Wheel: Spoking & Lacing?

meagain

About to replace rusty spokes on a pair of 27" wheels with stainless. On all the other wheels on which I've worked (not a huge number I admit) 3-cross spoking pattern has been inter-laced i.e. under/under/over or over/over/under. These are NOT so laced - just e.g. under/under/under. I'm assuming that to lace them is stronger - and yet the current pattern seems to have lasted well for a long time! The wheels are true enough considering age etc.
Any REAL advantage (for a very light rider) in going to the trouble of changing the pattern?
Thanks.

John.T

It probably does not make a lot of difference but it may stop them from chattering together.

robbarker

Conventional wisdom appears to suggest over-over-under, which is what I always use. It means you're not bending any spoke too much and it looks right, which, as usual in engineering, means it probably is right!

John.T

That makes the other spokes under-under-over then?. :roll:

andrewgturnbull

meagain wrote:

About to replace rusty spokes on a pair of 27" wheels with stainless. On all the other wheels on which I've worked (not a huge number I admit) 3-cross spoking pattern has been inter-laced i.e. under/under/over or over/over/under. These are NOT so laced - just e.g. under/under/under. I'm assuming that to lace them is stronger - and yet the current pattern seems to have lasted well for a long time! The wheels are true enough considering age etc.
Any REAL advantage (for a very light rider) in going to the trouble of changing the pattern?
Thanks.

Hi there.

Yes, i think it does make a significant difference to the lateral stiffness of a wheel. I've only ever used stainless steel spokes, but perhaps the older style ones weren't crossed because they are less flexible and more difficult to manipulate into position?

Cheers, Andy

meagain

"perhaps the older style ones weren't crossed because they are less flexible and more difficult to manipulate into position? "

That makes sense!

Thanks all. Laziness of course prompts me simply to follow existing pattern...I'll have to think about it....

Steve928

Our tandem wheels are laced under-under-under. They're the first that I've come across like that.

In this case it may be because the 2.3mm spokes are less flexible and less suited to bending around the other spoke to go under-under-over as usual..? Just guessing.

geoff_ss

I think non-laced wheels were machine built. Convention usually claims that laced wheels are stiffer and therefore better. All the wheels I've built are laced and I've built a few over the years; they seem to be sound and stay true.

It's not really any more difficult to do when you're building by hand. You just take the spoke behind the last cross before it reaches the rim.

btw I assume you're going to replace the rims with 700c whilst you're at it? 27" tyres must be geting difficult to source these days.

Geoff

Smokin Joe

Laced spoking does not make for a stiffer wheel. Spokes work in tension only, you could spoke a wheel with string and it would be just as true and stiff as a wheel built with stainless steel spokes - at least for the few minutes before the string started to break.

meagain

"btw I assume you're going to replace the rims with 700c whilst you're at it? 27" tyres must be geting difficult to source these days."

Nope! 3 out of the 4 bikes I've got (all acquired in last 6 weeks) have 27s - and I THOUGHT that the 4th would take that size also! I find frames built for 27s look gappy with 700s. And need longer drop brakes....all a chore. All wearing Conti Ultra Sports in 27x1 1/4 - from an ebay trader at less than 1/3 the price of a well known Somerset shop.

Complete bikes with 27s tend to come cheap: my 4 in total cost less than 400 quid. And I've decided to stop spending on bikes - at least 35 have come and gone in past 6 years, lost £'000s.

I think I shall cross the spokes!

meagain

Smokin Joe wrote:

Laced spoking does not make for a stiffer wheel. Spokes work in tension only, you could spoke a wheel with string and it would be just as true and stiff as a wheel built with stainless steel spokes - at least for the few minutes before the string started to break.

Does that mean I should or I shouldn't, Joe? I shan't try string either way...

geoff_ss

Smokin Joe wrote:

Laced spoking does not make for a stiffer wheel. Spokes work in tension only, you could spoke a wheel with string and it would be just as true and stiff as a wheel built with stainless steel spokes - at least for the few minutes before the string started to break.

So a cartwheel with wooden spokes only works in tension? Actually that wonderful invention the wire wheel works in both tension and compression; it's just that the compression in the bottom spokes is only apparent as a reduction in its tension. So the spokes are experiencing changing tension as the wheel rotates and the load experienced by each spoke changes. Whether lacing alleviates this is open to question but it certainly does no harm.

String would work as well, provided its tensile strength was adequate. Kevlar spokes might work but in my experience kevlar does stretch quite a lot. Kevlar fan casings distort alarmingly when a gas turbine fan blade is deliberately detached experimentally (but contain the debris) and kevlar spinnaker control cordage (sheets/guys) stretch on dinghies in a gust.

Geoff

meagain

"I think non-laced wheels were machine built."

Does seem to be the case.

M'cycle spokes are semingly never interlaced - I assume that this is because of gauge/strength and thus not really relevant?

"Convention usually claims that laced wheels are stiffer and therefore better. All the wheels I've built are laced and I've built a few over the years; they seem to be sound and stay true."

