[elvisVerde]

I really don't understand these modern pre-built performance wheels. They look seriously, unambiguously cool but I don't understand the underlying principles. For reference, when I began serious cycling, almost all hubs were 36 hole. I do get why we don't all have to use 36 anymore, but the order-of-magnitude leap from 36/32 to 16/20/24 is too much for my world view. Help. I have a few basic questions...

1. In general, are the rims and/or hubs used in 16-20 spoke wheels significantly stronger than the rims I normally use--Mavic CXP-33 or Velocity AeroHead/Fusion/Deep-V?? Or, are these modern pre-built wheelsets just taking advantage of the large margin of untapped/excess strength in the modern design and materials in more traditional wheels (Campy or Shimano hubs, rims as mentioned, DT or Wheelsmith spokes)

2. If I build up a Velocity Fusion, or a Mavic CXP-33 rim (or OPro for those of who don't know the 33) and only use 16 or so of 13/14 guage spokes, do I get a wheel that is comparable to some of these jazzy looking hoops I see out on the road??

3. Thanks in Advance.

 

[Mark McM]

Wheels - yesterday and today

I really don't understand these modern pre-built performance wheels. They look seriously, unambiguously cool but I don't understand the underlying principles. For reference, when I began serious cycling, almost all hubs were 36 hole. I do get why we don't all have to use 36 anymore, but the order-of-magnitude leap from 36/32 to 16/20/24 is too much for my world view. Help. I have a few basic questions...

1. In general, are the rims and/or hubs used in 16-20 spoke wheels significantly stronger than the rims I normally use--Mavic CXP-33 or Velocity AeroHead/Fusion/Deep-V?? Or, are these modern pre-built wheelsets just taking advantage of the large margin of untapped/excess strength in the modern design and materials in more traditional wheels (Campy or Shimano hubs, rims as mentioned, DT or Wheelsmith spokes).

Yes, many modern rims are significantly stiffer and stronger than rims of yore. But that has come at a price - many modern rims are also significantly heavier than rims of yore. The weight reduction of modern bicycles has often been touted, but while overall weights have gone down, there are a few components whose weights have gone up. These include brakes, shifters, derailleurs and rims. Back in the day, a typical standard racing rim (example: Mavic GL330 or Super Champion Arc en Ciel, etc.) weighed about 350 grams, and if you wanted really lightweight components, there were several lightweight alternatives that weighed less than 300 grams (Mavic GEL280, Super Champion Performance, etc.). There were fewer high performance clincher rims available, but there were still several models that tipped the scales at around 400 grams. These days, a 370 gram or 420 gram clincher rim is considered "super light", and most weigh more.

Several changes occurred in the early 1990's. As more sprockets had been added to cassettes, the wheel dish increased, until we pretty much reached the limit of dish with 8spd wheels (9spd and 10spd were accomplished by squeezing more sprockets and a narrower chain into the same space as 8spd). The larger dish required larger differentials in right/left spoke tension, which required a stiffer, stronger rim, and the weight of rims went up. The second change was a greater emphasis on aerodynamics, and in response rim depths started to increase. This also increased strength, stiffness and weight. Finally, wheel manufacturers realized that removing spokes gave wheels the appearance of being both more aerodynamic and airy, and used the extra strength and stiffness of deep rims as a way to reduce the number of spokes. Although these new reduced spoke count wheels may look light and airy, they are usually heavier (sometimes far heavier) than wheels with a standard complement of spokes.

2. If I build up a Velocity Fusion, or a Mavic CXP-33 rim (or OPro for those of who don't know the 33) and only use 16 or so of 13/14 guage spokes, do I get a wheel that is comparable to some of these jazzy looking hoops I see out on the road??

Probably not. Although Velocity Fusion and CXP-33 rims are deeper, stiffer and stronger (and heavier) than rims of yore, they aren't as deep, stiff and strong (and heavy) as typical wheels with 16 spokes. Fusion and CXP33 rims are about 25mm deep and weigh about 480 grams, whereas most 16 spoke wheels use rim that are 30+mm deep and 540+ grams. Fusion and CXP-33 rims are usually best with 24 or more spokes (preferably 28 or more spokes).

