32 vs. 36 spokes: is anybody concerned about limits for 32 anymore?

[mitch....@gmail.com]

It seems 32 spoke has become standard for any level of use (in trad-built wheels) and has not been considered a low spoke count wheel since the 80s. Anybody still think about limits for 32 spoke wheels, assuming basic 3 cross, strong rim, reasonable dish, etc.?

 

When I think about the 32 vs 36 spoke wheels I've used over the years, built by me or others, I have not seen durability differences between them nor have 32 spoke wheels needed more truing. I do notice this difference with 28 spokes though.

 

It seems that 650B wheels with their shorter spokes and (usually) wider rims may need the four extra spokes even less than 700C wheels.

 

Just curious about whether anybody thinks of 32 spokes as marginal anymore or as requiring a weight limit.

 

thanks,

Mitch

[Jan Heine]

Generally speaking, wider tires at lower pressures put lower point loads on the rim and spokes. So you don't need as sturdy wheels as you do with narrower tires. Since switching to 650B x 42 mm tires on most of my bikes, I don't think I have trued a single wheel after it was built... and I ride on rougher roads that before.

One concern is pulling trailers. If you do, it seems that this stresses the spokes from the torque of the pedaling action and the resistance of the heavy trailer. I used to break spokes with alarming frequency until I changed to a 40-hole rear wheel on my trailer-pulling bike. It could also be that the extra shear in the rear tire reduces the point loads even in acceleration, so perhaps it's not the spoke count but again the tire size. (The spoke-breaking happened when I pulled the trailer with a 700C bike.)

Jan Heine
Editor

Bicycle Quarterly

http://www.bikequarterly.com

Follow our blog at http://janheine.wordpress.com/

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[somervillebikes]

This is interesting, and I've been thinking about torque effects since I will be building a 20" dynamo disc-brake wheel for a cargo bike shortly.  Given that disc wheels put more torque stress on spokes from braking than any kind of pedaling torque you can achieve (if you could generate more pedaling torque than braking torque, you could overcome your brakes... this simply is not possible), it would seem unlikely that torque alone or tire size could explain the spoke breakage that you experienced before switching to 40H.  I wonder if it has more to do with the spoke angle, and whether your 650B wheel has a spoke angle that is closer to tangential to the hub flange than your 700c wheel, as opposed to simply a difference in the number of spokes.

The 20" disc wheel I will be building is only 32H, and will be laced 2X, giving a spoke angle from the hub flange that is near tangential. I haven't heard of many front disc wheels breaking spokes, even in low spoke counts, and even though those wheels see massive torque effects from braking.

Anton

[Jeff Bertolet]

Someone suggested riders over 175-180 pounds should consider using 36 spoke wheels. This sounds reasonable to me. I use 36 spoke wheels on my city and cargo bikes and 32 hole on my fast bikes. I weigh 150 pounds and haven't broken any spokes in 10 years. 

The nice thing about 36 spokes is when you break a spoke, the rim doesn't deflect as much, you may not even need to fix it to finish a ride, just open the brakes a little more or compensate with the other spokes.

[Leslie Bright]

Since I weigh more than 200lb, all of my wheels are 36h.    If I was under 200lb, I'd probably not be as shy about a 32h...   

-L

On Thursday, July 2, 2015 at 12:37:24 PM UTC-4, mitch....@gmail.com wrote:

[Ryan Watson]

> On 2015/07/03, at 6:30, Jeff Bertolet <jbf...@gmail.com> wrote:
>
> Just curious about whether anybody thinks of 32 spokes as marginal anymore or as requiring a weight limit.

I used to weigh around 200 pounds and would sometimes break a rear spoke on my skinny tired 700c bike. Now that I'm 170-185 and ride fat 650Bs, I've been fine with 32 and even 28. Don't think I've even had one go out of true in almost 10 years!

Ryan

[Scott Calhoun]

I had Anthony King at Longleaf build me a 28 hole 650b wheelset with Velocity A23 rims that I have used hard on my porteur bike for several thousand miles, loaded, over all manner of road and off-road conditions. I have yet to take wrench to these wheels. I weigh 165, but I've loaded the bike up with over 20lbs of gear on numerous occasions. 

