etherhuffer 

I just purchased a bike that has 3X on the drive side and radial on the left side. It's a Velocity rim with offset drilling. The owner has had no problems with it. I am unfamiliar with this pattern. Is there a reason for such a pattern?

mpetry912 

like many things in the bike world it is as much a matter of fashion as anything else.

some may try to make a case that "it's lighter" or "more aero" but that's mostly balloon juice

I run 3x drive side 2x off side on most of my rear wheels but again I could not give you solid evidence that such a pattern is better

I personally do not care for radial spoking in any case

/markp

etherhuffer 

agreed I may relace this one

KCT1986

Sheldon Brown's article on wheelbuilding touches on half radial lacing.

With a rim with asymmetrical drilling the benefit may not be as great.

Probably not worth the trouble of getting new spokes and rebuilding just to change this. As with all builds, wheel expected use and other factors should be considered.

FBinNY 

WHY?

As noted before, many of the arguments for atypical builds are nonsense, but that's equally true for those against.

If the wheel is OK now, I can't see a reason to take it apart.

In fact, many in my generation consider it bad Karma to intentionally destroy a wheel.

I suggest you continue to enjoy this wheel as is, despite any doubts. Worst case, it'll last forever just to spite you.

mpetry912 

Spence would agree with you !

@OP - at least ride it for a while. if it stays true you can always re-lace it some cold winter day.

/markp

HillRider

Speaking of odd lacing patterns, I have a Shimano factory rear wheel with 10 straight pull, bladed spokes laced radial on the drive side and 10 similar spokes laced 2X on the non-drive side. This is exactly the opposite of the normally recommended pattern but apparently the hub is stiff enough to transmit the drive torque to the 2X side. The wheel has almost 50,000 miles on it so the strange lacing doesn't seem to have done any harm.

Trakhak

About 30 years ago in the bike shop I managed at the time, one of our younger mechanics decided to learn to build himself a set of wheels. He used a spoke length calculator but left out some crucial step in the calculations, as a result of which the spokes he chose turned out to be too short for any pattern other than radial.

But he went ahead and built the wheels anyway - radial front, radial drive side and non-drive side rear. Rode them, too. Several months later, I mentioned the radial-all-around wheel-building project to a local guy who'd learned to build wheels a couple of years earlier and fancied himself an authority.

He said, "That won't work."

I said, "He built them, and they turned out fine."

He said, "They'll collapse as soon as he climbs the first hill."

I said, "He's ridden at least 1,000 miles on them at this point."

He turned sullen and changed the subject.

Edit:

I wasn't surprised. I'm no engineer, but it seems to me that the difference between 1-cross or 2-cross and radial for transmitting pedaling force is probably structurally insignificant - the equivalent of the likely insignificant difference between hardly-there tire tread patterns and smooth tires for high-pressure road tires.

urbanknight

I believe the thought was generally to save weight, and also that having all the NDS spokes "elbows in" made the wheel slightly more aero. Tiny advantages, but also tiny disadvantages. My only reason for disliking different patterns on opposing sides is it just looks weird to me.

Trakhak I saw all radial lacing on a lowrider once. Now it had something like 60 spokes on each wheel, but it made me wonder. I was taught to build wheels by someone who swore by "36 spokes 4 cross tied and soldered", and he was so mad at me when I showed up to the track with a front wheel radial laced. I weighed 120lb at the time and probably could have put only half the spokes on that wheel without issue. The funny thing is, here we are today with people insisting on crossing spokes on the side of the brake rotor, and it makes me wonder.

Trakhak

In fairness to your wheel mentor, he (like myself, having built my first replacement wheel for my track bike in 1965, at age 14) came up in an era when both spokes and rims for racing wheels were far below the strength we now take for granted - and also before any of us knew enough to worry about proper spoke tension, much less had any tools to measure it.

That rule of the use of 4-cross, 36 tied-and-soldered spokes ensured great wheel durability, in a time when such durability could not be taken for granted.

