Belvoir Castle Triathlon (Castle Race Series)
Grantham (Belvoir Castle estate), United Kingdom · July · Castle Race Series (Endorphin Sport ran it earlier)
Course: 0.8 km (0.5 mi) swim, 23 km (14.3 mi) bike, 5 km (3.1 mi) run. Sprint 750 m / 23 km / 5 km (820 yd / 14.3 / 3.1 mi) per Racecheck. Sprint Plus (800 m / 40 km / 8 km; 875 yd / 24.9 / 5 mi) is the headline race; a Sprint Qualifier ran in 2026. Super sprint 400 m / 23 km / 4 km and Starter 200 m / 13 km / 2.5 km also listed.
Why people love it
- Racecheck averages 4.32 of 5 from 114 reviews, with staff scoring 4.79.
- Starter (200 m (656 ft) / 220 yd) and super sprint options for newcomers.
- Race through the Belvoir Castle estate; 2026 lake water was 21.9 °C (71.4 °F).
- Sprint is 750 m (2,460 ft) swim, 23 km (14.3 mi) bike, 5 km (3.1 mi) run (820 yd, 14.3 mi, 3.1 mi).
Watch out for
- The organiser calls it one of the toughest in the series, with a hilly bike and run.
- Weedy, shallow multi-lap lake swim; Racecheck water quality scores 3.78 of 5.
- Roads are not fully closed and one reviewer reported cross traffic.
- Rough ground leaving T1; reviewers suggest trail shoes for the run.
- 2025 was wet and slippery, so plan for rain.
Race
How racers feel about it, how well it is run, and how it treats a first timer. Counts for 30% of the overall score.
Toughness: Tough
- Racer satisfactionLoved4.0
Racecheck averages 4.32 of 5 from 114 reviews, held back by weed and congestion complaints in the lake. · Medium confidence
- OrganizationWell run4.2
Racecheck rates staff 4.79 and navigation 4.68, with notes on a bottleneck at the T2 exit and cross traffic. · Medium confidence
- First timer friendlyFriendly3.9
Starter and super sprint options exist, and a first open-water Starter reviewer enjoyed it, but hills and weed remain. · Medium confidence
Course traits, not part of the score
- PR potentialAverage3.0
23 km (14.3 mi) bike and a hilly 5 km (3.1 mi) run; the 2026 Sprint Qualifier winner took 1:08:16. · Medium confidence
Swim
Wetsuit odds, water temperature, calm, and the experience of the start. Counts for 16% of the overall score.
- Wetsuit legalUsually4.3
2026 water was 21.9 °C (71.4 °F) and 20 °C (68 °F), just under the 22 °C (71.6 °F) wetsuit ban. · Medium confidence
- Water temperatureComfortable4.3
20-22 °C (68-72 °F) in 2026. · Medium confidence
- Calm waterGlassy4.5
Estate lake, ideal water conditions both days in 2026. · Medium confidence
- Swim easeModerate3.2
750 m (820 yd) horseshoe route. · Medium confidence
- Swim experienceFine3.2
Racecheck Water Quality 3.78 is lowest; weedy, murky, slimy; but castle backdrop. · Medium confidence
- Swim supportGood3.8
Lake with lifeguard and kayak cover, shallow enough to stand in places. Multi-lap congestion was reported. · Medium confidence
Bike
Road surface, closures, scenery and wind. Counts for 18% of the overall score.
- Road surfaceGood3.5
Estate and country roads; no surface complaints found. · Low confidence
- Road closuresPartly closed2.5
Reviewer reported cross traffic and road-safety concerns; not clearly closed. · Medium confidence
- Bike sceneryBeautiful4.2
Racecheck reviewers call the bike scenic; castle estate roads. · Medium confidence
- WindSome wind3.3
Hilltop estate; no wind reports. · Low confidence
Course traits, not part of the score
- Bike speedAverage3.0
Short hilly circuit. · Medium confidence
- Bike flatnessRolling2.9
Undulating 23 km (14.3 mi). · Medium confidence
- Bike simplicitySome technical parts3.0
Twisting circuit after a climb per a sprint preview; cross traffic and a T2-exit merge flagged. · Medium confidence
Run
Crowds, aid stations, conditions underfoot and scenery. Counts for 13% of the overall score.
- Crowd supportStrong3.6
Small and intimate (55% of reviewers) but festival weekend with 1,300 athletes (2026). · Low confidence
- Aid stationsGood3.6
Racecheck Aid Stations 3.82, lowest category score after water quality; reviewers want non-water options. · Medium confidence
- Run sceneryBeautiful4.3
Scenic estate trails per Racecheck. · Medium confidence
- Run conditionsModerate3.0
5 km (3.1 mi) mixed surface. · Medium confidence
Course traits, not part of the score
- Run flatnessRolling2.7
Hilly sprint finish per preview. · Medium confidence
Conditions
Air temperature, how predictable the weather is, setting, and spectating. Counts for 13% of the overall score.