Just so and yet the (old!) wheels (1980 I expect) on at present are really in pretty good shape!

I had intended just replacing one or two at a time rather than stripping completely, so I suppose all I do is in each instance lace it at the last cross?

Smokin Joe

Geoff_SS wrote:

Smokin Joe wrote:

Laced spoking does not make for a stiffer wheel. Spokes work in tension only, you could spoke a wheel with string and it would be just as true and stiff as a wheel built with stainless steel spokes - at least for the few minutes before the string started to break.

So a cartwheel with wooden spokes only works in tension? Actually that wonderful invention the wire wheel works in both tension and compression; it's just that the compression in the bottom spokes is only apparent as a reduction in its tension. So the spokes are experiencing changing tension as the wheel rotates and the load experienced by each spoke changes. Whether lacing alleviates this is open to question but it certainly does no harm.

String would work as well, provided its tensile strength was adequate. Kevlar spokes might work but in my experience kevlar does stretch quite a lot. Kevlar fan casings distort alarmingly when a gas turbine fan blade is deliberately detached experimentally (but contain the debris) and kevlar spinnaker control cordage (sheets/guys) stretch on dinghies in a gust.

Geoff

Spokes in bicycle wheels cannot work in compression. There is nothing for a spoke to compress against, it would just push through the hole in the rim. A reduction in tension is not compression.

andrewgturnbull

Hi there.

Smokin' is correct re the reduction in tension not being compression bit (leaving aside the Mavic's rather dodgy r-sys desgin).

I will take issue with the wheel made out of bits of string analogy though.

The string spoke wheel would only work on the front of a track bike. Any wheel which experiences either braking or accerating forces must also be able to handle torsional forces in the direction of rotation, as well as the reduction in tension stuff mentioned above.

Hang on a minute... I'm still thinking about this. A radially spoked string wheel would definately collapse when you applied the brakes, but if it was laced then it might be ok. I think.

Cheers, Andy

aracer

You're wrong, Andy. A string wheel would work for any wheel on a bike (provided the string was strong and stiff enough) since spokes do only work in tension. Torsional forces are handled by having the spoking tangential to the hub, as is the case with a standard 3 cross pattern.

Meanwhile you're also wrong about the spokes in a road bike front wheel having to handle torsion. Since the braking force is at the rim, then there is no torsion through the spokes (well only enough to overcome the bearing drag).

Regarding compression, it is correct that spokes only work in tension not compression (apart from the carbon ones in R-Sys wheels), which is a very fundamental issue with wire spokes wheels - when the spokes on one side go slack the wheel stiffness instantly halves, since those spokes are no longer contributing to supporting the rim. However Geoff is still partly right - he just didn't mention the magic word "superposition". A wire spoked wheel is a prestressed structure, which allows the spokes to support a superposed compression force.

Back to the original question. I have the wheel guru's book in front of me, and he says: "Interlaced spokes take up each other's slack during severe radial loading and reduce the chances of spokes becoming loose... Interlacing also gives more clearance between the spokes and the derailleur on rear wheels".

andrewgturnbull

That does makes sense.

meagain

"Back to the original question. I have the wheel guru's book in front of me, and he says: "Interlaced spokes take up each other's slack during severe radial loading and reduce the chances of spokes becoming loose... Interlacing also gives more clearance between the spokes and the derailleur on rear wheels"."

That suggests to me that for my purposes no need to interlace. I don't I think I impose severity of any form on my wheels and I check spokes regularly.

Sorry if my innocent question raised some "tensions" (sic).

andrewgturnbull

meagain wrote:

"Back to the original question. I have the wheel guru's book in front of me, and he says: "Interlaced spokes take up each other's slack during severe radial loading and reduce the chances of spokes becoming loose... Interlacing also gives more clearance between the spokes and the derailleur on rear wheels"."

That suggests to me that for my purposes no need to interlace. I don't I think I impose severity of any form on my wheels and I check spokes regularly.

Sorry if my innocent question raised some "tensions" (sic).

Not sure, what the above quote is saying is that interlacing your spokes might just save your wheel if it takes a bigger knock than the spokes are tensioned for. And it might stop your deraailleur becoming embeded in those spokes when that happens!

Cheers, Andy

meagain

Last response (honest!) but I don't see why (one) interlacing would counteract an impact greater than that which the spokes could otherwise withstand.

andrewgturnbull

Interlaced spokes take up each other's slack during severe radial loading and reduce the chances of spokes becoming loose.

Hi there.

Ok lets say a spoke is pre tensioned to 100N. This means that particular spoke can on its own withstand up to 100N of force and still remain in tension and thus supporting the rim. If the force increases to beyond 100N on that spoke, then it will become untensioned, and the spoke will bend under it's compression load.

The interlacing may stop the spoke from bowing out as it bends, as it's held in place by the spoke that it crosses. If this stops the spoke from hitting your deraillieur then you've won a watch.

Or something like that.

Cheers, Andy

meagain

OK, that makes sense (apologies for my lack of knowledge of the physical sciences).