Gravity racer - Calling all daredevils!

[mybike1]

Here's a vid of me on my bike and my friend Gordy on his longboard hitting up a local hill.... I was hitting 39 mph pretty consistantly but just couldn't get to 40
http://youtu.be/e67mah0fmFM

and a pic of my bike as it looked when it was first put together. It now sports new wheels with a disc in back, new bars and a few other changes...new pic soon

 

[SailorMac]

Vid is super Coolio! I didn't know you guys had those kind of hills in Michigan City. I need to build a gravity bike; been looking for hills, but very thing is pretty flat here.

 

[Philphine]

is this a pocket bike fairing? was it very hard to adapt?

any of the serious racers know if this would be santioned or whatever by whoever the g-bike powers that be are? not that i'm building for real competition, i just like the idea that the bike could do it given the opportunity.

 

[mybike1]

There a very few hills around here... We've narrowed it down to about 3 hills even worth riding on. This particular hill in the video is probably the fastest... and would be faster if I didn't have to check my brakes for that last corner... man that's frustrating
And yes, it is a pocket bike ferring.... It wasn't hard to get on the bike... I'll try to get better pics up in the next couple days and you'll be able to see how I mounted it.

 

[fast eddie]

dang where have i been !!! i didn't know there were gravity bikes getting built here !! here's some bikes ive built over the years, the cantilever frame bike pictured first is the one i have now, under it is some of the custom welds

[imghttp://i77.photobucket.com/albums/j64/gravityracing/FEGB08-11.jpg][/img]

[imghttp://i77.photobucket.com/albums/j64/gravityracing/scottysnewbike33.jpg][/img]

[imghttp://i77.photobucket.com/albums/j64/gravityracing/CafeRacer3.jpg][/img]

 

[mybike1]

Man... there are some sweet gravity bikes here!
As promised, Here are a couple new pics of my bike
and you can get a better look at how I mounted the
pocket bike fairing... and don't forget... Stickers
make everything look faster
I'm still waiting to make a few changes... and I still
need to put some weight on the bottom side.

 

[fast eddie]

nice, wher'd ya get that fairing??

 

[mybike1]

nice, wher'd ya get that fairing??

from a blown up pocket bike.

 

[fast eddie]

ive thought about trying that, is it functional or just for looks?

 

[mybike1]

I put it on for looks... but then after having it on there, I noticed how much wind it blocks when I'm ducking in. I really have no idea whether or not it helps aerodynamicly. It's a great place to put my stickers! :lol:

 

[Philphine]

ive thought about trying that, is it functional or just for looks?

if you showed up at one of the santioned races with something like mybikes's fairing, could you use it?

also what's a good tire width to use generally? 20x?

 

[fast eddie]

im sad to report that there aren't any organizations in north america that are currently including gravity bike classes. there werent enough bikes showing up to races. the bikes are awesome but they are a wicked pain to transport. 20" (bmx size) are good wheels to use, they're fast and sturdy. my wheel set up ups Crupi sealed bearing hubs, heavgy gauge spokes, and TaiPan double walled/deep walled rims with Tioga Comp Pool egg shaped slicks and a disc on the back. smooth as glass and fast !!

 

[jaysmo]

yo mybike1 where you get that red seat from.. i need one just like that... and man i wish there were hills is Florida

 

[breakurnees]

http://www.youtube.com/watch?v=L1duqc1fDwM

Hit 35 or so on my shakedown ride. I also highsided it at the end. Lots of fun. I will definitely repair, modify and ride it again.

 

[Philphine]

what happened there at the end?

congrats anyway, i guess that makes me "pokey", with the slowest time.

i plan to keep mine too though. never got tires to try the new wheels with, and never tried the other bike at all. i mean to keep both though. they were fun side experiments.

 

[Philphine]

hey, you never showed what it looked like.

 

[breakurnees]

Sorry about that. I meant to do a short ride, assess the effectiveness of my bungee dampeners and than come back and do a second video. I felt confident and went the whole way. The steering was shaky anytime it wasn't pointed straight, and it got away from me on that last curve. While my buddy was shooting the speedometer, I was picking up speed and then wobbling like crazy. I let off the front brake, grabbed the rear and tried to ride it out, but got sideways and then highsided it.

I'll try to shoot a video of the bike in its current state soon.

 

[fast eddie]

can i make a suggestion about wobbles? usually on g-bikes wobbles are not from speed. if you're going under 40mph then i would definatel suggest that it's not a speed wobble issue. get rid of the bmx fork and install a road fork w/ a negative angle and at least 3 inches of reach. set up your seat (i would highely suggest getting rid of the seat and resting on knee trays) so that none of your body weight is being supported by your arms. a correctly built bike should be able to be ridden w/ no hands, and you should be able to move the bike right/left under you while riding w/out moving your torso,head,shoulders. also, make VERY sure that your rear wheel is mounted straight, and that it is tracking in line w/ the front wheel.
fast eddie

 

[breakurnees]

Thanks Eddie. I don't have a seat, I have kneelers, but I don't think i could balance without hands. My bike has a raked out springer fork. I was thinking about swapping for a bmx, but I may look for a road fork. The bike caught wobbles anytime the front tire wasn't pointed straight. Since the frame is flipped and stretched, I think a BMX fork would still have some forward rake. Is there something other than the forward curve on a road fork that makes it better?

 

[fast eddie]

what kind of springer fork? i would definately suggest flipping the frame back to right back up, when ya lip the frame you increase the racke, which is good if your drag racing and only going straight, but terrible in turns as you have found. a rigid bmx fork would be great, some guys say shock forks are better, some say rigid is better, thats up to hte rider i suppose but i would definately suggest a normal fork and righting the frame. forks will usually either have a bend in the tubes or drop outs welded on, either way what they give the fork is caster, like a grocery kart caster wheel, it's steadier when trying to maneuver than if it were straight up and down. do you have a lowrider fork on the bike?