Wheels: Dura-Ace 50 vs. 35

Sep 2, 2009
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#1
Hi

I am considering buying a set of Dura Ace tubular carbon wheels.

The two sizes I am looking at are 50 and 35.

Now, I don't really know which ones to go for.

Currently, I have a set of Mavic Cosmic Carbone SR and a set of Mavic Ksyrium Elite.

The Cosmics are fairly deep, and feel bloody amazing when they are at full speed. I would be happy to get something the same depth as these again, but in a tubular (so, that would be the 50 right?). However, I am getting more and more into climbing, so would the 35 be more in line with that kind of riding?

Any experiences / ideas would be very welcome.

Cheers.
 

FarEast

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May 25, 2009
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#2
different horses for differenct courses - thats why they have different depths.

If you are getting in to climbing then you want the 24's
 
Sep 2, 2009
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#3
Right,

So, I really like the way the Cosmics work when I am legging it on the flat/downhill.

Considering I have the Cosmics, it would be foolish to buy something too similar to them, however I don't want to move too far away from that feeling.

So, 50 are pretty much out for climbing?
 

FarEast

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May 25, 2009
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#4
Go watch the TDF from last year or other Pro Tour races. Climbers go for the stiffest lightest rims they can get normally 20 or 24mm. The aerodynamic benifits of deep profile wheels are mute when climbing.
 

Mike

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Sep 24, 2007
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#5
Sounds like you're looking for something that is versatile i.e. light enough for climbing but still with good aerodynamics? If that's the case I'd say go for the 35's. I have a pair of Easton 90SL's which have 38mm rims and are very light, 1,212g for the pair, so a good all round wheel.

I wanted tubulars for racing and didn't want to spend the cash on two sets of wheels.

http://www.cyclingnews.com/reviews/easton-ec90-sl-tubular-wheels-1


But the Dura Ace wheels are probably better quality, just going from the brand name;)
 

GSAstuto

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Oct 11, 2009
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#6
It's a bit 'funny' to hear people talk about 'climbing wheels' when most of them are over 65kg. Not to be disingenuous, but if you are over 60-65kg, then losing a few hundred grams on your wheels means nothing. In fact, you're far better to go for a wheelset that is laterally stiffer as you'll be losing more power than gaining by virtue of the weight. If you are dead set on lightweight wheels, then start with a front wheel. It is the passive member and reducing the angular momentum here will have some benefit without sacrifice due to lateral flexing.

Perhaps the 'best' all arounder wheel is a 38mm carbon. You get good rigidity as well as reasonable aerodynamics. It's really the 'go to' wheelset for most serious riders. Just adding a 38mm front wheel to your arsenal is a good choice for those extra windy or hilly days where the 50/50 or 60/60 combo is a bit cumbersome.

Another secret - front wheels cost less than rears due to the extra cost of making a rear hub, and less spokes. So, you'll get more bang for your buck by buying the lightest front wheel than the rear.
 

Sikochi

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Sep 13, 2010
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#7
Be warned that Shimano are in the process of releasing new wheels, so I would hold my horses a bit. Similar to what GSAstuto pointed out, weight is only important if you are racing. A few hundred grams is neither here nor there. All my climbing is done with the Powertap on the back - doesn`t stop me.

proxy.php?image=http%3A%2F%2Fcdn1.media.cyclingnews.futurecdn.net%2F%2F2012%2F04%2F01%2F2%2Fsky_shimano_wheel_2_220.jpg&hash=2bc4bf5f2a4ce5165b0edb61ee957f06

From Tour of Flanders report:-
New gear was seemingly sparse in the pits this year but we still spotted some new carbon tubular wheels from Shimano. Measuring roughly 50mm in depth, the new wheels mark a new design direction for Shimano with their wide-section rims and distinctly rounder profile than in years past. We'd heard rumblings that Shimano is making a serious push towards improving wheel aerodynamics and this looks to be the first step.

Hubs look to have improved, too, with wider flange spacing front and rear for improved side-to-side stiffness and straight-pull spokes that are more easily accessed if one needs replacing. Also carrying over is Shimano's indexed cup-and-cone adjustable bearing system.

We're not terribly excited about the hidden nipples, though. While they certainly require a smaller rim hole – thus minimizing any reduction in strength due to drilling – it'll still make for a rough time in case the wheel needs to be trued.
http://www.cyclingnews.com/features/tech-gallery-pro-bikes-at-the-2012-tour-of-flanders
 

GSAstuto

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Oct 11, 2009
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#8
Jeez, it seems Shimano is actually just follwing basic engineering practices known to most cycling mfg for what, 20yrs or so? Nothing at all innovative here:

1) Wider tires result in less rolling resistance. This is a fact. Except for small gains in aerodynamics, narrowing the tire results in far worse losses in road resistance.

2) Increasing the spoke bracing angle results in stiffer wheels. DOH! Why do you think hub designers strive to get the spokes as outboard as possible? The counterpoint is getting the rear wheel balanced properly DS to NDS for tension.

3) 'Hidden' nipples? Come on. ANY rim maker knows that internal nipples result in a stronger nipple bed. Perhaps a tad less servicable, but if you're serious about making rims - and especially carbon, you will always opt for internal nipples. And if the wheel needs to be trued after its normal break in period, then it wasn't built properly. Besides that, rough time to service? Even with internal nipples and hard glued tubulars this is really no issue. Just break the tire at that point and insert the wrench.

Jeesh - where do these 'reviewers' crawl out from under?
 
Sep 2, 2009
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#9
It's a bit 'funny' to hear people talk about 'climbing wheels' when most of them are over 65kg. Not to be disingenuous, but if you are over 60-65kg, then losing a few hundred grams on your wheels means nothing.
Looking at them, I would say that most of the Pro-Peleton were over 65kg. The guys on the front of the pack, definitely.
 

