Dave's road tubeless doubts

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This post deserves a TL:DR summary, which is: If you aren't super comfortable with road tubeless and willing to spend some time and expense figuring out exactly which combo works for you, and also willing to petentially suffer a reduction in the lifespan of your wheels, stick to tubes. With a whole bunch of data now showing superior rolling resistance with clinchers and latex tubes, that may be the best way to go in any case. The ability to use latex tubes is another bonus of aluminum rims. 

For mountain bikes, tubeless is mandatory. For cross, it has its challenges (which we've done a heck of a lot to help eliminate) but the benefits can be so profound that the juice is for sure worth the squeeze. For road, though Mike and I personally use tubeless, we haven't been evangelical. It comes with downsides, which we'll talk about here. 

A potential "do as I say and not as I do" instance

We've been observing and talking about spoke tension drop in clinchers for a couple of years now. Since I've done THE WORST job at tagging posts, it's hard to find all the posts on the topic, but these two posts from last spring are good examples. There were a bunch of forum discussions in the spring of 2014, but I can't even recall which forum they were on. We even made a video to show the effect last spring. 

Wheel Fanatyk has what might be the second best wheel blog out there, and they did a series of posts in the fall about this whole topic, including the outward splaying of brake tracks which we'd discussed in above-linked post called "Pressure Drop Follow Up." What they did in particular, for which I have huge appreciation, is measure a bunch of tires to find how tightly they will fit. Their whole methodology and execution of this is excellent. What their measurements reveal is something that anyone who's installed more than one kind of tire will already have known - tire bead circumference varies by manufacturer and model. 

They've also measured overall circumference of a number of different rims, but they haven't shown the more relevant tire trough and bead seat diameters (which are simple secondary measurements from what they've done and shown). The overall circumference is of little value in its own right as, for example, a Zipp 404 shows a large outer diameter, but 404s are known to be relatively easy to fit tires onto (perhaps too easy?).

In order to resist the higher inflation pressures of road tires, road tubeless tires need a tight fitting carbon bead. The carbon bead more or less doesn't stretch, which is critical to having the tire not blow off the rim, and thus to keeping your teeth in your head. In that respect, it works quite well, but at what cost?

Non-tubeless road tires have either wire or Kevlar beads (if you're reading this, you probably have Kevlar beads). You probably notice that your tires get easier to install over time, which is because the beads stretch a bit over time. This stretch reduces the constricting pressure that the tire imparts on the wheel. 

Compressive tire loads cause a reduction in the circumference of the rim. Wheel Fanatyk estimates a possible 1mm reduction in the circumference, and my calculation gave me an estimate of .1mm in diameter reduction, so they estimate a bigger effect but we're not that far off in the absolute. I based mine off of "the spoke tension drop is x, the thread pitch of a nipple is y, the spoke tension drop is equal to z turns of the nipple, therefore the diameter reduction must be..." The important thing is that we're both seeing the same effect, in the same direction, with reasonably similar magnitudes. 

Compression is bad for the wheel for several reasons. It takes more initial spoke tension to maintain the minimum necessary functional spoke tension. Compression changes the dish of a wheel. Compression puts stress on the rim that almost certainly shortens a rim's useful life span. 

At the risk of speaking against my book somewhat here, I have two road bikes in current use (one disc, one rim brake, otherwise more or less identical) and those four tires are all tubeless. It works fine for me, but on a scale of 1 to 10 in tubeless experience, I'm about a 643. So if you are willing to invest time and money into getting your road tubeless set up perfectly, knowing that it comes with the potential to compromise your wheels, then it may be worth it to you. Otherwise, tubes are your best bet. 


