Carbon fork stiffness

[saab2000]

Alrighty then Kids. So Yesterday I am riding my Merckx Majestic Ti for the 5th time. This is my first ever non-steel bike. Still trying to decide if I need a 14 cm stem or if the 13 is going to be alright, but that's a whole 'nuther story.

I have a Ritchey WCS stem in place, with no spacers. The stem is clamping down on an ITM bar with a 26.0 clamp.

It feels flexible in a way my steel fork bikes don't. If I grab the bars while standing over the bike there seems to be a lot of flex back and forth. When I climb out of the saddle there seems to be less rigidity than with my steel fork bikes.

Is this normal? If it is, why are carbon forks thought of as so great?

The fork is a new Look HSC 3 fork. It is 1 1/8 inch and I have a King HS with no play installed.

I am not trying to start flaming here. This is my first experience with carbon forks (incredibly) as I have always been a bit wary and have had steel forks built for my Anvil and for my Strong. I have not regretted those decisions for a second.

But I thought with the Ti bike it would look odd to have a non-carbon fork. After all, the whole cycling world uses carbon forks with great satisfaction.

I know that the bars are not the stiffest things out there, but they are the same bars which were installed with a nearly identical stem on my Anvil and they felt stiffer in that application.

What gives? Are carbon forks just less rigid?

[bulliedawg]

I went from a C-II with a steel fork with a CSi with an F-1, and I think the F-1 in at least as stiff as the steel fork. I have heard other people say that the F-1 is a tank of a fork. I don't know about other carbon forks.

That's my only experience comparing the two.

[cs124]

What exactly is the flex like? Is the front wheel moving fore-aft or yawing side-to-side? Is it that the bars seem to roll (with the stem as the roll axis) when you pull on them? Could it be torsional flex in the front triangle of the frame?

Ride, test, observe. You'll probably find the answer before this thread dies out.

BTW, I once rode a bike with a Kinesis carbon fork with Al crown and steerer. Man, the front wheel wandered all over the place like an excited puppy on a long leash.

[saab2000]

The front wheel seems to move a bit side to side. Also, the bars will move a lot side to side when straddling the bike and torquing them side to side. I know that this is not really valid, but my steel fork bikes don't do this.

Today I am in Minneapolis and the weather probably won't cooperate for a ride, so I cannot really do any testing today.

I like the bike. That is not the issue. I just wonder if what some people here have said is true: that most ti bikes are not really stiff enough to be racing bikes. I may also be feeling flex in the front triangle of the bike.

I do think that stiffer bars would help. These ITMs are not their top model. I really should get some Deda deep drop round bars.

[ergott]

What wheel are you using? You can rule out wheel movement by bringing the brakes real close and see it the wheel rubs the brakes. You can't rely on sight because too many things are happening. Then you can try a different wheel and compare. Also try a good solid quick release with a steel axle for better results.

Keep us updated,

Eric

[Too Tall]

It's not the fork. Your intuition is correct, get better bars. Yank on some other folks setups and get an idea first. Setups I *thought* would be good for me were not and ones I never suspected to be as good as they are suprised me. For instance I used a salsa stem with ITM Milleniums and it was a rubber band. On the other hand Stella Azzura Mag. 14 with Salsa Pro bar is rock solid. High fiber diet??? My Zipp B2s with Ritchey WCS 13 also are rock solid.

[saab2000]

The wheels are fine. I have a Mavic steel QR in there. They are not Ksyriums, but are pretty good solid wheels. They felt stiffer in the other steel bike.

I will probably get new bars, but that will have to wait.

[hypnospin]

some bars are alarmingly flexy. the itm pro 260's i had would move around so much they would steer the bike for you.
i have a manual flex test i do to compare bars.
if bars are mounted on the bike, just grab and flex in all axis, including from the hoods.
if off the bike,
1. grab the flats of the drops and try to push together and pull apart
2. grab the flats and apply torque to see how much they twist

then trick to doing this in a shop is to not make eye contact, go about your mission quickly and with extreme predjudice.
lest you may get the dreaded "can i help you"

the stiffest bars i have found in side to side comparison like this were deda spectrum carbon and ritchey pro. the ritchey comp is stiff as well.
i have gone with the ritchey pro on three bikes now, i choose them over the wcs as they are -way- stiffer, might have to do with thicker walled tubing throughout,
as for the deda spectrums, i like the stiffness but am leary of their 10 piece bonded construction. also limited area on tops.

as for stems...
when spectrums paired with the deda magic OS stem this is the stiffest my grab test comparisons have encountered. but the magic stem faceplate is held on by three 4m bolts,
ritchey stems do use 4 bolts.
the stiffest stem i have used is an itm big one that does not use an open face clamp. there is a reason you will not find open face clamps as a popular choice on track bikes...


It's not the fork. Your intuition is correct, get better bars. Yank on some other folks setups and get an idea first. th Salsa Pro bar is rock solid. High fiber diet??? My Zipp B2s with Ritchey WCS 13 also are rock solid.