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Just watching this on Discovery. about all kinds of bikes, from road bikes to 120kph recumbents to mpv aeroplanes (it exists, and it works!, one crossed the 34km Channel).

The DH part was all old news to me, and I knew about speed racing straight down ski slopes. But it got me thinking. At the 100+mph these folks hit, over semi-packed snow, would 29" offer an edge, say if the ideal tire for the purpose existed?

What factors are relavant in this sport?
- weight - pretty much the same and neglegible at 100+mph
- aerodynamics - 10% more wheel spinning at 100mph, can't help, but then, overall frontal surface might be similar
- fork and frame suspension travel. Less room for travel when trying to stay low with a 29"er?
- shock imput, a 29" wheel would encounter the same bumps, but send them to the damper more smoothly. Would this be more efficient in a significant way?
- of course, rolling resistance. Although due to the steep slope maybe half the weight of the bike presses down on the tires' contact patches, 100mph will always be a bunch of watts worth of rolling resistance to save 10% from.
- staight line stability and grip. Seem vital in this sport, and 29" has got it.

There was also a report of the Megavalanche, the mass-start 22km DH run from alpe d'Huez. All the crashes seemed so typical of 26" bikes. The steepness of the slope made it happen to all the capable DH/FR bikes there. I'd love to see how a capable Megavalance rider would do on a specially prep'd Behemoth or El Capitan. Pugs would be interesting too.

Anyone here into speedbiking or whatever the going name is?
 

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The Megavalanche is down to tyres again.
You need some beefy side walls as there are some really cruel rock sections on it.
4-5" travel would be spot on if your going out to win it.
Oh and the top riders are all running semi slicks DH tyres too :0/
Most of the crashes on the glacier are because it basically impossible to ride if your not in the first 50 riders.
This is a short video of the start of the 2004 race.
https://www.hunkymalecyclist.com/rides/2004/040731megavalanche/megastart2004.mpg
The front guys go like rockets as the snow has been piste bashed to flatten it but the ground is soon chewed up.
This is my view of the snow 800 riders later.
 
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