100km on the Fatback

You want to be Soft and Fat

Pumping up road bike tyres is more challenging to the nerves than to precision; you attach a track pump and keep going. 100psi, 120, 125. How much safety margin did the manufacturer leave between their recommended maximum pressure and the point of explosion? In contrast I usually inflate mountain bike tyres to below the manufacturers minimum limit. The difference between 25 and 30 psi can be hard to see on a small gauge. A squeeze of the tyre is subjective, not objective.

I went for Schrader values on the Simpson Desert Challenge because you can get cheap, accurate pressure gauges. You can't control what you can't measure and I wanted to know what different pressures would feel like. What was the minimum pressure I could use before the tubeless setup failed? Once I had completed my ghetto tubeless conversion I tested it on the beach and made a note of the pressures that worked. I also tested it on my long 100km cycle; there are plenty of boulders on the descent from Andersons to Bedford Creek and if the setup would handle these I figured that it would stay together on the Simpson.

Tyres on fat rims have a very different feel to same tyres on narrow rims. For example, 25 psi might feel soft on narrow rims but feels as hard as nails on a fat rim. I think the answer lies in the profile. Fat rims give the tyre a much flatter profile which has to defect less in order to present the same surface area to the ground. Soft, fat tyres roll over small stones that would normally have you bouncing around.

It took a couple of goes to find some good sand. The ocean beaches around Sydney are too soft - the waves constantly lift and re-lay the sand. The sand on the harbour beaches is more settled. In the end I used Clontarf for my testing, in the early morning to avoid cycling over sunbathers. I started from 25 psi and worked down from there, repeating the same loop across the beach and back through the kiddies playground, loosing a couple of psi, then riding again.

What I found was this.

If you can't steer (the front wheel ploughs and bucks you off) you need to loose some air from the front tyre.
If you have too much drag you need to loose some air from the back tyre.
Small changes in pressure have big effects (15 psi is very different from 18 psi)

There are other considerations. Testing on the sand leads you to lower and lower pressures. When you cycle on the road again these soft tyres feel SLOW :- there is a compromise there. Tyres with thin sidewalls tend to crease when they get too soft - you have to worry about their longevity and wether they will delaminate during the race.

In the end, with 2.4 inch tyres holding up 95kg's of primate I settled on starting pressures of 15 rear, 12 front. I knew that 12 and 10 would go a little better on the sand, and that 10 and 8 would still hold together. I never got low enough to check the burping pressure of my ghetto setup.

As a final check I rode the Double Double @ 15 and 12. It was my fastest ever trip and proved to me that the rolling resistance was not a real handicap off-road.

When you think about it, the SDCC is basically flat. On a hard, flat surface anyone can cycle @ 12km per hour - you can even run at that pace. The real problem is the sand dunes that lie across the track. A bike that rides well on the sand is a great help.

From Evernote:

Right bike, wrong course

It's ironic that, after spending 12 months and several thousand dollars building a bike to ride on soft sand that the desert flooded and the course had to be changed. The SDBC committee did an excellent job in getting permits at the last minute for the Great Victoria Desert, a process that normally takes eight week. The race director plotted a 587km course along the Anne Beadell Highway from Mabel Station out to Annes Corner. The course included the nuclear test area of Emu - it's not everyone that can claim to have raced a bike across a nuclear blast zone. Lead might be a better material than titanium.

The highway has mainly hard surfaces with little sand. It's renowned for it's terrible corrugations. These were harder of the 4wd convoy that the bikes. Over the event the convoy destroyed four tyres, dropped two fuel tanks, broke the power steering on two vehicles and blew a complete set of shocks on a Pajero that then wobbled like a jelly.

On the bikes you could usually find a line around the worst of the corrugations, though if you miss judged it the deep ones would buck and thump until you lost all your forward momentum.

If you were building a bike for this kind of terrain you'd go for something with large springs front and back. That said, the Fatbikes were not disgraced. Simon and I came in 2nd and 4th. Rocket Ron had thin wheels but fat thighs. I saw him at the start of each stage and at the presentation when they handed him first prize. Lynton, winner in 2008, repeated his role as the man that would never give up. We passed him a couple of times only to have him come back in the last moments of the stage.

As well as wheel prints in the sand there where camel tracks. Simon surprised one that intelligently took off down the road. Simon followed it for 10km and got it up to 29kmh at one point. It was foaming at the mouth, which I believe is a sign of sexual excitement in the male camel.

On the Road

The last few weeks have been hot and humid. You may have seen Sydney on the news with it's heavy rain and flooding.

Rain means I'm back on the road. Manly dam shuts when it is wet. Even if it didn't, riding a mountain bike in the wet is just too damn expensive. The sandy trails around here eat chains, blow seals on shocks and buggers gears.

