AlmostTrick

After enjoying my new wheelset for several months, I happened to test my stainless steel spokes with a magnet on a whim. The results surprised me. On the rear wheel, (24 spokes) 7 had a very strong magnetic attraction and 17 had virtually none. On the front all 20 had very strong magnetic attraction.

I understand that stainless steel can have some light magnetic attraction, and the spoke manufacture has confirmed this. But it seems logical to me that this should be consistent within a batch, without a substantial difference like I found here.

Unless the wheel manufacture or builder used mixed spokes, it doesn’t make sense to me that they could react so widely differently to the magnet test. Wouldn't you agree?

I checked some of my other bikes with SS spokes and almost all reacted very consistently... Very little or virtually no magnetic attraction on all the spokes in the set. One set had one spoke on each wheel that had very strong reaction, while all the rest had virtually none. Strange, I thought.

Finally, if the spokes are mixed, stainless/non-stainless as I suspect, how much does it really matter for performance or longevity? The perfectionist in me says buy new spokes from a reliable source and re-build the wheels, just because I can. The pragmatist in me says just ride and forget about it.

ThermionicScott 

I wouldn’t be surprised if the company used multiple suppliers of spokes and this sort of thing were more common than we realize. As long as the wheels were well built it should never be a concern. I may be OCD, but I’m not all-my-spokes-must-be-equally-magnetic OCD.

dsbrantjr

Some grades/alloys of "stainless" (corrosion-resistant, technically) steel are highly magnetic, others less so to varying degrees. Heat treatment such as annealing and processes such as cold-working can change their properties as well. So your spokes are probably all "stainless", just from different manufacturers or grades as ThermionicScott suggests.
https://www.metalsupermarkets.com/is...teel-magnetic/
https://www.carpentertechnology.com/...ainless-steels

davidad

2 DT's sitting on a shelf are magnetic. I don't think the DT's on my wheels are and neither are the Wheelsmiths.

subgrade

If there are different spokes in a wheel, some might behave a bit differently over time - stretch more/less, loosen more/less, thus the wheel going out of true; or the nipples could tend to seize more/less than others, making trueing difficult.

HillRider

I checked the wheels on my bikes. Two set are built with conventional DT spokes and two sets are Shimano pre-builts with bladed spokes. None of the spokes are strongly magnetic, they very from almost no magnetic attraction to very mild.

Most stainless steel bike spokes are made from a 300-grade stainless that is only mildly magnetic at most. I don't know of any maker using strongly magnetic grades of stainless steel (400-series) so those may be plated carbon steel.

mpetry912 

did you buy the spokes in a manufacturer box ? "In theory" if you have a box of 100 spokes, they "should" have come out of the machine sequentially, drawn from the same batch of wire.

if you bought them from a dealer who had spokes in bins then just about anything is possible.

do the spokes have any different markings on the heads ? DTs will have a "DT", Wheelsmith will have a "W", Sapim usually a stamping above the elbow.

Mark Petry
Bainbridge Island, WA USA

_ForceD_

Perhaps another thing to consider with mixed spokes is the weight between the various composition/material used. If there's a difference in weight-per-spoke between the two materials, but they're distributed evenly around the wheel, I suppose there wouldn't much concern/notice. But if there is a weight difference, and they're all clumped together, it might make the wheel considerably out of balance. You may not notice it at low speeds, but at higher speeds it might become apparent...a bouncing feeling...like when a car wheel is out of balance.


Dan

ThermionicScott 

All of that is very unlikely, especially if the wheelbuilder is competent.

AlmostTrick

Wheels were bought already built from Bicycle Wheel Warehouse. I explained my case to them and asked for replacement SS spokes, so I could re-build them myself. They asked me to contact Sapim with my concerns, and said they would rebuild the wheels for me pending Sapims response.

From Sapim factory:

...which doesn't really explain the huge discrepancy I found. (I tested with both strong and weak magnets) It seems to me the mix was likely at BWW not Sapim. I have not followed up with BWW and don't know if I'll bother.

mpetry912 

yes, I agree with your analysis. Most likely cause is that the builder mixed and matched spokes of the same length, just pulling them randomly from the bin.

Not sure how to advise you here. Is the wheel behaving normally in use ? Maybe not worth worrying about ? I'm not saying it's ideal, but unless you want rebuild the wheel over the winter I'd let it ride until respoking / replacement was required.

Mark Petry
Bainbridge Island, WA USA

AnkleWork

Metallurgical analysis is slightly more complicated than your magnet test, but you could just spray the spokes with water and wait to see which rust first (HAW!). Really, if Sapim's explanation is not good enough for you then NO explanation will be good enough.

Never mind all that. This is not a question about metals. I hope you get some exercise and clear your head so you can think about something important. =)

nomadmax 

No way in this world I'd re-build a set of wheels because some of the spokes "might possibly" be different from the others based on a magnet test. What is important is spoke tension, uniformity and performance. I have some wheels built with the very same spokes, I couldn't tell you if they're magnetic or not.

Wilfred Laurier

Neither of these concerns have any merit. The mechanical properties - esp. stiffness (modulus of elasticity)) and density - generally do not vary from one alloy to the next, at least up until their yield/failure point.

noglider 

It is odd, for sure, but I agree with the others who say leave well enough alone. I never thought to do your test, and maybe I will now. Maybe I'll get the same results.

AnkleWork

I'd be more concerned about each wheel's interaction with the geomagnetic field, which is rapidly becoming chaotic. Just imagine how the OP's stability will be affected. And we don't need bike riders contributing to the imminent pole flip.

https://www.suspicious0bservers.org/

rumrunn6

is it Friday yet? I've been tempted to buy some bladed forks for my road bike, cuz when I break them, whatever shop I wind up in, doesn't always have the same (original type) to use. so my road bike has mixed spokes

subgrade

There is no mention of competent wheelbuilder though.

I said it because it has happened to me before. I had my rear rim crack at the spoke holes so it needed replacement. When replacing the rim, one side of the spokes were replaced with new ones (I don't know which side was the new ones, as I had LBS to do the job for me. My bet is that the former DS spokes migrated to NDS and DS had new spokes, since the new rim has slightly higher profile). The wheel kept going out of true, due to DS spokes loosening or stretching, and after a few weeks of winter riding all of DS spoke heads were seized, so I had to cut and replace all of them. Strangely enough, while the spokes most likely still are different on DS and NDS, haven't had any spoke related troubles since then. Go figure.

ThermionicScott 

Wheel builders should be competent if they are going to charge money for it. Even the best parts won't guarantee a strong or long lasting build if the build sucks. Sorry to hear about your experience!

dedhed

Ride'em like they are and ask the builder to give you an extended warranty.

Wilfred Laurier

Weird story. The weirdest thing is if your assumption about reusing DS spokes as NDS is true. When I worked in a shop I would not unlace and reuse spokes - not because they are no good, but because of the time it would take to get them out without damage and inspect them, and the customer would have to pay for that time - it would work out about the same to just charge them for new spokes, which gives them the added advantage of new spokes.
Another possible explanation is that they used all new spokes but forgot to put lube on the DS threads, which they should have done even if they were reusing spokes.

dedhed

How I like to reuse spokes, especially this time of year.

https://www.etsy.com/listing/7355516...SABEgJxSfD_BwE