Titanium Spokes!

3/16/2020 9:11am
Luxon MX wrote:
LuxonMX here. 1/2 a pound out of a wheel is definitely noticeable. Wheels are unsprung and rotational weight, plus they're the furthest components from the bikes...
LuxonMX here.

1/2 a pound out of a wheel is definitely noticeable. Wheels are unsprung and rotational weight, plus they're the furthest components from the bikes CG, so the polar moment drops a bunch when wheel weight drops.
Correct me if I’m wrong, but couldn’t the Ti change the rigidity in the wheel which could cause a negative or even a positive effect?
Luxon MX
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3/16/2020 10:46am
Luxon MX wrote:
LuxonMX here. 1/2 a pound out of a wheel is definitely noticeable. Wheels are unsprung and rotational weight, plus they're the furthest components from the bikes...
LuxonMX here.

1/2 a pound out of a wheel is definitely noticeable. Wheels are unsprung and rotational weight, plus they're the furthest components from the bikes CG, so the polar moment drops a bunch when wheel weight drops.
Correct me if I’m wrong, but couldn’t the Ti change the rigidity in the wheel which could cause a negative or even a positive effect?
Most metals have nearly the same stiffness to weight ratio. Because of this, lower density metals (like aluminum) are always preferable to higher density materials (like steel) for applications in bending as they'll be stiffer. For the same weight, an aluminum bar is thicker than a steel bar, so it has a higher area moment of inertia, and therefore a higher bending stiffness (generally much higher). That's why you don't see steel or titanium triple clamps, they're almost always aluminum. Magnesium would be even better, but it's expensive and has its own issues.

Spokes, though, are nominally loaded in tension only, and there is no bending. So we can look at the size of the spoke relative to comparable steel spokes and easily understand the difference in stiffness. Titanium has about half the stiffness of steel at about half the weight. You could double the cross sectional area of a titanium spoke relative to a steel spoke and end up at identical stiffnesses. But they'd be identical weights too, so not much point in doing that! Since these are lighter than steel spokes, it follows that they'll be less stiff. I'm guessing they're probably the same thickness as the steel spokes they're replacing, so they should be about half the weight, but also half the stiffness.

So yes, the wheel with be less stiff with the titanium spokes relative the the same wheel with steel spokes. Is this a good thing? Probably not. But that's one of the trade-offs for weight savings.
7
3/16/2020 6:19pm
Could you run a tighter spoke tension to tune that stiffness to more your liking.
Luxon MX
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3/16/2020 6:35pm
Could you run a tighter spoke tension to tune that stiffness to more your liking.
Well, sort of. You can think of a spoke the same as your shock spring. Increasing the tension on the spoke is similar to increasing the preload on your shock spring. It changes the preload (initial force required to start movement), but it doesn't change the spring rate. You can preload the crap out of your shock pring to "stiffen" it up, but the right solution is to change to a higher rate spring with less preload... The same can be said for the spokes, you can tension them a bit higher to make things "stiffer", but you can't do it all that much as you'll eventually start breaking spokes. You certainly can't do it enough to make the titanium spokes feel like steel spokes.
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HackMan162
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3/17/2020 6:04am
I know Dubya was testing titanium spokes a couple years ago, and never brought them to market. Guess there is likely a durability issue.
red_leader
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3/23/2020 10:56pm
I just received the KTM 2020.5 factory billet rear hub.
Happy to report it's the exact same weight as the stocker!
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Momus
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3/24/2020 2:58am
red_leader wrote:
I just received the KTM 2020.5 factory billet rear hub.
Happy to report it's the exact same weight as the stocker!
Do they say which alloy are they made from? Could be twice as strong...
spimx
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3/28/2020 12:33pm
Luxon MX wrote:
LuxonMX here. 1/2 a pound out of a wheel is definitely noticeable. Wheels are unsprung and rotational weight, plus they're the furthest components from the bikes...
LuxonMX here.

1/2 a pound out of a wheel is definitely noticeable. Wheels are unsprung and rotational weight, plus they're the furthest components from the bikes CG, so the polar moment drops a bunch when wheel weight drops.
Correct me if I’m wrong, but couldn’t the Ti change the rigidity in the wheel which could cause a negative or even a positive effect?
Luxon MX wrote:
Most metals have nearly the same stiffness to weight ratio. Because of this, lower density metals (like aluminum) are always preferable to higher density materials (like...
Most metals have nearly the same stiffness to weight ratio. Because of this, lower density metals (like aluminum) are always preferable to higher density materials (like steel) for applications in bending as they'll be stiffer. For the same weight, an aluminum bar is thicker than a steel bar, so it has a higher area moment of inertia, and therefore a higher bending stiffness (generally much higher). That's why you don't see steel or titanium triple clamps, they're almost always aluminum. Magnesium would be even better, but it's expensive and has its own issues.

Spokes, though, are nominally loaded in tension only, and there is no bending. So we can look at the size of the spoke relative to comparable steel spokes and easily understand the difference in stiffness. Titanium has about half the stiffness of steel at about half the weight. You could double the cross sectional area of a titanium spoke relative to a steel spoke and end up at identical stiffnesses. But they'd be identical weights too, so not much point in doing that! Since these are lighter than steel spokes, it follows that they'll be less stiff. I'm guessing they're probably the same thickness as the steel spokes they're replacing, so they should be about half the weight, but also half the stiffness.

