yannisg

I have Cannodale Synapse Hi mod, Ultegra 11 speed bike, Mavic Ksyrium Equipe S WTS rims, Mavic Ksyrium Equipe S Hubs, bladed Mavic Ksyrium Equipe S spokes.
Rear wheel lacing is radial on drive side, and tangential 2X on non drive side.
When climbing in 34X28 or 32 there is a "pinging" sound from the rear drive side spokes when pressing hard on the pedals or riding off the saddle. The derailleur is not touching the spokes.
Any recommendation why this is happening and how to eliminate it will be appreciated.
YannisG

RubeRad

Most likely some spokes are undertensioned, and pinging comes from expansion/contraction of cyclical forces being applied. If this is a new wheel, pinging indicates that the wheels need "stress-relieving", which basically means gripping bunches in your fist and giving a good squeeze/flex. But if it's not a new wheel, then undertensioning is undoubtedly the answer. If you don't see to it the spokes will eventually start to break on you from all the repeated tensioning/untensioning. If you don't have the skill to tension your own spokes, you should take it to a shop and ask them to tune your wheel, make sure it is true and the spokes are all up to proper tension.

yannisg

Thanks for yr reply,
Its a new wheel with 2500k on it. The tension has been measured, and is even. Also, the tension is within spec.
I would assume after 2500k the wheel has already been stress relieved. Usually, if you build or re-true a wheel, even though you have stress relieved it, you hear a few "pings" on the 1st
ride, but after that there is no more "pinging". Also, if the wheel has not been completely stress relieved you hear the "pinging" in any gear. In my case, the "pinging" only occurs in the 28 and 32 sprocket, and under pressure.
YannisG

Al1943

Low tension spokes often go ping ping ping, but usually on the non drive side.

Remember that radial true, lateral true, and dish are all affected by spoke tension changes.

RPK79

I had pinging on my front wheel recently and now I have a broken spoke so I recommend looking into it.

RubeRad

Yannis, you are correct, pinging due to needing stress-relief is a symptom of a brand-new wheel, and would not last 2500k. You say your wheel has been measured, and is even/within spec -- was that recently (within the time where you get pinging)?

About just the 28/32 sprockets, I have heard of situations where high torque of low gears has a special kind of stress for the drivetrain, but I don't know how that might affect spokes. It might just be because hill-climbing often has side-to-side rocking, or especially non-smooth mashing (stomp-stomp) cadence that puts the largest amount of force onto your spokes that they ever see. What if you were on the flat in a higher gear and really laid into the pedals?

I still suspect insufficiently tight spokes.

What do you weigh, and how many spokes are in your rear wheel? If you are heavy enough, and your spokes are few enough, the spokes could be to spec for that wheel, but that wheel could be inappropriate for the rider. I once had to get rid of a low-spoke count wheelset because of my weight. I moved up to 32-spoke wheels and bingo, no more broken spokes!

Bill Kapaun

Radial lacing on the DS?
That sounds "backwards" to me????

Plimogz

^^ My thoughts exactly!

Unless they've innovated in some way, this appears to go against the notion that DS should be laced tangentially to have the pulling DS spokes transferring drive torque. Although I suppose they must've specified a strong enough hub to have it carry the driving force to the NDS spokes. Still...

I just hope the OP is on the lighter side, because speaking as a big guy, I wouldn't dare ride a 20 spoke rear wheel.

edit: Come to think of it, seeing as how the 34 x 28 (or 32) low gear used when climbing is imposing higher torque on the wheel, tension is likely at cause.

yannisg

Thanks for yr response,
The "pinging" started from the start of using the new wheel, and still occurs after 2500k on those two sprockets. I weigh 75 kg. There are 10 spokes on each side. If I get into such a low gear on the flats (light pressure) it goes not occur. On an uphill in the 34X28 or 32 it occurs even at a cadence of 65-70. In other words, the more the pedal pressure, the more the pinging.
When I measured the new wheel rear wheel drive side tension with the TM-1 park tool spoke tension meter I got a reading of 19 with sdev of o.32 which translates into 74 kgf for a steel bladed spoke of 3x1.5mm. Whereas the Mavic manual recommends a spoke tension of 130 to 145 kgf. This agrees with the idea that the spoke tension is low. Could a new wheel have the spoke tension so far off? Well, my next step should be to increase the spoke tension to at least 130 kgf and see the result.
YannisG

Plimogz

Seriously, you mesure 74Kgf and Mavic recommends 140-ish? lol. Well look no further for your problem then.

