0:00:08 > 0:00:11I kayaked 2,000 miles along the Amazon...
0:00:17 > 0:00:20I walked a high wire at Battersea Power Station...
0:00:25 > 0:00:31And this time around, I'm going to be taking on my most physically demanding challenge to date.
0:00:38 > 0:00:42I will be attempting to get to the South Pole entirely under my own steam,
0:00:42 > 0:00:44and taking everything I need with me.
0:00:44 > 0:00:48I'll be walking, kite-skiing, and in a world first,
0:00:48 > 0:00:53trying to cycle part of my route to the Pole.
0:00:53 > 0:00:59It's the coldest and windiest place on earth. Temperatures drop to as low as minus 50 degrees Celsius.
0:00:59 > 0:01:05I have no idea how people do this. Honestly. Aaaah! Ahhh-ahhh!
0:01:11 > 0:01:15I don't want to play any more! This is just so frustrating.
0:01:28 > 0:01:32So far on Helen's Polar Challenge for Sport Relief,
0:01:32 > 0:01:38Helen's taken part in an experiment to see how her body reacts to the extreme cold...
0:01:38 > 0:01:41Your deep body temperature is now 36.85.
0:01:41 > 0:01:46She's been put through her paces by the world's greatest living explorer...
0:01:46 > 0:01:52Try it as much as you possibly can, and the moment you think you're not winning, turn round.
0:01:52 > 0:01:54And Helen's travelled to Sierra Leone
0:01:54 > 0:01:58to see how Sport Relief money really can make a difference.
0:01:58 > 0:02:03Just over here is a brand new well. It's so new that the concrete is still drying on it.
0:02:06 > 0:02:07In today's programme,
0:02:07 > 0:02:12Helen travels to California for the second stage of training,
0:02:12 > 0:02:15and gets to grips with her ice bike for the very first time.
0:02:15 > 0:02:19I'm not sure it's going to be that easy to pedal in all this gear!
0:02:19 > 0:02:22I can already see that she's exhausted.
0:02:22 > 0:02:25She heads to the desert to train with the only man in the world
0:02:25 > 0:02:28to have tested the bike in Antarctica...
0:02:28 > 0:02:33500 miles across some of the most inhospitable places on the planet is not an easy task.
0:02:33 > 0:02:36..And puts all her bike skills to the test...
0:02:36 > 0:02:39Let it roll, let it roll, let it roll!
0:02:39 > 0:02:42..In a punishing 15 mile off-road race.
0:02:42 > 0:02:44I haven't fallen off yet!
0:02:47 > 0:02:53Antarctica is a natural environment, so it's impossible to predict exactly what it's going to throw at me.
0:02:53 > 0:02:57That's why I've headed here, to meet some guys who can ride over just about anything.
0:03:01 > 0:03:03Oooooh!
0:03:05 > 0:03:07Oh, my word!
0:03:09 > 0:03:11That is seriously impressive.
0:03:13 > 0:03:18How long does it take you to get that good and be able to go sailing over those jumps?
0:03:18 > 0:03:21A couple of years of practice, at least.
0:03:21 > 0:03:25I... can ride a bike. But I don't really go off-road.
0:03:25 > 0:03:28What do I need to be good at this?
0:03:28 > 0:03:32It's all about just making sure you stay in control of the bike,
0:03:32 > 0:03:35make sure you're controlling the bike, it's not controlling you.
0:03:41 > 0:03:45There's only four months left for Helen to prepare for her polar challenge.
0:03:45 > 0:03:49She's going to need to put in some serious training
0:03:49 > 0:03:51to be anywhere near as good as these guys.
0:03:51 > 0:03:53How is he even doing that?
0:03:57 > 0:03:59It is ridiculous!
0:03:59 > 0:04:03I'm so impressed by these guys, it's got me excited about cycling.
0:04:03 > 0:04:08I am definitely looking forward to spending more time in the saddle.
0:04:09 > 0:04:14Antarctica is the coldest, windiest, driest continent on earth.