Scott Calhoun

Tucson, AZ

[Steve Palincsar]

On 07/03/2015 02:56 PM, Scott Calhoun wrote:
> I had Anthony King at Longleaf build me a 28 hole 650b wheelset with
> Velocity A23 rims that I have used hard on my porteur bike for several
> thousand miles, loaded, over all manner of road and off-road
> conditions. I have yet to take wrench to these wheels. I weigh 165,
> but I've loaded the bike up with over 20lbs of gear on numerous
> occasions.

You say that as though a mere 185 lb constituted "a load." Put your 20
lb on a bike with a 210 or 220 lb rider and it's a whole different
story: more like you and 4 fully stuffed panniers and a mountain of gear
piled high on top of the rear rack. I don't think that a 28 spoke wheel
would handle that nearly as well as a 32 (in 650B).

As for the durability of 32 spoke 650B wheels, my experience is confined
to Velocity Synergies, and I've had a boatload of rims that cracked
around the eyelets. On the other hand, Jan had those issues too, and
he's about your weight, so I'm not ready to attribute those issues to
the load so much as to issues Velocity had with its metallurgy. The
most recent rebuild has exceeded any of the previous rims in mileage and
so far, fingers crossed, no issues, so I'm hopeful Velocity has solved
the problem.

That said, the most recent 650B rear wheel I had built uses a 36 spoke
Grand Bois rim.

[Nick Payne]

Our touring tandem (26" wheels) has been running on 36-spoke wheels since I built it up in 1987. It's been over all sorts of roads, including some pretty bad condition unsealed tracks, still has the original spokes, and the wheels have remained true and we've never broken a spoke. It is on its second set of rims after the sidewalls on the original rims wore down. The two of us plus a full cycle camping load comes to about 400 lbs.

I've been racing on low spoke count (16 front, 20 or 24 rear) wheels for over fifteen years without any wheel problems. In fact, outside of wheel damage caused by crashes, problems with modern low spoke count wheels are remarkably few and far between, and some of the riders I see on these wheels are up around 85-95Kg. I think a large part of the reliability is due to the wheels using straight pull spokes, which eliminates the weakest part of the spoke (the J-bend) where spoke breakage normally happens.

Nick

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[Jeff Bertolet]

I highly recommend the wheel fanatyk blog for lots of good wheel/rim/spoke information, written by a co-founder of Wheelsmith spokes.

To answer the OP... Yes, you can build a 32 hole 650B wheel that will stand up to extended abuse. On the other hand, breaking a spoke happens occasionally, even when properly built. And it sucks when it happens in the middle of a 400K+ ride or a tour. Smaller bike shops in rural areas without a spoke threader may not carry the spoke for a 650B wheel (depending on hub flange size and rim profile) since it is in between the common 26" and 700C sizes.

A 36 spoke 26" wheel is probably equivalent to a 40+ spoke 700c wheel.

There are lots of ways to get a strong wheel...low spoke count+stiff rim; higher spoke count+lightweight rim; smaller wheels; precision manufacturing and assembly (high end wheelsets); but there is no free lunch, with the exception of a few overpriced wheels, you get what you pay for. Unless you build your own wheels, then you get a discounted lunch.

From an interview with DT Swiss about straight pull spokes...

J-bends spokes tend to suffer more breakage issues due to poor build quality and low spoke tension. Also, some hubs have spokes holes too large, which causes poor fit of the elbow. Most of the time you can chalk up premature J-bend spoke breakage to corners being cut in the wheel-building process. For example: it's always surprising to me to see a shop build wheels without the use of a spoke tensiometer. To me, that's like trying to build a house without a tape measure! I can't speak for other brands of spokes, but I can say that our J-bend and our straight-pull spokes are very close in quality and strength. Going forward, DT Swiss will be offering more versions of straight-pull spokes due to numerous requests as field replacements on other brands of wheels/build, or for new wheel builds on DT hubs.

