Koyote
My new-ish gravel bike was full custom, including the wheelset: DT 350 hubs, good alloy rims, and double-butted spokes laced 32h/3x.  They probably weigh around 1800 grams and are obviously not very aero. 

Now I'm considering some pretty ambitious (=looong and tough) gravel races, like the 210-mile Coast-to-Coast Gravel Grinder. Am wondering if lighter and more aero wheels will make enough difference to justify the cost; looks like around $1500 will get me some decent wheels of about 1500 grams, with carbon fiber rims of about 30-35mm depth, aero spokes, and good hubs.

So, will -300 grams and a bit of aero goodness make much difference? 

Am interested in all opinions, and I thank you in advance.
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chas
Hay sounds like a question for the heart.

Generally with a ride like that - weight makes a difference for my endurance more than my speed.  I"m not too sold on "aero" and gravel tires.  Realistically, that is not a fast race (well if you don't burn too many matches in the flatter first half).  15mph is a decent speed for the first half - is aero important for that?  (well, it does tend to be into the wind).

I had Brett at mill city cycles build me some light carbon wheels for a lot less than that - so keep him in mind.  

For that type of race - the most important thing is that the bike is super comfortable for you, and that your tires can handle the sand...
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spinergypaul
check out our GXC carbon wheels retail price is $1776 but we have a special going on right now for $999. use code carbon99

the PBO spokes are lighter and stronger than steel and do a better job of absorbing vibration on rough terrain. We have no weight limit on our wheels and sell them for tandem use as well.
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SWGraveler
Despite all the science, folks continue to doubt aero. I'll quote Gerard Vroomen; "watch a pro marathon; runners draft"; I think that says it all. However, it has been stated many times that the most gain/$ is an aero style helmet which is a relative bargain. Aero wheels will make a difference but don't expect to be wowed by them at typical gravel speeds. The simple fact is that unless you can ride the same ride in the same conditions and condition on the same bike with different wheels, you will never know if they made a difference. This applies to any part/bike. Ignoring the science is so funny; people act like we are being ripped off and tend to be righteous about it. Look at World Tour road riders; the highest dollar arena in cycling. Ineos went against their sponsored brand and provided Lightweight brand wheels for their riders for the TdF mountain stages this year. When it matters, wheel weight matters. 

If you are happy with your bike and have ~$1500 to spend, wheels will make a difference you will notice. All the accelerations will be a tad easier with lighter wheels and there are more of those than you may realize.. I've been riding for 30+ years and I've been a gear geek the whole time. Additionally, having spent 15 years in the industry which has facilitated my buying/trying things I would never buy otherwise and I have come to believe that the hype about wheels is not hype at all, it is real.

Don't fall into the all carbon wheels are the same belief; cheaper is cheaper, and probably not the same. My advice is to spend every dime you can afford on wheels.. But, look at rim weight, not wheel weight as hubs are an easy way to cut weight and potentially the last place you want less weight. The rotational effect applies to the rims much more than the hubs which are not really any different than say your stem.. I would rather have Enve rims with DT350 hubs than a heavier rim with light hubs and potentially the same wheel weight. You ask a lot of your hubs and if they fail, you are walking. Making a light hub is a relatively easy and inexpensive thing. Making a light, strong rim is much more expensive..

Go to a bike shop that stocks expensive wheels; hold the front wheel from a set of whatever gram wheels in your hand and have someone spin it as fast as they can. While it is spinning, move the wheel around. Repeat with the front from a set of ~300 less gram wheels. Understand the wheel is probably moving at less than 10mph. You will feel the difference and understand the effect of rotational mass. Consider what it means to steering/acclerations/ minor direction changes etc. I think your decision will be easier..


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ljsmith
Keep in mind that to get aero benefits, the external rim width needs to be about as wide as your tires.  Since there are no aero wheels as wide as gravel tires I doubt you’ll get much benefit.   I have a set of Zipp 303 Firecrests with 35c Hutchinson Overide tires, but I have found no benefit over non aero wheels I use on the same bike.  I really wish I could say they made a difference, they did make my wallet a lot lighter.  On my road bike the tire width is matched to the aero rim width and I actually am a little faster with the aero wheels.
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chas

So, look for good weight (in wheels and tires).  Aero is important (especially riding west for 210 miles).  There are a lot of ways to be aero – and wheels are the smallest bang for your buck – and hard to do with gravel tires.  Any (non bike item) that touches your body is likely to have a similar impact.  You are going to be glad the weight is light when you get to the second half of the C2C. 

As for bikes – the Aluminum Canyon Grail would be great for this race – and is a good bang for the buck.  But bike vs wheels – that’s up to you.