The tie-and-solder technique, by the way, was a holdover from way back in the penny-farthing era, before safety bikes were introduced. The long spokes used in those gigantic front wheels were composed of low-grade steel and were prone to breaking after not too many miles of use. Breaking, they would flap around dangerously, sometimes causing the rider to do a "header," as it came to be known. Tying and soldering kept the broken spokes away from the fork blades and the rider's legs.

In fact, I've sometimes wondered whether the use of crossed spokes was introduced for no other reason than to allow tying and soldering at the crosses. The earliest high-wheeler bikes appear to have used radial spoking for both wheels. (Photo is from this page.)

etherhuffer 

Yes, that is the plan. It's not dead or out of true so I am going to leave it. It's just hard on my brain to think of torque at a 90 degree angle to a spoke. It's like finding your dream bike but in puke green or lavender paint. You brain says it will ride just the same while your heart says walk away. I am a creature of habit and when something is different, my brain revolts!

rogerm3d

On (modern rim brake road bike especially) wheels the offset between the left and right side leads a large difference in spoke tension between the two sides (NDS spoke tension is ~40-55% of DS tension). By building radial non-drive side and 3 cross drive side you are able to increase NDS spoke tension a bit. Hubs with different flange diameters, offset rims, flange offsets, etc can all help alleviate this issue also.
The following will allow to roughly see what a wheel builds spoke tension will be:
spoke tension calculator

kommisar

This is why you would go radial on the non-drive side. If you lace them outside in it has a minor reduction on the bracing angle of the nds spokes. It is an attempt to increase the tension of the nds spokes because nds spoke tension is the main factor in determining the the durability of the wheel. The difference is small though, less than 5% IMO.

urbanknight

Absolutely agreed, I knew where he was coming from. I was also a tech and weight weenie who was always after the best equipment I could make/afford, even though I was far from winning championships either way.

Bike Gremlin

Years ago I did en experiment, measuring the drive torque transfer to the NDS spokes on a modern hub. They seem to be quite rigid and transfer a decent percentage of torque - which probably was not the case with old hubs when Jobst Brandt was taking the measurements for The Bicycle Wheel book.

Also, modern double walled rims are often quite stiff (transferring vertical loads to more spokes), and modern spokes are very strong and durable. I've seen a fully radially laced front wheel on a disc brake gravel bike of a heavy and strong rider. No cracks, no breakage.

Having said that, radial lacing puts a huge amount of stress on the hub's flanges (and on the spokes when transferring torque, for that matter), without any really measurable benefits. Now, as the rear NDS spokes have lower tension, I suppose going radial there is less detrimental.

With all that in mind, for the OP: if it were my wheel, I'd sleep better relacing it to a crossed pattern, but for most normal people with such a wheel, I'd say - "if it's working, no need to fix it."

Relja The-Retrogrouch Novović

FBinNY 

The torque consideration for the left flange depends on the hub.

Classic road hubs less than 3/4" dia between the flanges don't do a decent job transmitting torque to the aptly named NON-DRIVE side. So, the left side pattern barely matters.

There are some benefits to justify atypical builds, but the builder has to have specifics objectives, and carry through in specific ways to achieve them.

For example, Hillrider's counter-intuitive Shimano wheel makes sense, if you understand the logic. By going radial on the right, the bracing angle is improved, and gets closer to that of the left, thereby reducing the R/L tension difference. Of course, there's added stress on the hub, which has to carry torque to the far side, but that's easy to design for.

When builders ask me about alternate builds, I always ask "Why? What are you trying to achieve?". Sadly most cannot connect the dots between design and justification.

As I said earlier, while your radial left wheel doesn't make much sense, that doesn't mean it's no good. Use it as long as it lasts, and if anyone says boo, tell them that it was an emergency and you couldn't find the right length spokes.

SoSmellyAir

In the Mavic Ksyrium Elite wheelset I have ridden for 4.5 years (before upgrading to CF wheels), the rear wheel is laced exactly as you described above: 20 SP spokes total, laced radial on the drive side and 2X on the non-drive side.

