There are changes going on now in the < 30 profile.

I can only speak on what has been announced publicly.

I agree that in the 50/25wide the rims are pretty close. When we tested vs 80 and thereabouts we saw the larger was not faster and offered handling issues on the courses we were looking at. Our team was sponsored by HED and Specialized, so we had some options (the VOS rules had wheel rules). Anyway the fastest riders were on 50mm/25s.

I'm now seeing (public) changes in configuration. Rims higher than 2.5 cm, fewer than 16 spokes, spoke thicknesses of over 2.4 mm require UCI approval. So I just bought some non-UCI approved 25 profile that I believe are quite aero. And very light. Certainly to the point that it is an easy choice for anything hilly.

;)

indeed.

I remember reading an analysis years ago that said the aerodynamic gains of going from a 20mm rim to a 30mm were greater than going from 30-50. The point being that as the rim gets deeper, the returns diminish.

So it does not surprise me that we are reaching a point were companies can produce rims in the 50mm or 60mm range that are basically as aerodynamic as anything deeper.

head on, the aero rims don't differ very much. it's in cross wind conditions where most of the savings are made with deep rims.

That UCI rule that requires approval for profiles over 25mm costs MFGs money. If the wheel is 25mm profile or under - no money spent.
Normally a mfg donates some sets for testing and sometimes some airplane trips for UCI approval, paperwork and time. So even if you the racer never does UCI races, if your wheel MFG sell to that group, there is cost in the product for getting approval.
So a 30mm that is just a wee bigger than a 25mm could be a tougher justification as it carries UCI approval requirements for most brand name mfgs.


Part II
Similar subject - but different. I got these new Vittoria Speed G+ tubulars in 23mm (200g, measure 22ish) for 20.5mm wide/25 profile climbing wheels. The climbing wheels are delayed and not needed till summer. The 25mm tires are not here yet and needed sooner. So I put the 23s on the 25mm wide/50 profile for something to do, and they look good.
The tire rests in the rim well and maybe a thread of base tape is seen. I had never thought of doing this setup.
You can't see the rim is wider. I wonder how the wind feels about that. At 25-30 will the wind still be deflecting over the rim, or will it be coming back in to hit that edge? I'm going with deflecting. I hate this setup on a car as the possibility to curb the rims. But here, I'm wondering.

I'd be more concerned about grounding out in bumpy corners.

Definitely a rock could hit them, but I don't think corners would be that much worse.

Attachment 550546

So... I currently own ENVE 4.5s and I'm really happy with them in almost all scenarios, but I really, really, really hate how I feel on descents with gusty crosswinds because I lose steering control and it feels very sketchy and unsafe. Its been like 1.5yrs with them now and I don't really remember how I felt in these conditions with my old bike on normal alloy training wheels, but I'm quite concerned about the fact that there are a couple races I want to do this year that have descents where I would potentially encounter these conditions (or at least, I've noticed the gusts of wind to be an issue on the recce rides i've done of the courses)

Maybe the answer here is "yeah, gusty conditions suck no matter what, do some upper body work and practice so you have more control over your bike" or something, but I wonder also if an alternative set of wheels might make things easier? The 4.5s aren't that deep or that heavy, but I'm wondering if there is a wheelset which would be noticeably better in gusty scenarios? Also, if I were to get a less deep wheel would make sense to just buy a set of climbing wheels instead (if I'm only going to use them occasionally on races with windy descents, maybe I could even go tubular to save weight?). I've been hesitant to buy climbing specific wheels (and I'm implicitly assuming less deep = lighter = climbing wheels = safer handling, which isn't necessarily true) because a) I ride an S5, not a climbing bike already, so its hardly a weight weenie bike b) I'd only use them on special occasions like hill climbs or races so it would be harder to justify the cost than the 4.5s which I ride on every day.

Could also be a frame geometry/fit thing. But as mentioned, there are very fast narrow lower profile wheels. Have you ridden other bikes with these wheels, or other wheels on your bike? The next logical spend money thing to do is go lower profile on front.

My project.
This is Di2 and not lightweight stuff in any power area. DA pedals, cranks, front and rear shifters and brake levers and super crazy slippery drive train. It is a go up hill bike. I might move the big cassette cogs out from the wheel for chain line and gain a few grams. I have 50 extra grams in Di2 cable routing but it is so clean I can't give that up. Di2 cable route through stem into cavernous head tube and show up at top of seat post.

Anyway 12.25lbs (with WB cage and Garmin holder) is about the best I can do without sacrificing power transfer - that is an estimate of race weight - not done yet.
Likely will loose bar tape. Still working on it. I have little control over the engine anymore, but that does not stop the fun of the project.
Attachment 551101

Attachment 551102

The paint on that bike is probably costing you 200 grams.

I am aware of that.
I was thinking 150 - but whatever.

No pretense this is not my project. Most weight-weenie builds I see can't handle power. This can. Actually more than the stock build. That is just in case my engine is running well.

Some day, I'll post my bike (the one I pedal). I think you'd all be surprised.

[MENTION=350004]scheibo[/MENTION] - A possibility might be Specialized's CLX 32s. They're brand new this year and the last time I checked the dealer's website (I work at a Specialized LBS) they were out of stock with a get-well time frame of late January - right about now. I haven't seen any in real life and haven't read any non-Specialized reviews on them, but the ad copy sounds good. One possible issue - I have it in the back of my mind that S5s have relatively little clearance for tires, and they're wide rims. Since the back of my mind is pretty cluttered :), I might have that wrong.