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  • Hans on

    @MikeM, are you trying to fix the tire on the road? I would just put a tube in . But it is messier since there is sealant involved (but no boot needed).For fixing a tire on the road without removing, these work fantastic: https://www.amazon.com/Genuine-Innovations-Tubeless-Plug-Patch/dp/B00B139BA0 — To be honest, I haven't had to use them on my road tires, but have used those lots of times for MTB and 'cross tires. They address holes that are too large for sealant to just seal.But in general, it sounds like if you're not benefiting from fewer flats, there probably isn't a huge advantage . Maybe those aren't very good tires. Or maybe you've just been unlucky. I started road tubeless with Hutchinson tires. They are, IMO, garbage. The Fusion 3 flatted more than any other tire, including blowing out a sidewall once. I swore off road tubeless. Then decided to try again with Schwalbe One tires and had a very different experience. I'm a happy convert now, though I wouldn't be all that sad if someone forced me to ride GP4000SII tires with latex tubes :)

  • MikeM on

    I tried some Schwalbe Ironman 24 mm on Velocity A-23 rims. I know these aren't your favorite rims, and if I had to do it over, I'd go with the Kinlin or Hed Belgium rims. This is neither here nor there, though.The Ironman tires are much too easy to puncture, and when you do puncture them, they're so difficult to repair. I did repair the tire, but now I don't really want to ride it. It was a mess to fix on the road. I feel as though the glass I hit probably would have punctured a GP4000 as well — but that wouldn't have been so messy to fix on the road (no boot needed).I'm going to get another thousand miles or so out of these tires, and then I'm done. The tradeoff for the tiny performance gain is field service goes out the window. It's not worth it. I'm done with them.

  • dave on

    Cooskull – Correct. Haven't ever had EXACT same except for one being tubeless and one not rims to compare, but an Easton R90SL has a similar drop to a HED C2. Similar rims, the C2 is a bit smaller (shallower and narrower), they're within grams of one another, and they drop just about exactly the same. The caveat to that is that the tubeless tire, out on the shelf but uninflated, will still exert compressive force. On a non-tubeless rim, the tire doesn't compress the rim much if any until it's inflated. There's a bit of a prisoner's dilemma on rims – you either 1) make them light enough to make people notice, sell a ton, and deal with the consequences later 2) make them a bit heavier than that because you know they need to be, but pull "claimed weight" shenanigans so they're attractive and deal with complaints if they come (knowing that most people never really weigh stuff after basing a decision on what things weigh) or 3) just make them tough and have people call them tanks and boat anchors and don't sell any of them even though they're probably fine rims. Some rims thread the needle around this deal, but we've sure seen examples of each. Hans – I've never heard of or experienced a tubeless tire burping at high pressure. If one has ever happened, I'd love to know about it. Have heard of ill-advised attempts to use non-tubeless tires for road tubeless. That's just asking for it, but what happens isn't a burp, it's a blowoff – the opposite of a burp. And Stan's rims can be a bit "cheater" in their diameter – they're a shade big.

  • Hans on

    COOSKULL makes a good point; I don't think I'd use a rim that dropped 25% with or without tubes. And I've never heard of tubeless burping on road rims (at road pressures) ?? But perhaps the bigger point is that for professionals tubeless doesn't make sense. And I'd defer to others to comment on that. Certainly, if I had a car following me with spare wheels, I'd probably use tubulars too. But that doesn't look like it's gonna happen in my lifetime unless I hire an Uber^H^H^H^HLyft driver to follow me around with bottles. So I'll use tubeless since it works great. If a wheelset only lasts 30k miles instead of 35k miles because it was tubeless, that's probably longer than I'd have patience to use the same set of wheels anyway. I'm still interested in seeing some quantification to the effect of tubeless tires on tension (e.g. same tire in tubeless vs. non-tubeless versions with tensions measured every 1k miles?). I understand that's not easy to do. And it still sounds like you can just build with the tension drop in mind. I don't really see a problem here, just something to take into consideration when you're building a wheel for tubeless use.Incidentally, you also don't need a tubeless-designed rim to run road tubeless, though it does help when it comes to fitting tight tires. In that tubeless-specific rims have a deep center channel and shelf. But I've run tubeless on several Kinlin rims (XR300, XR270, and then a MTB rim that I used for 'cross) that weren't specifically designed to be tubeless and they worked fine.Rims definitely help, though. For the first time in years of road, cx, and MTB tubeless I had to give up mounting the Specialized Roubaix Pro 2BR tires tubeless on my Flo30 rims. The tires just aren't as snug as some others (e.g. Pro One, or the G-One tires that I have on there for winter) so they just refused to get enough traction to seat. But these tires have seated just fine on my Stans Grail rims. With a floor pump. So rims do make a difference, especially with a tire that apparently is not all that well engineered for the purpose.



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