17mm or 19mm rims?

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rides4beer
Posts: 690
Joined: Wed Nov 28, 2018 5:27 am
Location: VA

by rides4beer

rollinslow wrote:
Sat Mar 16, 2019 12:38 am
On my 21mm internal width Enve 3.4's, the Conti GP5000 25mm tires actually measure 26.5mm wide.
5000s or 4000s? On my 21mm internal rims, 25mm GP5000s measured out to 28.2mm after stretching. Just put on a set of 23mm GP4000S2s that measure out to 26.1mm new, we'll see how they are after stretching a bit.

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AJS914
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Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I'm curious about the 23mm 5000s. 23mm 4000s always measured 25mm+. Now that Conti has right sized the tires with the 5000 I'm wondering if those 23s will come in well under 25mm.

rides4beer
Posts: 690
Joined: Wed Nov 28, 2018 5:27 am
Location: VA

by rides4beer

AJS914 wrote:
Sat Mar 16, 2019 3:46 pm
I'm curious about the 23mm 5000s. 23mm 4000s always measured 25mm+. Now that Conti has right sized the tires with the 5000 I'm wondering if those 23s will come in well under 25mm.
My concern with trying the 23mm 5000s is that BRR reported that they are 1.5mm shorter than the 25mm version. The 23mm 4000s are about the same height as the 5000s on my wheels, not sure I'd want a shorter tire. But I might not have a choice when the supply of 4000s eventually runs out. :lol:

AJS914
Posts: 5392
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I think the 25mm 5000 is essentially equivalent to the 23mm 4000 in sizing. I'm interested in that 23 because I have an older bike with low clearance.

Hexsense
Posts: 3254
Joined: Wed Dec 30, 2015 12:41 am
Location: USA

by Hexsense

rides4beer wrote:
Sat Mar 16, 2019 3:36 pm
rollinslow wrote:
Sat Mar 16, 2019 12:38 am
On my 21mm internal width Enve 3.4's, the Conti GP5000 25mm tires actually measure 26.5mm wide.
5000s or 4000s? On my 21mm internal rims, 25mm GP5000s measured out to 28.2mm after stretching. Just put on a set of 23mm GP4000S2s that measure out to 26.1mm new, we'll see how they are after stretching a bit.
That's weird that it is only 26.5mm
My 23c GP4000sII is already 27.3mm on 21mm internal width. 26.5mm on 21mm internal width is like GP4000sII 21c's expected width...

clarinet5001
Posts: 32
Joined: Fri Jan 18, 2019 1:32 am

by clarinet5001

TimF wrote:
Sat Mar 16, 2019 10:34 am

I went carbon more for the feel and areo advantage over alloy. The 303's seem to absorb a lot of shock and are stiff too.
The AL33 are 2.5mm wider internally and only <1w slower in the wind tunnel at 30mph...and the rims are what, 1/5 the price? That said, if you're looking at the 2018+ Firecrest or the NSW then they are a bit lighter than the AForce. Also, notice I cherrypicked your previous post.

I can't tell you how I like them yet though because I probably won't have them for another couple days :( So also keep that in mind: I bought their rims so I'm probably a little bit biased. My main thing was I ride in the mountains a lot and don't shy away from there when the roads are a bit wet, that and I didn't want to pay the higher rim replacement costs for name-brand carbon when the time comes, since I use all my stuff until it's worn out.

The 303s are great wheels though. Do yours have the newer de-clutching mecanism or whatever their improved freewheeling thing is?

TimF
Posts: 106
Joined: Wed May 09, 2012 11:18 pm

by TimF

Hey Clarinet,

I have the NSW's with the newer clutch. For wind tunnel etc. you have to bear in mind that it's not just headwinds that matter, it is the sidewinds at slower speeds. What testing is done on the AL33 for this? I don't know these wheels. Bit suprised they have the same areo as the NSW's, that's very impressive.

Also need to take into account road feel and stiffness, I wanted comfortable wheels as a priority, these abosorb a lot of shock. Finally I have a very effective braking track along with considerable de-lamination and impact testing from Zipp.

Like any thing there's a law of diminising returns, however I bought second hand and saved a lot of money on new.

Cheers, Tim

AJS914
Posts: 5392
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I'm a little skeptical that the 32.5mm Aforce rim/wheel is only <1 watt slower than a 45mm Zipp 303 at 30mph. Hambini's tests show a 25 watt difference between rims of similar sizes.

The Aforce may be the fastest 32mm rim on the planet but Hambini's test seem to show that no amount of aero design can make up for depth. Sure, you can design a poorly performing deep rim but a well designed shallow rim can't best well designed deeper rims.

clarinet5001
Posts: 32
Joined: Fri Jan 18, 2019 1:32 am

by clarinet5001

AJS914 wrote:
Wed Mar 20, 2019 5:46 pm
I'm a little skeptical that the 32.5mm Aforce rim/wheel is only <1 watt slower than a 45mm Zipp 303 at 30mph. Hambini's tests show a 25 watt difference between rims of similar sizes.

The Aforce may be the fastest 32mm rim on the planet but Hambini's test seem to show that no amount of aero design can make up for depth. Sure, you can design a poorly performing deep rim but a well designed shallow rim can't best well designed deeper rims.

They're <1w slower at 30mph factoring in all yaw angles, and around 3w slower at more extreme wind angles, but this was against the 303 Firecrest, not the NSW. A2 did a wind tunnel test that included some other shallow wheels. The slower you ride or the windier it is the more high yaw angles matter.

