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Post by JimRatliff on Aug 16, 2014 5:51:20 GMT -7
This question is primarily for Svend since he is the only person I know running tubeless without sealant. I have been wondering if a puncture without sealant would result in behavior much like a car where the nail is usually retained in the tire and its just a slow leak?, rather than the explosive loss of air as is common with a tube. Svend, could you test this theory for me by intentionally running over a nail or tack or something?
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Post by Deleted on Aug 17, 2014 18:59:03 GMT -7
In all likelihood I will not even have to do this intentionally, as I have spotted my wife secretly stashing a little sachet of tacks in her cycling jersey to use in an emergency. You see, I've become rather a bit faster and more confident on my 29er since switching to tubeless, and there have been (albiet still rare) occasions when I've actually nipped at her rear tire. This has understandably caused her considerable shock and anxiety to see me there, this being an unprecedented occurrence. It's only a matter of time until she's had enough of the impertinence, and dispatches me into the undergrowth with a flick of the wrist. I will dutifully report to you my observations on the fate of the tires.
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Post by JimRatliff on Aug 17, 2014 19:16:01 GMT -7
In that case, let's hope for video, or at least an unbiased report from one of your daughters. However, I want to go on record as supporting any and all attempts to level the playing field to adjust for the extra ballast that we men are forced to carry up each hill.
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Post by Deleted on Aug 17, 2014 19:54:15 GMT -7
Hear! Hear! Speaking of extra ballast -- because the new full-suss bike that my wife has been riding only has one bottle cage, I am now forced to play the dromedary and carry an extra water bottle for her on long rides. Time to buy her a Camelback...preferably a very large one (= heavy ). Seriously, this tubeless thing really is the schizzle. Jim, I should have listened to you and BW years ago. I am now running a Bontrager XR4 (2.3") front, and an XR3 (2.3") rear, both tubeless without sealant. They hold air just as well as tubes, losing about 5 lbs a week. The weight saving is noticeable -- with a Conti tube (my brand) weighing in at 225g each, I estimate going tubeless dropped over 400g from the bike, and rolling mass at that. And these are much beefier tires than the Slant Six I had on before. Amazingly, these also roll just as fast or faster on hardpack than the Slant Six did with tubes. We did about 10 km on a gravel rail trail today as a warm up / cool down on our way to and from the singletrack, and the bike just flew along -- effortless pedaling, it felt like. This was my first rail trail ride since switching over. Remarkably, despite being wider and having much more aggressive knobs than the Slant Six, and being run at 15 psi lower than I normally would have for a rail trail ride, the Bonty tires felt like they rolled with less resistance than the Slant Six. Kinda makes me wonder how the Slant Six would behave if run tubeless(?). Now that could be REALLY good, as it is a fantastic tire. I was reluctant to take them off, to be honest, they just worked so well around here. A lot of locals, including racers, use the Slant Six here. They are a common sight, and popular for a reason. All things considered, the change over to tubeless has been an improvement in every way -- grip, handling, weight, comfort (important on a hardtail), speed, energy input, etc.. And for no more effort or fuss than using tubes. Even if I did have to use sealant to get the tires to hold air, it would be no big deal and I would do it without hesitation now -- the benefits are well worth it. I'll be converting my wife's full-suss bike soon, as it has Stan's Olympic rims and should be a cinch to do. But wait....that would make her even faster. Rats! Scratch that idea.
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Post by JimRatliff on Aug 18, 2014 3:53:44 GMT -7
You sound about as pleased as anyone could be with your current tire setup. Congrats!! Hard for me to relate to pressures on a 29'r, but what are you running front and back? Lynn and don't agonize nearly as much about tire pressures now as two years when we first started running tubeless, however. 400 grams is huge. WOW! Even greater savings on 29 than 26 I think although the 26" Slant Six always felt like a heavy tire (in the store).
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Post by Deleted on Aug 18, 2014 6:02:27 GMT -7
Jim, the weight savings were not from the tires -- the Slant Six weighs about the same as the XR3, and actually a wee bit less than the XR4. The -400g came from losing the two tubes.
