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Bipolar roller
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...You're really just relying on one row of knobs. Do you think increasing the width (the amount of rubber not in contact with the ground) is really going to help when the bike is leaned over?

I suspect that for cornering grip in mtb tire tread design you need 1) the tread blocks of the cornering knobs to have sufficient size for stiffness and stability (aka tread block stiffness) and 2) a longitudinal channel (void space) big enough to allow the biting edge of the cornering knobs to exert enough force against the trail surface.
Totally agree on both points there, and with the maxxis minions FBF 4.8, there are actually 2 rows of huge cornering knobs to rely on, both with nice big channels giving plenty of space to bite the terrain. Having an extra row of channeled cornering knobs makes the tires feel like they are eating the trail. Also, the fbf knobs are huge and very stiff. The large, spaced out channels really allow for the corners of the knobs to bite and grab dirt and rocks.

458DD017-BE1E-4033-8345-BD954CED9F23.jpg


You can see here maxxis did a great job with the channeling on these tires.

5F722C37-CA0C-445A-A73A-D584A3F2E00F.jpg
 

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OP question, I've done some testing relative to this. It's not by best work, but I've posted it here: https://crankjoy.com/tire-size-shoot-out-29x2-35-vs-29x2-6-vs-27-5x2-8/

My summary statements from the test:

Based on these results, I’m going to keep 27.5+ mounted. They were just more fun than the other sizes, and the speed advantage to the 2.35 set was small enough that I’m willing to compromise in climbing speed for the superior ride feel.

The 29×2.6 set offered similar composure to the 27.5+ over rough terrain, but it was resistant to mid-corner correction. The 2.6 didn’t offer the fun, intuitive feel that the 27.5+ setup had. Additionally, it did not present a noticeable or measurable decrease in rolling resistance. It wasn’t bad per se, but I didn’t feel that advantage was nearly enough to offset the better handling of the 27.5+ setup elsewhere.

I’d choose the 29 x 2.35 for a dedicated XC race setup. Despite similar overall lap times, XC and endurance races are won and lost on the flats and the climbs, and here is where the 29×2.35 showed and advantage.


Then win races on it?
I've won races on my fat bike. Open class no less. I've earned a buckle in the Marji Gesick aboard my fat bike. So I think your assertions regarding how slow they are are overblown. You're implying that they are entirely not viable as race bikes, which I disagree with. Yes, it's slower than my XC race bike...but I don't think that it is slower by much, and only at higher speeds where wind resistance or large/fast impacts come into play.

We've had this discussion before, but once again I am offering a counterpoint to your point. The reason I bring it up is that one should not summarily discount wider tires as slower. Usually, yes they are, but it depends on the surface and the rider weight.

I'll run some back to back testing in the next few weeks...my 24 lb carbon fattie w/ 4.8's VS my 23 lb XC whip, both with similar high end builds and same brand tires and compound. We have a lot of varied terrain here, what type of course would you like to see? Let's quantify it and put this to bed. Then folks can decide if the speed tradeoff is worth their perceived benefits.
 

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Elitest thrill junkie
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I'll run some back to back testing in the next few weeks...my 24 lb carbon fattie w/ 4.8's VS my 23 lb XC whip, both with similar high end builds and same brand tires and compound. We have a lot of varied terrain here, what type of course would you like to see? Let's quantify it and put this to bed. Then folks can decide if the speed tradeoff is worth their perceived benefits.
IDK, I really don't think there's any debate to it. They are slower and the results are definitive. While there are sometimes unique situations during a race where you can leverage an advantage of more traction, more rotational inertia, whatever, it never cancels out the negatives of the rotational mass, acceleration, rolling resistance, etc. I've done testing in a variety of races, including XC, cross, gravel, etc. I'm not sure what I'd "like to see", I don't see there being any question about it, otherwise, we'd see top ten and top 5 results in pro XC routinely on fat bikes or plus tires. Same with every other discipline.
 
