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TonyM
Aero is usually about rim height and rim width.

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droitaubut
TonyM wrote:
Aero is usually about rim height and rim width.



Yes exactly, and rims generally discussed as aero are deeper, and always made of carbon.
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clarksonxc
I always looked at it from a surface area standpoint.  How many small rocks are gonna get flung up and into a 50mm+ deep section carbon rim, or if the rim slid into a rock that's solidly connected to the ground.  Shallower climbing wheels have less carbon surface area exposed.
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droitaubut
clarksonxc wrote:
I always looked at it from a surface area standpoint.  How many small rocks are gonna get flung up and into a 50mm+ deep section carbon rim, or if the rim slid into a rock that's solidly connected to the ground.  Shallower climbing wheels have less carbon surface area exposed.


Yeah, looks like in certain terrains high rims are vulnerable....

Interesting in this discussion was that Enve staff opted to ride Dirty Kanza with G23 mostly and someone with an M525 wheel. However the winner also used Enve wheels, but opted for the Enve 3.4 AR, but then combined it with 42mm tyres. So there should be an aero advantage due to the wheels, but not optimally utilised as tyres are much fatter than the rims. Still interesting to see he opted for it, instead of G23. It looks like in that sense Dirty Kanza isn't rough enough rock wise to choose otherwise.
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TonyM
clarksonxc wrote:
I always looked at it from a surface area standpoint.  How many small rocks are gonna get flung up and into a 50mm+ deep section carbon rim, or if the rim slid into a rock that's solidly connected to the ground.  Shallower climbing wheels have less carbon surface area exposed.


small rocks hitting the carbon mid profile rim is probably better than small rocks hitting the spokes...
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chas
droitaubut wrote:


Well on that 7%, it sounds like a bigger thing than it is. I believe continental claimed a similar improvement of their slicks going from GP4000S2 to GP5000. But rolling resistance of GP4000S2 is <14 watts per tyre. 7% of 14 watts is 1 watt. So basically they claim you save less than 1 watt, which is close to nothing at all, but may well be true.


to be off topic.

I finally got some GP5000.  I didn't realize it until I road them, but they have less than 1/2 the rolling resistance of the 4Seasons I had been using. HUGE!  The tubeless GP5000 roll at 8 watts.   If I'm in a paceline at 30mph, that is about 22 watts vs close to 60 watts with my old tire.  I'm shocked a the low rolling resistance of the GP5000.

droitaubut wrote:

Yes exactly, and rims generally discussed as aero are deeper, and always made of carbon.


"Always" is a strong term.  My aero American Classic rims are light and aluminum.  Oh well...  
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JBarney
I would love to have multiple wheels but as my main 3 bikes ( MTB, Road, CX/Gravel ) all have different wheel systems, I had to pick one.  I went with light weight ( Bontrager XXX2's) for the quicker acceleration in  CX and slower speeds of gravel riding/racing.
Sadly, they weren't enough to get me on the podium....lol
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smoothmoose
Read through the entire thread.  Unless I missed it, I did not see any discussion around stiffness, compliance, and gravel buzz absorption of deep vs shallow wheels.  Can anyone tell a difference in comfort?

I am looking at semi-aero 700c wheels for my gravel bike.  I ride my 700c wheels 80% on tarmac, but once-in-awhile will hit gravel roads and tracks.  For serious fireroads and singletrack I have my 650b x 2.2" knobbies.
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widerisfaster
smoothmoose wrote:
Read through the entire thread.  Unless I missed it, I did not see any discussion around stiffness, compliance, and gravel buzz absorption of deep vs shallow wheels.  Can anyone tell a difference in comfort?


On the Silca podcast, someone asked a similar question. Their reply was that the tyres provide 10x the comfort and absorbtion as the frame, and the frame provides 10x the comfort and absobtion as the wheels. So any difference in wheel stiffness or compliance is a non factor compared to tyres.

