Pros and cons of spoke count
 

How much do spokes weigh?

It would seem to me that all the weight savings is to be had in the rims and the hubs....How much lighter is a 16 spoke wheel going to be compared to a 32 spoke wheel?

I think it would probably be wiser to look for weight savings elsewhere other than the wheels. THese days with carbon fiber frames we should n't have to resort to reidculously low spoke counts to make the 15 pound weight limit.

It's not just weight. Wheels with fewer spokes have lower drag. I'll see if I can dig out the wind tunnel data.

Wonder if aero spokes do anything? Since we are also on topic of drag.

They do, indeed! Now if I can just find that damn data......

After that guy posted his 15.4lb steel LeMond earlier (or was it yesterday), I
was sceptical, so I went to Weenies Weenies. Well, his storey matches, and
I noticed that the titanium spokes are quite light. ;)

So, if you want a light wheel, perhaps ti spokes could be the go.

well i just read the Art of Wheelbuilding by Gerd Schraner, he brings up lots of interesting points. One that generally speaking, lower spoke count means heavier rim. Says also that fewer spokes only improve aerodynamics from speeds of 30mph and upwards so i dont think its really worth it and ti spokes are pretty expensive.

Wheelsmith/Dt's are around 5.1 grams for 264's while bladed Sapim Xrays are 4.3 grams, and Ti Dt's are 4.1 per spoke.

So if you you knock out 16 spokes per wheel you could save up to 80 grams, .35 pounds for the set. Not inconsequential considering it's rotating mass.

Bladed spokes make a difference, especially at higher speeds. How much? Let me go find the data :)

The thing with building something light is that you can look at it two ways: Most bang for the buck if you're on a budget, or:

Every little bit counts.

You'd be surprised at how much a gram here and there can add up to once you're done.

Well, I think that you're on the right track - sort of. There's at least a couple of different ways that I can think about it.

First, it doesn't matter how much the rim or spokes or hub weighs. What matters is what the completed bicycle wheel assembly weighs. As a general rule, I think that you'll find that the minimum spoke count wheels tend to weigh a bit more than a lightweight 32 spoke wheel assembly. The reason is that they have to use a deeper, stronger, heavier rim to maintain a reasonable degree of durability.

Second, what are you trying to accomplish? Do you want a lightweight bike just so that you can brag about how little it weighs or do you want to ride faster? Sometimes those can be two different things. The guys who research those things say that, for a flat time trial, a wheelset with at least 30mm deep rims and the minimum number of spokes, even though heavier, will definitely be faster than a conventional wheel.

Thread title: "Pros and Cons of Spoke Count"

Given the choice of a professional counting my spokes vs. a convict counting them, I'll choose the professional, thank you. :)

I must disagree with you on that one. Rotating weight is a far greater factor than simply the static weight of the entire bike. I understand that removing only 1 gram from a wheel is the equivalent of removing 2 grams from the frame. You want light wheels.

Obviously, lower spoke count means lower spoke weight, but this doesn't mean lighter wheels. Paired spokes (such as my Shimano 7701s) require very strong rims because of the span between spokes. This usually mean deep rims. Not sure if this has anything to do with deep rims being a pain in the !@)(*& when installing a new tire (mine sure are).

I think rotational weight makes a bigger difference than just "weight". E.g., the 7701 spokes are threaded at the hub, not the rim. Supposedly this reduces weight at the rim. Of course, then again, you need a sturdier, heavier rim cause the thing's only got 16 spokes. It is interesting to note that with the radial-cross laced technique used on rear wheels, the 7701s have the radial on the drive side since the spokes are attached to the opposite side. Thus, the cross-lacing appears on the non-drive side.

There's an interesting article at CyclingNews.com
http://www.cyclingnews.com/tech.php?...ura-ace_wheels
that describes how the new DA wheelset deviates from the previous design and goes with non-paired spokes and a lower rim profile. Those wheels are quite a bit lighter than my 7701s.

Best.

Losing weight in the the spokes, while gaining weight in the rim is a bad idea. Since the moment of inertia (difficulty of accelerating the wheel) varies with the square of the distance from the skewer, the weight of the rim is much more noticeable than the weight of anything closer towards the hub. Granted, this depends to a degree on how much weight you lose with less/lighter spokes, and how much heavier a stronger rim will be, but I'm just speaking generally. Let me know if this comes through as english or not...

Disclaimer: I don't actually know anything about bikes.

It seems after this discussion we have two different sorts of wheels....

1. Aero wheels: Usually heavier overall (because of heavier deep V rim), but more aero....less drag is accomplished by reducing number of spokes. Useful for maintaing high top speeds, but possibly poorer acceleration due to increased rotating mass because of heavier rim.

2. Climbing wheels. Usually lower weight overall despite increased spoke count. Better acceleration accomplished by reducing weight of rim. Weaker rim design is offset by increasing spoke count at the cost of more drag at high speed.

