First off you have to draw the line somewhere. You can always keep overbuilding and overbuilding to get ever diminishing returns on increased reliability. So at some point you have to decide how much maintenance/replacement you're willing to do and pick the parameters which meet that criteria. There's no difference between counting UP and counting DOWN. In both cases you're finding the parameters which achieve your criteria so you know how much slack you have to accommodate other factors. For example, you wouldn't use 40 spokes because you know 36 spokes also satisfy your strength criteria in addition to satisfying further goals of parts availability and weight.

Second off, I think your experiment for determining power loss is completely flawed. The human body can only convert between 0% and 25% of it's input energy into mechanical work and while it is, in general, difficult to predict exactly where in this range the efficiency will be, there are a few simple experiments which make certain factors quite clear. For example, while you might have no trouble turning the crank with your bare hand it is interesting to note how well you can turn the crank while also holding a 25 pound weight, or a 50 pound weight, or a 100 pound weight in your hand. In each case the power required to turn the wheel as a percentage of the power at the pedals is increased even to the point of exceeding 100% (ie when you can't turn the crank while holding a 100 pound weight). Moreover, one can note that the mechanical power required to move the dumb bell around the circle is actually zero; So the power efficiency of the human muscle is highly nonlinear with respect to the force it must operate at, regardless of whether that force is actually providing energy to the outside world, and the marginal increase in power expended by the body in order to turn a heavier wheel while simultaneously riding the bike is much larger than the power required to turn the wheel alone.

Since it's tax time perhaps it might be helpful to note that this is like the progressive income tax system in the US where, for example, someone making and spending $100k per year has to make a lot more extra money in order to save $1000 than someone making and spending $10k per year.

Sheldon said
"how many spokes?.... How many can I get?"
32 minimum

I'll 2nd that. I have Bontrager select race X lite and about to get some 32 or 36 laced wheels. I have had the rear trued 4 times now. Great wheel if you are not hauling too much stuff on the rear.

36 Front and rear. 3 cross. 145# rider 40# bike. Wheels have never been trued in >30,000 miles. *shrugs*

Are the wheels straight? No, probably not. With a roller drum rear brake and a nearly dishless IGH, I don't really care either. The front? That's a rim job. It matters a little I guess, but as long as the brake doesn't drag I don't really care.

Tension? I just checked the wheels in a few place. I thought I found a loose spoke, but it was just a fender stay.
It certainly isn't a TIGHT wheel, but I'm not getting any spoke punctured tubes either.

Heavier? yes. Does that really matter? I'm sure my insulated coffee cup slows me down more than the 8 extra spokes.

haha, well said!

I build and work on a lot of wheels and rarely build any wheel with less than 32 spokes and often build with as many as 40... just finished a wheel for a customer and it is a 36 / 4 cross wheel built with a SA AW hub and 27 inch rim for a vintage build. The front wheel on the bike is also 36 spokes / 3 cross and it will be used for daily commuting so strong wheels were the order of the day.

If I did my job right these wheels will not need to see a spoke wrench until the rims wear out... and I do my job right.

I run a 32 spoke rear wheel on my commutourer, have a 32 spoke rear wheel on my extrabike that carries excess amounts if cargo and have a 32 spoke rear wheel on my fixed road bike that only carries my 142 pound self... these have never needed any touch ups and they all see some decent mileage and abuse.

You can't go wrong with a 36/3 wheel, especially in the rear... I build plenty of touring wheels with this configuration and also build a lot of 36/3 and 36/4 fixed wheels for utilitarian riding and commuting purposes.

My vintage racing bike uses 36/3 lacings on 27 inch double walled and eyeletted rims... these are very strong and very light wheels.

You can build a strong low spoke wheel but to do this you need a heavier and stiffer rim which cancels out any weight savings you got by reducing your spoke count... these fewer spokes will be under more tension and if one spoke fails the wheel will fail whereas with a 36 spoke wheel you can often limp home if you break a spoke.

I have seen old Raleigh 3 speeds come into the shop with numerlous broken spokes in the rear and not had the rear wheel go out of true to any significant degree... many of these are 40 / 4 cross wheels.

I've been reading touring journals up on CrazyGuy, and a couple of days ago I read about some poor sod who had taken the advice of the "experts" at the obviously racing oriented, know squat about touring but had to pretend to be experts at everything LBS guys, and went on a cross country tour with a bike with I think 24 spoke wheels. She was apparently breaking spokes every day or two and was about to give up on the tour. What kind of moron recommends anything less than 36 spoke wheels for fully loaded touring?