My flo 30s have wide rims but I have 23 tires. The gap on the rear is miniscule. 25s don't fit.

Buy a shallow front wheel.

I've found that even 45mm rims are sketchy for me once I'm doing 50 mph. I can't imaging descending in a race where I've gone well into 60 mph (box section front wheel, Zipp 440 or TriSpoke rear I forget).

You can always run a tall rear wheel. It's actually so stabilizing it's harder to initiate turns at much higher speeds (55 mph?).

As far as bike weight goes... for me I've always found that once I blow up I'm pretty slow no matter what stuff is on my bike.

Gusty winds suck no matter what.. you are a lightweight compared to my 84kgs. I have 4.5s Clincher and 2.2 tubs and I can feel the wind for sure even with 2.2s. But I'm out in the east bay where it might be a little more windy. Last time I climbed Mt Diablo for example, I got up around 2500ft and the winds really picked up and even with 2.2s, I was getting blown.

Finished building, setting up, fitted my new race bike. Shake down ride tomorrow morning.
Can't believe it came in at 16.2 pounds. I know for some here it's "heavy", but I think this is is the lightest bike I ever had.

:thumb:

As luck would have it, I decided to ride my 'rain bike' (a CAAD10 with aluminum wheels) today and it was crazy windy. There were a couple gusts and I felt like 1000% safer than on my S5 w/ 4.5s (ie/ I didn't feel like I wanted to sh*t myself and quit cycling the entire time like I do when theres gusty descents on my S5). This is hardly conclusive evidence though, because:

a) I always feel more comfortable handling on the CAAD10 (even in non windy conditions). My S5 setup is twitchy AF, I can barely ride with no hands for longer than a couple seconds compared to comfortably riding with no hands on the CAAD (that being said). They *fit* roughly the same (the Cervelo handlebars are a little lower currently, but even when I had them up higher I was still having issues with its 'twitchiness').
b) Different day, different descents. These weren't exactly the same descents/winds/gusts that gave me problems on my regular bike, so its hard to tell.

So, I can't *really* tell what variable actually made me more comfortable today, but I'd say theres maybe some small positive evidence that lower profile wheels might have helped. The answer also might just be - when I'm racing in potentially windy conditions (backside of Mt.Hamilton/Mines road descent in that RR, Pescadero RR along Stage on a bad day, Patterson Pass/races out in Altamont etc) I should maybe just ride my 'rain bike' which is a perfectly acceptable bike and the 3lb difference and lack of aero probably won't make *that* big a deal.

Yeah, clearance is possibly an issue. I also have a visceral dislike Specialized as a brand, for reasons I've never actually been able to articulate to myself.

Maybe I'm crazy, but I think it would look weird to have like a regular wheel in the front and deep section wheel in the back? I realize I shouldn't care about looks and just mainly care about function, but I think going both deep section or both shallow would look more aesthetically pleasing (though clearly more expensive, and potentially less effective if what carpediemracing says is true about the rear wheel offering stability).

A 16 spoke narrow 25 is likely as aero as a 20-24 spoke 25 wide 50 profile. Or close. There is a lot of focus on things that don't matter that much. I have it on good authority that spoke count matters more than profile these days.

I like function for looks. If it's functional I like it.

45mm front, 90 rear.
https://4.bp.blogspot.com/-UB40AQ5qP...816161859c.jpg

75mm front, 90 rear.
https://3.bp.blogspot.com/-c0lZp-NXL...607161858a.jpg

24mm front, 90mm rear.
http://2.bp.blogspot.com/_TbmplkIYLx...10202_Bike.jpg

In the opposite direction I used to train and race with a front Specialized TriSpoke, regular spoke rear wheel. I did this when I realized that the fastest wheels around were the TriSpoke, and I used it up front because 2/3 of a pair of wheels' aero benefits are from the front wheel, or so it goes. I have no pictures of me on such a set up although I'd pair it with a box rear (Campy Eurus), a Spinergy Rev-X, or a second TriSpoke. Video of my bike here (at the beginning):
There were other riders who did this as well. Nate... Shaeffer? US National team, used to ride a front TriSpoke, in the video Hammer and Hell he's featured prominently as he and Lance work over Sean Yates to get 1st and 3rd on one of the stages. https://vimeo.com/82999933 go to 15:30 and 16:30.

OK, so zero-dollar, zero-commitment testing option, take the front wheel off the rain bike, put it on the Cervelo, ride it in the wind. You have your answer about whether the wheel helps. If it does, you can keep riding that combo, or buy a prettier low profile front wheel. Does not have to be carbon, skinny alu wheels are plenty light, so it doesn't have to cost a lot. Since it's not your permanent set up, just live with the aesthetics those few times you use it.

I have a friend who had a Cervelo S3, and when she changed to a non-aero frame bike, mentioned that the Cervelo itself was horrible in the wind - she thought the frame itself was the issue.

Personally, I race Zipp 303/404 combo (I think that's about the same depth as your Enves), and when it's windy put my aluminum training wheel on the front. That does seem to help. My frame isn't aero, though.

I pulled up to race once and as I picked up my Zipp 404, the wind got it and lifted it so it was almost perpendicular to the ground. When that happened, I put the Zipps back in the car and went with my basic aluminum rims.