Where: Peebles, Scotland
This has to be one of our favourite non-tri events. Take on an 11km trail run through the stunning and beautiful Glentress forest during the Friday evening, and then the following day you've seven hours to see how many laps you can do of the 11km mountain biking course. Each lap has around 380m of climbing, and includes single track, some technical parts, and some fantastic and fun descents.
And let's face it incorporating mountain biking into her training schedule has done ITU world champ Flora Duffy no harm at all, and she credits it with keeping her life fun and interesting... wonder if she'd like to join our team next year?!
And who do you have to beat? In 2017 the winning pair (from our sister website BikeRadar) were doing each lap in around 40-40 minutes, and managed 11 laps, just one off the record.
Where: Various locations
For the serious it’s a fun, furious and fast downhill race; for the others and the majority it’s a great day/weekend of mountain biking in beautiful countryside, with women’s downhill world champion Rachel Atherton for company.
The aim of the race is to stay ahead of Rachel (she starts a couple of minutes after everyone else) who will be hunting down the 200 or so riders taking part.
If you are fairly new to mountain biking, don’t be put off, just ride at the back and enjoy the stunning scenery. I was caught before the first corner! It's also perfectly acceptable to dismount and walk any of the technical parts – you definitely won't be the only one. And during the practice sessions don't be afraid to ask more experienced riders for help and advice for riding certain sections.
The atmosphere is friendly and is all about having fun and, as it takes place at the end of the tri season, it's a great way to end the season and improve your mountain biking skills before the off-road duathlons you have planned.
Where: Chipping Sodbury, Gloucestershire
Planning to ease into winter and start slowing down? Why not make this the last challenge of the year and slog it out over this nine mile cross-country run? Described on their website as a “lung-busting, trainer-ruining, hill-climbing, multi-terrain challenge held over and through some of South Gloucestershire's most stunning countryside,” this nine miler isn't for the faint hearted.
It’s not just a mud run; it’s a mud, marsh and bog fest over hilly terrain that will sap the energy out of any runner’s legs, and just to be extra helpful the organisers place hay bales in gateways for the competitors to clamber over – too kind…
It is held on Remembrance Sunday and attracts about 1,300 runners annually. If you do enter then don't expect to be able to reuse your trainers afterwards - and make sure they're on tight...
Do you have the fitness and tactics to make it to the end of this 23 mile knockout moorland run? This gruelling run is set over Exmoor’s unforgiving terrain, and has three knockout stages where the 400 participants will get whittled down to the top 20 in each category.
So with this in mind how do you race it? You don’t want to use all your energy up on the first few sections, but then you can’t afford to hang around at the back and risk getting eliminated – and to win you’ll need a turn of speed for the last phase.
With pacing being a crucial part of tri, this has to be a fantastic test of your pacing abilities.
Where: Llanwrtyd Wells
Can you outrun a horse over mountainous terrain? This 22 mile (35km) classic began in 1980 and since then a runner has just beaten a horse twice (2004 and 2007) but it doesn't stop hundreds of people trying every year.
The race emerged after the local pub landlord overheard two men discussing which is faster/better over fell land, a horse or a runner?
Two famous athletes that have tried are European champion sprinter Iwan Thomas and former Wales Rugby Captain Gareth Thomas, who both took part in it for a BBC2 documentary.
What do you think - can you do it? There’s a rolling jackpot to win for the person that does...
Where: Maryhill Locks, Glasgow
How about this for a pre-season open-water warm-up? Can you brave the icy waters of Maryhill Locks near Glasgow and climb loch gates with icy hands and feet in March? As well as swimming 420m, competitors have to clamber over eight canal gates (a total climb of 18m). Each canal gate features a different obstacle to climb up – including cargo net, ropes, wood ladder, rope ladders and a climbing wall.
The event sells out quickly and 2017 competitors included tri Olympian Gordon Benson.
Fancy swimming the famous Henley Regatta course? This 2.1km swimming race takes place in the early morning of the Sunday before the famous Regatta starts on the Wednesday. Once done you can then take a break, enjoy some Pimms and strawberries, and watch Regatta entrants practicing their rowing on the banks of the River Thames; not a bad way to spend the day if the sun is shining!