And some interesting info on butted spokes

Contrary to popular belief, butted or bladed spokes are not "drawn" or stretched into their butted profiles by DT Swiss. Most people think the butted portion of the spoke is stretched into shape that is the finished product. This is not the case because it would leave the metal strained and weak. The butted spoke is actually is forged into its shape and while the process may seem similar, it isn't. The forging process allows the metal to be compressed into a denser package and this strengthens the metal by aligning the grain, giving rise to a part with improved strength characteristics. 
In essence, the spoke can do more with less - if you get my drift. Think of a blacksmith manufacturing horseshoes. The metal for the shoes is not only hammered into shape, but is made denser through the process, thus removing voids and gaining durability through working the metal. 

Although I think this is a little misleading since butted spokes never fail in the middle of the spoke. They should have noted that butted spokes are essentially the same unbutted spokes, strengthwise. since they are the same where they fail, at the ends.  But that's a bit nitpicky.

[Jim Bronson]

I'm pretty heavy at 265 and generally speaking I haven't had significantly worse luck with 32H.  However, if you do break a spoke, there's going to be a lot more hop in a 32H than a 36H.

I broke a spoke on a 36h wheel in December and I just thought it was a little out of true.  It wasn't until I really started looking that I realized that not only had I broken a spoke, but that it had completely departed the wheel. 

This has never been the case on 32H.  You can't miss a broken spoke on 32H.  You'll probably have to back your brakes off the rims some if you do it on something like a long brevet like I did last year, otherwise it will rub.

-Jim

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[Scott Calhoun]

Haha, well, your point it well taken Steve. I'm a tall skinny guy between Froome and Wiggins in height and a bit heavier than both. Regardless of spoke count, when I have wheels made by a well-regarded wheel builder, I rarely have to touch them after an initial tweak or two. I typically wear-out the rim track before they ever need any serious work. I think I'm fairly light on the bike so-to-speakl. Still, for the 28 hole set I mention above, even when I explained to Anthony King how I'd use the bike loaded and off-road at times, he said he'd stand by the wheels. So far, they are rock solid. 

I am about to build up some 650b tandem wheels, and for those I'll be doing 36 spoke. 

Scott Calhoun

Tucson, AZ

[Guy Washburn]

I'm 6"1" and weigh in around 190-195. I've been using 32 spoke for years and have never had a problem.

[Harald Kliems]

Fun story: When building up my Gunnar Roadie, I bought a used Mavic Cosmos rear wheel. For years I believed it was a 32-spoke wheel, and I figured this was a good thing given that I weigh close to 200lbs and rode 25mm tires. Indeed, the wheel held up really nicely. At some point I actually counted the spokes, only to realize that there were only 28 of them. After that discovery, building a 36-spoke wheel isn't on my radar any more, except for maybe special cases like a cargo bike or a tandem, or if you happen to already have a nice 36h hub.

 Harald.

[satanas]

Given decent quality rim and spokes, well-shaped hub flanges, a competent builder and no intervention from crashes (or airlines), then 32° should be enough for most purposes these days. In fact, many rims now come only in 32°, or else 32° max.

I have a pair of Velomax wheels with what are effectively Velocity Aerohead rims and 18/24 spokes and they've been totally reliable, despite being slightly used when I got them. It's important though that the parts are good quality, and the build.

Later,
Stephen

[Mark Bulgier]

Coming in very late to this thread, apologies for responding to a post from almost two months ago, and only tangentially connected to the title subject at that.  But I am agitated by this quote from DT Swiss passed on by Jeff Bertolet on July 3:

> The forging process allows the metal to be compressed into a denser package

Can anyone decisively confirm or refute this claim?  Sounds wrong to me.  I am not a professional engineer or metallurgist, but I took some Mechanical Engineering courses in college including Strength of Materials, and was in a metal trade (bike framebuilding) for 20 years. 

I don't think a drawn wire can be made denser by forging.  Unless there were voids -- air -- in the steel to begin with, which would be a very poor quality wire indeed.

If I'm right and DT is wrong, doesn't it call into question everything they do, at least a little?  Do you really want to buy spokes from a company that spreads myths and misinformation on the web?  Yes I may be getting ahead of myself in the DT-bashing, since I haven't yet gotten an expert opinion on whether there's any truth to that DT quote.  If I'm wrong, if increasing the density of solid steel by forging is an accepted fact, then I'll apologize.

