In Equipment

May 25, 2009

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Larry Gallagher created an adjustable, stable box nearly five feet tall to challenge even the mightiest of CrossFit’s leapers.

Sometime last fall after a workout at San Francisco CrossFit, I was pulled aside by Kelly Starrett. He had a vision of creating the ultimate jumping box, a platform that would be stable and high—higher than anything anyone at SFCF had ever ascended. Confident in my modest but solid woodworking skills, I accepted the challenge.

After a few weeks of head-scratching and sketching followed by a day of cutting, gluing and screwing, I was able to present him with the prototype adjustable jumping box. In the long-standing American tradition of semi-literacy, we dubbed it “Kelly’s Koffin.”

The Koffin has quickly worked its way into the culture at SFCF. Coach Adrian (Boz) Bozman has added a Koffin T-shirt to his line of homemade silkscreens and has also offered a challenge to all CrossFitters: mount the box at the highest setting (58 inches) and receive a free T. Thus far only two SFCF athletes have achieved this distinction.

Do you have what it takes? Planning a trip to the Bay Area soon? The Koffin beckons.

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10 Comments on “Kelly’s Koffin: Five Feet Over”


wrote …

Great article, good way to keep Crossfit fun, 58" Damn that is a challange. I wonder how tall the two studs are that made it!!


wrote …

Actually we just added another member of the club:

Austin B of CrossFit Unlimited.



wrote …

My gym biggest box is only 42". I can do it, but adding another 18" looks insane. The concentric phase only box jumps sound like fun.


Justin Riley wrote …

We were just in SF Sunday and did a WOD using the Koffin at its lowest height of 30 inches, what a great piece of equipment, and a another reason to invest in the RRG. Much of the equipment at CFSF is home made and unique. If you have never visited CFSF you should. It is a sweet CrossFit, super hardcore, outdoor, phenomonal coaches and great community. I didn't even realize that thing went up to 58". We too have a 42" box and are able to add a couple plates to that and still get up, but 58", HOLY SHIT! That is something to strive for.


wrote …

Couldn't a box jump be built with a padded top to further reduce bloody shin syndrome? Check out out Shane Hamman here:


wrote …

Awesome ingenuity Larry and some great thoughts from Kelly Starrett - as a 6'5" former volleyball player I've never really felt that 20" jumps were really that challenging. Instead of building one 40" plus box just for a few elite jumpers, the idea of an adjustable box that'll challenge everyone is a great solution. I can't wait to build one!


wrote …

58" box jumps are legit... no question about that, I respect anyone who can get up that high! I like not only the hip flexibility diagnosis but also the ability to move rapidly from extension into flexion of the hip is excellent training for various jumps and sprints and even might have crossover to OLifts.

That being said, box jumps with barbells is absolutely one of the worst ideas I have ever heard. No extra benefit (weight vests are much better) but much more potential damage. I honestly can't believe that this is being suggested in the article... where's that RRG again??

Also, not to doubt too much, but I call BS on the Michael Johnson "squat before sprint" comment. The idea that sprinters use complexes like this is a very widespread myth that needs to not be propagated. I do believe that utilizing complexes may be beneficial but to suggest that top level sprinters use this technique prior to actual sprints is ridiculous.


wrote …

I agree that loaded box jumps seem a bit crazy. However, I would like to point out that there is a loaded barbell jumping exercise: the jumping squat. It fits right in with the aims expressed in the article.§ionID=2&exerciseID=104

Also, it seems that Michael Johnson "did not perform Olympic lifts or Squats. Also he did almost zero plyometrics." Although I can't attest to the quality of, I've read that on other websites as well. Maybe the writer had another sprinter in mind?

Links WFS


wrote …

I am building this soon. Like as soon as frickin humanly possible. Actually I am going to go get someone else to build this for me as soon as humanly possible.


wrote …


Thanks for a great article and for patiently answering my email questions. I just finished building my own "home-sized" box. It runs from 28" to 40" in 1.25" increments. I followed your instructions pretty closely with a couple of minor "innovations"--
1. I used a zig-zag drill pattern so I could pack more increments in. There are four separate lines of holes, a pair towards the front and a pair towards the rear of each side of the box. This allows for 2.5" hole spacing in each line of holes.
2. I used 1" lead pipe for my adjustment pegs. This allowed for smaller holes, which will hopefully make the inner box stronger.
3. I added a fair amount of grit to the paint on the top to create a non-slip surface. I plan on using the box on grass and I worried about landing with wet feet on a slick surface (I didn't use any grit on the paint for the sides).
4. I rubbed a fair bit of beeswax on the inner box which makes adjustment much easier (even with one person).

Again, thanks for the inspiration. I'm really happy with the results.

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