Diablo Summit Stomp
Walnut Creek, CA
- 30K, Half Marathon, 10K, 5K
- Trail (Unpaved)
- Official race website
Summits are made to be reached! Discover the beauty of Mount Diablo! All Diablo Summit Stomp! courses are on trails. While there are some hills, this event, like all Brazen Racing runs, is very friendly to first-time trail runners and experienced runners alike. Depending on the weather, all distances may … MORE
Local Historical Weather (Oct 17):
| 2025 | 2024 | 2023 | 2022 | 2021 | |
| H (°F) | 76 | 72 | 83 | 76 | 73 |
| L (°F) | 50 | 56 | 58 | 50 | 50 |
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Fun run!
After the challenging hills this course was really fun running fast on the downhills to the end! Great scenery and views throughout the course. The large grassy field at Castle … MORE
After the challenging hills this course was really fun running fast on the downhills to the end! Great scenery and views throughout the course. The large grassy field at Castle Rock made this a really nice place to have an event where family and friends could enjoy too.
Easier than I Expected, But Very Hard!
So I downgraded to the half marathon hiker division, which is an early start. I finished in 3:45, with a measured 14.09 miles and 2782 feet vertical gain (Garmin Fenix … MORE
So I downgraded to the half marathon hiker division, which is an early start. I finished in 3:45, with a measured 14.09 miles and 2782 feet vertical gain (Garmin Fenix 3). I was last for men my age (52). I was not last among hikers, and I would not have been last among runners either. Take what I say with the proverbial grain of salt.
This is not easy. I almost tried to upgrade to the 30k to see the summit, but I thought it was wiser not to tempt fate. I am only saying if you have done a big race in Tilden or Mt. Montara or another of the hill climbs common in the Bay Area, this is ever so slightly easier. The reason, I believe, is it is a solid 9 miles of ascent (with minor dips along the way), but that is much less steep than some rivals. Then from the 9 mile mark, it is basically downhill the whole rest of the route (I have not studied the map — it is a loop, not an out and back, but the loop doubles back onto the outbound path at some point).
Some of my sense also is my own condition: better rested and not sunburned and happy to be out there. The climate was good: the start was in the 40s, which was good. It warmed up enough to sweat pretty good, but it wasn’t sweltering all day.
Brazen is my favorite local organizer. I have run with them dozens of times. I’m not sure why the distance was longer than 13.1, but I am sure it was not just me or my watch. I am usually fine with discrepancies; I’m just noting it (so I would have had more of a 3:30 at the proper length!).
The scenery was varied. There isn’t a single vista that is worth a postcard, but that is by Bay Area norms that spoil you with natural beauty. Nobody will be disappointed. I would run this again, but I should progress to the longer option.
Weather varies, views stunning!
Mt Diablo in the fall is a challenge. Has it been dry or wet? The course will vary between dry trail and sloppy mud/overgrown weeds given recent weather. AS support … MORE
Mt Diablo in the fall is a challenge. Has it been dry or wet? The course will vary between dry trail and sloppy mud/overgrown weeds given recent weather. AS support is great. There are AS cutoff times so be aware. The half goes on at same time as a 30k to the summit so watch your ribbons/signs. Miles 4-8 are uphill and exposed. 8-10 downhill. If it’s been a wet fall (not often) there can be up to 25 creek crossings! I prefer the spring version, the Diablo Trails Challenge. There is a 50k going on as well at that one. And it is usually wet. Well run with great medals and T-shirts
My 1st 30K
If you have a chance to run a Brazen race - do it. This is a incredible group. They genuinely care about their races, the runners and the environment. It’s … MORE
If you have a chance to run a Brazen race – do it. This is a incredible group. They genuinely care about their races, the runners and the environment. It’s a family friendly atmosphere and people really want to be there.
Made the deal with El Diablo
A tough race up the incredibly scenic trails of Mt Diablo. This is a great one for beginners and pros alike as you follow the same course with different turn … MORE
A tough race up the incredibly scenic trails of Mt Diablo. This is a great one for beginners and pros alike as you follow the same course with different turn around points for the different distances. I completed the 30K in 2017 but fatigued in 2018 and did the deal with El Diablo and completed the half marathon instead. The scenery and organization makes this a great race.
A good hill challenge
Rained like mad the day and night before so huge chunks of mud clung to our shoes. Views obscured by fog due to inclement weather. Challenging, for sure. I’d have … MORE
Rained like mad the day and night before so huge chunks of mud clung to our shoes. Views obscured by fog due to inclement weather. Challenging, for sure. I’d have to do on a sunny day to really say whether vertical challenge and looooong downhill slog worth it. Brazen always does GREAT job with organization, email updates, medals, shirts and post race hydration/nutrition. I’ve done multiple brazen races. Such nice people!
Fun, well organised
This was my second Brazen Racing event and I loved it! I travel to the US for work and love the fact there is always going to be a run … MORE
This was my second Brazen Racing event and I loved it! I travel to the US for work and love the fact there is always going to be a run organised by this group no matter when I travel.
