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Offset rims

Joel

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I did a search for the title and did not see any hits, so here it goes,

On occasion I've looked at offset rims. I get the concept of more even spoke tension, fine. But now you have uneven rim forces. Which is worse? On narrow rims, it may not be a big issue either way because the offset is small. But lets talk rider rims where you can get the spokes almost the same length and tension, but now you have a lot more rim hanging off one side of the spoke line than the other. To me, it seems you just move a problem from one place to another.

Anyone riding a wide offset rim hard, any comments?

Joel
 

Tom K.

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I'm going to say that I think that even spoke tension rates more highly than uneven rim forces. Especially with carbon, since it's so stiff.

However, if you were to email Rolf/Astral Wheels, I would bet hard money that you'd get a great answer, though it might not be instantaneous:


Interesting topic!
 
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Joel

Joel

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When I think about the rim aspect, I think it matters a lot on the rim. I've never had a CF rim but tend to agree with your thoughts. I have had many different Aluminium rims with various degree of hardness. Some were soft enough that they dented if you looked at them wrong, others were quite hard/rigid. Never had one fail, but I would expect if one did, it would be a fracture in the Aluminum. But then, rim material and failure modes are a whole other topic.

I occasionally ride with a friend that still uses rim brakes, I know what his failure mode is going to be.........:geek:
 

Tom K.

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I occasionally ride with a friend that still uses rim brakes, I know what his failure mode is going to be.........:geek:

I remember when I first learned that rim brakes eventually wear an aluminum rim to the point of incipient failure.

It could have been horrible. Luckily, it just turned out to be amusing to my friends who were watching. I just had to push my bike a few miles afterwards.....
 

scott43

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I built some offset rims back in the day. Never saw what happened to them. Then they seemed to fade away. Not sure they solved any issues..
 

Dave Marshak

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I trained as a structural engineer and I've been built wheels for 40 years and this is the answer. Modern wheels have much more offset, much heavier rims and fewer spokes than were common before 1980 or so. With the heavy rims we use now, an asymetric rim can easily be strong and rigid enough. With a symetric rim, it's hard to get enough tension on the left side without overtensioning the right side. Offset rims allow more or less equal tension on both sides, which makes it easier to build a reliable wheel. You can also use fewer spokes without any loss of strength because all the spokes are equally carrying the load.

mm, P.E.
 

Tom K.

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I trained as a structural engineer and I've been built wheels for 40 years and this is the answer. Modern wheels have much more offset, much heavier rims and fewer spokes than were common before 1980 or so. With the heavy rims we use now, an asymetric rim can easily be strong and rigid enough. With a symetric rim, it's hard to get enough tension on the left side without overtensioning the right side. Offset rims allow more or less equal tension on both sides, which makes it easier to build a reliable wheel. You can also use fewer spokes without any loss of strength because all the spokes are equally carrying the load.

mm, P.E.

Now THAT is an answer.

Thanks!

But really, what else should we expect from the "All Time World Champion"?! ;)
 
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Joel

Joel

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So after Daves comment and a lot more research, I think I will try some asymmetrical rims next go. I think I need to bang up the ones I have now a bit more before I'll do that, but then, winter is coming so a good time to lace up a new set.

I'm afraid of what I'm going to find skiing wise this winter. My go to place is Cameron Pass in Colorado which has been on fire since August 13th. As of today, it's 4% contained. I hope the snow we just got at least helped a little.
 

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