As an ultramarathoner, I’m always open to new challenges. One of our closest endurance brethren is cycling and I’ve done a few “ultra” cycling events, such as a century bike ride, a double century and even a 24-hour mountain bike ride. But it just wasn’t the same as running. Something was missing.

Then I came across this contraption called an ElliptiGO. As the name suggests, it is an elliptical device – like at the gym – only on wheels. The ElliptiGO resonated with me for a couple reasons: one, if you enjoy working out on an elliptical machine at the gym, here was a way to take your workout outdoors. And two, the action of riding one very closely resembles the movement of running, only with zero impact. I was hooked. (Full disclosure, I was so hooked I invested in the company.)

After the success of the original ElliptiGO, the company released several updates and new models. These were largely iterations of the original, though with some notable changes, such as upgraded components, different stride variations and handlebar configurations. The popularity of SUB’ing (i.e., Stand Up Biking) continued to rise.

Then, early this year, they released a new model called the MSUB (pronounced, em sub), and it was a total game-changer. MSUB stands for “Mountain Stand Up Bike” and as the name implies, it’s designed for trails. As a trail runner, this was the missing link.

I ordered one and started riding it around the iconic mountain biking trails of Marin. It was love at first pedal. With knobby tires, front suspension, eight gears and disc brakes, it handled beautifully. I did a couple longish rides of about 20 miles and found it to be a really good cardiovascular workout, without the pounding of traditional running.

But being an ultramarathoner, I longed for more. Then I heard about the Marin Century ride coming to town. The ride offered several different categories and distances, most being on the road, but there was a Gravel Grinder division for mountain bikers. This sent my mind whirling. The Gravel Grinder was 58-miles with 5,088 feet of climbing – could I tackle this baby on my ElliptiGO MSUB?

I got in touch with the race director who said it was fine for me to ride the MSUB on the Gravel Grinder (I presume they had a good insurance policy), so I registered. The event draws thousands of cyclists from all over the country and you can imagine some of the comments I got come race morning. “You’re gonna ride that? Do you think you can make it?” and “Hey, you’re missing a seat.”

I tried to maintain my confidence, but even I was having my doubts. The first section of trail was fairly groomed and manageable, but the climbing was brutal. Although the ElliptiGO gearing allowed me to downshift, the grade was 12%, which is pretty darn steep. I was able to pedal the entire way, but it was slow and arduous. The downhills were even steeper, approaching 20% at points. This was a bummer because I couldn’t let ’er rip on the downs, and had to stay on the brakes due to the sharpness of the decline. Just when I wanted to make up time, I really couldn’t without risking a crash.

The course continued like this for about 40 miles with a couple steep climbs and descents, and a lot of rollers. Thankfully I’d installed toe cages on my ElliptiGO, which allowed me to pull on the uphills and stabilize on the downhills. It also allowed me to wear trail running shoes, which I find much more comfortable and breathable than cycling shoes. When compared to a traditional mountain bike, the dynamics of riding an MSUB are more like surfing. The cornering is more fluid and the whoop-de-doo’s are more like a rollercoaster. And there’s something about standing up that makes the experience more enjoyable.

How did riding an ElliptiGO compare with running? The obvious difference is the lack of impact. My quads, calves, hamstrings and glutes were every bit as sore as when running an ultra, perhaps more so given that the toe cages allowed me to both push and pull. But the most pronounced differences became apparent the next morning. Because there was less joint impact, I was able to sleep more soundly through the night compared to the quality of sleep I get after running an ultra. I awoke more rested and refreshed. And getting out of bed was a lot less painful. My muscles were still plenty sore, but the sting of joint pain was far less severe than with running.

Will riding an ElliptiGO replace running? Not for me (though I know plenty of injured runners that replaced running with riding one). For me, the ElliptiGO augments my running. It allows me to get a great run-like workout without the impact. The fact that it’s more strenuous to ride than a traditional bike makes it quicker to get the equivalent training (i.e., fewer junk miles). So I’ll continue using it as an efficient and fun training tool.