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IDK, I really don't think there's any debate to it. They are slower and the results are definitive. While there are sometimes unique situations during a race where you can leverage an advantage of more traction, more rotational inertia, whatever, it never cancels out the negatives of the rotational mass, acceleration, rolling resistance, etc. I've done testing in a variety of races, including XC, cross, gravel, etc. I'm not sure what I'd "like to see", I don't see there being any question about it, otherwise, we'd see top ten and top 5 results in pro XC routinely on fat bikes or plus tires. Same with every other discipline.
Let’s see that testing, otherwise your assertion about it doesn’t mean much.
 

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OP question, I've done some testing relative to this. It's not by best work, but I've posted it here: https://crankjoy.com/tire-size-shoot-out-29x2-35-vs-29x2-6-vs-27-5x2-8/

My summary statements from the test:

Based on these results, I’m going to keep 27.5+ mounted. They were just more fun than the other sizes, and the speed advantage to the 2.35 set was small enough that I’m willing to compromise in climbing speed for the superior ride feel.

The 29×2.6 set offered similar composure to the 27.5+ over rough terrain, but it was resistant to mid-corner correction. The 2.6 didn’t offer the fun, intuitive feel that the 27.5+ setup had. Additionally, it did not present a noticeable or measurable decrease in rolling resistance. It wasn’t bad per se, but I didn’t feel that advantage was nearly enough to offset the better handling of the 27.5+ setup elsewhere.

I’d choose the 29 x 2.35 for a dedicated XC race setup. Despite similar overall lap times, XC and endurance races are won and lost on the flats and the climbs, and here is where the 29×2.35 showed and advantage.




I've won races on my fat bike. Open class no less. I've earned a buckle in the Marji Gesick aboard my fat bike. So I think your assertions regarding how slow they are are overblown. You're implying that they are entirely not viable as race bikes, which I disagree with. Yes, it's slower than my XC race bike...but I don't think that it is slower by much, and only at higher speeds where wind resistance or large/fast impacts come into play.

We've had this discussion before, but once again I am offering a counterpoint to your point. The reason I bring it up is that one should not summarily discount wider tires as slower. Usually, yes they are, but it depends on the surface and the rider weight.

I'll run some back to back testing in the next few weeks...my 24 lb carbon fattie w/ 4.8's VS my 23 lb XC whip, both with similar high end builds and same brand tires and compound. We have a lot of varied terrain here, what type of course would you like to see? Let's quantify it and put this to bed. Then folks can decide if the speed tradeoff is worth their perceived benefits.
Church!!

Praise be to the plus/fat gods!!

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RAKC
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i30. The construction is too light regardless of rim size though. The regular 2.3-2.5 trail casing tires are already a bit too lightly built for me (6'5" 215 lbs). On my 'trail setup' on my enduro bike I run a 2.35" 1015g semi-slick which is just enough to keep the tire from folding in berms at 30 psi.

Also, the semi-slick is perhaps the best example of why width doesn't mean much for cornering traction. Those 2.35 e13 semi-slicks have amazing grip in the corners (way more than something like a 2.6 XR4 or 2.8 Rekon). You're really just relying on one row of knobs. Do you think increasing the width (the amount of rubber not in contact with the ground) is really going to help when the bike is leaned over?

I suspect that for cornering grip in mtb tire tread design you need 1) the tread blocks of the cornering knobs to have sufficient size for stiffness and stability (aka tread block stiffness) and 2) a longitudinal channel (void space) big enough to allow the biting edge of the cornering knobs to exert enough force against the trail surface.
People blame tires for this.

If your folding tires over on berms you have bad technique.

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You're conflating a few things. 1) Mass is a major contributor to RR period. 2) Width and weight are not the same thing. 3) Rider efficiency and tire RR is not the same thing. 4) RR coefficient is not the same as overall efficiency.

