Road Cycling - Frame strength on roof rack

I've whipped up a homemade roof mount for my roadie. It consists of a board of wood with a front fork mount and a rear tire channel with strap. When I put this on the rack and get the bike settled in, it's quite sturdy. There's no lateral or front/back movement of the mount. The bike, however, has a nominal amount of sway if I push on it. I assume this is normal and is the reason why newer racks have a bar that clamps to the downtube. I don't have this and was wondering how strong the frame is compared to the lateral force. The bike has an alu frame and weighs about 20 lbs. Do I need to be concerned about a fork cracking or something odd like that if I go around acurve in a highway at 75 or take a kind of sharp in-city corner? I can't really figure out a way to tie the bike down to add more stability w/o messing up components, wires, etc.

Also, what do you use to protect the bike if you don't have one of those $35 covers?

Thanks for your help!

I use a "Fork mount" Yakima viper roof rack. I can't imagine anything more solid. I have logged thousands of miles with bikes in these racks (Carbon Forks), as long as you keep the G force on turns under 2 G's I think you'll be fine. :D

Cool. I had already planned to take it easy on the turns, but I'll pay extra close attention during those high-G Combat Manuevers ;)

Most of the mounts that grab the frame by the BB or one of the tubes, actualy do not have a fork mount, that is the reason they require it.

Do I need to be concerned about a fork cracking or something odd like that if I go around acurve in a highway at 75 or take a kind of sharp in-city corner? I can't really figure out a way to tie the bike down to add more stability w/o messing up components, wires, etc.
I had my bike mounted in my Yakima Steelhead roof rack yesterday and was heading south out of Atlanta on I-85 doing 75-85 mph for a while. (I was running late for the Lewis Grizzard ride.) No damage to the bike or fork.


Also, what do you use to protect the bike if you don't have one of those $35 covers?
My wife told me to order "one of those $35 covers" and I always do what she tells me to do. :D

The bike, however, has a nominal amount of sway if I push on it. I assume this is normal and is the reason why newer racks have a bar that clamps to the downtube.

Untrue. I've got a set of Hammerhead fork-mount bike holders on my Rhode Gear Mondial rack (don't look around for those... been out of production for a while now). The bikes are pretty solid in there. There's a very tiny bit of motion but I wouldn't even come close to saying nominal.

Side-to-side motion is likely due to flex in your rack's crossbars or the roof mounts. Are you using good quality bars or the cheapy all-purpose ones? True multi-sport rack crossbars are unbelievably strong. The ones on my rack could probably handle being driven on in a ramp-like situation.

First, you accept the responsibility if your rack fails. But, the bikes will be fine. I've had 4 on the car on fork mount racks going 75 mph in a 30 mph crosswind going across the Texas panhandle and all of New Mexico with no problems. And get a bike bra.

wood- flexible,

aluminum tubing- not so flexible

hmmmmm!

DEMON