asymmetric vs symmetrical rim

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tiz92
Posts: 190
Joined: Tue May 04, 2021 3:36 pm

by tiz92

Hi,

lately Im searching the internet for chinesese road wheels. Lots of them state that asyemmtrical rims are more stiff etc. I owned just symmetrical wheels and I have no issues I think. So I am asking are asymmetric really needed? Or is it more a gravel/CX stuff? Arent asymmetrical less aero?

Im really confused about this right now and I want to hear some opinions.

greetings

Tiz

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Hexsense
Posts: 3270
Joined: Wed Dec 30, 2015 12:41 am
Location: USA

by Hexsense

the narrower hub, the more asymmetrical rim make sense to balance out spoke tension. I think it's worth it for rim brake wheel (130mm rear hub). Still can be considered for road/gravel disc (142mm rear hub).
But don't bother on MTB with its 148mm wide boost hub.

It usually weight more for the same depth and width though.
So it rarely is the worth it.

alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Asymmetric rims have only a 2-3mm offset so it's not a gigantic change but yes, for asymmetrically dished wheels it helps to have an asymmetric rim.

If you're building a triplet then I personally wouldn't bother.

Marin
Posts: 4035
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

Definitely makes sense and will build a more durable wheel

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IrrelevantD
Posts: 857
Joined: Sun Nov 29, 2015 5:47 pm
Location: Near DFW Airport

by IrrelevantD

I've built a few, and it definately helps even out the spoke tension, seems to stay true better, and in my opinion, bulds up a little quicker and easier.

On the MTB side, with boost hubs, I had near identical spoke tension and spoke length on the front with the 4.5mm offset of Easton ARC 30 rims. Made for an absolutely great wheelset. Front may as well have been a rim brake front as well as it stayed true and evenly tensioned; until I cracked the rear rim casing a jump (story for another time). Replacement rims were carbon and only 3mm offset, still closer in tension between the sides and builds up really well, but not the near perfection of the 4.5 in the front.

The only other build I've done with an offset was a 650B ARC25 (again 4.5mm offset) for a rear on a mullet set for my gravel bike. Again, more even spoke tension between the NDS and the DS.

All of that being said... make sure you put the offset on the correct side. It really sucks getting to the point of dishing the wheel and realizing you put the offset on the wrong side.
* There is a 70% chance that what you have just read has a peppering of cynicism or sarcasm and generally should not be taken seriously.
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alcatraz
Posts: 4064
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Equal tension left/right is not very important. The main benefit is the spoke bracing angle. However, they do often go hand in hand, unless it's a triplet etc.

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Miller
Posts: 2764
Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

I think it's worth it for a rear wheel. It's clearly better from an engineering point of view, it doesn't cause any extra hassle when building and I expect the aero impact is approximately zero. Also suitable for front disc wheel.

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