***

And yes, I'd say unless you build the wheels yourself or know for a fact that they've been built (or at least checked) by somebody with a proper reputation to maintain, their tension should be regarded as suspect and something to look into. It is after all, much less obvious than lateral or radial true at first glance.

***

You did however say something to the effect that:
...which gives me pause; who then measured its tension and found it to be within spec? I'm assuming that it wasn't you, or in case that it was, that you've revised what "to be within spec" entails. I only mention it because a doubling of the tension is significant and only advisable if all known readings of tension are in accord with each other. In other words, if a previous measurement of tension was properly taken and found the tension to be within spec (which you say is 130-145 Kgf) I find it hardly advisable to go about doubling the tension now based on your latest reading of 74 Kgf. It would be a shame to crack the rims based on a latest very-low measurement which was later determined to be faulty, after all.

***

That being said, assuming the tension measurement of 74 Kgf (average) is to be trusted, and that Mavic does indeed recommend 130-145 Kgf for that rim, look no further for your problem. And maybe look elsewhere for advice than wherever you had that first measurement taken, in the future.

Al1943

Yes, very common problem with new machine built wheels.

You will need to raise the tension on both sides of the wheel to center the rim. This should be done gradually while checking radial and lateral true and dish.

Al1943

Several years ago one of the wheel companies, maybe Velocity, was building wheels this way on the idea it would be better to transfer more torque to the left side of the wheel by lacing the drive side radially and the NDS tangentially. I remember seeing the ads.

RubeRad

75kg is I think plenty light enough for any wheel. Just get those spokes up to tension (while maintaining radial/lateral true and centered dish) -- or have a pro do it (somebody different than whoever said this was up to spec before), and you should be ok. Or maybe some spokes have been irreparably damaged and will break anyways, it's not the end of the world, just replace broken spokes.

If you are willing to pay the cost of extreme caution, then rebuild the wheel (or have the wheel rebuilt) with new spokes. And perhaps a more conventional lacing pattern, I wouldn't really be able to advise on that, but there are plenty others at BF who can. Moving away from a radial lacing would require suitably longer spokes; there are calculators for that sort of thing.

yannisg

Thanks for yr reply.
I got the 74kgf from the PT TM-1 spoke tension calculator, but I must have gotten the incorrect spoke width from somewhere. I measured the spokes, and they are 3.0x1.0mm instead of 3.0x1.5mm which gives a spoke tension of 150-168 kgf according to the spoke tension calculator. So the tension is correct, and maybe slightly high. So tightening them more is out.
Whenever I buy a new wheels I always check it for trueness and tension, and record the readings for future reference. I have found new wheels being out-of-true and/or with uneven tension, if so, I correct them. I check for trueness, and tension at the end of the season or if I suspect something is wrong. I have checked the PT tensionmeter against one at a LBS, and the readings are similar. This is the best I can do from sending in for calibration.
This particular lacing seems to work, Mavic calls it the isopulse, because after 2500k and some rough roads the wheels are running true. I will re-check the tension on the drive side spokes.
I could probably live with the "pinging" as long as I know that it is not indicating that something is wrong.
Thanks,
YannisG

Plimogz

Well, if tension is alright, or even slightly on the high side already, I suppose the low tension diagnosis is firmly eliminated.

For the time being you could try applying a drop of lube at each of the spoke crossings on the NDS. It won't actually change anything if the wheel is indeed shifting under load, but it costs next to nothing and if it quiets the pinging you'll at least know precisely where it's been coming from.

Also (and dumb as I might feel for suggesting it after my previous guess of low spoke tension) I've had too-high tension wheels start pinging at around the moment when I noticed cracks in the rims around spoke holes, so you might check to see if that isn't happening to yours.

Either way, sucks that the problem wasn't as simple as too-low spoke tension.

edit: although hey, and I think this is a longshot because I tend to believe you with something like spoke width, but you might double check by contacting Cannondale to inquire as to the width of the spokes used (or see if you find the specification online, though spoke detail may be beyond what the manufacturer puts in their specs page). I mean, obviously the width would be easily measured with half-decent calipers, but who knows...

yannisg

Thanks for replying,
I couldn't find the spoke spec for width and thickness so I measured a few with a caliper, and came up with 3.0X1.0mm. So the spoke tension is correct.
I'll try the drop of lube, and see what happens.
YannisG