TallRider

I'm replacing the rim on a rear wheel. The spokes (all 14/15/14 butted) are fine, but I'm planning to replace either the drive-side or non-drive-side spokes so I can compensate for wheel dish. Non-drive-side spokes are under lower tension in a dished wheel, and using relatively thinner spokes on the non-drive-side means that the amount of spoke stretch (once wheel is built up to proper tension) is more comparable to the drive-side spokes.

I'll either swap the drive-side for 14g straight-gauge spokes, or swap the non-drive-side for 14/16/14 (or 14/17/14) butted spokes. For a 32-spoke rear wheel (10-speed Shimano hub, 130mm spacing) and a 200# rider, is there any basis to prefer the thicker spokes (14g + 14/15/14) vs the thinner spokes (14/15/14 + 14/16/14)?

Edit: the rear rim finally succumbed to an injury from 10 years prior, where a machine screw punched through an Armadillo tire and embedded itself in the tire-facing wall of the rim. See original thread for photos. At the time, I drilled out the punched section and sanded/polished it to remove stress risers. The rim developed a crack at the eyelet closest to that hole. Wheel wasn't over-tensioned and had never needed truing until someone improperly mounted the bike on a roof rack which ended up twisting the rim out of true.

shelbyfv

You don't want straight gauge spokes, whatever else is involved.

fietsbob

I have a 30 year old set of 36 spoke wheels with 15ga straight DT spokes.. for my Road bike .

Retro Grouch 

How much wheel building experience do you have? The issue with 17 gauge spokes is they wind up more easily so they are a little bit harder to work with. If it was me, (and it's not) since you are replacing the rim anyway, why not pick one of the asymmetric rims to minimize the amount of spoke tension differential.

79pmooney

Yes. Intended purpose for this wheel, your weight, your riding style (including the hard to measure but real "how hard are you on wheels" and the roads you ride on. I'm 155 lbs and relatively kind to wheels and have been riding 14/17/14 (or 15/17/15) spokes forever except 14/16/14 on the drive side. (But I've been using the DT spokes for a while so it is 2.0/1/8/2.0, etc. I go one step heavier on my commuter/winter wheels.) If I were your weight I doubt I would use anything lighter than 14/15/14 (2.0/1.8/2.0.

2.0 ~/= 14 ga
1.8 ~/= 15 ga
1.6 ~/= 17 ga
1.5 = light!

I use either 14/2.0 or 15/1.8 for the ends. 14 only for the right rear. I get told regularly that going 15 ga/1.8 will lead to heads snapping off. Maybe so, but in my experience not until long after I've replaced them and the rims for other reasons.

Ben

TallRider

Good question, I should have mentioned that I'm a fairly experienced wheelbuilder. It's nice to have a discrete project to work on, compared to academic work which is rarely truly finished.
Asymmetric rims have never really caught on, in large part because they solve a problem that's not a big or common problem (plus some extrusion issues have led some asym rims to more cracking, which has hurt the reputation fo the category). Building with thicker drive-side spokes on a dished wheel is an alternate method of getting similar spoke stretch (though doesn't cover all the issues of dished wheels).

Thanks. My guess is the only downside to 14/16/14 or 14/17/14 is controlling the windup, with the value of a bit of weight savings. Wheels that I build tend to stay true unless subjected to some trauma, but I always use 14g at the ends. I'll probably build this wheel with straight-14-gauge (2.0) on the drive-side and keep the existing 14/15/14 on the non-drive-side.

79pmooney

Use lots of grease on the threads. I also take a Q-tip dipped in grease and spin it in each spoke hole from the tire side of the rim. When I check the dish, I also put weight on my hands at 3:00 and 9:00 with the wheel laying on the floor to relax the spokes and let them unwind. (Not too hard or you will taco the rim.) A little grease on the hub spoke holes is also good but I usually don't remember.

Ben

fietsbob

+DT Alpine are 13-15-14, FWIW ..

TallRider

That sounds like it's for tandems or loaded tourers

fietsbob

I liked my touring wheels ..

ThermionicScott 

Thicker spokes on the drive side will stretch less, but do you have a problem that can be definitively traced to DS spokes stretching too much?


There are reasons for using thinner NDS spokes, but if you only beef up the DS spokes instead, you haven't done anything to help the former, to my understanding.

Trevtassie

I'd probably only do it if the DS spokes are really thick. I had issues with Sapim Strongs on a 26" wheel, the NDS would keep unscrewing because I couldn't get enough stretch on them without the DS being 160kg! That would have been a candidate for thinner NDS spokes to get enough elasticity to keep the nipples under load (I used Loctite instead, because that's what I had...it worked)

shelbyfv

I don't see the point in using a straight gauge spoke, proven to be less durable than its DB sibling, in an attempt to prevent a "problem" that may not exist. Do the wheels you (OP) build suffer from too little NDS tension? Are you breaking spokes? AFAIK, most modern rims are not so fragile that you cannot achieve adequate NDS tension.

Bill Kapaun

If I'm building a wheel, I use a thinner NDS spoke, but I certainly wouldn't change 1/2 the spokes just because.
Wait until you have a problem.

