Titanium spokes - immediate hazard?

[NHAero]

In the thread I posted earlier today about the Bilenky tandem I bought from Steveandbarb1, I was kindly warned to not ride it further with the existing front wheel because it was built with titanium spokes (40 spokes, Hugi hub, Mavic Module 3 CD eyeletted rim). I've done some Web crawling and so far haven't surfaced dire warnings about this. Certainly some people, mostly MTBers, have broken Ti spokes, and on the rear wheel. I have other front wheels around, though they aren't 40 spoke - one is a vintage Campy Nuovo Record high flange 36H hub laced 3X to a Mavic Open Pro CD eyeletted rim, the other is an Ultegra 6500 32H hub laced to a Mavic CXP21 non-eyeletted rim. Would either of those be preferable from a safety standpoint?

The existing wheel looks to be in excellent condition. I don't want to be foolish or unsafe (I put new cables on, using compressionless housing on the brakes, and new Conti GP 4 Season tires), and on the other hand, people's opinions about many things vary widely, and I don't want to forego using a good wheel that came with the bike if Ti spokes don't present a hazard. If it helps, we're about 260 pounds as a tandem team. Would it help if I got the spoke tension measured? If so, are there different tensiometers for different spoke materials?

[smead]

I broke a spoke on a 40 spoke tandem wheel and never even noticed it!

I can't imagine the wheel exploding all at once - at worst you might break a spoke or two, but again with that spoke count, it'll still get you home. I'd say ride 'em.

[ergott]

It's not like ti spokes are a death trap. If well built they will be fine.

[bikinchris]

I agree. If you start breaking spokes, rebuild the wheel. They are not likely to break all at once. My Ti spoked wheels where 20 years old when I sold that bike. Never broke a spoke.
If you are really that worried, get the wheel rebuilt.

[martl]

As an old school engineer, i wince when something like a spoke is made from a material with a low e-modulus. Steel (or CFK) are just perfect for the job at hand, Ti less so, Al even less so. And i *am* a weight wheenie.

Doesn't mean that, with extra-extra effort, it can't be made to work (some Ksyriums actually seem to hold). Not worth the gain, imo.

[jumphigher]

I'd ride the wheel if in good shape with no worries..

[merckxman]

I had a pair of 32 Ti spoke wheels. Broke one spoke in front and one in back, gave up on that experiment. They just went, just riding around. My weight 162 lbs.

[oldpotatoe]

In the thread I posted earlier today about the Bilenky tandem I bought from Steveandbarb1, I was kindly warned to not ride it further with the existing front wheel because it was built with titanium spokes (40 spokes, Hugi hub, Mavic Module 3 CD eyeletted rim). I've done some Web crawling and so far haven't surfaced dire warnings about this. Certainly some people, mostly MTBers, have broken Ti spokes, and on the rear wheel. I have other front wheels around, though they aren't 40 spoke - one is a vintage Campy Nuovo Record high flange 36H hub laced 3X to a Mavic Open Pro CD eyeletted rim, the other is an Ultegra 6500 32H hub laced to a Mavic CXP21 non-eyeletted rim. Would either of those be preferable from a safety standpoint?

The existing wheel looks to be in excellent condition. I don't want to be foolish or unsafe (I put new cables on, using compressionless housing on the brakes, and new Conti GP 4 Season tires), and on the other hand, people's opinions about many things vary widely, and I don't want to forego using a good wheel that came with the bike if Ti spokes don't present a hazard. If it helps, we're about 260 pounds as a tandem team. Would it help if I got the spoke tension measured? If so, are there different tensiometers for different spoke materials?

I'd at least have a competent wheelbuilder check true/round/dish and tension..DT spoke tension meter has a page for 14g titanium spokes..maybe Wheelsmith and Park do to..Good that it isn't a disc brake wheel..titanium spokes can be kinda flexy..

[peanutgallery]

Last time I encountered ti spokes they were pretty bad and it was the 90s. That particular bike had ti chainrings too. Can't remember which was worse

If the former owner said they were terrible, I would defer to their judgment

[GonaSovereign]

Why not ask your tandem partner how they feel?

Data point of one: this 150lb rider was given a couple 36-hole wheels with ti spokes. Union brand, IIRC, and built by an experienced builder. They didn't like me powering out of corners and would break at the thread or j-bend. After using up the spares, I pulled them apart and salvaged the hub and rim.

It's a bad application of ti if you ask me, although you can recycle the spokes by winding them into nice springs for post-mount brakes...

[19wisconsin64]

Do yourself a favor and learn from someone who had a spoke break and then had a serious accident....don't experiment with titanium spokes. Good steel spokes and a competent wheel-build is the way to go!

Everything will be sort of fine until that whole "catastrophic failure" sets in.

Stay safe, fellow forumulite!

[smead]

Do yourself a favor and learn from someone who had a spoke break and then had a serious accident....don't experiment with titanium spokes. Good steel spokes and a competent wheel-build is the way to go!

Everything will be sort of fine until that whole "catastrophic failure" sets in.

Stay safe, fellow forumulite!

Having broken more than my share of spokes, I can't fathom how that could cause a crash? Can you explain how popping a spoke caused your accident? Maybe a 16 spoke front wheel?

[NHAero]

I'm actually an old school mechanical engineer myself, but above all I'm an empiricist - I like data. The original owner AFAIK rode this wheel happily for many years. If I consider that about 2/3 of my weight and perhaps 1/6 of my wife's weight is on that front wheel (eyeballing our centers of mass relative to the wheelbase) that wheel is loaded with 120 pounds. A weight thread about a month ago here showed that a significant number of forumites may be loading their front wheels more heavily, and I wager few have 40 spoke wheels. I'd be grateful of incidents of actual front wheel Ti spoke failures and of course especially those that took a bike down. And secondarily, any spoke failures that caused a crash, steel, Ti, or ???.

