life of me couldn't find the source but it turned out that that hub flange had separated from the hub shell. So when I pedaled hard it would twist the two hub flanges relative to one another and make a heinous noise. I found it by spraying some WD-40 at different things until the noise went away....not a fix but it did point me in the right direction. DT gave me a new wheel and life was quit and nice.

dave

joosttx · #15 10-04-2019, 09:40 AM

Quote:

Originally Posted by NHAero

Would you please say more about the brand of chain and quicklink? I didn't know there was a right side up!

Sram Axs Eagle 12 chain and link. The link in curved and you need to make it "frown" as it goes over the cog. I installed it up side down so it was "smiling" as it travel the cog. No problems until I got to the smallest cogs.