0:04:14 > 0:04:18Helen will be cycling across the polar plateau,
0:04:18 > 0:04:22a vast ice desert which is unpredictable and dangerous.
0:04:22 > 0:04:28Ice obstacles and snow ridges mean that Helen needs to get confident riding over difficult terrain.
0:04:28 > 0:04:30And her lessons start now.
0:04:31 > 0:04:37Helen is heading to the hills of Orange County to pick up some proper off-road bike skills.
0:04:39 > 0:04:42I love going out on my bike and I always have done,
0:04:42 > 0:04:45but generally I stick to the road or pavements.
0:04:45 > 0:04:51I have, however, entered an off-road race and it's totally different to what I'm used to.
0:04:51 > 0:04:53So, I need some expert tuition.
0:04:55 > 0:04:57Meet Joe Lawwill.
0:04:57 > 0:04:59He turned professional at the age of 21
0:04:59 > 0:05:03and in 2002 became the Masters World Champion in Downhill.
0:05:03 > 0:05:06He now runs a successful bike skills course
0:05:06 > 0:05:09and will be teaching Helen the technique she needs.
0:05:12 > 0:05:15Before I came here I would have said to anybody,
0:05:15 > 0:05:18"I can mountain bike, I've had a bike since I could walk!"
0:05:18 > 0:05:20But this is totally different, isn't it?
0:05:20 > 0:05:24A lot of people think mountain biking's just riding along on a bike path,
0:05:24 > 0:05:26but this is the mountains.
0:05:26 > 0:05:30Joe will teach Helen three key skills to help her control the bike.
0:05:30 > 0:05:33In Antarctica, it could make all the difference.
0:05:33 > 0:05:37If Helen falls off, she could risk serious injury.
0:05:38 > 0:05:41First up, Helen needs to learn how to do a track stand.
0:05:41 > 0:05:45This demonstrates good bike control by bringing the bike to a stop
0:05:45 > 0:05:47and balancing it in one position.
0:05:47 > 0:05:50So what I'm going for is to be able to stop?
0:05:50 > 0:05:53Yeah, you want to come to a stop, hold your balance,
0:05:53 > 0:05:57and if you start to lose your balance, then just start pedalling.
0:05:57 > 0:05:59- And ride it out.- OK.
0:05:59 > 0:06:02Remember, both fingers - there you go - on the brakes.
0:06:02 > 0:06:06OK, so don't do full pedal strokes now, just little half pedals.
0:06:06 > 0:06:09Just inch yourself along. Get your head a little more forward.
0:06:09 > 0:06:13There you go, there you go. Good! Pedal out, pedal out. Good job, good job.
0:06:13 > 0:06:17OK, so you're ready for the next step.
0:06:17 > 0:06:18But now she's showing off!
0:06:21 > 0:06:23- OK, good.- That was good.
0:06:23 > 0:06:26So now, when we get into a situation where the hill's going down,
0:06:26 > 0:06:30we need to be comfortable getting our weight behind the bike.
0:06:30 > 0:06:36Next up is Body Position. Helen needs to learn how to throw her weight to the back of the bike.
0:06:36 > 0:06:40This will allow her to ride downhill and over uneven ground safely,
0:06:40 > 0:06:44without being thrown over the handlebars.
0:06:44 > 0:06:48Neutral. You bring it back, up, and then you push out.
0:06:48 > 0:06:52I'm riding along, starting to get a bit shaky, so I'm going to push the bike out?
0:06:52 > 0:06:54Exactly. Just like that.
0:06:54 > 0:06:56OK. Right, I'm going to go for one.
0:06:57 > 0:07:02Oh! I'm going over... I'm going... Oh yeah, I see what you mean.
0:07:06 > 0:07:08My thighs are too big, I think!
0:07:08 > 0:07:10Oh yeah, my stomach hit the saddle!
0:07:10 > 0:07:16That was good. So the next step, we just work on our body position and getting our weight back.
0:07:16 > 0:07:18We're going to go into a manual, so it's the same move,
0:07:18 > 0:07:21but we put a little more oomph into the front,
0:07:21 > 0:07:23and let our body weight hang nice and now in the back.
