Rear Spoke Twang

[Splash]

When I ride up steep inclines and applying a lot of torque in the crankset, I often hear rear spoke twang. No spokes are broken.

Should I be concerned? Is this normal?


Rear wheel make up - Enve 6.7, CKR45 hub, aerocomp/aerolite spokes..


Splash

[R3awak3n]

Maybe rd cage is slighly touching the spokes. when you put torque on the crank the frame flexes.

[happycampyer]

Twanging or other noises are not normal. Sometimes a twang means a spoke has lost tension or is loose. An unscientific way to check is to pluck the spokes to hear if one is "detuned." A shop could check the tension properly.

[Tony T]

What gear are you in when this happens?
If in the lowest gear (largest cog), then as said, it's probably the rear derailleur hitting the spokes.
If so, just need to adjust the limit screw (had this happen to me awhile back).

[R3awak3n]

and its true what happier campier has said, if one spoke is loose you can hear it grind on the crossing spoke also making a twang sound.

Both these things have happened to me.

[Splash]

Thanks guys

Yes , I am in the largest rear sprocket when I hear the twang.

I will have the limiting screw looked at and spoke tension checked out.
Splash

[oldpotatoe]

When I ride up steep inclines and applying a lot of torque in the crankset, I often hear rear spoke twang. No spokes are broken.

Should I be concerned? Is this normal?


Rear wheel make up - Enve 6.7, CKR45 hub, aerocomp/aerolite spokes..


Splash

If the rear der isn't hitting the spokes, sounds like the tension is a bit low. I just trued a set of ENVE's for a gent on this forum and the tension was about 1/2 of what it should be(Herb, your wheels are done)..Carbon rims are very stiff and supported by thin spokes, and not very many..tension needs to be proper.

[Peter P.]

When I ride up steep inclines and applying a lot of torque in the crankset, I often hear rear spoke twang. No spokes are broken.

Should I be concerned? Is this normal?


Rear wheel make up - Enve 6.7, CKR45 hub, aerocomp/aerolite spokes..


Splash

Sounds like the wheel was built with Country and Western spokes. Rebuild with the correct spokes and the twang will go away.

[Splash]

Peter

Can you elaborate how these spokes are incorrect?

Wheel buil by Fairwheel bikes in Tuscon, Arizona.


Splash

[ultraman6970]

When I read twang I thought this was going to be a duane eddy thread.

[Tony T]

Peter

Can you elaborate how these spokes are incorrect?

Wheel buil by Fairwheel bikes in Tuscon, Arizona.


Splash

Country and Western spokes go "Twang!" :)

[Splash]

Peter - what are the correct spokes in your opinion for this wheel?

Splash

[jc031699]

(Was a joke). Twang is slang for a "country" or southern accent.

[Peter P.]

(Was a joke). Twang is slang for a "country" or southern accent.

Exactly. I KNEW I should have added a smiley...

To make up for my lapse:

How are you sure it's the spokes? Have you swapped out the wheel?

[Splash]

No wheel swaps.

But, what spokes should have been installed in your opinion?

Splash

[Tony T]

No wheel swaps.

But, what spokes should have been installed in your opinion?

Splash

The longish thinny kind made of steel. :):):):):)

[R3awak3n]

he was saying the tension was too low, not that the spokes were the wrong ones. You probably have cx rays on those wheels which are great and totally fine. Fairwheel knows what they are doing so I would not worry about how the wheels are built. Really do check the RD first because its a common problem, then move to the tension of spokes and if that is fine then I don't know :)

[Splash]

I have their job card in front of me and in their own hand writing, these are the spokes that they stated were installed on this wheel.

Splash

[Tony T]

he was saying the tension was too low, not that the spokes were the wrong ones.

He was saying that "C+W" spokes are supposed to "Twang" ;)

…anyway, the problem will most likely be solved with a ¼ turn of the limit screw.

[sandyrs]

No wheel swaps.

But, what spokes should have been installed in your opinion?

Splash

It was a joke about the music genre(s) country and western and its association with "twang," not a literal criticism of your wheels' spokes.

[Mark McM]

I have their job card in front of me and in their own hand writing, these are the spokes that they stated were installed on this wheel.

Splash

You didn't mention how many spokes (or how much you weigh).

All else equal, fewer or skinnier spokes make a more flexible wheel, increasing the chances that the derailleur will hit the spokes. Do you find the twanging louder or more common when standing out of the saddle? When you rock the bike laterally, it has two affects: The wheel will flex more laterally; and there will be greater detensioning of spokes on "uphill" side of the wheel as the bottom of the wheel passes through the LAZ (load affected zone) at the bottom of the wheel. The lateral flex will increase the chances of derailleur rub, and the greater spoke detensioning increase the chances the spokes will completely slacken and make a ticking or twanging sound.