So yes, the wheel with be less stiff with the titanium spokes relative the the same wheel with steel spokes. Is this a good thing? Probably not. But that's one of the trade-offs for weight savings.
I would give up some stiffness just to not have the problem of a steel spoke corroding with an aluminum nipple.
GCBC
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3/28/2020 3:39pm
Anyone doing different lacing patterns? like in MTB world there's multiple lace patterns.
AJ565
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3/28/2020 7:10pm
GCBC wrote:
Anyone doing different lacing patterns? like in MTB world there's multiple lace patterns.
I don’t think they make rims in different patterns or spokes longer for different patterns.
Andy7
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5/2/2020 5:58pm
Luxon MX wrote:
Well, sort of. You can think of a spoke the same as your shock spring. Increasing the tension on the spoke is similar to increasing the...
Well, sort of. You can think of a spoke the same as your shock spring. Increasing the tension on the spoke is similar to increasing the preload on your shock spring. It changes the preload (initial force required to start movement), but it doesn't change the spring rate. You can preload the crap out of your shock pring to "stiffen" it up, but the right solution is to change to a higher rate spring with less preload... The same can be said for the spokes, you can tension them a bit higher to make things "stiffer", but you can't do it all that much as you'll eventually start breaking spokes. You certainly can't do it enough to make the titanium spokes feel like steel spokes.
Billy why haven't we seen carbon spokes yet? Taking into account that they are only subject to traction (as far as I know), and carbon fiber respond well to that situation.
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Luxon MX
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5/3/2020 4:22pm
Andy7 wrote:
Billy why haven't we seen carbon spokes yet? Taking into account that they are only subject to traction (as far as I know), and carbon fiber...
Billy why haven't we seen carbon spokes yet? Taking into account that they are only subject to traction (as far as I know), and carbon fiber respond well to that situation.
Carbon spokes would have a lot of challenges. You can't thread carbon, so you'd need to have some sort of metallic insert that's threaded bonded to the rest of the spoke. Also, they should really be completely straight with no bends, so you'd likely need a custom hub to get around that issue. And then they'd likely have to be a bit thicker than an equivalent steel spoke, so again, custom hubs and difficulties getting them routed correctly without bends. And in the end, you'd have a pretty lightweight spoke that's fairly brittle. You could blend in some kevlar to toughen it up a bit, but that comes with weight gain. Also, it would be really expensive relative to a steel spoke. Basically, it's a lot of challenges to overcome, and not a whole lot to gain when factoring in the downsides.
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FWYT
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5/3/2020 5:24pm
Andy7 wrote:
Billy why haven't we seen carbon spokes yet? Taking into account that they are only subject to traction (as far as I know), and carbon fiber...
Billy why haven't we seen carbon spokes yet? Taking into account that they are only subject to traction (as far as I know), and carbon fiber respond well to that situation.
Luxon MX wrote:
Carbon spokes would have a lot of challenges. You can't thread carbon, so you'd need to have some sort of metallic insert that's threaded bonded to...
Carbon spokes would have a lot of challenges. You can't thread carbon, so you'd need to have some sort of metallic insert that's threaded bonded to the rest of the spoke. Also, they should really be completely straight with no bends, so you'd likely need a custom hub to get around that issue. And then they'd likely have to be a bit thicker than an equivalent steel spoke, so again, custom hubs and difficulties getting them routed correctly without bends. And in the end, you'd have a pretty lightweight spoke that's fairly brittle. You could blend in some kevlar to toughen it up a bit, but that comes with weight gain. Also, it would be really expensive relative to a steel spoke. Basically, it's a lot of challenges to overcome, and not a whole lot to gain when factoring in the downsides.
Man, you guys need someone to sweep the shop? I feel like I should get an education
while I'm furloughed and the Continuing Ed welding classes are closed. LaughingLaughing
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red_leader
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2/16/2021 11:11pm
Stock wheel: 7 pounds
(This scale may read a touch high)

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red_leader
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2/16/2021 11:13pm
Same rim.
Titanium spokes
Factory Hub
6 pounds 3.4 oz


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cdoggy81
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2/18/2021 10:23pm
Thanks for updating!
~ 12oz/ 350g is a nice savings. How do they feel when riding on them?
Have you had to retighten them much?
Any issues?

I will note they are slightly bigger than oem for my Yamaha hubs. You will need to ever so slightly clearance the holes.
I still have not built mine yet though as my ocd has prevented me from picking a hub & rim color thus far🤦‍♂️
Get their titanium rim locks too (or the plastic MP) for additional weight savings. And go ahead & through in some titanium rotors, rotor bolts, sprocket bolts, too.... It’s a slippery slope 🤣






red_leader
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2/19/2021 7:14am
Haha, way ahead of you!
So pretty!

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HackMan162
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2/19/2021 11:35am
I have heard the Ti rotor doesn't stop as well as steel, but that is heresay. Anyone with actual real experience?
Falcon
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2/19/2021 3:39pm Edited Date/Time 2/19/2021 3:40pm
HackMan162 wrote:
I have heard the Ti rotor doesn't stop as well as steel, but that is heresay. Anyone with actual real experience?
I have no experience in the matter, but I can guarantee you there is some truth to this. Steel has a certain coefficient of friction, and titanium has another. For the same set of brake pads, one will return more friction at the same pad pressure, and thus stop better. (I don't know which, but I'd bet steel is better.) EDIT: The difference we're talking about may be VERY minimal.
One may be better than the other with regard to heat dissipation than the other (probably Ti,) and one may expand less due to heat than the other.
yz133rider
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2/19/2021 5:29pm
Is there a link to these for sale?
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red_leader
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2/23/2021 4:44pm
You have to call Warp9 for the spokes.

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