0:07:23 > 0:07:26So the reason we do this is in case you come across an obstacle,
0:07:26 > 0:07:28it could be a rock or a hole,
0:07:28 > 0:07:32instead of riding into that obstacle, you actually go into your manual position
0:07:32 > 0:07:36and you push the front end out. You can hover the front end right over that obstacle.
0:07:36 > 0:07:40- OK.- So then you don't even miss a beat, you just keep on going.
0:07:40 > 0:07:44Helen will face lumps of ice and uneven ground in Antarctica.
0:07:44 > 0:07:47The manual will help by allowing her to raise the front tyre
0:07:47 > 0:07:50so she can go over obstacles without slowing down.
0:07:51 > 0:07:54OK. OK, go through the motions, trust it.
0:07:58 > 0:08:00Little more speed.
0:08:01 > 0:08:02And... now! Oooh!
0:08:05 > 0:08:07OK, looks good. Perfect, perfect. And... now!
0:08:07 > 0:08:08That was awesome!
0:08:10 > 0:08:12And this one. Yeah!
0:08:12 > 0:08:17- OK, you made it!- Ooooh! That was all right, wasn't it? - That was really good.
0:08:17 > 0:08:19Yes!
0:08:19 > 0:08:22It's not just practical skills that Helen needs.
0:08:22 > 0:08:25Cycling to the South Pole will require nerves of steel
0:08:25 > 0:08:28so downhill champion Joe has a test in store.
0:08:28 > 0:08:31So far, you've been able to do a lot of moves
0:08:31 > 0:08:35on relatively flat ground. Now it's time to do some downhill.
0:08:35 > 0:08:39Are you joking? Look how steep this is!
0:08:40 > 0:08:42It's much easier on a bike.
0:08:43 > 0:08:45I can ride stuff I can't walk.
0:08:45 > 0:08:50This type of biking should not be attempted unless you're under expert supervision.
0:08:50 > 0:08:52I'm not one bit sure that I should be doing this!
0:08:52 > 0:08:54And I don't want to do it!
0:08:54 > 0:08:56But I want to be able to say that I've done it.
0:08:56 > 0:08:58That's why I'm going to give it a go.
0:08:58 > 0:08:59What's the worst that can happen?
0:08:59 > 0:09:04I get to the top of that rock and I say, "Do you know what, this isn't for me!"
0:09:04 > 0:09:07I can say that now, but I'm going to give it a go.
0:09:07 > 0:09:09Joe shows how it's done.
0:09:10 > 0:09:17I'm in my attack position, arms are bent, ride over, go right over the rock.
0:09:17 > 0:09:18Keep my weight back...
0:09:20 > 0:09:23You're right here. Manual... and down.
0:09:25 > 0:09:28OK, right. Come on, I can do this. I can do this. I can do this.
0:09:28 > 0:09:29Let's give it a whirl.
0:09:34 > 0:09:35Not the best start!
0:09:35 > 0:09:38Looking good, Looking good. Let it roll.
0:09:38 > 0:09:41Let it roll, let it roll. Let it roll!
0:09:44 > 0:09:47- OK.- Let's get you set up.
0:09:47 > 0:09:50All right, you got it, you got it! Let it roll, let it roll.
0:09:50 > 0:09:52- Let it roll, let it roll! - I can't. I can't.
0:09:52 > 0:09:54Keep it going, you're looking good.
0:09:56 > 0:09:58Why? This is absolutely doing my head in!
0:09:58 > 0:10:02It's hard when your confidence is broken. Hopefully, she can block that out.
0:10:02 > 0:10:05There you go! Good. Feet are level.
0:10:08 > 0:10:12OK, remember to get your butt behind the seat, keep your weight back.
0:10:12 > 0:10:16You got this. You got it! Keep it going! Keep it going, keep it going!
0:10:16 > 0:10:17Yeah!
0:10:17 > 0:10:18SHE WHOOPS
0:10:18 > 0:10:20I did it!
0:10:21 > 0:10:24Awesome! Especially after all those fails.