Also it's possible for a craftsman to make an excellent object without understanding the science behind his craft, happens all the time.  I'm just surprised a company as large as DT doesn't have their Internet pronouncements vetted by an engineer.  So maybe DT says dumb things but then still makes the best spokes? Possible I guess, though I've caught them making engineering mistakes that made weaker wheels too, like their ill-fated move to a longer "neck" on their J-bend spokes, back whenever that was, early-90s maybe?  And when they wrote (I forget where) that stress-relieving means allowing spokes with a residual  twist, from turning the nipples, to untwist.

Reminds me of way back in the 70s when Reynolds said in print that you can't cold-set 753 because it is too stiff, as a result of the heat-treatment.  When in fact 753 was the most flexible (least stiff) tubing they ever made.  And heat-treatment can't change the inherent stiffness of steel (Young's Modulus) one bit.  I imagine some engineer at Reynolds wincing when he read that, and wishing the marketing department wouldn't try to say technical things without help from a grown-up.

Mark Bulgier
Seattle

[Brad]

Spokes are key.
I too have been a skeptic about butted spokes.  I build 36 spokes 14 gauge (2mm) because the weight saved from 4 spokes just isn't worth it.
I think the forging to butt the spoke might change the crystal structure.
A long time ago "The" spoke in North America was made by Torrington (from about 1890-1984).  They would wear out and go pop pop pop pop after about 2 years of hard riding in my experience.  I have not had that happen with the DT or competing stainless spokes. Now granted since I started using a Yankee spiral ratchet screwdriver to tension the wheels I have probably reduced flex in the system and thus fatigue.

[Nick Payne]

Spoke usually break at the J-bend where they exit the hub because of work hardening due to cyclic strain at that point. Using butted/swaged spokes reduces the work hardening because the centre section of the spoke is thinner and more elastic than a plain gauge spoke. If you look at the Sapim web site, they reckon the most durable spoke they manufacture is the CX-Ray, which has a centre section of 0.9x2.2mm.

--

[Jeff Bertolet]

While I can't confirm your analysis of DT Swiss' claim, I think it's moot since spokes never fail in the middle. Who cares if it IS stronger in the middle!

The DT Swiss rep also claims that a blacksmith is removing voids during the shaping process, when in fact they are mostly removing impurities as far as I understand.

My wife has done work trying to translate engineering language into accessible english and it can be surprisingly difficult given the low fluency in science of the general population.

On Monday, August 31, 2015 at 6:43:57 PM UTC-4, Mark Bulgier wrote:

[Alex Wetmore]

A wheel built with 32 Sapim CX-Ray spokes will be about 100 grams lighter than one built with 36 14g DT Swiss spokes.  200 grams for both wheels is a pretty significant savings, and is bigger than the difference between most lightweight vs heavier rims.

The CX-Ray is not a cheap spoke, but using butted spokes gets you increased durability and about 50 grams savings for a pretty minor increase in cost.  Since it is such a minor extra cost in the overall wheel (normally the difference is under $20) I see little reason not to use butted spokes.

alex

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From: 65...@googlegroups.com <65...@googlegroups.com> on behalf of Brad <riendeau...@gmail.com>
Sent: Monday, August 31, 2015 4:06 PM
To: 650b
Subject: Re: [650B] Re: 32 vs. 36 spokes: is anybody concerned about limits for 32 anymore?

 

[Peter Adler]

I'm confused. The Sapim CX-Ray is a bladed/aero spoke, not a round, double-butted one.

I regularly tout this deal, but I don't think I've ever touted it here:

DansComp (in the Indianapolis area) is a mailorder retailer that exclusively serves the BMX market, with one exception: Sapim spokes, which are available in all sizes. I particularly like the price on stainless double-butted Laser 14/15 spokes, at $0.40 each including brass nipples (on the last order I made, they sent Sapim Polyax nipples, which I'd whined for about a year earlier - proof that they listened to me).

Here's the catch: They will not fill a spoke order through the website - you have to call in and talk to one of their very knowledgeable operators. My guess is that enough people ordered the wrong sizes and then flipped out, and DansComp decided: Let's make sure people are ordering spokes they can actually use.

