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EB16: Ursus holds out new handlebar/stem combo, sidestepping carbon mountain bike wheels & more

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Ursus has shown some interesting concepts before, like copper-infused brake tracks, and they make some darn nice looking kickstands. This year, the Italian brand had a new one-piece carbon fiber handlebar-stem combo, new carbon mountain bike wheels with offset spoke placements on the rim, and updated tubular road wheels.

The Magnus H.01 handlebar unit is full carbon and weighs in at just 330g, making it a very light part on its own, but especially so considering it’s designed as an aerodynamic piece…

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The tops use the UCI-allowable 3:1 ratio in a tapered foil shape and tuck the cables inside the bar to minimize drag.

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It’s available in six sizes that scale the reach and drop proportionately. The stem hardware is nicely integrated in a way that doesn’t require bonding threaded inserts into the carbon fiber, which simplifies construction and should prove more durable over time. Or, at least, replaceable should you accidentally strip the threads.

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The underside is ready for bolt-on out-front cycling computer mounts.

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Click image to enlarge for all the tech details.

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The new Kodiak mountain bike wheels use a full carbon rim with offset bulged spoke insertion points.

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Interestingly, they don’t cross spokes from one side of the hub to the other side of the rim (meaning, left flange to rim bulging out on the right), which would offer better triangulation. The reason? They tout the wheel’s ability to track the terrain and ride comfortably, so it’s to provide a little more vertical compliance and rely on the inherent stiffness of a carbon rim to reduce lateral play.

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Alloy hubs with 28 straight pull Sapim CX-Ray spokes per wheel and thru axle readiness finish the package.

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The 29er comes in two rim widths (24mm or 29mm internal, click image to enlarge), and the 27.5 in just one (29mm internal). It’s a hookless bead that’s tubeless ready with the addition of rim tape. Note the weights, particularly for the narrower 29er set…complete wheelset at just 1,295g!

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The Ursus Miura carbon tubulars switch from their older 12K woven finish to a smaller, 1K finish to better match modern bikes.

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Otherwise, they carry over much the same. There’s also a T37 size, and clinchers and disc brake models are also available.

Ursus.it 

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Greg
Greg
7 years ago

Wheel lateral stiffness is a funny thing. Spoke lateral crossover increases bracing angle, but promotes rim cross-section torsional flex. So I can see their point, but I’d like to see hard numbers on how it all works out in the wash.

JasonK
JasonK
7 years ago

Can you expand on that, Greg? What do you mean by “cross-sectional torsional flex?”

I think you mean torsion about the centroid of the rim cross-section…but that doesn’t make much sense to me. Sure, you have a potential moment created by the offset spoke holes, but any displacements have to be tiny.

Or have I misunderstood?

Greg
Greg
7 years ago
Reply to  JasonK

I believe you are understanding me correctly, but I don’t believe the displacements are that small (relative to all other associated displacements). it’s the only reason I can give to explain why lateral crossover wheels are never as laterally stiff as expected, and some rims with staggered drillings (like Mavic bmx wheels from maybe 15 years ago) weren’t that laterally flexible.

Greg
Greg
7 years ago
Reply to  Greg

…the rims in the article have minimal stagger. I was thinking more along the lines of first generation Shimano wheel system wheels, and the aforementioned Mavic BMX rims (XY).

DominicBruysPorter (@BruysPorter)
Reply to  Greg

I can attest to the relative stiffness of the XY, but I always suspected it left a little something on the table, especially compared to what is essentially a copy but with crossover spokes, the G-Sport Ribcage. I suppose it depends some on how you stress the wheel too.

JasonK
JasonK
7 years ago
Reply to  Greg

I’m not sure why you think lateral crossover wheels are never as stiff as you expect. It’s true that the original Shimano wheel you mentioned (WH-7700) is not very stiff laterally, but that has a lot to do with its low spoke count (16) and relatively shallow depth.

In fact, spokes crossed over make the rim *more* resistant to torsional deformation, as the spokes in that case create a couple to resist torsional deformation of the rim. If all the spokes are at the centerline, the spokes cannot resist any torsional deformation of the rim.

When the spokes cross the centerline, any torsional deformation would not only cause the rim to bend (as with centerline spokes) but also require the spokes themselves to displace. For a given rim profile and spoke count, spokes crossing the centerline makes the rim *more* resistant to torsional deflection. The bracing angle is also increased, so the wheel is stiffer laterally than it would be with spokes that ended at the centerline.

Mavic BMX wheels: While they had staggered spoke holes, the spokes didn’t cross the centerline, which actually reduced the bracing angle and made the wheels more flexible.

BMW has built their spoked wheels with spokes crossing the centerline for decades. There’s nothing wrong with doing so. And the relatively low stiffness of Shimano’s WH-7000 wheel shows that wheels with spokes that cross the centerline are stiffer than they would be if the spokes ended at the centerline, but not much stiffer.

Greg
Greg
7 years ago
Reply to  JasonK

When the rim bends, it naturally also has to twist (the torsional flex I was referring to). On lateral crossover wheels, the spoke tension increase of the rim’s lateral deflection tries to twist the rim in the direction it needs to go anyway.
The reason I brought up the Mavic XY rims was specifically because it was NOT lateral crossover, yet had heavily staggered drilling. From purely a bracing angle standpoint, it should be laterally flexible, but it is not. This supports my argument.

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