0:10:24 > 0:10:27You didn't give up. See what happens when you don't give up?
0:10:27 > 0:10:30- Ah! Wow. - I think you're ready to race.
0:10:30 > 0:10:32Oh yeah, I forgot about that!
0:10:35 > 0:10:38Helen's entered a gruelling 15 mile off-road race
0:10:38 > 0:10:40to test all skills Joe's taught her.
0:10:40 > 0:10:43And she'll be racing against professional riders.
0:10:43 > 0:10:46If she completes the race, Helen will have the confidence
0:10:46 > 0:10:48she needs to bike to the South Pole.
0:10:54 > 0:10:58The one thing that I am going to have to do is keep a lid on my nerves.
0:10:58 > 0:11:02I can't panic at the starting line, "Oh, do you know what? No, let's start again!
0:11:02 > 0:11:04"Let's have another go." I just can't do that.
0:11:04 > 0:11:08I couldn't let myself chicken out, because then further down the line,
0:11:08 > 0:11:12what's to stop me in Antarctica going, "It's tough today, this one just isn't for me"?
0:11:12 > 0:11:14I've set out to do a job, to go to the South Pole,
0:11:14 > 0:11:17I've set out to do this. It's all relative.
0:11:17 > 0:11:20It doesn't matter who you are or what your challenge is,
0:11:20 > 0:11:22if it's pushing you to the edge, you get past that edge,
0:11:22 > 0:11:25you will be so proud of yourself.
0:11:25 > 0:11:29People train all year round for racing like this.
0:11:29 > 0:11:32She's driven, and now that she has some skills in her pocket,
0:11:32 > 0:11:34It's no question of her finishing,
0:11:34 > 0:11:37and I don't think she's going to be finishing last, either.
0:11:45 > 0:11:48Now that Helen has some skills under her belt,
0:11:48 > 0:11:50she can turn her attention to the special bike
0:11:50 > 0:11:54she's hoping will help get her to the South Pole - the ice bike.
0:11:57 > 0:12:02Helen's ice bike is one of a kind, built for her Sport Relief challenge.
0:12:02 > 0:12:05The super light frame is made from weatherised aluminium
0:12:05 > 0:12:08to prevent damage by the harsh weather conditions.
0:12:08 > 0:12:11Modified handlebars will allow Helen to move
0:12:11 > 0:12:14into different positions so she can stay comfortable
0:12:14 > 0:12:15riding hour after hour.
0:12:17 > 0:12:19And the bike will be fitted with fat tyres,
0:12:19 > 0:12:22allowing her to travel on the snow and ice.
0:12:22 > 0:12:25Measuring just over 20 cm wide,
0:12:25 > 0:12:29the tyres on Helen's ice bike are some of the widest in the world.
0:12:29 > 0:12:32They're designed to spread the weight of the rider
0:12:32 > 0:12:33over a wider surface area
0:12:33 > 0:12:37by increasing the contact between the tyre and the snow.
0:12:37 > 0:12:39This prevents the tyres from sinking.
0:12:44 > 0:12:48Today, Helen's meeting the creator of the ice bike, Dan Hanebrink,
0:12:48 > 0:12:49and his team at a wind tunnel.
0:12:49 > 0:12:52They want to find out how Helen and the bike perform
0:12:52 > 0:12:55when put to the test in Antarctic wind conditions.
0:12:56 > 0:12:58The wind tunnel!
0:12:58 > 0:13:01Two factors that affect the performance of cyclists
0:13:01 > 0:13:04are wind resistance and drag.
0:13:04 > 0:13:09Wind resistance is the energy it takes for Helen to push the bike through the wind.
0:13:09 > 0:13:15The faster she moves, the more energy is needed to overcome the wind and move forward.
0:13:15 > 0:13:18Drag is the pulling force created when air hits a solid object,
0:13:18 > 0:13:21in this case the body of the cyclist,
0:13:21 > 0:13:24and is forced to go around, dragging them backwards.