Sikochi

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#10
1) Wider tires result in less rolling resistance. This is a fact. Except for small gains in aerodynamics, narrowing the tire results in far worse losses in road resistance.
This has been the subject of a couple of recent discussions:-
http://velonews.competitor.com/2012/03/bikes-and-tech/technical-faq/tech-faq-again-bigger-tires-roll-faster_209888
In an email, Zipp lead engineer Josh Poertner said:
In general, a wider tire of (the) same construction will have lower rolling resistance for exactly the reasons (you stated). Ironically, the best description and data on this comes from studies done in Britain in the 1800′s looking to optimize the width and diameter of wheels for locomotives. There is also a lot of great info related to this in “Bicycling Science” from MIT press, as well as Paul Van Valkenberg’s writing on racecar tires.

Generally, though, the decrease in rolling resistance becomes smaller as the tires get bigger. So for example, going from a 19mm to a 20mm may save 1 watt, from a 20mm to a 21mm may save 0.8 watt and from a 23mm to a 25mm may save 0.3 watt. There is great data on this in “Bicycling Science,” using old Avocet Fasgrip tires, which were available from 18-32mm. The 28mm and 32mm were nearly identical, but moving from 18mm to 25mm saved a few watts.

What they are missing is the aerodynamic piece. We have data from the Zipp 303 launch showing the 303 with different width tires (see graph). The figure tells the story of how you can really optimize for tires below a certain (width) number, but eventually the tire really dominates the airflow and ruins everything. In general, our wheels are optimized around 23mm tires, which means that 21mm tires usually run about equal, maybe a fraction of a watt faster, but don’t change the behavior of the wheel. Moving to a 25mm adds drag, but can also change the stall behavior of the wheel. And by the time you are at 27mm, you have something that behaves quite differently.

The question really needs to be in regards to the balance of lower Crr (coefficient of rolling resistance) from the wider tire against the aero penalty. The 303 was designed to be as good as possible with 23mm tires, and as a result, its rim is 28.5mm wide. To behave similarly with the 25mm, it would likely have to be at least 2mm wider. In the graph you see how the 25mm tire has the same curve shape as the 23mm tire on the X45 (code for 303FC clincher). The 27mm tire is on the 285FC (code for 303FC tubular), and you notice that not only is the drag higher, but the curve shape is completely different. In fact, the curve shape looks more like the Easton or Mavic. This is indicative of the rim not being able to clean up the dirty air behind the tire. Ultimately, the offset should be Crr watts vs. Aero watts. In this case you have grams of drag on the left; every nine grams is one watt, so from 23mm to 25mm, you have nearly no penalty up to 10 degrees, and then three-to-six watts at the higher yaw. With the 27mm, you have something like no penalty to five degrees, and then a five-to-eight watt penalty after that.

Ultimately for the Specialized I would say that the 0.2 watt (0.3 to 0.8 watt) of rolling resistance does not overcome the zero-to-six-watt aero penalty.

Last interesting note: we have been working with Jordan Rapp on this since he noticed that his ‘training Firecrest’ wheels with 25′s were ‘twitchy’ compared to his race wheels with 23′s… we thought this might be largely aerodynamic, but the shorter contact patch (you) discuss is actually the culprit; the longer contact patch serves to resist steering input and adds a slight damping effect to steering inputs. By lowering tire pressure to increase contact patch, the effect could be eliminated, even though the aero properties of the wheel remain the same.

****
And this discussion - importance of tyre aero vs rolling resistance datas:-
http://forum.slowtwitch.com/forum/Slowtwitch_Forums_C1/Triathlon_Forum_F1/importance_of_tyre_aero_vs_rolling_resistance_data_P3823231
 
Sep 2, 2009
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#11
Interesting,

I did once bar-spin drop a 9 stair with no tyres or tubes on a set of G-Sport hubs (hardest hubs ever made PM me for info) laced to DT with G-Sport rims.
 

GSAstuto

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#12
Schlecks, Evans and ur countryman world champ, Cav are all around 65kg. Pure climbers are lower by 5-10kg, easily. Rouler / TT specialist heavier by 5-10kg.

Choosing wheel sets involves a lot of variables. But for the last 50yr or so, surprisingly hover within similar characteristics. One mans 23 is another's 25. With the preponderance of deeper (and lighter) rims, aero effects become much more noticeable positive and negative. There is no magic bullet. Rims optimized for laminar flow may suffer more at yaw angles, whereas rims designed to spoil, may suffer more at direct angles. As your speed lowers below 20kph, then aero is less a factor and tire choice / weight / rigidity play more roles.

Come out and play sometime and I'll let you spin up the hill on a 450gr (total) front wheel. You'll see what I mean. Both uphill and down. Same with the 38. It's quite an interesting experience.

So, by the way, why doesn't Mavic or Shimano let you test their wheels? Then you could more easily make a qualified decision. Im ALWAYS open to this.


Looking at them, I would say that most of the Pro-Peleton were over 65kg. The guys on the front of the pack, definitely.
 

Captain

Warming-Up
Mar 3, 2012
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#13
Did last years Etape on a set of Dura Ace 50mm carbon clinchers as could only take one set of wheels to Europe. Very happy with them and maybe a bit heavier on the long climbs but boy...were they a blast on those long descents :D
The tubs are even lighter so unless you want to spend silly money, you cannot go wrong with Dura Ace. Still managed to finish in top 2000 so don't think the weight penalty was too much and by the time I'd done another weeks riding in the Alps, was probably better than spending the money on a lighter set of wheels. Also the deep dish looks goooood on the bike :)