Gravity Bikes

Back in August, I dreamed about the ultimate downhill road bike. I was assuming that this bike would also be peddled uphill. Say you didn't assume that. Then you'd end up with something like these nut jobs built for themselves:
They're competing in something called the MaryHill Festival of Speed which is basically a gathering of people (mostly young males) wrapping themselves in leather and helmets and then placing their bodies on wheeled objects that seem to me like carbon fiber skate boards and like-a-bikes and pointing them down a big hill.

Here's a pretty good blog entry on the world's fastest gravity bike. CNC'd aluminum components, gigantic custom motorcycle style disc brakes, and shocks to cushion your ass while you kiss it goodbye.

http://bikeporntour.blogspot.com/2008/10/worlds-fastest-g-bike.html

Of course, nothing this crazy goes un-Youtubed. I'm sure you can do some good research there.

Picture from bikeportland on flickr.

The ultimate downhill road bike

On some recent ride up to Skyline and down highway 84, I started thinking about what would make a great descending bike. The right geometry, the right rubber, the right brakes. Then, I let my imagination roam a little bit, and considered what might make the ultimate descending bike. No, not a downhill mountain bike, or even a road bike, but something purpose built for carving up road descents. What's out there already? Some companies in Hawaii used to truck people up to the top of Haleakala and then send them down with a jumpsuit, motorcycle helmet and modified cruiser bike.

Fun, but you'd sweat buckets pedaling it up hill, or even across a flat section. Plus, the position is probably too laid back to be fast and what's with 26 inch tires? Anyone who's ridden their mountain bike down a screaming road downhill ala Super Walker knows that it works pretty well, if not for cornering on those sketchy tire knobs. So, start with that platform and begin perfecting.1

Here's my dream component list for a downhill road bike:
-Disk brakes to save your rims from failing and your tires from exploding
-Brakes accessible in an upright riding position (on flat bars or bar tops)
-700C wheels for the best selection of road going tires
-28-34mm smooth wheels for the perfect combination of low rolling resistance and pavement imperfection absorbency
-Aluminum (or otherwise lightweight) frame
-Some flavor of gearing for uphill, flat and downhill riding
-Maybe just maybe, an adjustable seatpost to drop for the downhill

So, I thought about how to build one.
-Start with a Niner Air9 Scandium frame. Light weight, 700C, upright position.
-Put a carbon disc brake fork on it for light weight and smooth riding (like the On-One Superlight Carbon)
-Any available drivetrain with a nice wide range
-Some hydraulic or mechanical disc brakes (not sure what rotor diameter would be the best)
-Michelin Dynamic 700c x 32 tires
-Nitto alloy mustache bars
-Maybe, just maybe, a Maverick Speedball Seatpost

Then, it got sent to me in yet another Performance bike mass marketing spam-0 mail:

The Mongoose Sabrosa Ocho commuter bike. Ok, so you need to dump that coffee thermos, but it's got everything. The disc brakes, the big fast tires, and a Shimano Alfine internally geared hub with a nifty dropout adapted attachment. Then, when you're done riding the railway up to some fantastic Swiss mountain pass and bombing down on your bike, you can throw your panniers back on and roll on down the road.

Anybody got any other ideas?

Pics purloined from www.buzzhawaii.com, www.performancebike.com