Tubeless spoke tension drop
#1
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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.
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.
#2
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derp
EDIT: Sorry...in a mood. This is a well known thing.
EDIT: Sorry...in a mood. This is a well known thing.
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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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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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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.
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.
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
Q: Why are (some) engineers so bad at explaining things simply?
A: Because they don't adequately understand the problem.
Last edited by terrymorse; 06-17-21 at 02:38 PM. Reason: some rewording
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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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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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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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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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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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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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#14
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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.
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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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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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.
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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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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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.
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.
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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Internet forum scaremongering at its finest!
I’m now thinking I should get my wheel spoke tension tested every couple of hundred kms even though I’ve 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 didn’t notice if he was running tubeless or not, lol.
I’m now thinking I should get my wheel spoke tension tested every couple of hundred kms even though I’ve 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 didn’t notice if he was running tubeless or not, lol.
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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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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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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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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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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.
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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