Mud and Mayhem Swinley Duathlon (Berkshire, October 9)
Distance: 5K/ 20K/5K
Even if you've never dipped your toe in duathlons before, you're bound to enjoy this royal offroad adventure. Set in Swinley Forest, an area of the Windsor Estate between Bracknell and Bagshot, you'll run and cycle through delightful Scotts Pine woodland. Enjoy an undulating trail run, before getting stuck into a technical bike section where you'll really have to focus to stay seated. A winning combination of picturesque scenery, spot prizes and great camaraderie should guarantee a great race. Enter online.
Run Rider - The Bristol Offroad Duathlon (Bristol, October 16)
Standard distance: 5.4K/18K/5.4K
This new addition to the duathlon calendar already looks like a corker. Head to Ashton Court estate for a rough and ready offroad race that'll really test your mettle. Over a short 5.4K course, the run manages to pack a punch with 145m of climb over energy-sapping terrain including dirt, grass tracks and gravel roads. Hop onto your bike for furious 9K laps of the virtually weather-proof circuit, already home to the Bristol Bikefest and Bristol Oktoberfest race. Upgrade to the classic distance for an even tougher challenge covering 10.8K/ 27K/ 5.4K. Enter online.
GRIM Duathlon 5K/20K/5K (Hampshire, October 22)
Survivors of this tough offroad race will emerge tired, wet and mud-splattered. Take on trails, hills, mud, cammo nets and a teasing sand dune on a circuit usually designed to break in army vehicles. Keeping dry will be mission impossible; prepare to hoist your bike over your head as you wade through a seemingly endless water course. Recruit fearless friends to enter in a team of three or just enjoy the bravado of being man (or woman) enough to take on this mission solo. Enter online.
Cheshire Classic Aquathlon (Nantwich, November 13)
Distance: 750m swim/ 7.5K run
If you don't fancy a chilly open-water dip in late autumn, practise your racing skills in the comfort of a heated indoor pool. Set off in waves based on your estimated time, then pull on your trainers for a flat road race along the River Weaver. Choose from three race distances; a 750m swim/7.5K run; 500m swim/5K run or a 250m swim/2.5K run. Wind down a great season with this fun event, or start your step up to your first triathlon next year with this multisport treat. Find out more.
Asics Off Road Race Series - IceMan (Surrey, November 19)
Make your final mission this season a gruelling duathlon on terrain even army vehicles struggle to cover. Scramble over rocky trails during the first 10K run, then take on a fierce offroad cycle route with four testing hills will en route. The final 5K run is a little more kind to your legs, so power to the finish line with any remaining strength. You can also earn the respect of your friends or work colleagues with a team relay challenge. Find out more.
Dirt Half Marathon Challenge (Leighton Buzzard, November 19)
Explore new challenges as the season comes to an end with this popular trail adventure. Run along a delightful mix of quick canal paths and off-road trails through stunning open countryside and woodland. Just make sure you save a little strength for a killer hill in the middle of this fun chase. Triathletes - including World Champion Alistair Brownlee - have been increasingly entering off-road runs in the winter months for their endurance-enhancing qualities and for their sheer variety. With a mix of great scenery and chip-timing, this chase offers a great offroad introduction. Enter online.
Find out why you should train on trails.
Hamsterley Mountain Bike Duathlon (Durham, November 20)
Keep legs ticking over with the prospect of this hilly duathlon. The bike route runs along a black mountain bike trail but don't let that put you off - the race organisers promise it's no tougher than red routes used in previous years. Keeping your eyes peeled for the large tree routes across some of the trails and still managing to pedal fast is all part of the fun on this adrenaline fuelled-event. Once you stumble past the finish line and collect your goody bag, you can start planning next year's challenges. Find out more.