Bora WTO

[robertbb]

I’ve ridden the Shamals. They’re fine. Not even close to what you experience on Ligthweights. Have you ridden Lightweights in any kind of gusty conditions, descending or otherwise, doesn’t really matter. If there’s a gust they will catch it.

Yeah. I'm not saying they're bad, just that those thick spokes make a meaningful (negative) difference in handling. I've never ridden lightweights, but I imagine given their light weight, this'd translate even more.

[Calnago]

Yes, the wider spokes, the ultralight weight, the shape perhaps... whatever it is they have found the combination for some pretty scary wheels. I was just curious if those analyzing all these different wheel shapes etc had any more thoughts on why Lightweights in particular seem to be extra susceptible to gusts etc.

[robertbb]

Right. Sounds like you just listed three very pleausible factors. And one gets to pay thousands for the privilege!

[bilwit]

Yes, the wider spokes, the ultralight weight, the shape perhaps... whatever it is they have found the combination for some pretty scary wheels. I was just curious if those analyzing all these different wheel shapes etc had any more thoughts on why Lightweights in particular seem to be extra susceptible to gusts etc.

Yeah it seems backwards to me with regards to my personal experience with "V" versus "U" shape rims. I had 38mm V rims and any tiny bit of crosswind turned into a wrestling match with the front of the bike. I'm on 40mm U rims now and haven't had any issue Makes sense to me that the sharp V would a lot of deflect a lot of sidewind whereas air could more easily flow over a toroidal shape

[TobinHatesYou]

Yeah it seems backwards to me with regards to my personal experience with "V" versus "U" shape rims. I had 38mm V rims and any tiny bit of crosswind turned into a wrestling match with the front of the bike. I'm on 40mm U rims now and haven't had any issue Makes sense to me that the sharp V would a lot of deflect a lot of sidewind whereas air could more easily flow over a toroidal shape

Those hybrid V/toroidal cross-sections (think open-mold Chinese rims) are okay for cross-wind stability so long as narrow tires are used, but yeah old-school Vs have nowhere near enough symmetry between leading and trailing edge, which causes lots of detachment on one edge but not the other.

[Beaver]

Side force isn't the same as crosswind stability - side force for any wheel fluctuates as airflow breaks away and reattaches. The frequency and sharpness of that cycle is also important to how the wheels feel and handle. A greater side force that varies (comparitively) slowly and smoothly can feel more stable than a lower total side force that varies rapidly and suddenly.

True, the Zipp 454 NSW are an example for frequent changing stability - they are worse than Zipp 404 and both were tested with 7 Nm.

In general, besides a high rim, an overlapping tire, thick spokes, a box shaped or torodial rim and a very low weight will decrease crosswind stability.

This Zipp explanation is true for low drag but not crosswind stability:



And this Zeal "Kamm-tail" (aka high box shape) rim seems to have the worst shape - the 44mm high Camerig has 11 Nm, just like Zipp 808:



If the rim doesn't get narrower towards the hub, the airflow just gets "compressed", it seems:



So, this should be the same with Bora WTO, despite the teardrop shaped skewer.

[mpulsiv]

It's the spokes. My Shamal C17's are way harder to handle in the wind than my Zonda C17's - the only difference is the spokes. (OK, I know the rim is slightly more square on the Zonda's, and the hubs are different, but these differences are tiny).

Tangent: and the Shamals are wayyyy stiffer than the Zonda's. No matter what anyone tries to say about Zonda's being 90% as good, they are basically 1/3rd as good... and the price reflects this.

Wait, are you saying that Shamal is not the same rim as Zonda due to slighly more square rim profile? This is the first time I hear this. Perhaps you are thinking of Scirocco C17 (e.g. 35mm deep)?

[robertbb]

It's the spokes. My Shamal C17's are way harder to handle in the wind than my Zonda C17's - the only difference is the spokes. (OK, I know the rim is slightly more square on the Zonda's, and the hubs are different, but these differences are tiny).

Tangent: and the Shamals are wayyyy stiffer than the Zonda's. No matter what anyone tries to say about Zonda's being 90% as good, they are basically 1/3rd as good... and the price reflects this.

Wait, are you saying that Shamal is not the same rim as Zonda due to slighly more square rim profile? This is the first time I hear this. Perhaps you are thinking of Scirocco C17 (e.g. 35mm deep)?

Have a look at the rims on a Shamal C17 and a Zonda C17. They are different. The Zondas are squared with hard edges, whereas the Shamals are smoother.

Different rims, different spokes, different hubs and different bearings. The Zonda drive side hub flange is interestingly identical in shape, construction and geometry to the Bora drive side hub flange. The Shamal is different to both.

Shamals are amazing - just wish they weren't such a pig in any cross/head wind. So much so that I'm about to move them on and get a set of customs built around Easton R90SL rims and spokes that aren't as wide as my kitchen knives.

[mpulsiv]

Have a look at the rims on a Shamal C17 and a Zonda C17. They are different. The Zondas are squared with hard edges, whereas the Shamals are smoother.

Different rims, different spokes, different hubs and different bearings. The Zonda drive side hub flange is interestingly identical in shape, construction and geometry to the Bora drive side hub flange. The Shamal is different to both.

Shamals are amazing - just wish they weren't such a pig in any cross/head wind. So much so that I'm about to move them on and get a set of customs built around Easton R90SL rims and spokes that aren't as wide as my kitchen knives.

