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Tubeless spoke tension drop

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Tubeless spoke tension drop

Old 06-17-21, 09:54 AM
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popeye
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Tubeless spoke tension drop

https://cyclingtips.com/2021/06/why-...-tension-drop/

Did you know that a tubeless tyre puts more compression force on a hooked rim than one with a tube? That increased force effectively shrinks the diameter of the rim.
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Old 06-17-21, 09:55 AM
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derp

EDIT: Sorry...in a mood. This is a well known thing.
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Old 06-17-21, 10:00 AM
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Old 06-17-21, 10:13 AM
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Originally Posted by Psimet2001 View Post
derp

EDIT: Sorry...in a mood. This is a well known thing.
Justtifed, but news to me. Do you suppose this is why Spec dropped the road tubeless?
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Old 06-17-21, 11:03 AM
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Originally Posted by popeye View Post
Justtifed, but news to me. Do you suppose this is why Spec dropped the road tubeless?
I'm not aware of anything specific with Specialized and I don't know what you mean by them dropping road tubeless - in generalities no one in this business is "dropping tubeless" or ever will. They especially wouldn't over this specific issue as it's a non-issue. You build up the tensions on the wheels to compensate for the drop. The only time we have ever had any issue is on super tight rim brake frames as the dish can move over ~1mm and sometimes that's enough to cause rubbing as everyone wants to run tires their frames weren't designed for nowadays.
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Old 06-17-21, 11:18 AM
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Originally Posted by Psimet2001 View Post
I'm not aware of anything specific with Specialized and I don't know what you mean by them dropping road tubeless - in generalities no one in this business is "dropping tubeless" or ever will.
He's referring to one or two of their Roval wheelsets that Spec has stated are not tubeless compatible (despite having the typical tubeless rim bed profile). Saying that Spec "dropped road tubeless" because of this is just a wee bit of hyperbole.
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Old 06-17-21, 11:34 AM
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Originally Posted by popeye View Post
https://cyclingtips.com/2021/06/why-...-tension-drop/

Did you know that a tubeless tyre puts more compression force on a hooked rim than one with a tube? That increased force effectively shrinks the diameter of the rim.
Yes a tubeless tire will exert more rim force than a tire+tube at the same pressure, but for a much simpler reason than the engineer-splaining in that article, above.

Quite simply:

Air pressure always exerts a force perpendicular to its container walls. Remove the inner tube, and:
  • you slightly increase the size of the container
  • the total force from air pressure on the container rises
  • the air pressure produces more radial inwards force on the rim
  • the rim diameter shrinks
  • the spoke tension drops
That is all. NBD.

Q: Why are (some) engineers so bad at explaining things simply?
A: Because they don't adequately understand the problem.
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Last edited by terrymorse; 06-17-21 at 02:38 PM. Reason: some rewording
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Old 06-17-21, 12:40 PM
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My wheel builder does (when building for tubeless) have me bring back the wheels soon after with the tubeless tires on so he can check the spokes unless I let him start out that way. He did that with the road bikes quickly but not the MTBs, though he wants to see the MTB wheels after 200-300 miles or so. Road tubeless with its high pressure is still a bit more complex and may never be as easy and simple at MTB ro gravel tires running tubeless, though these new hookless beads are changing things, as long as you use far less pressure. I can't on my old school bike, unfortunately. Even if I run tubeless, I run into this issue since my tire size is 25. If I get those tubeless rim-brake 303s, I'll have to tension up after the first tubeless tire install.
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Old 06-17-21, 12:48 PM
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I've been riding tubeless for about 5 years now and this has never been a real world problem for me. I love my wheels! ❤️
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Old 06-17-21, 12:56 PM
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I don't think it is a problem as long as you re-tension the wheels after the initial build, right? Which wheels are you using? Rim brake tubeless?
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Old 06-17-21, 01:35 PM
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Originally Posted by Chandne View Post
I don't think it is a problem as long as you re-tension the wheels after the initial build, right? Which wheels are you using? Rim brake tubeless?
You don't have to do that if they are stressed relieved fully during the build. Over the last 12 years I have found that's what sets us apart from just about every other builder. Even the ones who build purpose built machines to try and automate it. We just do it better.