As for pressures, I am running 35 psi front and back, which is the same as I had with the Slant Six. I am still experimenting with this, but my first forays into these lower tubeless pressures that everyones keeps banging on about, just haven't been satisfactory. Maybe it's the tire, but I tried the XR4 (front) at 30 psi and found it too squirmy and wouldn't track a straight line. Then tried 28, then 25, finally 22 psi, but it just got worse. More cush and grip, to be sure, but the handling basically sucked. Bumped it to 35 psi and it's perfect -- handles great, grips well, and I just let the fork absorb the bumps (the tire certainly isn't bouncing off of things at that pressure). As for the XR3 on the rear, I will try going lower and see what happens.
I think tire pressures for 26 vs. 29 have little to do with wheel size, and more to do with rider weight, rim width, tire volume, and sidewall stiffness. I am 225 lbs, so logically need higher pressures than you and Lynn to prevent rim strikes. The Bonty tires are high volume, so I'm sure I could go down to 25 psi or lower without a problem, and I will try that on the rear and see how I like it.
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Post by JimRatliff on Aug 18, 2014 6:58:36 GMT -7
I ride 30/35, so not real low pressure either. Lynn is 3-4 less.
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Post by JimRatliff on Aug 18, 2014 18:51:11 GMT -7
First there were regular tires with ghetto tubeless, then the manufacturers introduced real UST tires that were typically 100-150 grams heavier than the tubed equivalent. The real big recent change was the introduction of so-called tubeless ready at the same weight as the tubed tire, with the expectation that sealant would be needed. It now appears that Bonty has upped their game even more, with TR (tubeless ready) that, as Svend says, actually hold air just as well as true UST tubeless AND still hold the weight down. That is a lot of engineering progress by the tire companies in just a few short years, IMHO.
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Post by Deleted on Aug 20, 2014 7:36:24 GMT -7
Yeah, it's pretty impressive. I can't speak for how "tubeless-ready" tires from other makers perform in that regard, but my experience with Bontrager has been excellent. Part of it, I think, is that Bontrager has created different rim strips that are molded to exactly match the profiles of their various TLR rims. I must say that the Rhythm rim strips fit perfectly into my Rhythm rims. The strip curls up and nestles into the bead hook on the rim, so the tire bead seals against the rim strip surface, rather than the rim itself. It certainly works well, and combined with the airtight tire carcass it does not leak at all. No sealant required. I am not aware of other rim manufacturers who have such a system, but have not looked into this, to be honest.
As for weight, the XR3 and XR4 weigh no more (significantly less in many cases) than comparable tubeless-ready tires from Kenda, Maxxis, Conti, etc.. They are certainly much less than full-on UST tires. Which speaks to your point, Jim -- why buy a heavy UST tire when a much lighter tubeless-ready like a Bonty holds air so well?
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Post by Deleted on Aug 20, 2014 15:05:14 GMT -7
Jim, since you seem rather interested in tire weights, here are some comparisons for tires of comparable size purpose, tread, TPI, tubeless-ready, etc., as referenced to the Bontragers that I've just installed:
All Mountain/Trail/XC Bontrager XR4 Team Issue, 29 x 2.3", 120 TPI, TLR -- 790g Conti Trail King, 29 x 2.2", 4/240 TPI (not sure what that means), Protection Revo -- 815g Maxxis Ardent, 29 x 2.25", 60 TPI, EXO/TR -- 800g Kenda Nevegal, 29 x 2.2", 60 TPI, KSCT -- 945g Specialized Purgatory Control, 29 x 2.3", 60 TPI, 2-Bliss Ready -- 755g
All Mountain/XC Bontrager XR3 Team Issue, 29 x 2.3", 120 TPI, TLR -- 705g Conti Mtn. King, 29 x 2.2", 4/240 TPI, Protection Revo -- 740g Maxxis Ardent Race, 29 x 2.2", 120 TPI, 3C/EXO/TR -- 720g Kenda Karma, 29 x 2.2", 120 TPI, KSCT -- 756g Specialized S-Works Ground Control, 29 x 2.3", 120 TPI, 2-Bliss Ready -- 650g
So you can see that the Bontrager tires, despite their large size at 2.3", have a similar weight to others in the same class. The sidewalls seem reasonably strong for 120 TPI - certainly much more there than others I have seen (Small Block 8, Ignitor, Trail King) whose sidewalls are paper thin.
I did not find any 29er tires in UST build, but in 26er size the UST versions were about 150g to 200g heavier than their equivalent TR counterparts.
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