And I'd be pleased to have someone say more about why modulus of elasticity is key in selecting a spoke, which I expect mostly is stressed in tension. Is the key issue at the place where the spoke elbows through the hub flange?

[Mark McM]

I'm actually an old school mechanical engineer myself, but above all I'm an empiricist - I like data. The original owner AFAIK rode this wheel happily for many years. If I consider that about 2/3 of my weight and perhaps 1/6 of my wife's weight is on that front wheel (eyeballing our centers of mass relative to the wheelbase) that wheel is loaded with 120 pounds. A weight thread about a month ago here showed that a significant number of forumites may be loading their front wheels more heavily, and I wager few have 40 spoke wheels. I'd be grateful of incidents of actual front wheel Ti spoke failures and of course especially those that took a bike down. And secondarily, any spoke failures that caused a crash, steel, Ti, or ???.

And I'd be pleased to have someone say more about why modulus of elasticity is key in selecting a spoke, which I expect mostly is stressed in tension. Is the key issue at the place where the spoke elbows through the hub flange?

I've only had spoke failures on the rear wheel, and it has never caused a crash. Once, another rider put their front skewer into my 20 spoke rear wheel, resulting in 6 spokes snapping, and I stayed upright until I rolled to a stop. I once had a rash of aluminum nipple failures on a 32 spoke rear wheel, and didn't even notice until the 3rd nipple had broken!

Modulus of elasticity (material stiffness) comes into play because spoke stiffness affects wheel stiffness (the only thing connecting the rim to the hub is the spokes, afterall). Titanium has roughly half the modulus of steel, so a titanium spoke will have half the stiffness of a steel spoke of the same dimensions. Of course, spoke thickness also plays a role, so a thick titanium spoke may have similar stiffness to a thin steel spoke.

[jumphigher]

I've only had spoke failures on the rear wheel, and it has never caused a crash.

^This is me as well. Cant imagine how a broken spoke or two would cause a catastrophic situation. It's more of an annoyance than anything.

[Gummee]

It's not like ti spokes are a death trap. If well built they will be fine.

IME they start breaking one at a time at about year 3 of the wheel's life.

In the 'better safe than upset' school of life: have that wheel re-built before spending too much time on it. It really isn't worth the risk of 2 of y'all augering in due to broken spokes

M

[smead]

Heck anyone who runs a tire other than a gatorskin is taking a huuuuge risk for a catastrophic blowout. :confused:

[buddybikes]

As the previous owner of the bike! The rear began popping occasionally, I replaced 1 by 1 for bit, then rebuilt. When they broke, at the J, barely noticed. Front never caused issue so I left it. The wheels were built by Bilenky. I just got the bike and rode it.

Hope it is coming close to done. If nothing else, rebuild with that rim using some thin spokes due to 40 holes, would be surely fine (in my opinion)

Have fun
Steve

[bigbill]

I had a set of wheels with Ti spokes in the 90's. 32 spoke (rainbow finish) Ti spokes on DA hubs with Open4CD rims. Not the stiffest wheel, but really light for the time. I never broke a spoke but the movers broke several on both wheels. I ended up getting the hubs relaced to Campy U19's with DB spokes.

[NHAero]

I NEVER let the movers ride my bikes :-)

I had a set of wheels with Ti spokes in the 90's. 32 spoke (rainbow finish) Ti spokes on DA hubs with Open4CD rims. Not the stiffest wheel, but really light for the time. I never broke a spoke but the movers broke several on both wheels. I ended up getting the hubs relaced to Campy U19's with DB spokes.

[zap]

I inspected titanium spokes using a magnifying lens when I broke down a front wheel after a spoke broke. A number of spokes had cracks at the elbow. The thinking is that titanium work hardens and become brittle as they squirm in spoke holes.

This was before I found out how quickly cracks propagate in titanium hence my current caution regarding titanium in a number of applications.

[oldpotatoe]

As the previous owner of the bike! The rear began popping occasionally, I replaced 1 by 1 for bit, then rebuilt. When they broke, at the J, barely noticed. Front never caused issue so I left it. The wheels were built by Bilenky. I just got the bike and rode it.

Hope it is coming close to done. If nothing else, rebuild with that rim using some thin spokes due to 40 holes, would be surely fine (in my opinion)

Have fun
Steve

IMHO and yes, 40h but still 260 pound package, which is VERY light...think that’s riders, not bike and riders. So, use 14/15 spokes, nothing to be gained by saving a few grams on a 135,000 or so gram package with thin spokes.

[Mark McM]

I inspected titanium spokes using a magnifying lens when I broke down a front wheel after a spoke broke. A number of spokes had cracks at the elbow. The thinking is that titanium work hardens and become brittle as they squirm in spoke holes.

What you saw were fatigue cracks. Metal fatigue can affect any and all metals (steel, aluminum, magnesium, brass, etc.) - titanium is not unique in this respect. Poorly shaped or matched parts (such as spokes and flanges) can have stress concentrations, which can increase the prevalence and growth rate of fatigue cracks. Since titanium has a lower tensile strength than steel, it will fatigue at lower stresses. If these spokes had been made of aluminum (even lower tensile strength), they would have fatigued at even lower stresses.

(Also, the "work harden and become brittle" view of metal cracks is vastly over-simplified and close to a century out of date. Fatigue cracks are a much better understood phenomenon today.)

[BryanE]

Twenty years ago I proudly laced my bike with tie dyed, blades titanium spokes.
Then every third ride I broke a spoke. Three broken spokes
later I said to hell with it. Someone later told me they
stretch and need to be tighten every three rides.
Have fun.