Game changer - 36er CARBON wheel!

This thread has discussed a few different carbon rims and wheel builds. Just to be clear and for future reference can you list the make, brand, size and model of rim you used and any other wheel build details that may be useful?

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Edited above - and done so:

I did create a thread for this new LightBicycle rim but all content started to drift to this thread and now it is too fiddly to request it is moved over.

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I’ve not been able to ride this as I’m under hospital advice to avoid over exerting myself (possible retinal tear!)… but happily it has held 50PSI without issue and I would happily add more if I needed it.

Braus needed around 49PSI to feel stable for my 81kg - but I think this rim will feel just as stiff at 45PSI - tested to 50 as a max for me.

Very happy indeed :star_struck::gear:
(Just hope I could get back to riding soon)

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IIs it still those values after inflation and the adjustments you made afterwards?

Regarding the acronyms DS and NDS, I’ve just seen that they stand for Drive-Side and Non-Drive Side. I’m sure I’ve missed something, I’m basing this on the side of the disc.

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Yeah these terms really drive me mad -

But I’ve learned to stick to looking at drive and non-dive sides - remembering that non-drive is where the disc goes.

Yes 25 was for the short spokes on NDS - and 20 for DS.

25 seems to equal 120 kgf with 26 being more like 135 - which is the rim’s upper limit. But that was before I inflated it.

I need to recheck numbers and tighten again - I suspect 1 perhaps 1.5 turns all the way around.

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So, I had to remove my NightRider tire today. A spoke snapped yesterday and the nipple went into the rim :frowning:
I have not found how to use the tool to remove the tire. I had to do it all by hand. No big deal, but I doubt the tool has ever been designed to remove a tire. Sorry about that!

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I’ve now put it back to 45ish PSI and then noted the spoke tensions had dropped around 2 full points on the scale.

A half turn on each spoke got them back to 20-22 DS, and 25-26 NDS -

This does mean should I take the tyre off tensions would be over spec. For this I’d either not worry as the wheel won’t be ridden like that or drop the tensions all round before deflating.

I just gave it a test ride at 45PSI and it glides along but perhaps it isn’t as nimble a feeling as I got from the Braus. This could be due to the wider hub being heavier and err… wider, and also due to my needing more PSI in the tyre for it to feel as firm as the Vee tyre I run on the Braus rim.

Just tested it at 50ish and the system is much firmer for me - so this will likely translate into a more directional feel.

No more time to test right now but the main takeaway here is that I’m happy running it at 50PSI - I could even test 55 without worrying - and I will one day try the King George Ultimate again to see how it behaves in this rim (didn’t like it in the Braus at 50PSI).

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I‘d say either don‘t care at all or drop it all round so that the tensions are within specs limits when the tire is deflated. Because fiddling with spokes just to change a tire or a tube doesn‘t seem a welcome thing to do in my view. But most importantly, you can end up having a flat anytime (don‘t even needs to happen when you ride the thing), which means the spoke tensions can end up being too high at any moment.
Just out of curiosity (since I tend to ride with not so high tire pressures): Is the effect of tire pressure on spoke tension equally pronounced with aluminium rims or is this a peculiarity of carbon rims?

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It’s something I’ve only heard of / seen with carbon rims. Perhaps it happens to a lesser extent on aluminium rims.

I’ve been told categorically that I’m imagining this issue - and that rim’s spoke tension cannot be lessened due to tyre pressure - but the fact remains that they do. (So it seems some people out there don’t think this can physically happen!)

I know my pro wheel builder accounts for this when tensioning rims - so yeah it probably happens on all rims but carbon more so.

I think you’re right about just leaving it high. I very much doubt it will actually break the rim. I think the spec is for ridden rims - as the stresses on the spokes and nipples will be extreme then and this is when over tensioned spokes could be bad. But stationary, unweighted and with a tyre off - I highly doubt it is as issue.

Far greater issue would be to ride with loose spokes at 50PSI.

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Have you tried measuring the tensions right before inflating the tire ? And have you tried inflating, measuring and then deflating before re-measuring it ?

I cannot see how inflating the tire could cause the spokes to lose tension, but I can see the spokes losing tensions overtime.

It’s normal!

I found the same thing with the Braus carbon rim. When you inflate the tire, there’s a force that pulls inwards. This has a significant influence on the overall tension and centering of the rim.

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Carbon fiber is very strong in tension but much weaker in compression. When a tire is pressurized that puts the rim in compression and results in a smaller rim diameter. A smaller rim diameter reduces the spoke tension.

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Oh ok, I didn’t know about that, makes sense.

This is also true of the Nimbus Stealth2 aluminum rim. Without a tire/tube mounted, my Park TM-1 measures about 1-1.5 (unit-less) digits higher than with a tire mounted at 40psi. that’s about a 10-15 kgf difference.

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So that would have been a contributing factor in the tire blowout incidents over time (older Coker rims and more recently Nextie dont-inflate-too-much carbon rim) :thinking:

That’s a very interesting point, a drop in spoke tension plus stretch over time in the tyre.

I wonder if this is just because of the size of the wheel, as my carbon rims on my uniycles 27.5 and 29," didn’t drop spoke tension after the tyre was inflated. Never experienced it either on aluminium rims either