 

[den bakker]

Yes, many modern rims are significantly stiffer and stronger than rims of yore. But that has come at a price - many modern rims are also significantly heavier than rims of yore. The weight reduction of modern bicycles has often been touted, but while overall weights have gone down, there are a few components whose weights have gone up. These include brakes, shifters, derailleurs and rims. Back in the day, a typical standard racing rim (example: Mavic GL330 or Super Champion Arc en Ciel, etc.) weighed about 350 grams, and if you wanted really lightweight components, there were several lightweight alternatives that weighed less than 300 grams (Mavic GEL280, Super Champion Performance, etc.). There were fewer high performance clincher rims available, but there were still several models that tipped the scales at around 400 grams. These days, a 370 gram or 420 gram clincher rim is considered "super light", and most weigh more.

Several changes occurred in the early 1990's. As more sprockets had been added to cassettes, the wheel dish increased, until we pretty much reached the limit of dish with 8spd wheels (9spd and 10spd were accomplished by squeezing more sprockets and a narrower chain into the same space as 8spd). The larger dish required larger differentials in right/left spoke tension, which required a stiffer, stronger rim, and the weight of rims went up. The second change was a greater emphasis on aerodynamics, and in response rim depths started to increase. This also increased strength, stiffness and weight. Finally, wheel manufacturers realized that removing spokes gave wheels the appearance of being both more aerodynamic and airy, and used the extra strength and stiffness of deep rims as a way to reduce the number of spokes. Although these new reduced spoke count wheels may look light and airy, they are usually heavier (sometimes far heavier) than wheels with a standard complement of spokes.



Probably not. Although Velocity Fusion and CXP-33 rims are deeper, stiffer and stronger (and heavier) than rims of yore, they aren't as deep, stiff and strong (and heavy) as typical wheels with 16 spokes. Fusion and CXP33 rims are about 25mm deep and weigh about 480 grams, whereas most 16 spoke wheels use rim that are 30+mm deep and 540+ grams. Fusion and CXP-33 rims are usually best with 24 or more spokes (preferably 28 or more spokes).

Slightly off topic question:
Would using an old (light) rim then be an issue with a modern (8+ speed) group?
Use GL 350 or 280 as reference.

 

[asgelle]

Slightly off topic question:
Would using an old (light) rim then be an issue with a modern (8+ speed) group?
Use GL 350 or 280 as reference.

I used a GL330 rear (32 spoke) as my race wheel for several years with 8 or 9 speeds without any problems, and I weigh 178 lbs. I only stopped when I picked up a set of Zipp 404's.

 

[rruff]

If I build up a Velocity Fusion, or a Mavic CXP-33 rim (or OPro for those of who don't know the 33) and only use 16 or so of 13/14 guage spokes, do I get a wheel that is comparable to some of these jazzy looking hoops I see out on the road??

If you used a Deep V or similar rim, you'd be real close...

It really isn't the best way to build a wheel, though. Using more of the lighter spokes will produce a longer lasting wheel... even if the total weight is less. You could instead use 24 CX-rays, for instance.

 

[FORT-Cyclist]

1. In general, are the rims and/or hubs used in 16-20 spoke wheels significantly stronger than the rims I normally use--Mavic CXP-33 or Velocity AeroHead/Fusion/Deep-V??

The Deep-V ist stronger than many rims used in prebuilt wheel sets, f.e. stronger than all the Shimano Aluminium rims.
There is no need even for a heavy rider to use the Deep-V with 32 or 36 spokes.
It's the same with the Fusion rim. 20 spokes front and 24 Spokes rear should do with most riders.
The CXP 33 is strong enough for a front wheel with 24 spokes and a light rider.
http://forum.tour-magazin.de/attachment.php?attachmentid=7075

2. If I build up a Velocity Fusion, or a Mavic CXP-33 rim (or OPro for those of who don't know the 33) and only use 16 or so of 13/14 guage spokes, do I get a wheel that is comparable to some of these jazzy looking hoops I see out on the road??

A light rider could give a try for a front wheel made of Fusion rim and 16 spokes but a CXP33 is too weak for that.

 

[rruff]

It's the same with the Fusion rim. 20 spokes front and 24 Spokes rear should do with most riders.
The CXP 33 is strong enough for a front wheel with 24 spokes and a light rider.
A light rider could give a try for a front wheel made of Fusion rim and 16 spokes but a CXP33 is too weak for that.

The CXP33 and Fusion are nearly the same dimensions and weights... so how do you get the Fusion being so much stronger?

 

[FORT-Cyclist]

The CXP33 and Fusion are nearly the same dimensions and weights... so how do you get the Fusion being so much stronger?

Don't think of the CXP 33 as a strong rim.
It has very thin walls.
A big part of the weigth of the CXP 33 (460g in heaviest 36-hole version) comes from the big eyelets and not from the rim itself.

The Fusion's profile is 2mm higher than that of the CXP33 and it's chamber is much wider than that of the CXP 33.
The Fusion has no eyelets so it's weight goes all to stiffness.