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I am looking at semi-aero 700c wheels for my gravel bike.  I ride my 700c wheels 80% on tarmac, but once-in-awhile will hit gravel roads and tracks.  For serious fireroads and singletrack I have my 650b x 2.2" knobbies.


I'm running similar. I have tried 32mm, 38mm, and 44mm slicks on shallow 23mm x 700C wheels, and deeper semi aero 36mm x 700C wheels. I cant detect a difference in comfort.

The 32mm are great handling, the 38mm are a good mix of road handling and off road comfort. The 44mm slick roll as fast, but turn slower, and provide great comfort on rougher gravel. For the gravel we have locally, I think 38mm is a good middle ground.

For a route which is mostly rough gravel and washboard corrugations, 650b x 2.1" Thunderburts at 22psi are just sublime. 
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smoothmoose


On the Silca podcast, someone asked a similar question. Their reply was that the tyres provide 10x the comfort and absorbtion as the frame, and the frame provides 10x the comfort and absobtion as the wheels. So any difference in wheel stiffness or compliance is a non factor compared to tyres.

  Nice - that's my anecdotal experience as well.  Have only A/B testing carbon/alloy wheels on MTB - and can't really tell the difference.  I have an alloy gravel frame - but agree, most of the subtleness comes from tire pressures.



I'm running similar. I have tried 32mm, 38mm, and 44mm slicks on shallow 23mm x 700C wheels, and deeper semi aero 36mm x 700C wheels. I cant detect a difference in comfort.

The 32mm are great handling, the 38mm are a good mix of road handling and off road comfort. The 44mm slick roll as fast, but turn slower, and provide great comfort on rougher gravel. For the gravel we have locally, I think 38mm is a good middle ground.

For a route which is mostly rough gravel and washboard corrugations, 650b x 2.1" Thunderburts at 22psi are just sublime. 
.  Good to know.  Yes, I'm thinking something in the 30-35mm deep rims.  And my goto tires are the 700x38c GravelKing slicks.

Not seeing a lot of options in terms of deeper (>30mm) and wide (>22mm ID) though...
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widerisfaster
 
Not seeing a lot of options in terms of deeper (>30mm) and wide (>22mm ID) though...


Check out the November Bicycles (36mm deep 21mm ID) RCG36 https://novemberbicycles.com/collections/rcg36-wheels
or their (38mm deep 25mm ID) All Road 38 https://novemberbicycles.com/collections/all-road-disc-wheels
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TonyM
I am using 700C DT Swiss GRC 1400 Spline 42 with Schwalbe G-One Allround in 35mm for my rides on smooth gravel.
The rims have a 24mm inner width and the 35mm G-One all-round measures 38mm at 45 psi on these.
Everything runs smoothly. Fast and comfortable enough. I however would use wider tires (38 or 43mm) for rough gravel or even more (2.1" with 650B wheels) if I were riding in single tracks or trails.
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Volsung


Check out the November Bicycles (36mm deep 21mm ID) RCG36 https://novemberbicycles.com/collections/rcg36-wheels
or their (38mm deep 25mm ID) All Road 38 https://novemberbicycles.com/collections/all-road-disc-wheels


These Novembers look a lot like Light Bicycle rims.  .5mm difference, but that could just be a more accurate measurement 
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smoothmoose
FYI...I've been rabbit holing on aero gravel wheels.  Seems like the aerospace engineers say don't buy into the straight line wind tunnel tests most bike/wheel manufacturers measure with.  Also for aero benefits, the tire width needs to be within 100-105% of the rim width (external).  So if you are running 40c tires, you'll need 38mm external wide.  This then forces you into a much deeper wheel as well to ensure the right angle for smooth air flow.
https://www.hambini.com/blog/post/bicycle-wheel-aerodynamics-which-one-is-fastest/

Net-net, I think I'm going to do a wide/shallow/light wheel build.
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