Same 24 spoke wheels as tsl. Same weight. Same issues. 5 trues of the rear wheel since June 2009

32 spoke cross laced wheel is in the mail. It can't come soon enough.

Wow this thread is timely for me. I weigh 190 and I ride with panniers loaded with clothes and a lap top, so it's pretty heavy. I have a Bianchi Volpe touring bike with 28 cc tires and heavy rims (heavy compared to my road bike).

After the 2nd broken spoke in two months, my bike mechanic told me I needed heavier spokes, so he put them on for me. One week later the wheel was out of true and a couple of spokes were very loose, but none broke. He trued it for me again, and said he tightened all of the spokes down real tight. It's been two weeks and so far so good. But I'm not confident this will last...

My bike mechanic seemed very surprised at how quickly i keep destroying this back wheel. But I don't hit curbs or do anything crazy. I'm on paved roads for the whole 18 mile commute. I just ride hard, fast, and fully loaded. I feel as though all I have to do is hit a "normal" bump at 20 MPH with 200+ LBS on my bike and it blows up the wheel. There is one 15 MPH speed hump I was hitting at 17 - 20 MPH, so I'm making sure to take that at 15 or less now.

I realized my racing bike has far fewer spokes than my touring bike, but I had no idea you could go even hire - I would assume my touring bike is 32 if that is the more common configuration. Now I want to go count my spokes. All I know is, I need a rear wheel that can take the punishment I mete out. I get the feeling my LBS is not used to dealing with riders like me. I'm not sure he understands what kind of equipment I need.

Five. Arrospok FTW!


Seriously, though... I weigh 230, ride a 28 pound bike, and load it with 10 more pounds of crap for 300 and 400k rides which include some of the gnarliest potholed and chip-sealed roads, or sometimes just dirt/gravel paths.
I don't build with anything other than 32 spokes. It's enough to get the job done without going overboard. I use strong profile rims (DT RR465 *used to be the RR1.1*, and my new wheels will be Sun CR-18 rims) and DT Champion 2.0 spokes.
If you want some extra protection, a wider tire (32 - 35mm if you can clear one) is just as effective as the extra 4 spokes.

I wonder if that wheel wasn't trued up right to begin with.

Sounds like it wasn't tensioned right to begin with.

I always assumed 36 spokes was pretty standard, but it sounds like 32 is more common. I know when I was buying components for my new rear a while back, it was a lot easier to find 32 spoke hubs than 36, but I eventually found what I wanted.

You know, it's odd. I weigh two *mumble* and have never broken a spoke on the Walmart Schwinn I've used as a daily commuter for the last 2 years.

Rear axels on the other hand ...

No longer a problem there though, I upgraded to some Rhynolites and Deore hubs with my tax return.

As I understand it, then engineer Jobst Brandt and others made some Finite Element computer calculations on different wheel configurations. The bottom line was (AFAIK) that 36H 3X spokes was the optimum sweet spot for 700c wheels regarding "strength" etc. 40H and or 4X designs could carry somewhat larger loads, but had other drawbacks when it came to spoke angles etc. 32H 3X wheels are apparently measurably "weaker" than 36H 3X designs while only having a tiny weight advantage (4 spokes and nipples are very few grams per wheel). The aerodynamic difference is so small I even doubt it can be measured in a wind tunnel. Spoke count plays a little role when it comes to aerodynamics, while rim depth and design are important.
So all in all, for general all round riding, 36H 3X wheels is the optimum design.

If you want faster, more aerodynamic wheels, then deep rims and aerospokes are a must if there should be a measurable difference. 32H or even 28H spokes in them self hardly makes a difference, while making weaker wheels so why bother.

--
Regards

I'll start by saying I'm not an expert about bikes or physics. However, doesn't the weight of the spokes (or any part of the wheel) factor in differently than the weight of anything that's not subject to centrifugal force? In other words, it's harder to spin 36 spokes than to carry 36 spokes in your backpack. I'm still not sure that this difference is significant when it comes to commuting, but every little bit helps, right?

Additionally, I don't think it's really relevant if they weigh less than your lunch or your clothes. Either way you need, lunch, clothes, AND spokes, but if you can get by with less weight somewhere, why not?

FWIW, I ride a Trek Portland with the stock 24 spoke wheels. I haven't had a problem (yet), but I also only weigh about 135 lbs and carry only a small trunk bag with clothes and lunch. It's been less than a year of commuting, so we'll see how it holds up in the long term.

Spinning or not, extra weight can only make any difference during acceleration. If you maintain a constant speed, no amount of weight will make any difference.