0:13:26 > 0:13:30The team want to find out if they can reduce both the wind resistance
0:13:30 > 0:13:33and drag by changing simple things.
0:13:36 > 0:13:38I want to make this as realistic as possible,
0:13:38 > 0:13:45so when I go into the wind tunnel, I'll be wearing the clothes that I will take to the South Pole.
0:13:45 > 0:13:49I'm not entirely sure how we're going to make things like this more aerodynamic.
0:13:49 > 0:13:52But... that is the plan.
0:13:54 > 0:13:57It just feels a little bit bizarre that this room is filled
0:13:57 > 0:14:00with pictures of people who've been in the wind tunnel,
0:14:00 > 0:14:04and they're wearing tiny, skimpy little lycra outfits!
0:14:04 > 0:14:08I will be wearing more clothes than I've ever worn in my life!
0:14:14 > 0:14:16OK, we have zero. Go again, pedalling.
0:14:16 > 0:14:19Oh, oh, there it is. Oh, hello, wind.
0:14:19 > 0:14:25Helen's pedalling into wind that's blowing straight towards her at 20-30 mph,
0:14:25 > 0:14:28exactly the type of wind conditions she can expect in Antarctica.
0:14:30 > 0:14:33Ever since Amundsen and Scott first made it to the Pole,
0:14:33 > 0:14:37explorers have attempted to find new ways to travel there.
0:14:37 > 0:14:42Helen is hoping to become the first person ever to use a bike on a journey to the South Pole.
0:14:42 > 0:14:44If she's successful, it will be a world first,
0:14:44 > 0:14:50and her achievement will encourage others to push the boundaries of exploration.
0:14:54 > 0:14:57I'm not sure it's going to be easy to pedal in all this gear.
0:14:57 > 0:14:59Look at these boots!
0:14:59 > 0:15:04One man who knows exactly what Helen is going through is Doug Stoup.
0:15:04 > 0:15:08He was the first person ever to test the bike in Antarctica in 2003.
0:15:08 > 0:15:13I can already see she's exhausted from just fighting the wind
0:15:13 > 0:15:19and that really gives her a little perspective on what she's about ready to get involved in.
0:15:19 > 0:15:25Professional cyclists use body positioning to be as aerodynamic as possible.
0:15:26 > 0:15:29The team want Helen to try three different positions
0:15:29 > 0:15:33to see what difference it makes to her speed through the air.
0:15:35 > 0:15:40Smoke is used to show how the flow of air changes as she changes position.
0:15:42 > 0:15:48The straighter the line of wind, the more aerodynamic and efficient Helen's position is.
0:15:48 > 0:15:51As Helen moves into the third and final position,
0:15:51 > 0:15:55the team start to see real improvements in the results.
0:15:57 > 0:16:04Her body positioning is excellent. As long as she can keep that up for 500 miles.
0:16:04 > 0:16:07OK, Helen, we're done with that run, you can stop pedalling. Nice job.
0:16:09 > 0:16:12The tests have shown that a racing body position can help Helen
0:16:12 > 0:16:16lose five minutes of time for every hour she's on the bike.
0:16:16 > 0:16:19I want to make the three of them proud.
0:16:19 > 0:16:22I want to get to the South Pole
0:16:22 > 0:16:25and for them to all go, "Yeah, we were involved in that.
0:16:25 > 0:16:26"We helped her get there."
0:16:26 > 0:16:29They've got the expertise and the experience between them,
0:16:29 > 0:16:33and I've got to deliver the will power.
0:16:34 > 0:16:38And I guarantee, it is people like those three and their three faces,
0:16:38 > 0:16:41that I'll think about when I want to moan and I want to give up.
0:16:41 > 0:16:43I have to make this a success.
0:16:43 > 0:16:46I've got to see it through now. Got to do my bit of the deal.
0:16:52 > 0:16:55And the hard work starts now, as Helen is about to experience
0:16:55 > 0:16:59what it's like to ride a bike on a soft surface for the first time.
0:16:59 > 0:17:01Expert Doug has brought her to the desert
0:17:01 > 0:17:04to train on a prototype ice bike.
