My post is not exactly a tyre review, but a set of questions I thought I’d ask where people are knowledgeable about 29" tyres.
I bought a new uni with a Kris Holm Cross Country rim (37 mm wide) in July 2011. To my order, it had the Schwalbe Marathon Supreme 28 x 2.0" on it. After about two months and probably less than 1000 km, the tyre blew off the rim with a loud BANG, on an otherwise totally uneventful stretch of straight flat road. I had pumped it that morning to 4.8 bar, so well within the rated pressure of 5 bar as printed on the sidewall.
Fast forward to July this year. I finally bought a new tyre (again a Schwalbe Marathon Supreme 28 x 2.0") since I wasn’t sure the old tyre was undamaged, and a tube, and mounted them. Within a month (in fact, during the 100 km race at Unicon ) it blew off again! Again, I had pumped it that morning, to exactly 5.0 bar this time.
Today I mounted a Schwalbe Big Apple 28 x 2.0" on the same rim. The Big Apple is a non-foldable tyre whereas the Marathon Supreme is a folding tyre. I assumed (admittedly with no basis at all) that a non-folding tyre might be stronger. On the tyre sidewall the print says pressure MIN 2.5 bar, MAX 5.0 bar. Confusingly, in the instruction leaflet is a picture of the tyre’s sidewall that stated MIN 2.5 bar, MAX 6.0 bar! Next to it is a drawing of a rim without an inner holding protrusion (I don’t know the name, it is apparently intended to “hook” the bead under it). In that picture it says MAX 5 bar. As if the protrusion makes for a higher max pressure, which makes some sence. Maybe on the XC rim (which does have this protrusion) the max is 6 bar? By way of precaution, though, I pumped it to no more than 4.5 bar.
I should add that both types of tyre mounted very easily on the rim. The Big Apple mounted even easier than the Marathon Supreme. No force at all, it just “flopped” in place. I found that actually disturbing, in light of my experiences.
Questions:
Does easy mounting of a tyre indicate that the tyre is more prone to blowing off the rim?
Is the Kris Holm Cross Country rim known to be a bad combination somehow with the Schwalbe Marathon Supreme 2.0"?
Can it be true, as someone suggested to me, that the 37 mm wide rim is actually too wide for a 2.0 tyre?
Pressure recommendation for the Big Apple, in light of the above?
Suppose this combo fails again. Being stuck with the rim, would it be better to mount a wider tyre? I have some experience with the Big Apple 28 x 2.35 and did not like the sideways rolling effect on slanting roads. Any other tyre suggestions for road use that are more stable on this rim, both in terms of sideways roll, and in terms of not blowing off?
@Klaas, I don’t run road tyres on my 29er, but FWIW from my general experience:
A 37mm rim is certainly wider than people would normally use for a 2" tyre on a bike, but as long as the tyre is wider than the rim it shouldn’t slip off. I run a 2.1" tyre (WTB Prowler) on my KH29 XC rim with no problems, but not at such high pressure (it’s an XC machine, so usually around 25psi). 5 bar is around 70psi according to a quick google.
I would say 70psi is an extremely high pressure for a 2" tyre though. Are you sure you really need it that hard? I would say it would feel pretty firm even for road riding at 50psi (3.4 bar).
On the other hand, I run 1.5" tyres at 85psi on my tandem - obviously different rim and tyre, but still wide-ish tyres at high pressure.
Perhaps the hook (that is indeed what it’s known as) on the KH rim is a bit small or not “hooky” enough for running such a high pressure, even if the tyre is rated that high.
Another thing that comes to mind is that sometimes a catastrophically failed (split) tube can blow the tyre off the rim as the air escapes, making it look like the tyre was the cause of the failure. Could you perhaps have a sharp bit of swarf or something on the inside of your rim that’s bursting the tubes? Or could the tubes have been pinched on fitting? (not meaning to suggest you can’t fit tyres properly :o)
If I was Riding road and wanted to run high pressure, I’d get a narrower rim with a better “hook”. The KH rims are not designed for high pressure road use. What is probably happening is the rim is wide relative to the tire, so it’s spreading the tire and you are not getting a good “hook” on the bead. You probably want to get a road bike rim, one designed for touring or tandem use. I’d suggest a Stan’s tubless set up, make sure and coat the tire bead and rim edge with Stans, that’ll increase grip at the bead. Take a look at the new Nimbus Stealth 2, the 36er version has an excellent hook, so maybe the 29er version is made the same?