Prior to upgrading to those Mavic Ksyrium Elite wheels, the bike came stock with Mavic Aksium wheels, and the rear wheel (which likewise has 20 SP spokes) was laced 2X on the drive side and radial on the non-drive side.

mpetry912 

I have the WheelFanatyk instrumentation for measuring spoke tension and building the "radar plot" (see below) and have not really observed any difference in spoke tension or differential that can be attributed to lacing pattern.

in fact, inflating the tire has a bigger effect on spoke tension ! on clincher wheels at least.

/markp

grumpus

I'd not seen that before, I look forward to playing with it when I have some measurements to hand.

ericoseveins

I like to reuse spokes, so sometimes I choose alternative lacing to be able to make use of spokes that are slightly too short. And sometimes it's just a way to keep your mind engaged with a task that is time-consuming yet mostly repetitive.

FBinNY 

Yes, contrary to popular belief, radial spoke patterns can transmit torque. Anyone with a sense of bike history would know this. The reason for tangent spokes is that they do a better job of transmitting torque with lower stress on the hub.

In order to transmit torque, the hub has to wind up slightly to move the spokes off radial and create a moment. So that moment is tiny, it implies a greater tension spike vs. that of tangent spokes. The spokes have no problem, but it's harder on both hubs and rims. So what was fine BITD, is less OK for modern bikes with light rims and hubs not engineered for those stresses.

Another argument favoring crossed spokes is the interlace at the cross. By creating a bend in the spokes, it creates a bit of resilience in the wheel since it allows attenuation of tension spikes as the tightened spoke can straighten slightly, transferring to it's partner which gets bent a bit more.

The combination of the above considerations is why some makers of light race hubs will not warranty flanges if the wheel is built radial.

Trakhak

The topic of radial spokes being hard on hubs reminds me of a seminar for personnel from local bike shops conducted in the early '80's by a guy from Campagnolo's U.S. headquarters. He spent a surprising amount of time explaining why Campagnolo would disapprove various categories of warranty claims, this having been back when Campagnolo warrantied all their products for life.

When he came to talk about their hubs, the first two things he mentioned were these:

One, they would not cover under warranty flange failures of hubs that showed (by the markings at the spoke holes) that they had been built first with one pattern and then another. As I recall (possibly inaccurately), he said that spoke tension work-hardens the flange material such that it becomes brittle and is prone to breaking if the direction of the forces exerted by the spokes changes.

Two, they would not cover hub failures that showed the tell-tale sign that they had been built with the spokes on one side offset one hole from where they should have been. "Campagnolo can do amazing things with metal fabrication," he said, "but even we can't drill an oval hole."

oldschoolbike

With loose reference to the Brandt book, there would be only one real issue with such a wheel: Radial spoke tensions would work together to pull outward on the hub flange, while crossed spoke tensions largely oppose each other, with a resulting lower outward force. This is a problem for a 36-hole low flange hub (think classic Record low-flange) with very little metal between adjacent spoke holes. You could break a chunk of flange off along the spoke holes, like separating stamps. The consequences could be ugly.

That said, modern hubs are not as low-flange and have fewer spoke holes. Both trends result in more metal between the holes. It also helps immensely that it is the NDS, with much lower tension anyway. So unless it is a low flange 36-hole hub, make sure it is solidly and uniformly tensioned and just ride it. Your wheel is in some pretty well-respected company as far as that configuration goes. Unless you find it ugly or otherwise irksome, in which case go ahead and rebuild it. You will only need half a wheel worth of spokes.

oldschoolbike

etherhuffer 

Cool! I have learned a ton from this post!

Dan Burkhart 

And yet, some high profile wheel manufacturers defy logic by doing exactly that. The only time I will build like that is if I am supplied with a straight pull hub which does not give you the choice of lacing pattern or spoke orientation.
I have seen several Zipp straight pull hubs with drive side radial with broken flanges, including this one that exploded right in my truing stand.