On Rim Dimples, Active Turbulator Lips, Depth, Width - ??

Back by popular demand, the general all-things Road forum!

Moderator: robbosmans

Post Reply
User avatar
prendrefeu
Posts: 8580
Joined: Wed Oct 31, 2007 10:32 pm
Location: Glendale / Los Angeles, California
Contact:

by prendrefeu

Pre-post note: I genuinely miss what Roues-Artisanales was doing years ago when they took a wide range of wheels and charted their aero qualities against each other. It was an actual 3rd party, non-industry, non-media, non-corporate test of products against each other and stood as a benchmark for comparison for quite some time. We, both roadies and Tri riders, are seriously at a loss since no one has truly taken the place of the extent of his testing. :(

Anyway... on to the post:

I have an opportunity being presented to me: ZIPP 404 FC rims, custom drilling that I can lace to hubs of my own choosing, rims at dealer cost (someone owes me something, this is a drop in a pond to be fair). My research on the rims however hasn't been very fruitful: reviews on ZIPP have tended to be on the negative side wherein people are comparing them with ENVE, Bontrager, Roval and so forth - yet in all of these situations the 'reviews' and 'comments' I'm finding in my search are pointing to fully built, factory-delivered wheelsets where ZIPP is notoriously bad in the hub department. It's been genuinely difficult to find data and reviews on the qualities of the rims vs. rims vs. rims

This has lead me to investigate qualities of the rims and try to make some kind of judgement about what rims are better, and this has been rather difficult: I'm unable to find any rim profiles for the Roval CLX 60 or the Bontrager Aeolus series, nor the ENVE SES series, nor Xentis but they do have their "active turbulator lips"

Furthermore: dimples (ZIPP) and Active Turbulator Lips (Xentis). Do they work? Are they real? When ZIPP's patent expires in a few years will we see other manufacturers pick up similar surface treatments? Searching on the internet has been inconclusive: some say no, some say yes, ZIPP says yes, m.e. engineers are split on the decision, F1 aero engineers have no comment. Xentis lips say yes, but all I hear are crickets when it comes to comments about if that works or not.

So what's the deal? Should I go for the opportunity to get these rims, or should I pass?
If pass, why? Is the FC suddenly not aero anymore whereas the FS is? Are the Roval CLX 60 rims that much faster?

Also assume the following: I'm not interested (at this time) in ANY factory built wheelset and actively seek the rims as separate items for a custom build.


I miss Roues-Artisanales testing. :(
Exp001 || Other projects in the works.

nathanong87
Resident master of GIF
Posts: 3405
Joined: Mon Jul 18, 2011 2:44 am
Contact:

by nathanong87

prendrefeu wrote:o for the opportunity to get these rims, or should I pass?


well, how sick would they look on your whip? aesthetics metric seems critical at this juncture based on your build up thread

i've also been beaten in a RR by someone on zipp 404 FC

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
prendrefeu
Posts: 8580
Joined: Wed Oct 31, 2007 10:32 pm
Location: Glendale / Los Angeles, California
Contact:

by prendrefeu

They'd look hella sick. :twisted:
But is that the depth? You know, deep rims, rollin' deep? Because they're all going deep these days and fat, which is all phat. (pretty hot and tempting)
But you know, dimples? Are the dimples doing anything? What about lips?

(This could all be euphemisms of course)

So if I'm going deep, and I'm going fat, which rims should a person be rollin' ?





unrelated pic:
Image
Exp001 || Other projects in the works.

User avatar
ergott
Posts: 2870
Joined: Tue Apr 18, 2006 3:03 am
Location: Islip, NY
Contact:

by ergott

If you have the opportunity to get some Firecrest 404s for a good deal do it. They are great rims. I'd use them in builds if they were regularly available. I've build a bunch of them either for PowerTap hub swaps or for people that don't like the stock hubs (plenty of that going around).

mimason
Posts: 654
Joined: Tue Feb 24, 2009 11:43 pm
Location: Florida

by mimason

I miss their testing too. Funny you brought it up as I pulled it up recently.

Regarding the rims I'll echo what ergott said and he should know. At dealer pricing(I know what that is) you'd be near crazy not to. I've always said I'd jump for Zipps if they would build with Shimano, CK or WI hubs. 58mm rims are nice too and are good in the crosswinds.....very fast.

Dimples? Not sure but golf balls like them.

You got my vote...but they ain't weenie if you care about that.

Marin
Posts: 4035
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

prendrefeu, are you set up to do some Chung method testing? Would be very interesting!

User avatar
Kayrehn
Posts: 1776
Joined: Thu Mar 24, 2011 6:06 pm

by Kayrehn

Paul Lew said before dimples on side walls doesn't work and my unscientific mind is inclined to believe that too. It should only work if it is facing straight on into the wind.

Sent from my SM-G900F using Tapatalk

User avatar
prendrefeu
Posts: 8580
Joined: Wed Oct 31, 2007 10:32 pm
Location: Glendale / Los Angeles, California
Contact:

by prendrefeu

So at 0 yaw the dimples are affective, but not useful (at all) at different yaw angles?
Yet with very (very) subtle changes in shape we're seeing charts where a rim from another brand at a similar depth and width is "dramatically" faster at 0 yaw and elsewhere?

It's very frustrating that there is no true credible source for outright comparable data anymore.
Exp001 || Other projects in the works.

RyanH
Moderator
Posts: 3185
Joined: Tue Jan 17, 2012 4:01 pm
Location: Los Angeles, CA
Contact:

by RyanH

I don't think the aero gains are being made at the 0* yaw angle but more so fine tuning the 5-15* yaw angle drag. From what I saw, the big difference between FC and FS was that they found they could move the drag curve down to the 10* range or so rather than it being optimum at 15*+.

My guess is that even with this said, there is going to be very little real world difference that unless you're racing a TT, it probably won't matter. Now, what I'd be buying them based on, would be: braking and handling in crosswinds. I think Zipp excels in both of those arenas.

Derf
Posts: 99
Joined: Wed Jun 13, 2012 11:23 pm

by Derf

404 is used often enough as a "compare-to" wheel and Tour has tests that show them to be quite competent. The dimpling is going to have a small effect on the boundary layer, but if it were a major effect, you'd see it show up in comparisons. Definitely less than playing around with different tires. Lots of very competent, low drag wheels in this range that are all within margins of each other.

So, I'm with RyanH here--braking/crosswind performance (and cost!)

User avatar
F45
Posts: 1077
Joined: Wed Jun 08, 2011 6:08 am

by F45

Were you unable to locate the everything wheels forum?

User avatar
prendrefeu
Posts: 8580
Joined: Wed Oct 31, 2007 10:32 pm
Location: Glendale / Los Angeles, California
Contact:

by prendrefeu

I'm well aware of the Everything Wheels forum, however I've been observing that a lot of the 'aero' discussion, wheels or not, tends to be in the Road forum.

Hence the intentional posting of the subject here.
Exp001 || Other projects in the works.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



Post Reply