The issue is as a riders you guys think rolling resistance means 'how fast the tire feels'. Talking about RR in isolation is honestly a waste of time for consumers. You're not designing tires, you're riding them. Just find something that seems to roll well.
Morsa 2.3 is a 1000g tire, rr 22.8. Bonty XR0 is a <700g tire, same rr.
 

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i30. The construction is too light regardless of rim size though. The regular 2.3-2.5 trail casing tires are already a bit too lightly built for me (6'5" 215 lbs). On my 'trail setup' on my enduro bike I run a 2.35" 1015g semi-slick which is just enough to keep the tire from folding in berms at 30 psi.
i30 sucks for 2.6. I'm only 160lbs; can't imagine how bad riding them at 215lbs would be. I use i35-38mm depending on the tire's knob profile. No wonder they didn't work out for you. I mean, how can you make such a bush league mistake and then come on here and tell us how it is like you're some expert?
 

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i30 sucks for 2.6. I'm only 160lbs; can't imagine how bad riding them at 215lbs would be. I use i35-38mm depending on the tire's knob profile. No wonder they didn't work out for you. I mean, how can you make such a bush league mistake and then come on here and tell us how it is like you're some expert?
You're the size of a child, no wonder you can get away with such light duty tires. How can you make such a little league mistake by coming on here and telling us how it is like you're a full grown man?
 

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change is good
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You're the size of a child, no wonder you can get away with such light duty tires. How can you make such a little league mistake by coming on here and telling us how it is like you're a full grown man?
Kind of harsh, but there’s some truth. I can ride lighter and smaller tires on my Switchblade, but at 225lb I currently have a 2.6 Butcher Grid Trail on a 36mm rim and a Purgatory 2.6 Grid on a 29mm rim. Obviously on the downs in loose over hard, this combo rocks. On the flats it’s not bad. Most of the trails I ride are chunky. They are feel good tires.


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You're the size of a child, no wonder you can get away with such light duty tires. How can you make such a little league mistake by coming on here and telling us how it is like you're a full grown man?
So, what other obvious noob mistakes do you make and then type on your keyboard like you are some expert? It's common on the internet but usually people are better at not broadcasting their ignorance.
 

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People blame tires for this.

If your folding tires over on berms you have bad technique.

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So let's add this up: bad riding technique, blames tire construction while using them on narrow rims, doesn't understand rolling resistance....I'd like to see some video of this expert riding down a trail; probably dead sailors jumps and stops every km to catch his breath.
 

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So, what other obvious noob mistakes do you make and then type on your keyboard like you are some expert? It's common on the internet but usually people are better at not broadcasting their ignorance.
I call people out on the internet for making bush league mistakes when their experience doesn't align with mine as an adult trapped in an eight year old's body.
 

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It would be nice if there were more charts like what Varaxis posted. That Morsa is so fast it's amazing. It's like riding an xc tire with enduro cornering ability. Since it's discontinued, makes me want to know what Vittoria has in store as its replacement.
 

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I call people out on the internet for making bush league mistakes when their experience doesn't align with mine as an adult trapped in an eight year old's body.
I agree, you are much like an eight year old. Thanks for clearing that up. You are released from this conversation; go forth and shytepost elsewhere, brave expert.
 

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Interesting perspective/science/opinion in this thread, but going back the the OP’s original question: “Do people really benefit that much from 2.5-3.0 tires? Are we crazy for wanting the lightest tires possible?” - I can say, unequivocally, yes. For me.

Turns out I ride the exact same central Texas limestone techy, chunky, ledgy stuff as the OP. Also turns out that I ride 100% rigid singlespeed.

So I get that I’m a bit of a corner case w/out gears or squish, but for folks like me, plus tires are fantastic.

One thing no one mentioned in this entire thread is rollover. For the constant rock gardens here, 29x3.25 rollover is magic. Add the braking, turning and climbing traction, and the cush, and I get a winning equation.
 
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