Modern gravel tires: an in-depth look at the Donnelly EMP and MSO

August 28, 2021

Modern gravel tires: an in-depth look at the Donnelly EMP and MSO

For me, it's been a year of gravel. In 2020, with most races and group rides cancelled due to the COVID-19 pandemic, I dove deeper than ever before into solo riding, and in particular, gravel / adventure type riding on my cyclocross race bike. 

I've ridden more in the last year than I have in any of the previous 20 years, and much of my riding has been done on dirt, gravel, decomposed granite and other non-pavement surfaces that ever before. It appears that I'm not the only one - sales of dedicated gravel bikes are booming and I'm increasingly seeing bikes like the Canyon Grail, Giant Revolt, and Trek Checkpoint on the roads and trails. 

10 years ago, for this type of riding you used A: a mountain bike or B: a cyclocross machine with the widest possible tires mounted (which often weren't very big, due to the race-oriented designs of those frames and forks.) These days, you have many more choices. Cyclocross bikes - my preference - are increasingly designed with more tire clearance than ever before, and dedicated gravel bikes are of course designed from the ground up around even bigger tires. 

With a wealth of gravel tire options compared to a decade ago, I thought I'd share some of the tires I've been using on these types of rides, with a special focus on a couple new models that have arrived into stock for the first time.

The Donnelly EMP

This was one of the first gravel tires I mounted up to my cyclocross bike. It's about the widest tire that will fit on my cyclocross frame and fork, which is a couple years old. The "EMP" name comes from Emporia, Kansas, home of the Unbound Gravel.

Since the first version - a 700x38 - Donnelly has expanded the EMP line and it's now offered in a much wider, higher air volume 700x45 too. Both have knobs that are closely spaced together to roll fast, but still has edge knobs for cornering. The edge knobs are the same as those used on the BOS mud cyclocross tire, so plenty of cornering grip. There is no center strip (more on that later.) 

Since I started riding those, Donnelly has also released a 45mm wide version which looks interesting, but it's too wide for my existing bike - a model that wide is going to require a dedicated gravel bike designed around bigger tires. In a nod to the increasing amount of riders using 650B wheels EMP comes in a variety of 650B / 27.5" options as well as traditional 700c.

Donnelly MSO

Put this tire side by side and you'll notice it's very similar in design to the EMP - lots of small, closely spaced knobs. The MSO is a little less aggressive, designed more for straight-line riding. Blindfold test? I'd be hard-pressed to tell them apart unless I was cornering. Neither are mud tires, and the small gaps between knobs quickly fill up. These are dry conditions choices.

A key differentiator, however, is the availability of the MSO in both standard version, as well as a faster, lighter WC ("World Cup") version, which the EMP does not have. Perhaps we'll see a WC option on the EMP in the future, but for the time being, the MSO gets you the World Cup upgrade option that the EMP does not. 

With some competitive gravel races on my calendar, the MSO WC will be my tire of choice when light weight and raciness are desired. The WC versions are manufactured in Europe instead of Asia and use a higher thread count casing which creates a lighter, more supple tire. If you aren't racing, the standard MSO is a more economical but still high performing choice. Like the EMP, the MSO is offered in 700c plus 650B sizes.

Donnelly X'Plor CDG

The CDG ("Charles de Gaulle") tire is completely different from the EMP and MSO. This one lacks the knobs of the EMP and MSO in favor of a file tread. It's basically a wider, higher air volume file tread road tire and it's a delight on bad pavement. For those who came of cycling age when it was thought that narrower was faster (I used to ride time trials on 700x19 tires with 130 PSI...) the trend toward wider, more comfortable road tires is refreshing.

Can you ride the CDG on the trails? Sure. Is it ideal? No, it's not particularly comfortable and the lack of any edge knobs are quickly exposed on loose gravel.

This one thrives on chunky, poor quality urban paved and dirt roads. It doesn't hurt that the CDG is available with the brown sidewalls for that classic look, either!

Kenda Flintridge

Remember I brought up the lack of a center strip on the EMP? Both the EMP and the MSO work fine on pavement (for example, if you're riding the roads to get to the trailhead) but they're really not designed for pavement - they excel on dirt and gravel.

Kenda's Flintridge takes a different tack, providing a solid center strip reminiscent of the Panaracer Gravel King. This means they roll great on pavement. I'll often ride at a higher tire pressure on pavement using the Flintridge, then release some pressure for off-road riding once I arrive at the trails. This approach works well, making the Flintridge a favorite when I only have one bike or one wheelset that sees a lot of pavement but also hits the dirt.

In 2021, we have an embarrassment of riches when choosing a gravel tire. Whatever you select, stay safe and I'll see you out there! 



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