You're also correct in that it's not faster than 'Well Designed' deeper rims because physics is physics. It's those lower yaw angles that make them score so closely to the Zipps. I'm not saying the Zipps are 'poorly designed' but that they're more or less 'average' for their depth. Wheels like the Hunt 50 would be 'very poorly designed.' I suspect that at slower speeds the gap between the AForce and the 303 Firecrest would increase by a couple watts.

The main point is that between a 'well designed' shallower rim and a 'decent' deeper rim like the 404, the difference is there but it's not crazy. Compare the AForce to the Aeolus 6 and the gap between a 60mm rim with 808 aero cred and a good but inherently shallow alloy rim should be enough to be just big enough to be tangible if you ride the two back to back. But even if the NSW are 2-3w faster in the real world, that's still within the realm of 'splitting hairs' and would be of infinitessimal importance apart from time trials...in which case no one would use 303s anyway.

Comfort-wise, any rim with internal width in the 19c+ realm is reasonably comfortable combined with the lower tire pressures one can and should run.

TimF
Posts: 106
Joined: Wed May 09, 2012 11:18 pm

by TimF

Thanks for this guys, very interesting...

"Comfort-wise, any rim with internal width in the 19c+ realm is reasonably comfortable combined with the lower tire pressures one can and should run."

True, but I'm using 23c tires and therefore I have a high pressure hard tire and need compliant wheels. Yes of course if I run 25c+ wide tires with lower tire pressures it'll matter a lot less.

JoO
Posts: 439
Joined: Thu May 04, 2017 7:30 am

by JoO

TimF wrote:
Fri Mar 22, 2019 1:44 pm
Thanks for this guys, very interesting...

"Comfort-wise, any rim with internal width in the 19c+ realm is reasonably comfortable combined with the lower tire pressures one can and should run."

True, but I'm using 23c tires and therefore I have a high pressure hard tire and need compliant wheels. Yes of course if I run 25c+ wide tires with lower tire pressures it'll matter a lot less.
I am a bit sceptical about the difference in comfort between wheels. It is my belief that tire pressure is the dominant spring in the system. 5psi more or less will likely make a bigger difference than any differences between wheels.

clarinet5001
Posts: 32
Joined: Fri Jan 18, 2019 1:32 am

by clarinet5001

JoO wrote:
Fri Mar 22, 2019 6:16 pm
TimF wrote:
Fri Mar 22, 2019 1:44 pm
Thanks for this guys, very interesting...

"Comfort-wise, any rim with internal width in the 19c+ realm is reasonably comfortable combined with the lower tire pressures one can and should run."

True, but I'm using 23c tires and therefore I have a high pressure hard tire and need compliant wheels. Yes of course if I run 25c+ wide tires with lower tire pressures it'll matter a lot less.
I am a bit sceptical about the difference in comfort between wheels. It is my belief that tire pressure is the dominant spring in the system. 5psi more or less will likely make a bigger difference than any differences between wheels.
I would generally agree. The only wheels I found to be significantly less comfortable were the alloy-spoked Fulcrum / Campag wheels. I have not tried very deep wheels in 808 territory, though.

And even with 23c tires on wider 19c+ rims, unless you're a heavier rider you can still probably run 85psi just fine, so comfort isn't going to be THAT bad. As long as you don't spec beefy, rough-riding tires such as GP 4 Season or Durano (or their Gatorskin / DD cousins) and your frame isn't exactly an Allez Sprint or first gen Scott Foil that is.

The wheels I ordered should ride a good bit firmer than my particularly comfy [for narrow rims] Shimano RS81 wheelset. With the Fulcrum / Campags it was more than a 5psi tire pressure differential. I expect that from the Shimanos to a White T11 / AForce / CX Ray 24f/28r build it will be <5psi, but since they're a good bit wider internally I'll be experimenting with pressures up to 15 or maybe even 20psi lower as well.

menkar
Posts: 19
Joined: Tue Aug 10, 2010 5:23 am

by menkar

clarinet5001 wrote:
Fri Mar 22, 2019 8:53 pm
"The only wheels I found to be significantly less comfortable were the alloy-spoked Fulcrum / Campag wheels."
With the same tires and pressures and bike I don't detect any difference in comfort between my C24's and alloy spoked Fulcrum's.

I wouldn't expect the material of the spokes to affect comfort since according to physics steel and alloy spokes of the same weight are the same stiffness. The weight of the spokes on these wheels is similar, maybe slightly lighter on the Fulcrum's.

petosagan
Posts: 83
Joined: Sat Feb 27, 2016 8:06 pm

by petosagan

Do you know an app or something which we can calculate the pressure.
I know the mavic apps, but the max width is 17 inner.
Thanks

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clarinet5001
Posts: 32
Joined: Fri Jan 18, 2019 1:32 am

by clarinet5001

petosagan wrote:
Mon Mar 25, 2019 3:26 pm
Do you know an app or something which we can calculate the pressure.
I know the mavic apps, but the max width is 17 inner.
Thanks

Envoyé de mon SM-A530W en utilisant Tapatalk

An app? not really sure. But the Berto % drop chart is a decent place to start. Just remember its pressure values use actual tire width not printed tire size and are for each wheel, not for the whole bike. I go with the Berto recommendation for my rear tire and run the front a little higher than it recommends or else hard braking can get squishy.

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