But yeah if a builder tells you that you have to bring it back and they see pretty unilateral tension changes then they didn't stress relieve hard enough for those spokes and rim combination. It's not something to hang a builder for but that's what causes it to drop. Over the super long term rims can settle even more if they are carbon. On some there are just small moves most likely in the micro level that amount to just enough compaction to drop the tension slightly. This is after a year or two of riding.
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Old 06-17-21, 01:43 PM
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Yeah, you certainly know all the nuances here. I'll reach out the next time I need a set built. My builder does not see many changes but he always likes me to bring them back after a few rides so he can check them out. I am always there since it only takes him a few minutes. His builds are very nice and I have never broken a spoke or loosened one much or anything, and they last years. Unfortunately for me, he is now part owner of a small chain of shops and really does not build wheels much.
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Old 06-17-21, 01:51 PM
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Originally Posted by Chandne View Post
Yeah, you certainly know all the nuances here. I'll reach out the next time I need a set built. My builder does not see many changes but he always likes me to bring them back after a few rides so he can check them out. I am always there since it only takes him a few minutes. His builds are very nice and I have never broken a spoke or loosened one much or anything, and they last years. Unfortunately for me, he is now part owner of a small chain of shops and really does not build wheels much.
Yeah my years of trying to poach customers are long over. If you like what you're getting then stay with it. Everyone needs to make a buck and there's no one way for things to be done. That said if they can't help you anymore... we're here.
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Old 06-17-21, 02:19 PM
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Originally Posted by Psimet2001 View Post
I'm not aware of anything specific with Specialized and I don't know what you mean by them dropping road tubeless - in generalities no one in this business is "dropping tubeless" or ever will. They especially wouldn't over this specific issue as it's a non-issue. You build up the tensions on the wheels to compensate for the drop. The only time we have ever had any issue is on super tight rim brake frames as the dish can move over ~1mm and sometimes that's enough to cause rubbing as everyone wants to run tires their frames weren't designed for nowadays.
Our CLX 32, 50, 64, Terra CLX, Terra CLX EVO, C38, SLX 24 and all Contol and Traverse models are compatible. Rapide CLX and Alpinist CLX wheels are not compatible with tubeless road tires. By making them tube-type specific we were able to create lighter and better complete wheels systems for performance road riders. To render these wheels tubeless would have required extra materials, and that extra mass would have outweighed the benefits of tubeless tires.

I not sure what Specialized is still offerling in tubeless in their high end bikes but your choices are now limited. It looks like the answer to my question is weight/mass rather than the rim changing dimenions.
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Old 06-17-21, 02:56 PM
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Originally Posted by Chandne View Post
Yeah, you certainly know all the nuances here. I'll reach out the next time I need a set built. My builder does not see many changes but he always likes me to bring them back after a few rides so he can check them out. I am always there since it only takes him a few minutes. His builds are very nice and I have never broken a spoke or loosened one much or anything, and they last years. Unfortunately for me, he is now part owner of a small chain of shops and really does not build wheels much.
​​​​​​I broke most of the spokes on the wheels that came with my GT Grade. Half a dozen on one ride once. I'm shocked I was able to get back on it. The shop replaced the wheel on the spot and the new one started breaking spokes like crazy too. That was my first gravel bike, we don't have a lot of cell reception here, I bought the strongest wheels I could find to replace them because I didn't want to hitch hike or walk 30 miles. Got a set of Enves which are overkill but wonderful, and there's one thing for me to stress about.
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Old 06-17-21, 03:14 PM
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ENVE makes a great wheel. I had some regular 3.4 SESs on one bike. They were stellar! On this bike, I'm tempted to use some Zipp 303s but my alloy builds have been 100% with 24x28 CX Rays.

