Bikealangelo

Why do people opt for wider rims (e.g. Reynolds assault's) instead of older designs that have spokes that go almost all the way to the tire (like Shimano WH-RS500)? I tried out the Reynolds Assaults, and while they were faster on a straightaway, whenever I had a crosswind AT ALL, it was like I was riding a sail and I felt like I was working harder to keep the bike upright than I was working to get a reasonable speed. What am I missing? Do the gains somehow outweigh the cons?

datlas 

That’s not wide, that’s “deep section.” More aerodynamic so faster, but might be heavier and tougher in crosswinds.

Wider means rim width not depth.

Bikealangelo

Thanks for clarifying, so in specific instances it makes sense?

Russ Roth

Rim design matters for how well the wind effects things but I have my 12yo daughter on 32mm deep rims on her road bike and 45mm deep on her track bike and even in stiff winds on the track has never struggled to control her bike or riding along the ocean with high wind speeds. At only 41mm deep I wouldn't think they'd be effected that badly unless they're not a newer shape or you're riding in really high winds. Basically though, unless you have a tailwind that's faster than you're going, you're always riding into a wind and an aero profile rim when specced with a proper size tire will always help you save time/energy. When companies speak of watts saved at 40kph/25mph which seems like an absurd speed for the average rider to maintain, they're actually referring to combined speed, if you're doing 15mph into a 10mph wind you're hit their 25mph, so they really do have the benefits reputable companies claim for the average rider.

tempocyclist

In most circumstances, yes. Plus they look hot. 😎

Zaskar

Look Bikealangelo, just because you have the coolest username... okay, that's all I got.

Weight can a factor too - in that lighter AND newer riders might feel uncomfortable on deep section wheels.
But yeah, there are pros and cons...
Cons:
- can be heavier
- are more expensive
- can be a factor in strong cross winds
Pros
- faster
- look cool
- look cool (worth mentioning twice)

WhyFi

When it comes to cross-winds, rim profile is important. My Reynolds Assaults were significantly worse in cross-winds than my current Zipp 303S; I don't really feel much wheel push, at all, with the Zipps; it's less prominent than on the frame/my body. With the Reynolds, it's was like an invisible hand nudging my bars.

Zaskar

I'm curious WhyFi - what do you weigh and which Assaults did you have? I'm about 180lbs and love my 42mm Assaults - haven't felt any adverse effects from the wind.

Eric F 

My older Shimano C50s are like that. My current Enves, not much at all.

msu2001la

I've noticed crosswinds buffeting me around a few times while on my Zipp 303S, but only in some pretty extreme conditions, and even then it's relatively minor.
I have a shallower depth wheelset and I've never felt the need to swap due to wind conditions.

WhyFi

Roughly the same weight. They were a disc brake model, the SLG, I think? This was before they went to the wider internal width, so 17mm internal, maybe 25mm external.

Bah Humbug

Experience also affects the perception of the wind - at first it feels a lot stronger than it will after a season of adjusting to it. Shape still affects it, though.

Broctoon

Something else worth mentioning in a discussion of deep rims is the shape. Early attempts at really aerodynamically efficient rims were V-shaped, with flat sidewalls and a fairly sharp apex. Later, engineers learned that it's better to make more of a U-shape, or even to bulge the sidewalls out slightly wider than the bead area. Today's fastest (and most expensive) rims have little bumps around the circumference of the apex, the area where the spokes enter. These are claimed to prevent a stall, or area of low pressure next to the rim, which could add a little inefficiency.

I'll add my own opinion with this... Among all the wheels I have for my several bikes, there's only one carbon set. They are Reynolds rims. I don't know the model, but they're ten or fifteen years old I think, with really nice but heavy hubs. They're my deepest rims (although not much deeper than some 20 year old alloys I have) and they're V-shaped and a bit on the heavy side. I don't have any illusions that they are faster than some much less "fancy" wheels. They *might* be no better than some really old-tech but lightweight box section rims, for the kind of riding I'm doing. I still love them. They look cool, they make me feel like I'll be able to ride fast, they're more than tough enough for the use I put them to. And did I mention they look cool?

LarrySellerz

They look really fast

Broctoon

People will laugh, but this is a thing.

I've made no attempts in this forum to hide the fact that I'm a Cat 6 racer. When you're trying to beat a guy who probably doesn't know he's in a race, image is important. Psychology makes a real difference in athletic performance. I show up with my coolest looking bike and my favorite bib and jersey, and I'm ready to push myself hard. With lesser gear, I'll have an excuse to underperform.

You can start making fun of me now. (Hides under desk)

Jrasero

You mean deep, but it really depends on the rider and where and when they ride. This is why personally I think a mid-tier depth wheel at 40mm-45mm makes the most sense, however there are some 35mm-38mm wheels that perform just as good aerodynamically as some 50mm ones yet will not have as much as a crosswind penalty.

My suggestion is to go staggered. My favorite wheelset to this day is the 2023 Winspace D45 where you have a 46mm wheel upfront and 54mm at the back, this allow for more control upfront while still getting pretty good aero gains.

Chandne

My newest wheels are not really deep at maybe 40mm but that is about as deep as I want for here in Colorado. It is pretty unaffected by crosswinds and similar to my 30mm alloy rims. I woudl not want deeper for two reason- crosswind stability and stiffness. Deeper carbon wheels tend to be stiffer/harsher and the crosswind stability is reduced. If I loved in flat terrain where it isn't too windy, I'd maybe step up to the 404s or keep 404s as a 2nd wheelset, but nothing deeper. The 303s are very comfy and light wheels and I bet the 404s are heavier and stiffer/less compliant.

RB1-luvr

I'll admit I only bought them for the hotness. I wanted hot wheels for decades. When I built my Ritchey (had it built), I went for it. Since 2016 when I got the bike, I can remember maybe a half dozen times when wind was a small issue. Maybe cuz I opted for a less deep v-section for the front.

Jrasero

I should also note while deep wheels will be faster it also really depends on your power. I am smaller rider and average 140W-150W, so nothing amazing and for me to get a heavier 65mm spun up to speed especially in a lot of stop and go cycling was tiresome. People will debate all day about rotational weight or if the weight of your wheels actually matters over watts saved via deeper aero wheels, but they always seem to forget these aero gains are mostly tested in win tunnels and as 20+ MPH. Again this is why I would recommend your front wheel being 50mm or less unless you are putting out some serious watts

HTupolev

What makes you think that people forget that aero differences are often tested at 20+ mph?

Jrasero

What makes you think most people understand any aero gains really start at 20+mph?

HTupolev

I'm not sure what you mean. Aero gains do not "really start at 20+mph."

PeteHski

While people endlessly debate it, engineers calculate what power it actually takes to accelerate a set of wheels. The answer is actually very little when comparing a typical weight difference between aero and lightweight climbing wheels eg 3-400g. The accelerations involved are also relatively small, even on a full bore sprint.

Russ Roth

That 20+ mph for best gains is a combination of you and the wind, not just you. The wheels in the wind tunnel may be spinning but they're not moving forward so in the windtunnel all of that 20+mph is how fast the wind is moving not the rider. On the road its a combination. So even a slow rider can find some benefit, even if they only average 14mph, a breeze can provide the other 6+ for full benefit.

msu2001la

Any?