0:17:06 > 0:17:10Training on sand is the perfect substitute for snow...
0:17:10 > 0:17:11dry and powdery.
0:17:13 > 0:17:15Hopefully, he'll give me some top tips,
0:17:15 > 0:17:18so I'll be efficient and I'll use this thing to its full potential.
0:17:18 > 0:17:21- Hey, Helen!- Hello.
0:17:21 > 0:17:23How are you doing? It's a scorcher!
0:17:23 > 0:17:25You must be exhausted.
0:17:25 > 0:17:28First, Helen wants to know more about Doug's experience
0:17:28 > 0:17:31of using the ice bike in Antarctica.
0:17:31 > 0:17:35The bike performed really well until a big, atypical storm
0:17:35 > 0:17:39came off the Weddell Sea and grounded me for about five days,
0:17:39 > 0:17:43with 150 mph winds and I had to sleep with my feet up against the tent.
0:17:43 > 0:17:45I didn't get to do exactly what I wanted.
0:17:45 > 0:17:49I wanted to do about 350 miles and I ended up doing about 230.
0:17:49 > 0:17:51So I know the bike works.
0:17:51 > 0:17:55Are there key things that I should do on this bike that will make it easier?
0:17:55 > 0:17:59I think it's very relative to riding a mountain bike.
0:17:59 > 0:18:02I think keeping your weight back on the bike will help
0:18:02 > 0:18:05because the sand is a little bit loose and really,
0:18:05 > 0:18:09the sand is a really great simulation of what the snow is like on the polar plateau.
0:18:10 > 0:18:16Doug wants Helen to see just how different the ice bike is to a normal mountain bike,
0:18:16 > 0:18:19so they set off for a ride, first on the road, then on the sand.
0:18:19 > 0:18:20Look at old slow coach here!
0:18:20 > 0:18:24Come on, I thought with those muscles, you'd be whizzing on past!
0:18:24 > 0:18:27Well, the ice bike isn't really made for speed.
0:18:27 > 0:18:32It's made for travelling on the ice, so it's more about endurance.
0:18:44 > 0:18:47This isn't that much fun, is it?!
0:18:47 > 0:18:49I think it's a lot of fun!
0:18:50 > 0:18:52All right, clever clogs!
0:18:52 > 0:18:55Look at the smile on that face!
0:18:55 > 0:18:58- You're so pleased with yourself, aren't you?- Absolutely!
0:18:58 > 0:19:02Once you get going, it's all right, but getting going in the sand,
0:19:02 > 0:19:04on a bike like this, is virtually impossible!
0:19:04 > 0:19:09Well, this is why this bike is better than a typical mountain bike.
0:19:09 > 0:19:13It has bigger tyres for more surface area to travel on softer conditions,
0:19:13 > 0:19:15and that's why it was a success in the Antarctic.
0:19:15 > 0:19:18And why we can, you know, train out here in the sand.
0:19:21 > 0:19:27The tyres make a massive difference, but it's still surprisingly hard work to pedal through sand.
0:19:28 > 0:19:31You definitely feel it in your legs, don't you?
0:19:31 > 0:19:35Oh, absolutely. So, the training needs to just do a bunch of biking,
0:19:35 > 0:19:37and to be ready for your trip.
0:19:37 > 0:19:41And Helen's about to work even harder.
0:19:41 > 0:19:42For her Sport Relief Challenge,
0:19:42 > 0:19:46she'll be carrying all her equipment in a sled,
0:19:46 > 0:19:49so Doug's making her practise with it attached to the bike.
0:19:55 > 0:19:57Keep your weight on the back!
0:19:59 > 0:20:00Good job!
0:20:02 > 0:20:04You got it! Keep going!
0:20:10 > 0:20:13I am whacked. And not just a little bit out of breath,
0:20:13 > 0:20:18I am in that state where I feel like someone's punched me in the chest.
0:20:18 > 0:20:21I'd love to say that I'm struggling because it's really hot,
0:20:21 > 0:20:25and oh, that's fine, I won't have this type of heat in Antarctica.
