Built a pair of 24mm internal (30mm external) 29er LB rims on DT Swiss hubs for myself a few weeks ago. Have only ridden them a few times, but they've required a LOT of attention (well, specifically the rear has).
I've been building wheels for many many years. Have certainly built well over 100 wheels, until the other week, none of them with carbon rims. I'm finding that my own rear wheel goes out of true very easily/quickly compared to an equivalent ally rim, and that I'm having to get the spoke tensions almost ludicrously high to stop this from happening.
Also... To say the wheels have needed bedding in is an understatement. Also built a similar set for a friend at the same time, both wheels built with good (even) spoke tensions all round. Then both wheels were fitted with tubeless tape and valves, and had 2.3" Tubeless tyres fitted and inflated to about 50psi (to make sure of a seal). Both wheelsets were then ridden up the road, and all 4 wheels immediately required at least a full turn on every single nipple! 😯
I've since done a few more rides on my own wheels (with retruing required after every ride), and though they are light and very resilient, they do seem to be prone to coming out of true very easily.
The other thing is that the rear in particular, feels almost like riding with a flat tyre most of the time! It's a very odd sensation... Anyone else noticed this, or am I really odd? Is this just a trait of carbon rims full stop (I'm guessing not, I've got Reynolds Assaults on my road bike and they don't suffer from this)?
Your thoughts and feedback if you've experienced any of this please...
Had none of the issues you listed with my 30/24mm 26 inch rims. They kept there true, were ridiculously straight and they felt a lot stiffer than my Flows.
I don't know what you mean by them feeling like you have flat tyres, do you mean flexy or a lack of contact patch feel?
Not had any spoke tension issues with the set I have - the older wide 29er ones on dt240 hubs. They built up really nicely and I don't recall ever having to touch a spoke and its not like I've babied them
Nope. Built a set of LB 30/24mm 29er rims on Hopes last month, done 250km on them so far clattering over all sorts, and they seem fine. To be fair I haven't had them in the truing stand to check precisely, but they look ok in the bike, no wobbles. Normal tensions and that, nothing out of the ordinary. If anything I was a bit worried that I'd undertensioned them as carbon is supposed to need higher tension than aluminium.
The flat tyre thing, I have had a moment where I thought I'd flatted but hadn't, but I think that was because I *had* flatted just before that and wasn't convinced the sealant had taken. They do seem to sound and feel different from metal rims to me, particularly when they take a bigger hit, so maybe it's that difference that feels weird to you?
Normal tensions and that, nothing out of the ordinary. If anything I was a bit worried that I'd undertensioned them as carbon is supposed to need higher tension than aluminium.
Ah, this might explain why I've had to tension mine higher than I would normally expect with an aluminium rim at least. Where had you heard this previously?
They do seem to sound and feel different from metal rims to me, particularly when they take a bigger hit, so maybe it's that difference that feels weird to you?
It's more just when riding along, the rear tyre feels more squirmy than I'm used to (coming off ally rims with almost identical internal width)... Not when taking hits as such.
You may have stressed relieved as much as you thought you did if a wheel needs attention this is normally the cause. I have built with lots of carbon rims and never had any issue. You have not mentioned spoke tension i hope ds rear is 1200n.
Carbon rims do not need higher tension than alloy rims. Spoke tensions much higher than 1200n risk the flanges on hubs anyway.
The tension in a wheel only needs to high enough to avoid spoke loosening off and to avoid early fatigue. There is no wheel that benefits from tensions higher than 1200 to 1300n on the ds Rear. Front wheels can be tensioned abit less but i would tension the disc side to 1100n.
I have been using two sets that I built myself (both are about 2 years old) I haven't had to adjust them once. Although I did build them with Pro Lock nipples. One thing I did notice when building them is that due to the stiffness it was very easy to get them true, but with the spokes at an uneven tension, riding them like that would cause the spokes to un-tension.
Nope I had the 33mm 26" ones and they were fantastic, barely went out of true in 10 months use.
I really don't mean to question your competence, because I know nothing about you, but everything you list sounds like poor build issues coupled with not knowing enough about the materials you're building with.
Ah, this might explain why I've had to tension mine higher than I would normally expect with an aluminium rim at least. Where had you heard this previously?
No, i didn't mean to mislead, my point was kind of that I don't think it will be that! I didn't add any extra tension at all. It was something I read on a couple of websites (naming no names). I suppose the theory is that carbon rims have less give or something? Anyway, I didn't change my build cos I wasn't convinced by the arguments, but I have kept an eye on them to see if they acted differently and needed more tension. They don't! 🙂
Carbon rims do not need higher tension than alloy rims. Spoke tensions much higher than 1200n risk the flanges on hubs anyway.
