Carbon Fork Flex?
 

Here's my bike...
http://www.garberdesign.com/bike/mutt1.jpg

Here's a picture of my fork on a cooler bike.
http://www.thresholdsport.com/sitebu...ad-668x498.png

The issue is that this is my first and only carbon road fork. One thing I've noticed is that it's a little more soft compared to my steel fork. If I straddle the bike, hit the front brake, and use my torso to push the bike backwards, there is some flex in the front of the bike. I can see the frame shift a bit under the weight :eek: . I triple checked the load on the headset, and everything was snug.

So, dear carbon experts, is this normal?

Yes.

there are many many many stiffnesses between different forks, carbon or steel.

just need one built for the intended application.

So chucklehead, I read Vireo's thread about the FC508, is your avatar a reference to the 'great evacuation'?

No, but good call! I hadn't even made that connection. Nope, just one of my favorite movie moments of all time:lol:

So everything sounds peachy :-) . I'm going out tomorrow to ride around, so hopefully everything goes well.

I replaced my stock fork with an all carbon fork and noticed a difference in stiffness, espeshilly with the test you mentioned. I have noticed little affect on the road, maybe a slightly more forgiving ride (AL bike)

I can however notice a difference in weight/responsiveness of the front end (400 gram weight savings makes a difference in the feel of a bike when it comes to the fork)

My steel fork did the same thing.

Is that an older model fork? My last bike had a 1996 Look carbon fork which flexed a lot. At 150 lb I was able to make the rims rub the brake pads just from sprinting. How I have a newer fork (Reynolds Ouzo Pro) which does not give me that problem at all.

Despite what many denying weight-weenies say, most full-carbon forks flex a lot, and often too much for bigger guys. Beefy forks with alu crowns and alu steerers flex much less.

Also, despite what many think, carbon steerers flex in the head-tube. It was pretty much proven in a test done by the German Tour Magazine

I've got rid of all but one of my flexy "bling" full-carbon forks for cheaper forks with alu steerers, coz I prefer the stiffness for the extra 150g or so

:thumb:

Loose headset?

I ride a Cervelo soloist team with the stock Wolf CL carbon fork... I can feel a lot of flex, especially when braking hard.

The first generation Time Equipe forks are quite flexi - despite a heavy steel steerer tube. The later models, were the opposite - very stiff. Just goes to show how much the details matter.

I had one of the Time Equipe forks on a Eddy Merckx EX Ti frame. Rode like a magic carpet but was not the stiffest bike around. Fork matched the bike nicely in my opinion. Had a Kestral fork on the bike before getting the Time fork and didn't like it - too stiff. To each their own.

That's what I thought at first! Last night I rebuilt the headset twice, just to make sure everything was seated right, and everything was fine and snug. I did 32 miles today, and everything went super. It rode great, in and out of the seat. Though I had some issues with braking, you get some flex under a heavy load.

For what it's worth, I use a Nashbar carbon fork (1" steerer), and there isn't any noticeable flex.

Maybe it's because it's an older CF fork? I heard that older CF components in general were really flexy.

Flex is built into a lot of composite components to achieve a desired feel. Look at golf club shafts, tennis racquets, skis, etc. My fork flexes front to back, but not side to side. During hard braking, I can see the legs get pushed back slightly. it seems to me that if the fork legs are flexing, then there's probably less stress on the crown, steerer, head tube and joints. Nothing to do with the era a component comes from.

Maybe I'm just a total weakling, but I am not sure I flex anything on my bike... I mean, my frame is fairly stiff, and my fork is a fork considered stiff, but I don't really budge them I don't think.