I got an invite for a bunch road ride this weekend to Ettalong. In the end the roadies didn't turn up and Mat and I cycled together through the rain and humidity. It's a great route and one that should have some great views on a day with less mist and rain. Mt White wasn't really a hill but I had some back-wheel-sliding action on some wet overbanding on one of the bends downhill.

All in all a good day out, though the 4:00am wake up call is a kicker.

We're in!

I've entered the Simpson Desert Challenge once again. So has Alex (#10). David and Trevor are coming back to support us.

It's the same team over again - I couldn't be happier.

Training Diary

Apologies for the format on this one - I've added a table in HTML and for some reason it shoots to the bottom of the page.

Some people has asked about my training program. I'm not sure I know much about cycle training but I've read quite a few articles on running.

In running they talk about cycles, progression and specificity, training that is specific to the task in hand. Basically you can choose between endurance, strength or speed. In running circles they say if you don't know what you're training, give up and go home. Given my race plan of 'hanging on' and the nature of the event I chose mainly endurance exercise with a little strength training.

Given the time available I built a plan around 3 week micro-cycles - easy, medium and hard weeks. I then put these together in threes, easy, medium and hard to give a 9 week progression. I had time for 2 of these 9 week cycles, one easy, one hard.

I do all my training with a Polar heart rate monitor. This gives me a training log, reproduced below. I use the calories as a measure of the work done in any one week. You can skip down to the last line to see the answer: In the 2009 Simpson I cycled for 38 hours at a cost of 25,000 kCal.

Note that the Polar has a simple alogrithm for guessing calorie expenditure based on weight and heartrate. These figures won't relate to what you see on your watch. Relatively, I think we can compare. The 'Double Double' costs me 5000 kcal, about the same as a morning stage on the Simpson. An afternoon stage costs me a further 3000. If you're comforable on the DD, I think you'll do well on the Simpson.

What will I do next year? Well, more on the road. Mountain biking on the dirt costs a fortune in spares and repairs. I'll add more hill repeats as well. Seated spinning helps you clear the dunes and it's far easier to cycle than walk. I'll propably aim to spend less time on the bike.

Anyway, if you're ready for the long scroll down, heres the key.

R = running
MD = Manly Dam
DD = Double Double - up the Oaks, Ingar, down Andersons, down the Oaks
C = cycle on the road
HR = Hill repeats

Week	M	T	W	T	F	S	S	Summary
18	MD 1:40	R 1:25		MDx2 2:00		R 1:50	DD 8:30	13.5 hrs 10400 Kcal
19	C 0:45	R 1:00		MDx2 1:45		MDx3 3:20	R 1:10	8 hrs 5800 Kcal
20	C 0:45	R 1:00		C 1:30		C 1:00	R 1:45	6 hrs 4800 Kcal
21				C 1:30		C 1:00	DD 8:00	10 hrs 6850 Kcal
22	C 0:45				C 0:45	MD 1:00	DD 8:00	10.5 hrs 7000 Kcal
23	C 0:45	MDx2 2:00	C 0:45			DD 8:30	DD 8:30	20.5 hrs 12000 Kcal
24							R 1:00	1 hrs 740 Kcal
25	C 0:45	R 1:00				MD 1:00	R 1:15	3:75 hrs 4000 Kcal
26	C 0:45	R 1:00	C 0:45	C 2:00	C 0:45	C 2:00	R 1:30	8.75 hrs 5500 Kcal
27	C 1:30	C 1:30	C 1:30	C 0:45	C 0:45	C 6:00		12 hrs 8200 Kcal
28		R 1:00	C 1:30	C 0:45	C 0:45	HR 1:00	R 1:15	6.25 hrs 4850 Kcal
29	C 1:30	R 1:00	C 0:45	HR 1:15		DD 8:00	R 1:30	13 hrs 9700 Kcal
30	C 1:30	R 1:30	C 0:45	C 1:45		MDx4 3:45	R 1:50	11 hrs 7700 Kcal
31	HR 2:00	R 1:30	C 0:45	MDx2 2:45	C 0:45	MDx4 3:45	R 1:00	13 hrs 7300 Kcal
32	HR 1:15	R 1:00		C 1:30	MDx1 1:45	MDx4 3:30	City Surf 1:08	10 hrs 7800 Kcal
33	C 1:30	R 1:00	C 0:45	MDx3 3:15		HR 2:00	R 1:30	10 hrs 6650 Kcal
34	C 0:45			MDx2 2:00	C 0:45	MDx4 3:45	R 1:30	8.75 hrs 5900 Kcal
35	DD 8:00	R 1:00		MDx2 2:15		MDx4 3:30	R 2:00	16.75 hrs 11200 Kcal
36	C 1:30	R 1:30		MDx3 3:30	0:45 C	DD 8:00	R 1:15	17.5 hrs 11000 Kcal
37	Beach 1:45	R 1:00		Beach 1:45		DD 8:00	R 1:15	14.5 hrs 7800 Kcal
38	R 0:45		C 1:00	C 1:00			Sydney Half Marathon 1:42	4.5 hrs 3500 Kcal
39								0 hrs 0 Kcal
40		Stage 1 5:26 Stage 2 3:22	Stage 3 7:30 Stage 4 4:02	Stage 5 6:14 Stage 6 3:54	Stage 7 2:39	Stage 8 5:13		38.5 hrs 25700 Kcal