I've ordered spokes/nipples from DansComp five times, and I've gotten excellent service (and pretty fast shipment) every time. No financial interest; just a very satisfied customer.

Peter Adler

an inexperienced wheelbuilder who needs all the help he can get in

Berkeley, CA/USA

[Bill M.]

The link to the CX-Ray spokes tells the story - the center section is 0.9 x 2.2 mm.  That means it's area is about the same as that of a Laser spoke at 1.5 mm round, so functionally it is butted as well as bladed.

Bill

[Fred Blasdel]

On Mon, Sep 7, 2015 at 7:03 AM, Bill M. <bmen...@comcast.net> wrote:

The link to the CX-Ray spokes tells the story - the center section is 0.9 x 2.2 mm.  That means it's area is about the same as that of a Laser spoke at 1.5 mm round, so functionally it is butted as well as bladed.

That makes it much easier to build with than a superthin round spoke, because you can see it wind up and easily hold on to it to prevent that. The extra cold working they do to flatten it from a Laser also makes it stronger!

[Michael Mann]

I second everything Peter said about ordering Sapim spokes through Dan's Comp. Yes you need to phone the order in, but the operator is awesome and in my experience you will get exactly what you ask for, within about 1 week. My last order I was going for a "stealth" look so ordered black spokes with black brass nipples, so they cost a little more than plain stainless - the spokes were $.50/each I think and the nipples - normally included - were $.05/each. But still. Great service and about 1/2 what I would pay anywhere else I can find.

Mike

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Michael Mann

[Ken Freeman]

Overall I don't think I've ever seen a clear guideline, stating that above a certain wheel load you need 36 and below it 32 is ok.  Several people, including in this thread, have opinions, but I've not seen a science-based criterion.  It's certainly not wrong to use more spokes where you have a breakage problem to cure or if you are worried about wheel integrity, but I don't think anyone can say for sure that the benefit is predictable.

Jobst Brandt in "The Bicycle Wheel" looked at the stresses in spokes of different diameter and indicated the strong opinion that there is no danger of breaking a spoke strictly due to load stresses or expected load cycling.  If a spoke has surface imperfections which could lead to stress risers, I could see breakage at lower loading levels.

Still not really a scientific viewpoint, I guess.  I had a CX-ray break at the nipple a few weeks ago, while just riding around on a country road about 16 mph.  No jumping, imperfect road surface, 190# rider, 32 spokes.  The break wasn't even on the drive side, where the tension is much higher!  Neither I nor the builder have a good explanation, except that that specific spoke may have had a flaw.

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Ken Freeman
Ann Arbor, MI USA

[satanas]

On Tuesday, 8 September 2015 04:00:39 UTC+10, Ken Freeman wrote:

  I had a CX-ray break at the nipple a few weeks ago, while just riding around on a country road about 16 mph.  No jumping, imperfect road surface, 190# rider, 32 spokes.  The break wasn't even on the drive side, where the tension is much higher!  Neither I nor the builder have a good explanation, except that that specific spoke may have had a flaw.

Or maybe it was lacking tension, and then flexing at the nipple, and fatiguing? BTW, Sapim sells a tool to hold the CX-Rays and prevent them winding up whilst building, or to straighten them out after. Some people dislike being able to see the spokes twist, but IMHO it's a good thing as it makes things easier to correct. And the CX-Rays should of course be faster, all else being equal. They're regularly used in some wheels with very low spoke counts, so should be strong enough for most purposes.

As to how many spokes are needed, this depends on how strong and stiff the rim is, how big the tyre, rider and luggage weight, riding style, consequences of failure versus light weight/aerodynamic advantage, etc. For road rides near home I'm happy to use 23-25mm tyres and light wheels with 18/24 spokes, but no way I'd take them touring in the Himalayas; 32 holes and dishless Rohloff wheels with 50mm or wider 26" tyres are way better there.

Later,

Stephen

[Ken Freeman]

I don't think it was lacking tension.  I check them ever few weeks, and I think that if a spoke starts making noise as the rim is loaded and unloaded at that point, I hear it.

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