Brazen racing events are well organised, have great snacks and the best swag I’ve come across. Also all of the competitors are so friendly and welcoming. I highly recommend giving any of their events a shot!
Beautiful Hike
They call it an ultra half for a reason! The bad news is there are lots of hills, the good news is the views from the top are outstanding. I … MORE
They call it an ultra half for a reason!
The bad news is there are lots of hills, the good news is the views from the top are outstanding.
I like the hiker start – it’s a little cooler and I like the extra time, and it’s still just as tough as the “regular” half.
As with all Brazen races, the course is well marked and challenging, the aid stations are incredibly well stocked and the volunteers are awesome, the medals and t-shirts are fantastic. Brazen is just a class act all the way around!
Up Hills, Steep downhill, Nice medal
This race had a 30k, half marathon, 10k, and a 5k. It starts and finished at Castle Rock Park at Mt Diablo in Contra Costa County. It's a beautiful area … MORE
This race had a 30k, half marathon, 10k, and a 5k. It starts and finished at Castle Rock Park at Mt Diablo in Contra Costa County. It’s a beautiful area with lots of treee and hills. I signed up for the 30k, but ran the 1/2 marathon because of an injury. The half course is challenging with about 2500ft of elevation gain. Of course, what goes up, must come down. Mile 9 and 10 were tough on me because of the steep down hill. The course is very scenic with views of the East Bay and lovely trees and shaded areas. We had some rain about a week before the race and some of the stream crossings were wet, but nothing too bad. I do see potential for the crossings to be quite wet with a lot of rain.
All aid stations were well stocked with sweet and salty snacks, water, sports drink, and wonderful volunteers to help us along the way.
All finishers received an awesome medal. Tech tees for 30k and half runners. 10k and 5k received cotton shirts.
Looking forward to April when Brazen Racing will use this same course for their Diablo Trails Challenge.
Summit 30k? You had me at Summit!
There once was a race to the Summit. Only a couple other times had he done it. This time a 30K. It won't take all day. But took twice as … MORE
There once was a race to the Summit.
Only a couple other times had he done it.
This time a 30K.
It won’t take all day.
But took twice as long as the guy who won it!
(Can’t fit everything in a limerick, but had to try) 🙂 This was a super fun race, and the weather was perfect! As always, great crew and awesome volunteers makes this a great race. Hope they keep the 30k option. Amazing views from the Summit.
Don't surrender to Diablo
Brazen Racing produced the first time a 30K. I ran the Diablo HM from Brazen multiple times and the helipad was the highest point of the course and it is … MORE
Brazen Racing produced the first time a 30K. I ran the Diablo HM from Brazen multiple times and the helipad was the highest point of the course and it is practically only downwards from here. For the 30K course they put the aid station at the helipad and added a 10K back and forth loop to the summit. Sounds easy. This little loop to the top was exactly what the name of that mountain is. The course got steep and the temperatures warmer, much warmer. Brazen offered to make a deal with the devil at the helipad, you can switch from the 30K to HM and it is not a DNF. I did the reverse and switched from HM to 30K. Well, Mike Beckwith ( the guy with bib #111) and Brad Gaiser talked me into it. Half a mile under the summit I immensely regretted that decision. Nevertheless, I got to the top, rested 10 minutes in a great chair they offered, and finished that race. I am glad and proud of it. I added 4254 feet to the high flyer account from Brazen. Well that is another crazy thing Brazen does: for 21,120 feet from the ultra series races, you will become a member of the Brazen high flyer club. I might do the 30K next year again, for sure the HM.
Beautiful Scenary
The Diablo Summit Stomp 10K was at Castle Rock Park, Walnut Creek, CA. Three race distances were offered, 30K, 1/2 Marathon, 10K, & 5K. I ran the 10K in this … MORE
The Diablo Summit Stomp 10K was at Castle Rock Park, Walnut Creek, CA. Three race distances were offered, 30K, 1/2 Marathon, 10K, & 5K. I ran the 10K in this beautiful lush park. The beginning part of the course took us up over some embedded boulders and then through lush green, beautiful surroundings. We ran through several small creek that are now dry due to the CA drought. The course then winding up through a single trail up, up and up. I was so in awe of the beauty and fall colors surrounding me during this race. I finished my race and was greeted at the finish line with my name being called as I crossed the finish line. Friendly course monitors to help keep us on course and well stocked aid stations as well as a great after race table of food for runners as well as a bottle of water. About 5 minutes before my race started the race director said, ‘make sure your bib is pinned on the front of your shirt.’ Oh crap, I forgot my bib in my car which was parked about 1/4 mile away. I rushed back to get it got back to the starting chute. I told the race director what happened. He checked my bib and I was on my way. This was a beautiful course.