Thanks Rob and Ben, that gives me something to work with.
It’s not really that I need it, but generally I like high pressure for road riding, because of the associated low rolling resistance.
Is there a way of checking if the hookiness is sufficient. E.g. should it be “this size”?
I did a quick inspection before mounting the new tyre and tube and saw nothing, so this looks not too likely to me. And no, tubes have not been pinched on fitting - at least not the second one; the first one was mounted by municycle.com and they surely know what they do. And then again, not only do I know how to fit a tyre properly, but it went on with terrifying ease, in view of the earlier blow-off. So there was not the least temptation to use tools.
I think you’re onto the root cause there. I’m not a big fan of tubeless in view of the trouble that people sometimes have with it (until it’s properly set up, that is). But I’ll look at a more road-oriented rim. Not too narrow a rim though, I used to have a Big Apple 28 x 2.35 on a quite narrow rim, and its sensitivity to road camber was quite uncomfortable.
I built a wheel using a Velocity Dyad and Resist Nomad 700x45 tire. It’s quick and comfortable with 114mm cranks. See this thread for more: 29er rim options?
I much prefer my 36" for going fast on the road, but if you want a lightweight road 29" (700c), then you could probbaly just get a mtb rim and choose a wider road bike or tandem touring tire, say 35-40c, so a rim width of 25-28c.
One thing to consider is tire profile and how that is affected by camber. A wide rim and relatively narrow tire will have a flatter tire profile, which seems to reduce the affects of road camber.
@Klaas,
My 36er is my first dedicated tubeless, so I put a lot of thought into how the tire and rim work together. The Nimbus Stealth 2 has a very aggressive “hook” which grabs the tire bead and helps prevent tire blow off. Nimbus built this rim specifically to address tire blow off on the 36" wheels, but when the design was successful they decided to apply the design across all sizes. The 29" rim is 800gm and 42mm, so kinda heavy and big for a super light set up, but for running a 2" or large tire, it’s a good choice.
If you search MTBR under rim reviews, you can see what is popular and then use that info to search for rim profiles to find one that has a strong hook. Tubeless ready rims seemed to be designed with better hooks.
True enough. Some of the largest (e.g. 3") 29er tires coming online may not fit the KH29 frame, but one nice thing about the disk brake (if you want a brake) is that it doesn’t matter - can aways use a 36 frame with a 700c rim if needed.
I got yet another flat with my Stout and decided that enough was enough, I just put in an order for the Hans Pacestar.
When it arrives I’ll probably also go with a thick DH tube. I’m not looking forward to increasing the rotational weight of my 29er (that’s one of the reasons I prefer the 29er to my nimbus 26 with the duro) but I feel like I have to do something since my riding style seems to be ride with the pressure just north of flat.
You are going to love your Hans. The 29er tube that came in my KH29 was very thin. I use a thicker 26 inch tube in my Hans 29 with no problems. No more pinch flats.
So where are we in the freeride/DH (thick & stiff sidewalls, deep tread) department? Looks like the WTB 2.5s of last decade went away quietly without saying goodbye.
The WTB dissent and Kodiak rode like warmed over doo doo, I had em both, sold em both, neither is worth the trouble.
Sidewall stiffness alone is not what we need for a good tire, it also needs to be light, supple, and not suffer from cambered surfaces. That Kodiak was quite possibly the worst tire I’ve ever ridden when it comes to steering into the hill. The Dissent was bearable, but in contrast to the RR 2.4 it paled in all things but durability; the RR is kinda soft and not that rock proof.
The Ardent 2.4 is a great tire and well worth riding, but better tires keep coming out, like the Hans Dampf 2.35 and hopefull soon the Hans Dampf SG (Super Gravity); the SG was developed for extreme alpine riding.
If you have the frame (Oregon or maybe the Conundrum) the new Surly Knard 29 x 3" could be a winner, but so far it is vaporware, pics only, no good reviews.
It seems like the current generation of tires are treaded party balloons. I kinda prefer a wide, stiff, and heavy tire running at ~35 to 45 psi, not some squeaky airbag you can twist into a giraffe…but as usual, I’m a minority within a minority.