0:20:25 > 0:20:28But it's not, it's just hard on sand.
0:20:30 > 0:20:36This is the only opportunity Helen has to train with the ice bike before she reaches Antarctica.
0:20:36 > 0:20:40The sheer effort of training on the sand puts into perspective
0:20:40 > 0:20:44just how hard riding the ice bike day in and day out is going to be.
0:20:44 > 0:20:47This really is the toughest challenge of her life.
0:20:50 > 0:20:54Many explorers have tried and failed to make it to the South Pole.
0:20:54 > 0:20:57Helen's going to need real determination and endurance
0:20:57 > 0:21:00to keep going in temperatures of minus 50
0:21:00 > 0:21:03and winds that can reach up to 125 mph.
0:21:03 > 0:21:07But Helen's on a mission to inspire YOU to do the Sport Relief mile
0:21:07 > 0:21:12and to raise money for poor and vulnerable children in the UK and around the world.
0:21:16 > 0:21:19I've looked at loads of pictures and spoken to different people,
0:21:19 > 0:21:24but I don't think I know what to expect in terms of day after day.
0:21:24 > 0:21:25What is it actually like?
0:21:25 > 0:21:30There's no rest days. You can't sit in your tent and wait for the wind to blow, or whatever.
0:21:30 > 0:21:34You have to get out of your tent every day and put in your time, do your routine.
0:21:34 > 0:21:36It's a civilised way of life.
0:21:36 > 0:21:40Each day, you go through your routine and if you get your miles in each day, you'll get there.
0:21:40 > 0:21:44500 miles across some of the most inhospitable places on the planet,
0:21:44 > 0:21:46is not an easy task.
0:21:46 > 0:21:50You know, you have the best help and the best people and the best gear
0:21:50 > 0:21:54and you just have to take it one step at a time.
0:21:54 > 0:21:55And this is part of the process.
0:21:57 > 0:22:01I'm the person who always says, "Impossible and difficult are two different things."
0:22:01 > 0:22:07Now, actually, I'm the one going, "What... Helen, what are you doing?"
0:22:07 > 0:22:12I want to prove the point that you can do anything you put your mind to.
0:22:12 > 0:22:15But I'm questioning myself. And if I'm questioning myself,
0:22:15 > 0:22:16who's going to believe in me?
0:22:16 > 0:22:20You'll do it. You are a strong-willed human being.
0:22:20 > 0:22:23You're doing the training. I think it's just one step at a time.
0:22:23 > 0:22:27You've done this before with other things, and you can do it now.
0:22:34 > 0:22:38Time is running out and Helen wants to make the most of training with the ice bike
0:22:38 > 0:22:40so she heads back to the beach to put in some hours.
0:22:42 > 0:22:44I need someone to give me a push start!
0:22:44 > 0:22:45See, you can get your pedals...
0:22:45 > 0:22:49Even if you can make the pedals go round, you can't make the wheels go round!
0:22:49 > 0:22:52If the wheels aren't going round, I'm not going forward!
0:22:55 > 0:23:00Helen's still getting nowhere until she remembers there's something that might help...
0:23:04 > 0:23:08Doug said that if I let the tyres down a little bit, it should be easier.
0:23:08 > 0:23:11And he said a lot about the pressure of the tyres and all that,
0:23:11 > 0:23:14so it must be important. Fingers crossed.
0:23:14 > 0:23:16Yeah!
0:23:17 > 0:23:20Oh, that is definitely easier.
0:23:22 > 0:23:24"Easy" would be pushing it too far.
0:23:28 > 0:23:30I need to get seriously fit.
0:23:32 > 0:23:37If I want to stand a chance of making any mileage on this thing.
0:23:41 > 0:23:46Fun for five minutes, practical for 500 miles? I don't think so!
0:23:54 > 0:23:57Finally, after a week of training with the ice bike,
0:23:57 > 0:24:01it's back to the safety of a mountain bike for Helen's 15 mile off-road race.
0:24:01 > 0:24:05She'll be riding around Lake Irvine in the heart of California.