Great aid stations
The course was challenging with several hills. With this in mind, there were several aid stations and people on the trail to make sure people don't get lost. If you … MORE
The course was challenging with several hills. With this in mind, there were several aid stations and people on the trail to make sure people don’t get lost. If you have conditioned for a longer run, I would recommend that you go for one of the longer races since it felt more rewarding than when I ran the 5K earlier in the year. However, I’m not suggesting that people should over do it since the hills are challenging.
challenging, but fun
I have done both the 5k and the 10k. They both start the same, up a hill, but have rolling small hills through creeks that have been dry for a … MORE
I have done both the 5k and the 10k. They both start the same, up a hill, but have rolling small hills through creeks that have been dry for a couple of years, but were full of water when I did the 10k. The 10k has a great and interesting single track that goes up and up and up to another trail that goes down then up again. Very fun.
Looking for first place
Rookie mistake: I forgot that Brazen has TWO websites, one for their spring race Diablo Trail CHALLENGE and one for their fall, Diablo Trail ADVENTURE. Typically the DTC in spring … MORE
Rookie mistake: I forgot that Brazen has TWO websites, one for their spring race Diablo Trail CHALLENGE and one for their fall, Diablo Trail ADVENTURE. Typically the DTC in spring falls on Daylight Savings Day, and for that reason, they push the race an hour later. OOPS. I check out the DTC race webpage rather than looking at the confirmation pre-race e-mail, and show up what I thought would be ample time to set my stuff down, get a nice warm up in, and head to the start line…nope. I show up just as Sam is counting down the start to the 10k! The course was fantastic, the weather was perfect, and due to the lack of rainfall this year (2015), the trails were packed and creeks were dry. For my mistake I needed to make up as much time and get into place as soon as possible, passing on the single track was challenging per usual but everyone racing was courteous to slide over. The only wish I had was if the 5k was designated to stay to one side or their course looped a little differently if possible; just makes for a 10k/half finish challenging snaking through all the walkers, hikers, and 5k finishers.
Awesome
This racing crew is the best!! Everyone is helpful and encouraging. There is plenty of yummies after the race. It doesn't matter what kind of runner you are brazen has … MORE
This racing crew is the best!! Everyone is helpful and encouraging. There is plenty of yummies after the race. It doesn’t matter what kind of runner you are brazen has a spot for everyone!
Uphill run in Mt. Diablo hills!
I volunteered at this race. Located in the beautiful Mt Diablo park there were great views. It started raining lightly but that didn't stop the many runners who seemed to … MORE
I volunteered at this race. Located in the beautiful Mt Diablo park there were great views. It started raining lightly but that didn’t stop the many runners who seemed to have thoroughly enjoyed this run.
Ain't nothing like Diablo (babyyy)
This is always a favorite race of mine. It's out at Diablo and starts and ends at Castle Rock Park in Walnut Creek. This race is to help support Save … MORE
This is always a favorite race of mine. It’s out at Diablo and starts and ends at Castle Rock Park in Walnut Creek. This race is to help support Save Mount Diablo. Only half of Mount Diablo’s wilderness is preserved. The other half is at risk of being lost to development forever. (Taken from the Save Mount Diablo website at https://www.savemountdiablo.org). This half marathon has just under 2,500 feet of elevation gain, and some of the coolest views of the East Bay. You don’t make it up to the summit on this race (like you do the 50k), but the views are still stunning. The first nine miles is basically up hill, with some stretches of downhill. There is some beautiful single track as well. After you get to the highest point of the race (about 1,950′ at about mile 9), there is an awesome downhill trails for the next almost two miles. I love this part as it’s not too steep but allows you to turn on the gas a little. Be careful though as you start the downhill, as you do have to cross a road with cars. After that pure downhill, the last two miles is basically downhill with just a few small rolling hills.
This year it rained a little and at the very end (of my race) was coming down quite good. Lots of tree cover though throughout (I rarely bring sunglasses on this race).
Lastly, as always, Brazen has the best swag and food and people everywhere. You’ll absolutely love this race.
Diablo views will not disappoint!
My second time running this race, and it was just as enjoyable the second time. I love the views on this course, but you do have to do a bit … MORE
My second time running this race, and it was just as enjoyable the second time. I love the views on this course, but you do have to do a bit of climbing 🙂 River crossing may or may not have water, but the trails are technical enough to make this a challenge (as the name suggests) and the fact that there is a portion that goes to saving Mt. Diablo makes this race a winner! The AS and volunteers are amazing, as usual. Brazen Racing is top notch when it comes to making sure their races have everything you could need, and more.
OH MY HILLS
The elevation range for this was just about in the middle of Brazen's "Ultra" courses, so I went into this thinking "no sweat". yeah right - the 2500 feet of … MORE
The elevation range for this was just about in the middle of Brazen’s “Ultra” courses, so I went into this thinking “no sweat”. yeah right – the 2500 feet of elevation is pretty much all in the first half!! That being said, had I just read the course map, I would’ve known…. but that just made this all the more challenging. As always, the Brazen production was spot on – they had over flow parking with shuttles, but I didn’t see many people parked there, so I assume everyone could fit in the park’s lot. And of course, awesome swag and the best snacks at the end.