God or Gibbon?

So what worked and what didn't? What would I take again and what would I change.

Separating Gods from Gibbons:-

Gods.

The Bike

Lets start with the big things - the bike worked out just fine - many thanks to Aaron at Brookvale Bike Factory who recently rebuilt it. It's a 2008 Scott Genius with a carbon main triangle and an aluminium Horst link on the back. I got it as a 40th birthday present for myself to prove I was still young. I bought it on a Saturday then crashed it on Sunday, breaking my arm. Certainly, age has not made me smarter.

The great thing with this bike is the adjustable travel suspension. With a Fox Talas upfront and Scotts own rear shock you can set it up as a hardtail with 100mm at the front for going fast, or, as the wear and tear builds up on your rear loosen the back to 90mm, then 130mm of travel. In training I've run it hardnosed; locking the front and leaving the back @90mm. This means you can stand up and honk without having to touch the controls. There is no platform damping on the rear shock - I don't think it needs it with the Horst Link - it's such a good peddler.

The Wide Wheels

The Snowcat wheels I've already talked about at some length - I won't repeat it all here but I will just mention tyres. That Kenda Small Block 8 was a beast in 2.35 width. I was a bit worried about the very thin sidewalls bit it got through fine.

Puncture Sealant

Stan's No Tubes Sealant. The SDCC is probably the best advert for Stan's Sealant in the world. Leon got a monster thorn in his tyre. He pulled it out but the hole was too big for Stan's to seal, so he put the thorn back in the hole and kept cycling. By contrast, Aaron, rider 29 had 8 punctures. On one occasion he got 200 metres from the start before getting a flat. Freddy ran tubeless tyres but still got flat tyres until Richard sorted him out with some sealant.

The GPS

The GPS was great, both for overall speed and for the waypoints that help break a stage into managble chunks. On that hard second day I knew exactly how far I had to go before I'd turn out of the headwind. The screen can be a little hard to see on the Oregon and it's not really meant for cycling but it kept me company well enough.

Waxed Chains

Chains I've already spoken about. Not a problem with the sand.

The Bento Box

The bento box looks a bit odd on a mountain bike but did a good job of holding both my camera and my Uncle Tobies muesli bars.

My camera (a knackered Canon Ixus) was also a good thing to have along.

Finally, wearing 2 pairs of shorts was a great idea and something I should have done from day 1.

Gibbons

Cheap bar ends

Worst of the worst, the bar ends. Three weeks after the event and I still have no feeling in the smallest 2 fingers of each hand. Well, that's not quite true, and the difference shows what a curious creature the human is - I can feel the inside of my ring finger but not the outside - the feeling is split down the middle. The nerves for the little finger and half the ring finger must be routed in one direction and the nerves for the other half of the ring finger routed somewhere else. Interesting, but I'd rather have some feeling back.

I bought cheap barends in a panic after meeting up with the Sydney guys who were all using them. I only completed one circuit in the Blueys with them, had problems and bought some expensive track mitts to try and compensate. "never use anything in a race that you haven't used in training: - that's a good motto. The clamp has a bulge that bruised the ulna nerve in my palm.

Not everything about the bar ends was bad. I liked the wide grip with the extra leverage it gave for steering on sand.

My beloved saddle

The saddle - a Fizik Gobi. I've spent many a happy hour on this saddle. I’ve done 8 hour rides, 16 hour weekends. It’s amazing that one day in the desert and I'm in deep trouble. I think next year I'll get something big with springs.

Untested Cycle shorts

Nothing wrong with the shorts per say, they’re well made and I got a good deal. My idea here was to have a fresh pair on knicks for every stage – bibs in the morning and shorts in the afternoon. My mistake was not testing them out before I raced in them. I've been wearing bibs for a long time and think I get on better with something that has braces - it holds the chamois up and stops it moving around.