Interesting. I didn't pay close attention to rim profile and was under the impression that it's identical and the only thing that seperates Shamal C17 and Zonda C17 are: spokes, hubs and bearings. I have been racing on Scirocco C17, which are deeper "V" shape and they handle just fine in crosswinds.

I don't think that Easton R90SL will be as stiff as Campagnolo G3 geometry. I have a pair of Boyd Altamont (~180 grams lighter), laced 2x cross with 28 CX-ray spokes and brass nipples. They don't climb as well as my $300 Scirocco C17 wheeels.

I'd love to see what Shamal C17 is capable of, specifically mille brake track. Campagnolo Skeleton brakes are fantastic, they my put Dura Ace 9000 brakes to shame using same pads (e.g. Kool-Stop salmon).

[robertbb]

Have a look at the rims on a Shamal C17 and a Zonda C17. They are different. The Zondas are squared with hard edges, whereas the Shamals are smoother.

Different rims, different spokes, different hubs and different bearings. The Zonda drive side hub flange is interestingly identical in shape, construction and geometry to the Bora drive side hub flange. The Shamal is different to both.

Shamals are amazing - just wish they weren't such a pig in any cross/head wind. So much so that I'm about to move them on and get a set of customs built around Easton R90SL rims and spokes that aren't as wide as my kitchen knives.

Interesting. I didn't pay close attention to rim profile and was under the impression that it's identical and the only thing that seperates Shamal C17 and Zonda C17 are: spokes, hubs and bearings. I have been racing on Scirocco C17, which are deeper "V" shape and they handle just fine in crosswinds.

I don't think that Easton R90SL will be as stiff as Campagnolo G3 geometry. I have a pair of Boyd Altamont (~180 grams lighter), laced 2x cross with 28 CX-ray spokes and brass nipples. They don't climb as well as my $300 Scirocco C17 wheeels.

I'd love to see what Shamal C17 is capable of, specifically mille brake track. Campagnolo Skeleton brakes are fantastic, they my put Dura Ace 9000 brakes to shame using same pads (e.g. Kool-Stop salmon).

It's the spokes. I find I get blown around on my C17 Shamals more than my Zonda's (and my Bora's).

I'm not sure at this stage how the R90SL build will come together. I know I'll be using DT240 rear... the question is how many spokes, and which spokes. I want a set that reacts like the Shamals but doesn't suck in crosswinds and the Shamals most certainly do. Leaning towards 20/28 with DT revolutions.

[Noctiluxx]

Any info on these wheels? Price, release date?

[mpulsiv]

It's the spokes. I find I get blown around on my C17 Shamals more than my Zonda's (and my Bora's).

I'm not sure at this stage how the R90SL build will come together. I know I'll be using DT240 rear... the question is how many spokes, and which spokes. I want a set that reacts like the Shamals but doesn't suck in crosswinds and the Shamals most certainly do. Leaning towards 20/28 with DT revolutions.

So the aluminum spokes is the real handicap then. We trade stiffness of these spokes for crosswinds performance. You didn't mention whether you have Bora 35 or 50. Do you feel that Bora wheels are more responsive and stiffer next to Shamals C17 (e.g. aluminum spokes and USB bearings).

[robertbb]

It's the spokes. I find I get blown around on my C17 Shamals more than my Zonda's (and my Bora's).

I'm not sure at this stage how the R90SL build will come together. I know I'll be using DT240 rear... the question is how many spokes, and which spokes. I want a set that reacts like the Shamals but doesn't suck in crosswinds and the Shamals most certainly do. Leaning towards 20/28 with DT revolutions.

So the aluminum spokes is the real handicap then. We trade stiffness of these spokes for crosswinds performance. You didn't mention whether you have Bora 35 or 50. Do you feel that Bora wheels are more responsive and stiffer next to Shamals C17 (e.g. aluminum spokes and USB bearings).

They are Bora 35 tubulars, and they are more responsive than Shamals for sure. They handle the wind better. I can't tell the difference at all in the bearings.

[Wookski]

Yes, the wider spokes, the ultralight weight, the shape perhaps... whatever it is they have found the combination for some pretty scary wheels. I was just curious if those analyzing all these different wheel shapes etc had any more thoughts on why Lightweights in particular seem to be extra susceptible to gusts etc.

LW aren’t a tear drop, they are a straight and flat surface coming to a pronounced ridge. This shape is akin to a sail and hence in gusty conditions they feel like they are going to take off!

On another note can everyone please stop talking about the crosswind handling of shamals? Unless you have ridden a set of lightweights in strong gusty conditions then I’m sorry but you have no idea of what poor crosswind handling actually is.

[robertbb]

Yes, the wider spokes, the ultralight weight, the shape perhaps... whatever it is they have found the combination for some pretty scary wheels. I was just curious if those analyzing all these different wheel shapes etc had any more thoughts on why Lightweights in particular seem to be extra susceptible to gusts etc.

LW aren’t a tear drop, they are a straight and flat surface coming to a pronounced ridge. This shape is akin to a sail and hence in gusty conditions they feel like they are going to take off!

On another note can everyone please stop talking about the crosswind handling of shamals? Unless you have ridden a set of lightweights in strong gusty conditions then I’m sorry but you have no idea of what poor crosswind handling actually is.

So maybe lightweights are incredibly bad, and Shamals are just very bad?