That makes sense, thanks for clarifying. I build to ~1200 on the DS, yes.
One thing I did notice when building them is that due to the stiffness it was very easy to get them true, but with the spokes at an uneven tension, riding them like that would cause the spokes to un-tension.
This sounds more like it - I do always try to make sure that my spokes are very close in tension to one another, some people do it by pitch but I'm not a zen master so I cheat and use a gauge... 😉
I've got 3, one of the rears has lost a little tension and has settled just slightly off dish- suggesting it's pretty consistently lost driveside tension I suppose, since it's still within a bawhair of straight, just out of place. But then it's been well used. The other 2 have been perfect. Built by Steve Deas at Icycles, he did say they might need a little tweak after bedding in but that turned out not to be required. Steve seems to like a tight wheel.
I don't know about carbon rims needing more tension but the LBs certainly have a high limit, 180kgf for mine. As far as flanges go, I had a look, DT don't quote a maximum limit for a DT240S, they just say it's irrelevant as no rims get anywhere near to the limit of the hubs.
I really don't mean to question your competence, because I know nothing about you, but everything you list sounds like poor build issues coupled with not knowing enough about the materials you're building with.
Awesome! 😆
Is that the same as apologising before criticising someone? 😉
I'm asking cos there's guys on here that have been riding the rims for upwards of 12-18 months already. I've been building alloy rimmed wheels for the best part of 15 years, but until a few weeks ago, had never built a carbon one, hence throwing out a few questions on here where I know there's a lot of people who've plenty of experience of them.
Spent a bit of time retruing my rear last night, concentrating on even spoke tensions more so than perfect truness. It's not as perfectly round as I'd like now (though no doubt most people would say it's pretty damned near perfect), but all the spoke tensions are very even (and very high!). What I would say is that there does seem to be a settling period with carbon rims, which is less prevalent with ally rims (especially eyeletted rims).
Gonna ride the bike again tonight, will report back later.
what are you lubing your nipples with?
Interesting. I think I may have felt this "flat tyre" effect but not sure with all the variables of tires, pressure, tubeless, tubed, frame flex etc. I think Stevet1's question is a good one.
The XC 29er rims certainly seem stiff to me in unbuilt form, not rigid but pretty solid for the weight and I can't see any reason why they'd behave any differently under tension.
Perhaps it's opposite side deflection that you're noticing? I'm always surprised how much you can pull any rim / wheel to one side if you grab the rim and chainstay and squeeze.
[quote=Stevet1 ]what are you lubing your nipples with?
ice
How many spokes are you running OP?
...just a wild, crazy, random thought here.
Could the problem actually be a defect in the rim?
If the OP is as awesome as he says he is at building wheels - I don't doubt it - then perhaps the rim is at fault. A slightly oval, or warped rim would probably cause all sorts of spoke tension issues when ridden - if built up 'correctly'.
First set of wheels I built were LB rims on king, followed a books instructions, not adjusted in 9 months, done 2 lakes trips and multiple rock gardens regularly, no problems for me as yet?
Re:- The flat tyre effect, does it feel like the tyres rolling off the rim?
Hi
I've built 4 sets of these, just built them as normal, no problems.
I certainly wouldn't say they feel like you describe. They just feel stiff.
GB
what spokes are you using, DB 1.8, 1.7?
no_eyed_deer - MemberIf the OP is as awesome as he says he is at building wheels - I don't doubt it - then perhaps the rim is at fault. A slightly oval, or warped rim would probably cause all sorts of spoke tension issues when ridden - if built up 'correctly'.
The construction process for carbon makes that pretty unlikely, and I don't think it'd be realistic to get a post-production bend in one either. There's probably other ways it could be defective mind, maybe a low quality bead under the spokes allowing movement? But it doesn't seem a likely contender.
Just come back from a brief evening ride where I got the chance to give the bike a hammering.
No issues of note with the rims (the rear Conti MK2 Protection tyre is now a write off though as I pinched it badly when everything bottomed out on a rocky part of the descent). The "flat tyre" feeling has all but gone now too (until I did actually slice the tyre open at least!) and I've just checked and the rim is dead straight and true, and all spokes of even tension.
Seems that the rim does just need to be built with very high spoke tensions in comparison to a normal ally rim perhaps. Everything seems fine now, and I'm certainly not worried any more.
FWIW they're 32H, on DT Swiss 240 hubs built using Sapim D-Light Triple butted spokes (equivalent to a DT Super Comp at 2.0/1.7/1.8mm along their length) and pro-lock nipples. 1500g for the pair before tubeless tape and valves!
Oh and Park Tension Meter on its way to me in the post in the morning...
Oh and Park Tension Meter on its way to me in the post in the morning...
You wouldn't have had these issues had you have used one from the start.
