Donnelly is the new brand name for Clement tires. Since 2010, Donn Kellogg had been licensing the Clement name and developing his own road, gravel and cyclocross tire designs.
The second part of the X'Plor MSO name comes from the Missoula, MT airport code. The tires are aimed at working everywhere from the road to gravel trails.
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Donnelly X'Plor MSO specs
- 700 x 36mm / 700 x 40mm (tested) / 700 x 50mm
- Integrated puncture protection belt
- Tubeless compatible
- Actual weight: 560 and 570 grams
Fast rolling with decent grip
In the world of gravel tires, finding the Goldilocks formula between low weight, fast rolling, decent grip, and puncture resistance is difficult. There are trade-offs: light is puncture prone, grippy is slow, and puncture-proof can ride like garbage.
The X'Plor MSO tires manage to tiptoe around all those parameters.
The tightly packed, almost file-like center tread felt fast on pavement and smooth on hard packed gravel.
Dry gravel roads and pea gravel paths saw the majority of my ride time on the X'Plor MSOs. In these loose conditions the little transition and side knobs really worked. The transitional, middle knobs have a mix of small and medium knobs. The medium ones feature a sipe to increase grip a bit. Together they provided a predictable lean with no slip or vagueness.
The outer side knobbies are a mix of small round knobs narrow enough to poke through the top layer of dust down to firmer ground. They're mixed with bigger knobs that were stiff enough to lean on with no discernible squirm or wobbling about.
A bit heavy and a stiff ride
One of the trade offs for having puncture protection and easy tubeless set up is that the sidewalls are stiff — but not to the point of being detrimental to the ride, especially at lower pressures.
They're also heavy. The two X'Plor MSOs I weighed tipped the scale at 560 and 570 grams, which is 28–38 grams over the claimed weight and a bit heavier than similar gravel tires in the 40mm range.
Donnelly X'Plor MSO vs. the competition
True to the marketing hype, the X'Plor MSOs ride the middle ground in all-around performance. Schwalbe's G-Ones are lighter and faster in a straight line, yet more flat prone and with less cornering grip.
Maxxis's Ramblers come close to the puncture-warding abilities of the X'Plor MSOs, and add traction, but fall short on sheer speed and overall size.
Kenda's Flintridge Pros are most similar to the X'Plor MSOs, but like the Ramblers, give up a bit on the go-fast side of things.
Donnelly X'Plor MSO bottom line
The X'Plor MSO tires fit the gravel, all-road, adventure niche very, very well. They're plenty fast, decently puncture resistant, and have about as much cornering grip as most roadies slipping around on dirt roads will ever need.
If your gravel bike sees commutes to work, road spins at lunch, and dirt road adventures on the weekends, the X'Plor MSOs fit the bill.