From Evernote:

Everything changes, everything remains the same

The Simpson Desert Challenge is a race of contradictions.

It's not how fast you can ride, but how slow you can go without being caught.

It's not the lightest wheel that wins, but the biggest.

It's not the toughest rider that wins, but the one that can take the most tender loving care of their body.

It's not good food that's important but how much you can force down your neck.

It's not what you drink but how much.

Many people think that deserts are hot places but the correct definition is actually a dry place. The ultimate contradiction is that the Simpson Desert is actually underwater this year. While it would be good to see the wildlife it would be a pretty tough trip to get a vehicle through. Running a cycle race is out of the question.

Instead, we head north to Coober Pedy and then turn right. The Anne Beadell 'highway' runs due west towards WA.

I've been thinking about this race for a year; training, buying bicycles, testing, fettling, re-testing. After all that careful planning and preparation we're right back in the same position as last year - heading into the unknown!

Everything changes. Everything remains the same.

Tubeless Endomorph

And in the end a pretty easy conversion to tubeless. I used the ghetto style with 20x3 inch BMX inner tubes from Schwalbe. I went for Schrader valves as last year - it's easy to get a cheap, accurate gauge for car type valves. I used an expensive quantity of 3M double sided foam tape.

My bike has Uma 2 rims. I used one wrap of duct tape, one wrap of 50mm x 1.5mm double sided foam tape as a base then an extra 2 wraps each side of 19mm x 1.5mm double sided foam tape. In effect I brought the sides up by 4.5mm and the middle by 1.5mm. If I was trying to do this again, I think the middle wrap is the most important because until you get this in place it's hard to inflate, even with a compressor.

You can still fit the tyre by hand but once on the tyre will not spin around the rim; even though it's in the low centre of the rim the foam makes it too tight to spin. After that a track pump and some soap and water were enough to set the beads. I unscrewed the valve core and added 180ml of Stan's sealant per tyre. Contrary to what I've heard on the web, my Endomorph's were already almost airtight. One 'Shake and rotate' sequence was enough to have them all sealed up.

I've taken them for a spin at 8psi/12psi. I'll lower that then do some experiments on the sand to see if they burp.

Training On Manly Beach

The faty, tubeless on manly beach. In testing I took it down to 3psi in the front and 5 psi in the back to prove the tubeless conversion would not burp.

At 3psi if you stand up you can push the rim through the front tyre and onto the road.

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.