Sun, Mar 21, 2027

15th Annual Rock CF Rivers Half Marathon & 5K

Grosse Ile, MI

Opens Oct 15, 202615th annual

Half Marathon15K5K

About the 15th Annual Rock CF Rivers Half Marathon & 5K

The race loops Grosse Ile, an island on the Detroit River, so the surroundings are water and residential streets rather than a park or trail system. Some distances run point-to-point, with start and finish points spread across the island, including a naval air hangar and the airport area. All proceeds support cystic fibrosis programming, so the cause is woven into the event.

There is no parking at the middle school on race day. Shuttle lots near the airport feed runners to the start, with buses running continuously before and after. Packet pickup happens the week before at a Detroit running store, the day before at the middle school gym, and on race morning at the middle school or the Pilot House, depending on your distance.

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Finish-Time Stats

Going by the 2026 results, this is a decent-sized field, with a competitive front end and a big recreational middle.

13.1 Miles · 2026 results

672finishers

1:03:19winner

1:57:09median

3:36:06cutoff

Top 3: Andrew Bowman (1:03:19) · John Burchfield (1:06:48) · Nick Licari (1:07:24)

3.1 Miles · 2026 results

399finishers

17:24winner

35:35median

1:32:29cutoff

Top 3: Tyler Dew (17:24) · Donald Alexander (17:43) · Michael Grinols (17:44)

15K · 2026 results

186finishers

54:18winner

1:36:48median

2:43:08cutoff

Top 3: Adam Maier (54:18) · Sarah Kasabian-Larson (57:37) · Megan Muhs (58:59)

The 15th Annual Rock CF Rivers Half Marathon & 5K is in its 15th year.

Where Would You Finish?

Enter a finish time to see where it lands against the most recent 13.1 Miles results.

Median

See how your time stacks up nationally →

How we calculate these stats: RunSesh calculates these figures from the most recent published results of past editions, sourced from RunSignup. We show aggregates only: field size, winning and median times, and the cutoff. We never publish individual finisher tables. Last updated Sep 10, 2026.

Distances & Start Times

13.1 Miles3/21/2027 08:00$85

15K3/21/2027 08:00$70

3.1 Miles3/21/2027 08:15$40

Virtual Run3/21/2027 08:00$50

Going for a Time?

Set a goal and get a pace band: every mile split on a card sized for your phone lock screen, so race morning needs no math.

Plan Your Trip

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Common Questions About the 15th Annual Rock CF Rivers Half Marathon & 5K

Will I finish last at the 15th Annual Rock CF Rivers Half Marathon & 5K?

Almost certainly not. Half the 13.1 Miles field finished slower than 1:57:09, and the last recorded finisher came in around 3:36:06, so there is a long tail of runners behind the middle of the pack. Most fields are far slower than people expect.

Is the 15th Annual Rock CF Rivers Half Marathon & 5K a good first 13.1 Miles?

A field of 672 is big enough that you will have company at your pace without feeling lost in a crowd. There is no qualifying time, and the finish-time spread above shows how varied the field really is. If it is your first 13.1 Miles, that spread matters more than the winner's time.

How competitive is the 15th Annual Rock CF Rivers Half Marathon & 5K?

The 13.1 Miles winner ran 1:03:19 while the median finisher took 1:57:09. That spread points to a mixed field, with a competitive front and a big recreational middle.