The tyre rolling off the rim feeling is a symptom of insufficient tension, been there done it, then used a guage.
Built with Competitions and Revolutions.
Mine do this as well. I laced a pair and got my lbs to tension them so I'm not sure how much they were stress relieved. The front is perfectly true but the rear goes a few mm out of true and needs a tweak, it never goes past a that point funnily enough. I might need to get someone with more skill to sort it out.
My LBS built some 29 AM LB rims onto Hope hubs earlier this year for me. FWIW they're experience wheel builders - both mtb and road - and I've used them before.
I only ran the bike 4 times before rear went wobbly;
- CyB beast
- Two piss easy (for an AM bike) rides on Cannock Chase
- Bike Park Wales uplift
So, in short OP, it's not just you.
Have to say that IMHO an ali rim would have caved - I noticed the spokes were lose after descending "Rock n Roll" and "Zut Alors" - and when they're right they feel really good and nowhere near as dead or wooden as I worried carbon rims might.
Just popped my first spoke on my LB wheels 😥
Been riding them pretty hard for ten months so can't complain I guess. Just trying to get some spare spokes from the shop that built them up now. He said he'd been impressed with the ones he had built but made a point that he left the, to settle after building for a day or so them checked the spoke tensions before giving them the customer....
Just built one up for a mate. Rested it for a day once the tension was on before the final tweak. Tension per side is within 5% of the average tension which is half a scale unit on the park tool. I'll keep an eye on them and see how they go but they felt stiff and responsive on a quick blast up and down the road once the wheel was dressed.
An update...
First things first, the Park Spoke Tension meter... Great tool, useful for truing any wheel, but an absolute necessity for carbon rims from what I've learnt! Anyway...
My rear wheel tensions were a little inconsistent. Not hugely so, the differences probably wouldn't have mattered so much on a more flexible ally rim. I evened everything up, and since then everything has been fine. The Drive Side spoke tension in the rear wheel is almost off the chart high though! Park Tension Meter points to 25 on each spoke, and they're 1.8mm butted, which is about as high as they'll go. Still, it definitely rides better, there's now none of that flat tyre feeling, and the bike has been to BPW with the wheels on where I did a few of the black runs as well as the Blue's and the Red's, where they took a fair hammering and came out completely scathe free! 😀
You wouldn't have had these issues had you have used one from the start.The tyre rolling off the rim feeling is a symptom of insufficient tension, been there done it, then used a guage.
Like I said, built hundreds of ally rims over the years, these were my first go at building carbon. Never had a problem building ally rims on feel alone, they've always held up very well. Seems carbon rims really need the tension meter.
So, in short OP, it's not just you.
Glad to know I'm not the only one! Although now I'm happy to have fixed the issue.
Just popped my first spoke on my LB wheelsBeen riding them pretty hard for ten months so can't complain I guess. Just trying to get some spare spokes from the shop that built them up now. He said he'd been impressed with the ones he had built but made a point that he left the, to settle after building for a day or so them checked the spoke tensions before giving them the customer....
Just built one up for a mate. Rested it for a day once the tension was on before the final tweak. Tension per side is within 5% of the average tension which is half a scale unit on the park tool. I'll keep an eye on them and see how they go but they felt stiff and responsive on a quick blast up and down the road once the wheel was dressed.
It seems they can't be rushed. Ally rims are probably more forgiving of an imperfect build at least.
Great tool, useful for truing any wheel, but an absolute necessity for carbon rims from what I've learnt! Anyway...
Is that you eating humble pie?! I've managed to build without a tension meter and not have my wheels fall apart. HTH. 😉
Built up my first set of LB rims over the weekend. My first pair of carbon rimmed wheels too, so after reading a few of these threads I was even more careful to watch the spoke tension, and for the first time (for a home build) used a tension meter. I was also extra careful about doing loads of stress relieving (on the floor, with lots of force on the rim) and that seems to have worked.
Sounds like the OP has built loads more wheels than me though (I've probably only done 20-30), so maybe just unlucky with getting the tension a little under ideal?
H'mm will I really need one of these tension meters? I've only built 4 wheels before (but all are still in use and fine!). Anyone in South Hants got one I could borrow please? Or I could drop mine in at LBS
My LB rims (built by the lbs) have stayed really true, despite having had several spokes come loose, infact its a problem, spokes were loose but because rim was true i didnt really notice
anyway over a year on them now, 2 rounds of ews, DH races, 6 or 7 gravity enduros and they are still true
To get over the loose spokes problem the guys at the hope race wagon support kindly super tightened them up for me and theyve been fine ever since
Im no lightweight, lack finesse and dont have much luck with ally rims, so that these are still going strong and true over a year, I'd definitely buy again