[Tony T]

As it looks to be occurring when the RD is at its closest point to the wheel, my guess (as well as others) is that the RD is hitting the spokes.

[rustychisel]

As it looks to be occurring when the RD is at its closest point to the wheel, my guess (as well as others) is that the RD is hitting the spokes.

probably this.

A Roy Orbison, or Johnny Cash kinda twang?

[Peter P.]

No wheel swaps.

But, what spokes should have been installed in your opinion?

Splash

I'm not a fan of aero spokes. Their slim cross-section is oriented to result in reduced lateral strength. Any aero advantages aren't worth it.

I'd suggest a typical round spoke for increased lateral strength, but I'm not saying the spokes are the cause of your creak, until you've swapped wheels and confirmed it.

[Splash]

Great responses. Thanks.

The ol' 'twang' word certainly got me. lol:


SPlash

[Mark McM]

I'm not a fan of aero spokes. Their slim cross-section is oriented to result in reduced lateral strength. Any aero advantages aren't worth it.

I'd suggest a typical round spoke for increased lateral strength, but I'm not saying the spokes are the cause of your creak, until you've swapped wheels and confirmed it.

Wheels and spokes don't work this way. Spokes are only loaded longitudinally (along their length). Spokes are not loaded laterally, so the lateral strength (or stiffness) of the spokes has no affect on wheel strength (or stiffness) - only the longitudinal strength/stiffness of the spokes matter.

For longitudinal strength & stiffness only the length and cross sectional area of the spoke matter, not the shape of the cross section. It doesn't matter if the cross section is round, oval or square, as long as the cross sectional area is the same. So, oval spokes will make a wheel just as stiff and strong as round spokes, if the oval has the same cross sectional area as the round spokes.

[MadRocketSci]

I have the same thing on my neutrons with the bladed steel spokes. Had potter @ vecchio's look at it a while back, and he said the wheels were fine, but i think lube was applied to the spoke junctions at the hub and crossings. The problem went away for a while but then came back, presumably due to lube wearing off. now i just add a miranda lambert voice in my head while climbing and all is fine (except for the country music stuck in my head).

[Peter P.]

Wheels and spokes don't work this way. Spokes are only loaded longitudinally (along their length). Spokes are not loaded laterally, so the lateral strength (or stiffness) of the spokes has no affect on wheel strength (or stiffness) - only the longitudinal strength/stiffness of the spokes matter.

For longitudinal strength & stiffness only the length and cross sectional area of the spoke matter, not the shape of the cross section. It doesn't matter if the cross section is round, oval or square, as long as the cross sectional area is the same. So, oval spokes will make a wheel just as stiff and strong as round spokes, if the oval has the same cross sectional area as the round spokes.

Once the wheel is leaning at any angle but vertical, lateral stiffness becomes an issue.

[staggerwing]

Once the wheel is leaning at any angle but vertical, lateral stiffness becomes an issue.

No. Mark McM properly summarized. Their method of attachment to the hub doesn't support lateral loading.

[cdn_bacon]

what about pinching the crossed spokes together. does that replicate the sound?

if so just drop a bit of grease where they meet

may help?

[Mark McM]

Once the wheel is leaning at any angle but vertical, lateral stiffness becomes an issue.

Yes, when the bike is leaned, the wheel is under lateral force. But the spokes are not.

The spokes act similarly to the guy wires on a tower:

http://s3.amazonaws.com/answer-board-image/aa29e927-7145-4051-9199-75b8527976c2.jpeg

A long, slender tower has little lateral strength and stiffness. The guy wires also have almost no lateral stiffness unto themselves. But when the wires are attached to the tower at an angle, the longitudinal strength/stiffness of the triangulated structure can increase the lateral strength/stiffness of the tower.

A few other notes: If you compare the bending stiffness of the naked spokes compared to the lateral stiffness of an assembled wheel, you'll see that the wheel has a much, much larger lateral stiffness. This shows that there is something other than the lateral stiffness of the spokes giving the wheel its lateral stiffness. Also note that the spokes can rotate fairly freely (at least to some degree) at their attachment points (the spoke is attached by what is essentially a hook into the flange hole, and the nipple/rim joint is a type of ball-and-socket joint), so even if the spokes were loaded laterally, they would easily rotate.

Just as the tower and guy wires, the lateral strength and stiffness of a wheel is greatly influenced by the base width, which in the case of a wheel is the flange width. This is why rear wheels are weaker than front wheels - the dishing decreases the base width (flange width) of the wheel, decreasing the bracing angle of the spokes.

Another very direct example is the London Eye ferris wheel:

http://images.photowall.com/products/50043/london-eye.jpg?h=650&q=90&

This ferris wheel is built very similarly to a spoked bicycle wheel. The spokes I in this case are thin cables. This wheel relies entirely on the longitudinal strength and stiffness of the cables, and not their lateral strength/stiffness.