 

[SDizzle]

Just as a point of reference, in the shop the other day, I weighed a set of DA 7800 wheels at 1700g on the nose WITHOUT skewers. (This was on a Feedback digital hanging scale, so assume a 10g sensitivity/variance.) My all-purpose, 32h Ambrosio Balance/Campy Record/heavy 14-15 spokes wheels weigh 1780g WITH skewers, and I consider them very heavy.

In short, I'm with you.

 

[rruff]

A big part of the weigth of the CXP 33 (460g in heaviest 36-hole version) comes from the big eyelets and not from the rim itself.

I didn't realize that those have double eyelets... I thought they had no eyelets like my CXP23s.

 

[Mark McM]

Big eyelets, not double eyelets

I didn't realize that those have double eyelets... I thought they had no eyelets like my CXP23s.

The CXP 33 does not use a double eyelet. A double eyelet (also called a socketed eyelet) distributes spoke loads to both walls of a double wall rim. The CXP 33 eyelets are long enough to span the entire distance between the rim walls, but it doesn't actually have a lip that rests on the outside of the outer wall, so it doesn't distribute spoke loads to the outer wall. The reason that the eyelets are long enough to reach both walls is because, unlike most eyelets, it is not crimped into place, so has to be held passively between the inner and outer walls. If you shake an unbuilt CXP 33, you can hear the eyelets rattle around.

 

[rruff]

If you shake an unbuilt CXP 33, you can hear the eyelets rattle around.

Thanks for the info. So what do you think of that? Seems like an inefficient way to making a light and strong rim...

 

[rruff]

If you shake an unbuilt CXP 33, you can hear the eyelets rattle around.

Thanks for the info. So what do you think of that? Seems like an inefficient way to making a light and strong rim...

 

[il sogno]

I've never been impressed with the ride quality of modern wheels. Not only do they feel heavier and harsher riding but the prices are way more than regular custom built wheels.

I ride 28 spoke 2 and 3 cross tubular wheels. Ambrosio Chrono rim on the back, Campy Barcelona rim on the front. Campy hubs.

 

[California L33]

Finally, wheel manufacturers realized that removing spokes gave wheels the appearance of being both more aerodynamic and airy,

I assume by your italics that you're saying reducing spoke count doesn't increase the aerodynamics of a wheel that much. I always wondered about this. On the one hands spokes aren't big; on the other they do move as fast as the bike, and spin, and there are lots of them even on a "reduced spoke" wheel. Do you know how much reducing the spoke count decreased drag?

 

[Mark McM]

Zipp data on spoke count.

I assume by your italics that you're saying reducing spoke count doesn't increase the aerodynamics of a wheel that much. I always wondered about this. On the one hands spokes aren't big; on the other they do move as fast as the bike, and spin, and there are lots of them even on a "reduced spoke" wheel. Do you know how much reducing the spoke count decreased drag?

Zipp used to have experimental data on their web page showing the reduction in drag with reduced spoke counts (it used to be at http://www.zipp.com/tech/documents/ANoteonRimWidth_002.pdf), but they have unfortunately removed it. Anybody have a copy of the .pdf file?

Anyway, according to the data, the most important variables with tire/rim width and rim depth. Spoke count was a distant third. It is generally thought that the reason is because the spokes move through the turbulant air behind the leading edge of the rim. Reducing spoke count definitely does decrease drag, but it is only by a small amount, so spoke count is of secondary concern when designing an aero wheel.

 

[California L33]

Zipp used to have experimental data on their web page showing the reduction in drag with reduced spoke counts (it used to be at http://www.zipp.com/tech/documents/ANoteonRimWidth_002.pdf), but they have unfortunately removed it. Anybody have a copy of the .pdf file?

Anyway, according to the data, the most important variables with tire/rim width and rim depth. Spoke count was a distant third. It is generally thought that the reason is because the spokes move through the turbulant air behind the leading edge of the rim. Reducing spoke count definitely does decrease drag, but it is only by a small amount, so spoke count is of secondary concern when designing an aero wheel.

Thanks for the information. I don't have a copy of the pdf, and it's no longer on the ZIPP site, but you can view it, albeit with messed up graphs, by going to Google, doing a search for the file name "ANoteonRimWidth_002.pdf" and clicking, "View as HTML" when you get the results. You'll see a copy from Google's cache. It's interesting reading. (If anyone is interested, I'd suggest saving it as it'll probably be gone next time Google crawls the site and sees the original file isn't there anymore.)