- Air temperaturePleasant3.9
July in the East Midlands, about 15 to 24 °C (59 to 75 °F). 2025 was wet, 2026 sunny. · Low confidence
- Weather reliabilityVariable3.0
2024 sunny, 2025 repeated downpours, 2026 sunshine and rising heat. · Medium confidence
- Venue beautyStunning4.6
Castle estate and lake setting. · Medium confidence
- Spectator friendlySome viewpoints3.4
Large estate; lake and finish area accessible but courses spread out. · Low confidence
Course traits, not part of the score
- Low altitudeSea level4.8
About 90 m (295 ft). · Medium confidence
Stay and travel
Hotels, walkability, getting there, and the town around the race. Counts for 10% of the overall score.
- Hotel availabilityBook early3.0
Rural; Grantham and Melton Mowbray have limited stock on a festival weekend. · Low confidence
- Hotel valueNormal3.3
Not documented. · Low confidence
- WalkabilityWalkable3.5
Festival village; a 400 m (437 yd) uphill run from lake to bike racks in the 2024 super sprint. · Low confidence
- Travel easeOne connection2.7
Remote estate about 60 km (37 mi) from East Midlands airport; A1 and Grantham station about 10 km (6 mi). · Medium confidence
- LogisticsSimple3.6
Racecheck Logistics 4.59; multi-race festival with a merge at the T2 exit. · Medium confidence
- Town and foodFine3.0
Rural; Grantham and Belvoir village; festival food on site. · Low confidence
Key facts
- Location
- Grantham (Belvoir Castle estate), Leicestershire / Lincolnshire border, United Kingdom
- Typical month
- July
- Organiser
- Castle Race Series (Endorphin Sport ran it earlier)
- Field size
- About 244 athletes
- Distances (non-standard)
- 0.8 km (0.5 mi) swim, 23 km (14.3 mi) bike, 5 km (3.1 mi) run
- Swim venue
- Belvoir Lake on the castle estate (open-water lake, described as horseshoe or M-shaped; multi-lap because water is shallow farther out) (lake)
- Water temperature
- 20–22 °C (68–72 °F)
- Wetsuit
- Legal
- Swim start
- wave
- Swim laps
- multiple
- Key climbs
- Hills on the estate roads (organiser)
- Run shade
- Some
- Air temperature
- 15–24 °C (59–75 °F)
- Humidity
- Moderate
- Altitude
- 90 m (295 ft)
- Nearest airport
- East Midlands (EMA), 60 km (37 mi) away
- Where to stay
- Grantham, Melton Mowbray, Nottingham
- Booking
- Rural: Grantham, Melton Mowbray and Nottingham have hotels; camping and on-site options for the festival weekend.
What racers and reviewers say
- Racecheck (Belvoir Castle Triathlon Series page)Raced 2026 · aggregator · Positive
114 reviews average 4.32 of 5 (4.41 in 2026). Reviewers agree staff and organisation are the strength (staff 4.79, communication 4.69). The lake swim draws mixed comments: weed, low depth, murky water and congestion on a multi-lap course (water quality 3.78). Bikes are scenic and hilly with some road-safety worries and a bottleneck at the T2 exit; runs are scenic, hilly and mixed-surface, so trail shoes are suggested. Aid stations are adequate but short on non-water options.
- Lincolnshire Online (Belvoir Tri Club at the multisport weekend)Raced 2024 · article · Mixed
Club members' accounts from the 2024 Endorphin Sport weekend. One athlete found the lake swim hard because of an M-shaped course. The same athlete enjoyed the hilly, fast bike. A super sprint athlete noted a long uphill transition run from the lake across a 400 m (437 yd) field. Another member did a first open-water race in a club suit while most wore wetsuits.
“The bike section was both hilly and fast”
- Belvoir Tri Club (club news)article · Positive
Club news says the Belvoir triathlon returned after a long break under new management, with several distances. Three members placed in age groups: Olympic 2:52:52 and 3:12:39, sprint 1:30:13. Mentions no course or conditions comments; year not stated.
Raced Belvoir Castle Triathlon (Castle Race Series)? Your notes on the course, conditions and logistics help the next athlete decide.
Sources
Pages we used for facts and ratings. See how we rate.
Training for Belvoir Castle Triathlon (Castle Race Series)? Moku Coach builds your plan around race day.