Can a mega Aero & Wide gravel bike actually be fast? Chasing the 2.6" answer
I went looking for the fastest 2.6" tire on the market. What I found instead was a hole in the data — and a pretty good argument for buying one anyway.
Here's where this started. Everyone in gravel is chasing two things at once right now: aero, and width. Those used to be opposites. Narrow tire, slippery bike, go fast. But the last two years of testing have quietly demolished that, and frame makers have noticed — the OPEN WI.DE 2.0 now clears a 29 x 2.6" tire. That's 66 mm. On a drop-bar bike.
So the question I actually wanted answered: can I take a bike with monster-truck clearance and make it genuinely fast on our rough stuff? Not comfortable. Not capable. Fast.
What the lab says
The go-to source is Bicycle Rolling Resistance, who roll tires against a drum and measure watts. Great data, tightly controlled.
One problem. I pulled their entire MTB table — 91 tires — and sorted by width. The widest tire they have ever tested is a 2.4". There is no 2.5", no 2.6", nothing above.
You can filter their table by available sizes, which gets you a list of models you can buy in 2.6 — Vittoria Mezcal, Conti Cross King, Schwalbe Nobby Nic — but the watts next to those names were measured on the 2.2 or 2.25 version. It's a shopping list, not an answer.
What the real world says
This is where John Karrasch's work comes in, and if you only click one link in this article, make it his.
Karrasch tests tires outdoors using the Chung / Virtual Elevation method — real bike, real rider, real dirt — across five surfaces: smooth pavement, three grades of gravel, plus BRR's drum numbers for reference. That matters, because a steel drum doesn't reproduce what actually eats your watts on rough ground: casing impedance. The tire's carcass slamming into rocks, deforming, and turning your legs into heat.
His Cat 2 (medium) gravel results, in watts at 18 mph for a pair of tires:
The fastest tire on medium gravel is a 29 x 2.35" mountain bike tire. It beats a 45 mm gravel race tire by 30 watts.
Thirty. Watts.
Now the rough stuff — his Cat 3 track:
The spread gets worse for narrow tires. A Maxxis Reaver 45 needs 125 W where a G-One Speed Pro 2.35 needs 93 W. If you've ever wondered why you feel destroyed after a chunky ride while someone on fat rubber looks fresh, that's not fitness. That's 32 watts of casing impedance.
And here's the part that reframes everything — CRR by surface:
On smooth pavement the narrow tire is right there, barely losing. Every step rougher, the lines diverge. Width isn't a comfort tax you pay for capability. Past a certain roughness it's just free speed.
So why not 2.6?
Because the returns are still climbing at 2.35–2.4, which is exactly where the published data stops. Nobody — not BRR, not Karrasch — has run a 2.6.
I can make the honest case both ways.
For: every trend line in the data points that direction, and the WI.DE 2.0's whole reason for existing is that its designers ran the same numbers.
Against: width isn't what makes those tires fast — casing and tread are. The tires at the top of Karrasch's chart are fast-rolling XC race rubber with low, tightly-spaced knobs and supple casings. Almost everything sold in 2.6" today is a trail tire: taller knobs, heavier casing, built for grip on descents. Bolting on a 2.6" Nobby Nic wouldn't buy you the width advantage, it'd hand you a tread penalty that swamps it.
That's the real finding. 2.6 isn't slow. 2.6 is under-served. There's no supple, low-knob, XC-race-casing 2.6" tire being made, because until frames like the WI.DE 2.0 existed there was nobody to sell it to.
What I'd actually run
Given the WI.DE 2.0's 66 mm of clearance and our terrain, I'd go 29 x 2.35–2.4 in a fast XC casing rather than chase the maximum number:
- Schwalbe G-One Speed Pro 29 x 2.35 — fastest thing Karrasch has tested on gravel, full stop. Semi-slick, so pick your lines.
- Vittoria Terreno XC Race 29 x 2.4 — 72 W on Cat 2, real tread, sane compromise.
- Schwalbe Thunder Burt SG 29 x 2.25 — 70 W and available everywhere.
- Schwalbe Rick XC Pro Speed 29 x 2.4 — 75 W, more bite than the Burt.
That leaves clearance to spare, which on our routes means mud room rather than wasted frame.
About the traction question
People keep asking whether I'm worried about grip on a semi-slick that wide.
Not really. At 2.4" and sensible pressure there's an enormous contact patch, and if it does let go, it lets go slowly and predictably. I can slide. I'd rather drift a fast tire than grind a slow one — the watts are real every single pedal stroke, the traction only matters in the corners.
Ask me again after the first wet race.
Want the actual 2.6 number?
Karrasch takes testing requests, and he's the only person publishing this data properly. If enough people ask him for a 2.6, the number stops being a guess.
One honest caveat before you rebuild your wheels around this: Rene Herse have published a detailed critique of Virtual Elevation's repeatability. Karrasch's same-day A/B comparisons are the strong part of his data; treat absolute CRR values measured months apart with more caution. The direction of the finding is solid. The third decimal place, less so.
Anyone else running 2.4"+ on a gravel frame? Drop what you're on in the comments — and if you've got a 2.6 mounted on something drop-bar, I want to hear about it.
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Charts: built from John Karrasch's published CRR data (Chung / Virtual Elevation method) and the Bicycle Rolling Resistance MTB database.
Photos: "Mountain bike tyres from Maxxis, Schwalbe and WTB" and "Mountain bike tyre tread — Maxxis Assegai" by Alextredz (CC BY-SA 4.0), "Dirty Mountain Bike Tire" by Tony Webster (CC BY 2.0), all via Wikimedia Commons.