Seems like the width of wheels for road cycling continues to widen every year. I bought some Boyd Carbon Clinchers a few years ago with 19 mm internal width, which at the time seemed to be on the leading edge of wide road wheels. Now, over the past month or so, Flo has increased the width of their wheels from 17 mm to 21 mm, and the new Enve and Zipp wheels are 21 mm and 23 mm, respectively.
Any thoughts on whether these wider widths are being offered because they are better for road cycling speed/comfort, or is this just an attempt to offer a more versatile wheelset for road/gravel/path even though it may cause a slight penalty on the road?
I guess ultimately I am wondering what is the best width for road cycling for those who are not going to be riding on gravel or paths?
Iām also curious if something similar is happening in road that happened in MTB the past 3 or so years. It seemed they were touting the benefits of plus tires in the 2.8in range before relatively quickly scaling back to the 2.4-2.6 range.
On the road side I wonder if there is a sort of race to the widest road rim. Getting a little carried away with the falacy of āIf 19mm is better than 17mm then 21mm is better than 19mmā until they realize that they maybe went a little too far and start scaling back.
But what do I know? Iāve never bought aftermarket rims for my road bike. But on the MTB side I definitely felt that going from 27.5x2.8 to 29x2.25 was an upgrade rather than a downgrade.
I think you have to back into it based on what tires you ultimately want to run.
And then you need to factor in tire bulge and actual installed width.
And are you trying to be aero optimized? Iām talking about the 105% rule where the widest part of the rim is 105% of the tireās width.
That said, here is my dream bike / wheelset. Iād love to run fully aero optimized 28mm tires. They will probably stretch to 32mm and Iām not sure if you can stay aero optimized with 28mm tires. A Cannondale Knot 64 wheelset is 32mm wide but a 25mm tires that stretches to 28-29mm is still probably the fastest tire.
Why do I want this wheel? Well, we have some very rough roads around here. I think a higher volume, very aero wheel that can run at 50-60psi would be the fastest wheel on our roads.
The problem for me - my bike will only fit a maximum actual width 27mm tires which is a 25mm tire that isnāt too tall (like a GP5000). My next frame will be one that, at minimum, takes tires up to 30-32mm actual.
At only 27mm wide, that rim is not going to be aero optimized with a 28mm tire that stretches out to 30+ mm. To be aero youāll still have to use a 25mm tire (27mm actual).
I guess you will have to take that up with Zipp as they see it a bit differently. I donāt have a dog in the hunt as Iām on Enveās, just passing along their info
*The key innovation is in the 303 Sās rim design. Its 45mm rim depth is the same as its predecessor, the 302 Disc brake. But its external rim width is 2mm wider, at 27mm, and its tire bed is a full 7mm wider, at 23mm internal width. That rim platform is designed to be the fastest with a 28mm tire.
Iāve been following the 105% rule on my road bike, but have been wondering about it for gravel. Is it just not possible for gravel tires, say 38mm, and we just need to go as wide aero wheels as possible?
Iām thinking that when Zipp says 28mm tire, they mean a 28mm actual width tire. And in most cases that will be a tire marked 25mm.
In any case, I donāt care what their marketing speak says. If the tire is larger than the largest part of the rim then it will not be aero optimized.
Whatās your thoughts on that video. Iāve followed the 105% rule, but maybe specialized is saying the penalty isnāt as harsh as previously thought?
The problem of potentially having a rim that would obey the 105 with a 38mm gravel tire it it would change the shape of the tire and potentially compromise itās performance from a grim standpoint. If a tire manufacturer developed a tire so all the lugs were in the right place on a 19mm internal width rim, putting that tire on a 30mm internal width rim could move the lugs so they are less effective.
It will be interesting to see when the new ERTO standards come out what wheel and tire manufacturers will land on in terms of internal width to standardize on (ie a 28mm tire measures 28mm wide on a 21mm internal width)
Anyways, for what itās worth, Josh Poertner (of Zipp and Silca) said on his podcast a while back he thinks ultimately tire size will land in the 30-32mm range in the US and 28-30mm range in Europe
Interesting video BUT (without more test details) Iāll say this: Those quoted 40km ITT times are usually based on elite level ITT speeds (40km/hr or 30mph). Who is going to ride their gravel bike with 40mm tires @ 30mph for an hour?
Iām just speculating because we donāt have the test details but the 16/40 seconds saved probably falls to essentially zero savings at normal gravel speeds.
So one can look at their average speeds for gravel and decide what they are trying to accomplish. If I was an elite level rider doing the Belgium Waffle Ride (140miles with a lot of road) on 30/32mm tires then a small aero benefit would probably be worth it. But average joe riding 14-20mph on gravel probably doesnāt need and doesnāt make use of a $2000 carbon aero wheelset.
FWIW, I actually set a Strava KOM on a 10 minute gravel section the other day. My average speed was 19.2mph. What would an aero set of wheels saved me. 1 or 2 seconds?
So are you saying you wouldnāt recommend buying aero wheels on a road bike with say 25mm tires if you only average 19mph? My riding says at that speed aero wheels do provide a noticeable difference.
Iāll have to see if specialized list their test speed anywhere. I believe I remember them saying that their wind tunnel was special in that it was built for bikes allowing for slow speeds and granularity. Compared to normal wind tunnels designed for cars.
I thought we were talking about gravel tires here?
On the road I do think aero wheels are worth it if your goal is saving a few watts.
But in general you can look up any āsaves X seconds in a 40k TTā and the speed will be elite level ITT speeds. If they say you are saving 40 seconds then at pedestrian speeds you are saving maybe 1/4 or 1/3 of that.
As you can see, the slower less powerful rider saves more time in absolute terms than the faster more power rider. However, when expressed as a percentage of time saved, they are nearly equivalent savings, with the faster more powerful rider making very slightly better gains in percentage terms.
The issue comes where the faster speeds will lead to a smaller yaw angle depending on what the wind speed is.
When youāre going slower you save MORE time over a given distance by improving aerodynamics. If that elite itt rider saved thirty seconds or whatever, that ten watts savings would give you more, not less.