TallRider

I'm looking for feedback on which way to go of [14 + 14/15/14] vs [14/15/14 + 14/17/14]. Or, whether it's worth the effort (in this case) to re-lace one side of the wheel vs just swapping the rim and keeping 14/15/14 spokes all around without touching the lacing (as Bill Kapaun suggests).

It's probably worth clarifying the reasoning behind having thinner NDS spokes to begin with. here's the background.

The issue with building dished rear wheels is that you have a narrow range of optimal tension. DS spokes have higher tension than NDS spokes, but
a) DS spoke tension can't be too high, or the rim will end up cracking by the eyelets
b) NDS spoke tension can't be too low, or the spokes will borderline go slack during the rotation of the wheel (esp when the wheel rolls over a bump or edge of a crack). The spokes facing the ground have slightly lower tension as a bicycle wheel rotates. Spokes going in-and-out of tension means slight flexing of spoke at the elbow. Do this enough times (billions of cycles), and spokes crack at the elbow. This is why NDS spokes are more likely to break, whereas rims are more likely to crack at the eyelets by DS spokes.

The value in having *relatively* thinner spokes on the NDS is that they stretch more for a given tension, so even though they are lower tension than the DS spokes, they stretch close to a comparable distance under that lower tension b/c the metal is thinner. This means the NDS spokes are less likely to go slack.

Straight gauge spokes aren't automatically less durable. In some cases they make the wheel build less durable, because they don't stretch as much and thus de-tension under a lesser hit.

Bill Kapaun

A well built wheel with the same straight gauge spokes on both sides should last a very long time.

Since we obsess about minor things, I'd use this method-
Put your numbers in SpoCalc and determine what tension % you have on each side.

Calculate the cross sectional area differences of the "thin part" of the spoke.
Example- A 1.8mm spoke is 90% of a 2.0mm spoke.
90%^2 =81% cross sectional area.

I don't try to exactly match those, but stay "slightly thick" on the NDS.
I'm not totally sure if having exact "matching elongation" is "too much of a good thing", so I stay a bit conservative.

In the end, we can build fine wheels with a lot of different "theories" about what we want.
Quality of the build is more important.

ThermionicScott 

All of this is true. But as I said before, switching to heavier DS spokes wouldn't help your current NDS spokes at all! There's nothing magical about the proportion between NDS and DS spoke gauge; it's all about making sure you have the appropriate spoke gauge on the NDS.

BTW, in addition to 2.0/1.8/2.0 (14/15/14) and 2.0/1.5/2.0 (14/17/14) spokes, there are options for 2.0/1.6/2.0 (14/16/14) and 2.0/1.7/2.0 (gauge system is antiquated and we should stop using it). Consider one of those if your NDS spokes are coming loose.

TallRider

Yeah, the value of swapping out one side of spokes is probably pretty low. And my wheels always nail consistent tension. I think I'll just swap the rims without touching the spokes. Super-quick that way, too.

You're right, I should use mm instead of gauge for spokes. Never had issue with NDS spokes coming loose on wheels I've built or wheels I've tensioned.

My understanding is that the relative thickness of DS vs NDS spokes matters. I may be wrong. My understanding of the mechanism is that for a wheel with overall thicker spokes (that stretch less), the rim will deflect less than it would on a wheel with overall thinner spokes that flex more. This isn't the only factor, but it's *a* factor. Again, I might be wrong on this. I haven't read a lot about wheel physics in the last few years.

Kontact 

On a wheelset I built with a low spoke count and DT Revolution spokes(2.0/1.5), I chose to use 2.0/1.7 DS spokes. I did that because the Revolution spokes are so thin, I wanted to hedge my bets for the 14 spokes that are bearing the most load. If I had used 2.0/1.7 spokes on the NDS, I would have used the same on the DS.

It is popularly believed that straight guage spokes aren't elastic enough and more likely to break over time, so I don't see the point of using them combined with butted NDS.

If I was building a light wheel on the cheap, I could see using straight gauge 2.0 DS with 1.8 NDS. But that would again be to make up for the low strength of the thin spokes, not because of some balance theory.

Mr IGH

This is not based on any engineering reasoning. If you test either configuration the double butted spoke fails first, it's the law (of superposition)....

Kontact 

I'd like to read about that test.

shelbyfv

There have been numerous threads where Mr "explained" his theory. IIRC, one of the more entertaining involved his attempts to convince DT Swiss of their errors.

Kontact 

I personally am unconvinced that a 14 gauge spoke is actually less durable than a 14/15/14. I think most spokes fail because of lack of proper bending around the flange - which is why most broken spokes are elbows out.

But I would like to read any test the showed a narrower wire taking more cycles than a thicker one.

TallRider

I take back my earlier comment that these are for tandems or loaded tourers. Given that spoke breakage usually happens at the elbow, these make total sense with very little added weight by the flange.

davidad

At 200 lbs plus the bike I would recommend 36 double butted spokes. Since you are using the same type of rim to rebuild the wheel I wouldn't worry about the difference in spoke tension between the two sides.
Saying that I had a problem with a heavy, strong rider and a Power tap hub. The design of the hub made for more dish, so I added extra tension to the drive side to get a decent tension on the NDS and that solved the problem.