A friend had an issue recently but while it was odd, I think one has to be careful with the tubeless ENVEs. His was the AR version and tubeless. I don't think he used the ENVE tape but some other tape. Anyway, while the shop was inflating it to seat the new tires, air escaped into the lower chamber (that is not meant to be pressurized) and it blew up that part of the rim. ENVE warrantied it, which was great. ENVE later said to only use their tape and valves.
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Old 06-17-21, 03:33 PM
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I've got the 4.5 ARs. I bought them from a shop 250 miles away, had them set the wheels up for me so they were ready when I picked them up. Kind of a gamble on reliability, but it's a favorite mountain town so any excuse to go is good for me. Haven't needed to though. They came with Enve rim tape and valves. I considered getting my own valves in a color to match the frame and would have had to go too long, so I've just stuck with the ones they came with. Sounds like I need to continue, thanks for pointing that out. 🙂



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Old 06-17-21, 04:44 PM
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Originally Posted by Chandne View Post
ENVE makes a great wheel. I had some regular 3.4 SESs on one bike. They were stellar! On this bike, I'm tempted to use some Zipp 303s but my alloy builds have been 100% with 24x28 CX Rays.

A friend had an issue recently but while it was odd, I think one has to be careful with the tubeless ENVEs. His was the AR version and tubeless. I don't think he used the ENVE tape but some other tape. Anyway, while the shop was inflating it to seat the new tires, air escaped into the lower chamber (that is not meant to be pressurized) and it blew up that part of the rim. ENVE warrantied it, which was great. ENVE later said to only use their tape and valves.
I recently warrantied one that did the same. The issue is more their valves or rather their retaining nut for the valve. They drill it to allow any air that leaks into the lower chamber of the rim to escape. I have never had or seen this issue with any other rim when using it tubeless. Including the ones we use.

In other words if the lower rim chamber gets pressurized it will blow completely off the rim in the most catastrophic and exciting way.
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Old 06-18-21, 05:42 AM
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Just one more "non issue" with TL to add to the list .. ;-)
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Old 06-18-21, 07:18 AM
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Internet forum scaremongering at its finest!

Iím now thinking I should get my wheel spoke tension tested every couple of hundred kms even though Iíve never broken a spoke in the last 45 years. But last month I did witness another rider break a rear wheel spoke right in front of me on a steep climb. He said his wheels had just been re-built a week ago. I didnít notice if he was running tubeless or not, lol.
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Old 06-18-21, 10:49 AM
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Originally Posted by Racing Dan View Post
Just one more "non issue" with TL to add to the list .. ;-)
There are a lot of things that aren't wrong with tubeless, bit of you like having your panties in a bunch I'm sure you can imagine this is really scary. I'm sure the idea of actually riding a bike must be terrifying!
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Old 06-18-21, 11:11 AM
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Originally Posted by Seattle Forrest View Post
There are a lot of things that aren't wrong with tubeless, bit of you like having your panties in a bunch I'm sure you can imagine this is really scary. I'm sure the idea of actually riding a bike must be terrifying!
I've been trying to come up with something that I'm neither personally nor practically interested in, but about which I can study just enough to shake my fist at it whenever the opportunity presents itself. No luck, so far, though - I just can't get my undies bunched over something that I'm not interested in; I don't know how these guys do it.
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Old 06-18-21, 12:59 PM
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Originally Posted by terrymorse View Post

Q: Why are (some) engineers so bad at explaining things simply?
A: Because they don't adequately understand the problem.
I think it is more of a case of they are not used to talking to normal people about engineering. My Dad was an engineer and hated it when he tried to help me with math.
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Old 06-18-21, 01:34 PM
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Originally Posted by colnago62 View Post
I think it is more of a case of they are not used to talking to normal people about engineering. My Dad was an engineer and hated it when he tried to help me with math.
Probably true. I worked as an engineer in F1 motorsport and I used to really struggle to explain to "normal" people what my job actually was. I never did come up with a satisfactory answer. Trying to make the cars go quicker was about as far as it got.
Debating engineering issues with "normal" people is also often a pretty frustrating experience. People don't tend to argue with brain surgeons about brain surgery, but engineering seems to be fair game for anyone to have a punt, even if they struggled to get an O-level in maths and physics.
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Old 06-18-21, 01:54 PM
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Originally Posted by PeteHski View Post
Probably true. I worked as an engineer in F1 motorsport and I used to really struggle to explain to "normal" people what my job actually was. I never did come up with a satisfactory answer. Trying to make the cars go quicker was about as far as it got.
Debating engineering issues with "normal" people is also often a pretty frustrating experience. People don't tend to argue with brain surgeons about brain surgery, but engineering seems to be fair game for anyone to have a punt, even if they struggled to get an O-level in maths and physics.
I understand. I am a musician.
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