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rdavis32
Similar to Koyote, I am delving into determining a wheelset for my Gravel bike (likely a Carbonda 505 frame). Am trying to answer what mix of compliance, aero benefit, and rolling efficiency make the most sense.  I'm sure the "it depends" answer is apropo here.  However, is there such a thing as a wider aero rim, that has reasonable cross wind behaviors, is "soft" (compliant), and rolls really well? I can't, and wouldn't, spend $1200+ on a wheelset.  What about bladed spokes?  Important or a compliance penalty? There are lightweight aluminum rims too.  What's that mix or tradeoffs to consider?
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chas
For real gravel, I'm using fat tires (40mm+) and going relatively slow (average 15mph) - so I think Aero is a moot point.  And, on a windy open gravel road - deep rims are a nightmare.  My rims are about 24mm deep and 28mm wide (22mm inner depth).  
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spinergypaul
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https://www.spinergy.com/content/bicycle/gx-gravel
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rdavis32
chas wrote:
For real gravel, I'm using fat tires (40mm+) and going relatively slow (average 15mph) - so I think Aero is a moot point.  And, on a windy open gravel road - deep rims are a nightmare.  My rims are about 24mm deep and 28mm wide (22mm inner depth).  


Seems like 40+ will be needed.  In my area (DFW area), there's likely less of a "real" need very often but will travel.  I'm fine with several different tires styles to exchange as needed (horses for courses).  Eventually will have a road specific wheelset as well.
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weiwentg
ljsmith wrote:
Keep in mind that to get aero benefits, the external rim width needs to be about as wide as your tires.  Since there are no aero wheels as wide as gravel tires I doubt you’ll get much benefit.   I have a set of Zipp 303 Firecrests with 35c Hutchinson Overide tires, but I have found no benefit over non aero wheels I use on the same bike.  I really wish I could say they made a difference, they did make my wallet a lot lighter.  On my road bike the tire width is matched to the aero rim width and I actually am a little faster with the aero wheels.


I think this isn't quite true.

To maximize aerodynamics, you need the rim to be as wide or just a bit wider than the tires. I'm not sure which episode of Josh Poertner's (currently runs Silca, used to work at Zipp) Marginal Gains podcast this was on, but he did mention that a few pro teams were running 25mm tires on pretty narrow rims, and they were penalizing themselves a bit as a result.

You do get some benefit running aero wheels with gravel tires. Poertner covered the topic in this podcast (somewhere in the middle, don't remember specifically what time). Specialized also used their wind tunnel to compare the Roval CLX 50 (21mm internal width, 50mm depth) to the SLX 24 (20.5 internal width,  24mm deep) at 3 tire widths - 26mm slick, 32mm slick, and 42mm gravel. (To be clear, the comparison is 50mm vs 24mm deep wheel, with a 42mm tire attached to both, repeat for 2 more tire widths). They stated that with a 26mm tire, the wheel changed saved 20s over 40km without a crosswind, 60s with a crosswind. With a 42mm tire, the wheel change still saved 12s over 40km with no crosswind, 40s with a crosswind.

(I assume no crosswind means zero yaw. Not sure what yaw angle(s) they used for the crosswind comparison, but do remember that riders pretty frequently face wind with at least some yaw.)

So, clearly, gravel tires will attenuate the benefits of an aero wheel. You still get some benefit. You can and should question how much that benefit is worth. If you're looking to improve aerodynamics, then consider that an aero helmet saves quite a bit of time, is usable on your road bike, and is much cheaper than $1500. (But it may not be as well ventilated as a traditional road helmet.) Same with a skinsuit, if you're willing to wear it.

Weight savings definitely helps a bit, but I'm pretty sure the effect is pretty small compared to aerodynamics.
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nellborg
"...will -300 grams and a bit of aero goodness make much difference? "

(In the above linked podcast, Josh Poertner says that wider gravel tires on aero rims still have about 60% of the aero benefit.)

But over the 12-16+ hour C2C race?  Consider that you'll be off your bike messing around 3 times at the aid stations and maybe a half dozen other times as you walk your bike around short 20-100 yrd sandy sections.  In other words, this course is not a head down individual tt where every second or minute counts.  You'll be riding in groups, riding on some single track, lots of two track, etc.  If I were you, I'd spend that cash on more comfortable shoes, saddle, bars, frame bag, gps and things like that first.  On the other hand, if you only have one set of gravel wheels, then definitely buy another set and put a different tire on that set so that you can swap wheels during the season based on conditions as tubeless tires aren't so easy to swap out.  Should the second set be carbon?  That's up to you.  I'd get a lighter set, though, as they'd probably be more fun to ride on.
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