It matters a lot how good the wheels are too. My bike came with 36 spoke wheels and the rear was popping a spoke about once every week or two when new. I rebuilt with the same hub but with better spokes and a good rim, and it never even went out of true again, over the course of 4 years and about 15,000 miles (eventually the axle broke).

All of my spoke breaks were at the elbow, so I suspect the spokes were under-tensioned at the factory. Also the rim was crap, a single-walled very thin job. I replaced it with a Mavic MA-3. When I rebuilt the front for discs, I used an Alex Adventurer. When I built a new wheel on the back due to the axle breaking, I used a Salsa Delgado Cross rim. These have all been very durable.

Spinning IS accelerating. Acceleration is any change in speed or direction. So more spokes would make a difference. Still, I don't have the experience or math skills to say whether that difference is significant, just that it exists.

Fair-weather front wheel on my SWB commuter 'bent has 20 paired spokes and has stayed true since new around 1500 miles ago. Keep in mind, tho, that it's a 20"/406 wheel which is inherently stronger than larger wheels.

I will try to keep this simple. For more depth find a physics text at a level suited to your current level of preparation.
Yes, the parts of an object spinning at constant speed are accelerating, but only toward the center. There is no energy being imparted in this acceleration.
If you are pedalling your bike at constant speed, you are not using any energy to accelerate anything significant beyond your own body parts.
Any mass added to your bike is additional mass that requires additional energy to accelerate in speed when you are in fact accelerating.
Rotating mass in the wheels and drivetrain is special when it comes to acceleration. Mass at the very center of rotation counts the same as mass that isn't rotating. Focussing now on the wheels, which are the easiest and most important to analyze, mass at the outer edge (i.e. the tire tread) counts 4x as much as the same mass that isn't rotating. Mass located between these extremes counts in-between, duh, 1X and 4X in accordance with its radial distance from the center. This weighting factor counts for acceleration only, not steady speed.
One final point, incremental mass such as spokes, etc., as rightly said above, does not really matter for steady speeds on the flat. It certainly does matter for climbing hills, as we all know. And, to be sure, all incremental mass adds to tire deflection, so in theory increases rolling resistance, but you'd be hard pressed to measure the difference due to a few spokes & nipples, given that the rim mass were held constant.

Spinning is a stable state, you don't have to put energy into a wheel to make it keep spinning (except for air resistance, which is not what we're talking about here). In a vacuum, you can spin a wheel and come back 100 years later and it'll still be spinning.

Yes, something that's spinning is always accelerating, but it uses its own kinetic energy to do so.

I wonder about the physics model here. Yes, if you analyze a wheel on its own, spinning up or down in isolation, the outer edge is 4x mass. However, in the real world, the bottom of the wheel is never moving (it's stuck to the road) so you don't have to accelerate it at all; it's 0X mass. At the top, it's moving twice the speed of the bike. Maybe those cancel out? Or maybe there's a more complex relationship.

That's right, E, however in analysis, we would consider the linear acceleration first, with the total wheel mass assumed to be concentrated at the axle; then analyze the rotating acceleration separately, looking strictly at rotation, with the given radial mass distribution.

I'm 230 lbs, bike is 25 lbs, have carried as much as 40 lbs - 20 spokes front, 24 spokes rear. My Mavic Aksiums are indestructible and cheap. I was really worried about them at first but now I have supreme confidence in them. I have an 07 set with 38 mm cyclocross tires that I use for singletrack assaults (I have a full suspension mountain bike for really grarly stuff but the cross bike is super fun for XC trails). I try to avoid the roots and rocks but I've pegged a few really hard. I have another pair of 08s setup with 28 mm road tires I bunnyhop speed bumps, jump off curbs, and a few times have ridden down small sets of stairs. Have hit a few potholes at high speeds where the wheel and fork made some awful noises but it just keeps going.

If you're using good rims, hubs, and spokes I simply can't see why a normalish person you would ever need 36 spoke wheels for a road/commuter bike (tandems obviously excluded). My fixed gear has 32 sp wheels and I ride that bike hard as well (on 23 mm tires). 32 with decent modern components makes an extremely strong wheel.

Maybe 32 spoke would be fine. But what does it cost me to go 36 spoke? Nothing, as far as I'm concerned. I'd be amazed if the power requirement differences were even easily measurable, let alone noticeable. It's utterly inconsequential to me how many spokes a wheel has one way or the other for any reason, so I go with what's less likely to cause me trouble.

I ride 36h only. Destroyed far too much 32h's in the past. Oh, it may be an factor that I weigh 260 to 270, depending on the season