So it seems to me the optimal wheel is chosen by what speed range you plan to ride in. Obviously a set of climbing wheels doesn't have to be aerodynamic just light to accelerate up hills.

Thank you for all the posts.

With a conventional spoked wheel this is correct because alternating spokes pull in opposite directions. Lowering the spoke count means the spokes are farther apart, which causes the rim to bend one way and then the other at each spoke. To prevent this you must make the rim stronger and heavier.

Not true with paired spokes. Two spokes join the rim at the same place and cancel the bending force. That means you can lower the spoke count without having to make the rim stronger and heavier. Go to www.uspto.gov and look at one of Rolf's patents, say 5,445,439. In the background of the invention you can read how he measured forces and deflections as a function of spoke number and spacing. Good stuff!

Tom

I think I'll make up a set of Aero wheels too. Using Velocity Deep V rims I wonder how low of a spoke count can I go and still have to strength of say a 32 spoke Velocity Aerohead Rim?

Would a 24 spoke wheel using Deep V rims be equla to a 32 spoke conventional wheel.

At what spoke count does an Aero wheel begin seeing measurable benefits.....How many spokes will I have to eliminate to feel it on the road?

You missed the point. The point is that you don't ride on spokes or a rim, you ride on a whole wheel. You can save a little weight in one place and pay it back in another but the whole assembly is what counts.

Depending on what you are doing, it might be better to have a somewhat heavier wheel that's more aero. Certainly for criteriums, where you are constantly accelerating and brakeing, light wheels are good. On a flat time trial, however, a slightly heavier wheel that's aero will contribute a flywheel effect and help you to maintain once you get up to speed.

No, I didn't! I fully missed what you were saying! How dare you say I missed only one point when I'm entirely off the mark! :)

As with most things relating to bikes, the "lighter" usually means more expensive and less durable. I understand why "Pro" riders chose the lightest wheels they can find. A spare wheel is riding behind them on the team car.

For people that do not race, getting from A to B non-stop is usually of more value that getting half-way, but at record speed. Most of my road bikes have traditional wheels, with 36 spokes on the rear wheel, and one has 40 spokes on the rear wheel. Although I weigh about 50% more than most bike riders (they are too light - my weight is correct) I have broken one spoke in my life. I do pass a lot of folks who are at the side of the rode, trying to figure out what is wrong with their ultra-light wheels. They aren't fast when they are being repaired.

Some of the new designs seem to make spoke count less relevant. I wish there was a "Consumer Reports" mentality at some bike magazine to test some of the newer designs. Some of them seem to be very strong, and some less so. It would be helpful to see some objective data on wheel strength and durability.

Dont think rotating weight means as much once your going. Acceleration from a start,yes but after that, not that important

a couple of addtional points regarding spoke aerodynamics:

1) the spoke drag force is complicated by the fact that it's speed a top of wheel is 2x the bike speed and 0 at the bottom. With drag force being a square of the velocity the integrated wheel force from the spokes can be high. I know some of the earlier wind tunnel testing did not account for this.

2) with bladed spokes one has to be very careful to line them up in the plane of the wheel. Even a small angle (a few degrees) out of the plane will more than negate the aero advantage and in extreme cases be much worse than round spokes. A cross wind can also be problematic.

Rotating weight is really great, as long as you are riding at a steady rate on a flat road, or downhill. But the heavier the rotating mass is, the more energy is expended to increase speed, regardless of how fast you are going. In most real world applications you're not riding along at exactly the same speed.

And when the world tilts up, you start paying to maintain that speed.

Think about the big rig you were following at 75 MPH until you hit the first hill...

Best we have is Road Bike Review and forums like these, which provide a helpful sampling.

not that i have much moer to say about rotational mass and such but how about the (i just got) passed by a mack truck and my wide (aero) spokes caught his wind and blew my bike clear over...but damn they are light!!

I would disagree.
Think of a figure skater spinning ... when she pulls her arms in, she will spin faster.
I have tried Mavic Open Pros on my bike. As opposed to my Shimano 7701s, the OPs do not accelerate nor climb as well. Cruising up to 20 mph, I notice NO difference between the OPs and the 7701s. From 22-26 mph, there is a noticeable difference - the 7701s are hands down better.

I would hope so; they're much more expensive, are stiffer, and have more mass centered at the hub than the rim.
Best.

The algebraic inverse of this would mean cheap and heavy= durable. Think about the real value of a K Mart road bike that falls apart after a few weeks and weighs 40 pounds.

If I'm buying a washing machine I don't care how much it weighs. I just want clean clothes and for it to keep running.

For myself, and folks who are looking at spoke count as a matter of performance, we're not buying washing machines. We're buying Ferrari's and Porsches which some folks just don't understand, when all you need to get around is a pickup truck.