0:24:05 > 0:24:08Failure at this stage could shatter her confidence.
0:24:10 > 0:24:11This is it. Race day!
0:24:11 > 0:24:14I can ride a bike and I've had a special skills lesson,
0:24:14 > 0:24:17so I thought I'd get here feeling pretty confident. But look around!
0:24:17 > 0:24:21They're so professional. Everybody's head to toe in lycra,
0:24:21 > 0:24:23and I've got to take them on in a 15 mile race!
0:24:23 > 0:24:27All I've got to remember is, don't panic.
0:24:28 > 0:24:32There's so many people taking part and everyone has a story to tell.
0:24:32 > 0:24:35That girl just told me she sprained her thumb,
0:24:35 > 0:24:38she's broken her wrist, she's got bandages on.
0:24:38 > 0:24:42This isn't an amble in the countryside on a mountain bike, this is serious.
0:24:43 > 0:24:48As she lines up for the race, nerves are starting to show.
0:24:48 > 0:24:50I'm really freaking out now.
0:24:51 > 0:24:53STARTING HORN BLASTS
0:25:00 > 0:25:03I haven't fallen off yet!
0:25:06 > 0:25:09I didn't know that bit of the course, that's not fair!
0:25:11 > 0:25:14THEY SHOUT ENCOURAGEMENT
0:25:32 > 0:25:33Oooh!
0:25:33 > 0:25:36I'm absolutely spent.
0:25:36 > 0:25:40There were parts when I thought my legs were going to give out.
0:25:40 > 0:25:43But thankfully, there's a downhill not long after an uphill.
0:25:44 > 0:25:46Oh, my goodness!
0:25:46 > 0:25:48There were moments where I just thought,
0:25:48 > 0:25:51"I'm not going to finish this, I'm not going to finish this!"
0:25:51 > 0:25:52Oooh!
0:26:02 > 0:26:07I'm so happy that I finished. Plenty of people did not finish that race.
0:26:07 > 0:26:10And yeah, I'm not first, but I definitely wasn't last!
0:26:10 > 0:26:14I was 13th out of 20 finishers and I was just over ten minutes
0:26:14 > 0:26:17behind the leader. So, I'll take that!
0:26:17 > 0:26:21I just really wanted to beat a lady in an orange t-shirt, and I did!
0:26:23 > 0:26:28I really have been on a tall, tall rollercoaster of emotions while I've been in California.
0:26:28 > 0:26:31I've been scared, I've been excited, there's been tears.
0:26:31 > 0:26:33What I have to remember is, if you just keep pushing,
0:26:33 > 0:26:36there's always a little bit more in the tank.
0:26:36 > 0:26:38And that is a huge lesson that I want to take away with me
0:26:38 > 0:26:42and definitely something to think about in Antarctica.
0:26:44 > 0:26:47And if you've been inspired by Helen's challenge,
0:26:47 > 0:26:51why don't YOU go the extra mile and get involved in Sport Relief this year?
0:26:51 > 0:26:56Get a grown-up and sign up for the Sport Relief mile. There are hundreds of events,
0:26:56 > 0:27:03and by raising money, you can help poor and vulnerable people in the UK and around the world.
0:27:03 > 0:27:05Next time, Helen starts her kite-ski training,
0:27:05 > 0:27:09which means beginning on a beach with a power kite.
0:27:09 > 0:27:11I'm going to have to have strong arms, aren't I?
0:27:11 > 0:27:14This kite has got so much power in it!
0:27:14 > 0:27:17But training grinds to a halt after a fall in the water...
0:27:17 > 0:27:20I don't have time to be proper injured!
0:27:20 > 0:27:24She was getting overly confident, I think, and trying to progress really fast.
0:27:24 > 0:27:30..And Helen puts her new found kite skills to the test against three top young kite-surfers...
0:27:30 > 0:27:34We are clearly winning at the moment!
0:27:36 > 0:27:38Subtitles by Red Bee Media Ltd
0:27:38 > 0:27:39E-mail subtitling@bbc.co.uk