FrenchFit 

New cloth rim tape, then new 26" tire that's a very tight fit, then soon into a 40m ride the rear starts a little popping, creaking sound on rotation, same place under weight, forward or back, whether cranking or gliding. Checked the spoke tension and hub, perfect. Rim and eyelets are good. Tested for loose spokes, all's perfect. Finished the ride, no issues other than this constant sound. Tried hard left and right leans, sounds is about the same either way.

So then I dropped tire pressure from 90 to 50psi, sound is gone. (Tire rated 45-95psi).

Could this be the bead moving, grabbing & releasing inside the rim? I was thinking I'd deflate and add some lube on the bead, like soap/Aloe. Not really worried about this tire popping off, it's far too tight for that. Frankly, I couldn't get this thing off without irons & drama - would prefer avoiding a front to rear swap. Just want to quiet it down and run close to full pressure.

Thoughts/Ideas?

FrenchFit 

Grrr. Deflated, worked the bead, re-inflated it to 80 and road it hard for an hour. Last 10 minutes the creaking sound is back, but intermittently.

I guess I'm stuck swapping tires and see what happens.

rootboy 

One of those UN-answer-able questions. A rarity here.

sreten

Hi,

What width tyre ? 80 to 90 psi is far too high for most 26" tyres.

rgds, sreten.

techsensei

How did you check the tension? Are the spokes elbows fully bedded in the hub; is there are bowing of the outboard spokes as the leave the hub? I ask because I have had wheels creak due to the spokes rubbing/moving at the point where they interlace at the furthest cross.

FrenchFit 

(1.5 tires Vittoria Rando Pros; creaking aside, I really like these tires, sweet.). Tension was spot on, meter & plucking, and the little tweaks & relief I did do changed nothing. But I'm suspicious it could be a badly seated spoke, something new to check. Swapping the tires is the acid test, just too lazy to do another dismount/mount round.

The fact that it disappears at a lower psi should tell me something, just not sure what.?

ThermionicScott 

If nothing else, the lower pressure means there is less force on the rim to counteract (and lower) the spoke tensions. Perhaps it isn't the nipples creaking in the rim, but the spokes rubbing against each other?

sreten

Hi,

"close to full pressure" is an enduring myth. It leads to
underinflated skinny tyres and overinflated fatter tyres.

For 38mm tyres 70psi rear and 60 psi front should be plenty enough,
though the optimum pressures depend on rider weight and the
general condition of the surface you ride on.

https://www.bikequarterly.com/images/TireDrop.pdf

rgds, sreten.

FrenchFit 

I could go with the theory that hi pressure unloads the spokes and causes them to rub or actually move in their seats, at least 2 or 3 in the one critical area that is complaining. I don't need the hi pressure, just having fun with the road bike feel of 38s at 90psi. I run my other 1.5s at 60, so I'll see what happens if I go with a more conventional pressure.

ThermionicScott 

What spoke tensions are you seeing right now? Perhaps if you've been checking them with the tires off, you have a little margin to tighten them up.

Homebrew01

Valve stem noise in the rim hole ?? Doesn't really seem likely, but you could try wrapping a bit of tape around the stem as a cushion.

mechanicmatt

My guess is stress relieving spokes. Was the wheel made by you? or ordered (possibly machine made)?

Tension spot on doesn't mean that the spoke may not still be in a twist. Two ways of relieving that kind of stress. The first is to spin the wheel around (truing stand or upside down on a bike) and squeeze the spokes in pairs on both sides at the same time, usually a couple of times around is good and a swift cruise around the block to get all the pops out.

The second method is the over and back on tensioned nipples. Basically, go over all the nipples (one side at a time), and do an over tighten (1/4 to 1/2 turn) and then back. If some nipples don't thread then you have one bound up. I would do both sides around once and then do the first step of squeezing the spokes again to relieve stress. Then do one last re-true to make sure it all lines up right.

Anyway, you may already know this and my apologies if the description is overkill.

ThermionicScott 

I'm doubtful that the noise is from wound-up spokes. Usually that pinging is from recent re-tightening of the spokes, and goes away after a little riding. FrenchFit hadn't touched the spokes, and the noise only started when he installed the new tires and pumped them up to 90psi.

If the spokes haven't been adjusted in a while, it may be a good idea to actually loosen each one before adding more tension, to make sure they aren't frozen. Stress-relieving and all that isn't a bad idea.

sreten

Hi,

FWIW AIUI overinflated tyres feel fast but simply are not.

They are great on smooth tarmac and worse on rough tarmac.
On rough tarmac the feel of speed is energy fed into the bike
that must be eventually absorbed by your body, and it is tiring.

Good pressure depend on the average quality of tarmac you ride,
foremost, but should be lowered for bad roads like in my local
city, with bumps all over the place due to various road works.

If you like high pressures then skinnier lighter tyres than work
best at higher pressures are the way to go IMO. The penalty
of extra weight for fatter tyres is outweighed by the comfort
aspects run at the right pressures, too high IMO just wasted.

rgds, sreten.

DiabloScott

Another FWIW - aluminum nipples can make a noise that sounds an awful lot like a creaky chain if they get just a little bit corroded. If that's a possibility you might as well drop some oil around the head while you have the tires (and rim tape?) off.

FrenchFit 

ANSWER! Removed and polished the rim, found a long hairline crack in one wall. Surprisingly hard to see until I put a little shine on the wall. Hah, I knew I was on fumes with this rim; the noise was a much nicer wake-up call then a rim failure. The creaking was the split sections of the rim wall moving past each other under pressure - logical. Thank you bike Gods.

Best of all, I had a nice, unused, Deore LX Matrix single track rear wheel hanging on a hook; today it feels good to be a hoarder.