Seth’s Fat Ass 50K

29 days to go

50 km Distance

not publishedn/a Climbing

2.5 est Grit · Entry level

Calculated from 50 km alone — the organiser has not published an elevation profile. Read 2.5 as a floor, not a verdict.

42.1015° N, 72.5898° W © OpenFreeMap © OpenMapTiles Data from OpenStreetMap

What the course asks

Field size ~40 Small. Long stretches with nobody in sight.

DUV results for the 2025 edition (50km) — finishers only. Starters are not published, so the field was at least this big and no finish rate can be given.

Typical conditions, December

Daytime high 3°C

Night low -5°C

Rainfall Showers likely

Daylight 9 h 10 m of light

Regional 2001-2020 average for December — NASA POWER, grid elevation 159 m. Not a forecast.

Results history

Year	Race	Finishers	Men's winner	Women's winner
2025	50km	40	Eric Ciocca · 04:02:31	Emma Duncan · 04:22:55
2024	50km	32	Seth Cutler · 03:47:57	Gabrielle Cook · 04:16:41
2023	50km	36	Matt Pacheco · 03:37:08	Sarah Nelson · 04:53:07
2022	50km	22	Albert Mendes · 04:08:15	Theresa McBride · 04:16:01
2019	50km	41	Eric Ciocca · 03:55:18	Martha Berrouard · 05:01:18
2018	50km	32	Brendan Chambers · 04:16:31	Christin Doneski · 04:11:40
2017	50km	21	Eric Ciocca · 04:04:22	Heather Brochu · 04:48:13
2014	50km	31	Peter Zelken · 04:09:03	Sarah Bousquet · 04:46:48
2013	50km	39	Jason Bigonia · 03:28:10	Martha Berrouard · 04:21:02
2012	50km	54	Dave Thoman · 03:58:10	Martha Berrouard · 04:20:30

The field grew 25% between 2024 (32) and 2025 (40). 35% of the 2025 field were women.

DUV results for the 2025 edition (50km) — finishers only. Starters are not published, so the field was at least this big and no finish rate can be given.

Course notes

gear With trail terrain, choose a shoe with moderate cushioning for optimal performance.

Gear for this race

Chosen for 50 km of trail.

Trail Running Shoes 50 km of trail — cushioning that is still there in the last quarter.
Race Nutrition 50 km of self-supported fuelling between aid stations.
Hydration Vests Flask capacity for 50 km, without the bounce.
GPS Watches Battery life first — a 50 km day outlasts most full-GPS modes.

Brooks

Catamount 3

RunRepeat found the Brooks Catamount 3 to have a cozier upper that enhances the overall fit, though breathability and durability could be better. iRunFar noted…

★★★★★ 4.5

Salomon

Sense Ride 5

RunRepeat found the Salomon Sense Ride 5 to have immaculate lockdown and a smooth and stable ride, making it confident on moderate trails and steep downhills. I…

★★★★★ 4.5

Skratch Labs

Sport Hydration Mix

Clean electrolyte drink mix with real fruit flavor. Low sugar.

$20 ★★★★★ 4.5

Salomon

ADV Skin 12

Industry-standard 12L race vest with front flask pockets and minimal bounce.

$180 ★★★★★ 4.8

COROS

APEX 2 Pro

GPS running watch with 75-hour GPS battery, topo maps, and training metrics.

$500 ★★★★★ 4.7

All gear guides →

Overview

Seth’s Fat Ass 50K is a road ultra organized by Cyclonaut Multisport Club in Springfield, MA, scheduled for December 12, 2026. The 50-kilometer route requires runners to complete 10 laps of the Harrier’s Snow Storm Classic 5K circuit, setting up a repetitive loop format where pacing and aid access recur every 5 kilometers.

With 40 finishers in the 2025 edition, the event maintains a mid-pack turnout that is bigger than 52% of 50k fields and smaller than 47% across 2840 peers. First held in 2012 across 10 editions, entry ranges from 40 to 45 dollars, keeping financial barriers low for late-season road mileage.

Similar races

Other 50K trail ultras, closest in distance first.