Raudonas21

Hello, I have a problem with Focus Mares CX carbon fork drop outs. If I install the wheel with medium quick release tension the wheel shifts violently when braking. I found out that the wheel lies down nicely into into the dropout grooves and the distances between the tyre and the fork are equal on both sides. But when I tighten the wheel with the quick release nut, it shifts and the distances become unequal. I suspect that this is due to the incorrect installation of the wheel by the previous owner. The flat where the quick release nut rests has a groove pressed into it, therefore when the nut is tightened the axle jumps into that groove shifting the wheel out of alignment. I have not done such repairs previously and the fork is made out of carbon, what can I do to fix this?

freeranger

An indentation in carbon does not sound good. Have a shop with a good, experienced mechanic take a look at it to see if it may be repaired to where it is safe to ride. Do you know if the dropout itself is carbon or carbon over metal-either way, have someone familiar with carbon take a look.

Dave Mayer

This text concerns me. When you mean: "tighten the wheel", I assume you mean tighten the nut on the quick release skewer? Regardless, you do not tighten the quick release skewer with the nut - you tighten it by flipping the QR lever. Simply rotating the nut will not allow you exert enough force to properly tighten the skewer - not even close.

I volunteer at a high-volume bike co-op. A large percentage of the folks we work with have never properly learned how to use a QR. On newer bikes with 'lawyer lips', this is a minor inconvenience, as their wheels rock back and forth in the frame dropouts during the stresses of riding. On those older bikes without the lawyer taps, not knowing how to properly use a QR on the fork is truly life-threatening.

So if you had a frame with carbon dropouts, and the wheels were rocking back and forth due to inadequate QR clamping force, I could see how this could erode the dropouts and possibly destroy them.

Raudonas21

Thank you for the reply, I will try to find a good mechanic then. I am very sure the drop out is carbon, because it is black ( in the worn out spot), does not give the cool "metallic" sensation when touched and it is thicker than regular metal drop out.

Raudonas21

Oh yes, sorry about my hastily typed text. I do use the quick-release lever to tighten the nut completely by flipping it. My suspicion is that the previous owner used to rotate the lever and never flip it, as you described, that's why the dropout could be worn out. I want to emphasize that the bike is used, it was freshly bought by my friend and I only took it for a test ride. From my experience, the wear out of the dropouts can also occur if the wheel was sometimes not properly seated (if the axle does not rest at the bottom of the dropout), this causes the skewer nut to slide upwards on bumps and it violently digs into the dropout material.

The top of the wheel, as I was braking with the front brake, shifted to the left (and the bottom to the right, sort of a counter clockwise motion along the axis of travelling) with great force, although I took extra care in seating the wheel properly in the fork and tightening it with the QR lever. So the skewer had to move along the lenghth of the dropout. This lead me to believe that the seating flats have grooves or are worn at an angle.

I would be tempted to try and fix the drop out with a dremel and some sharp tools, but as it is not my bike, I do not want to ruin it. I figured that there could be a procedure of fixing the problem that I am not aware of, therefore I am consulting the forum.

Homebrew01

I'd be concerned that one of the fork tips is loose.
Also, check that they are parallel to each other.

Andrew R Stewart 

Soft drop out materials are known for developing indentations from the QR end caps and thus the wheel will tend to settle into these "points of lowest energy". Have you tried a different QR skewer or a different wheel yet? Also the QRs with the fashionable exposed plastic bearing cams are notorious for their less clamping force compared to Enclosed metal on metal cams.

A loose drop out should be fairly easy to check for, not a bad thing to check but pretty uncommon, thankfully for the millions that ride bonded frames/forks. Andy

tFUnK

I've used JB weld to add some material back into a dropout to fix a similar problem.

Raudonas21

Yes, the exact thing has happened here, lowest energy point is a good way to put it. I guess you should take extra, extra care in seating the wheel all the way in when the bike is new, otherwise you will have the same problem. Yep, these ones have the plastic bearing on them and I have not tried any new ones, will look for them.

Well I tighten the quick release as much as I can without pulling out the thread or snapping it in half, seems to fix the problem. However, it would be nice to fix it and use force that is nt on the edge of destruction.

Raudonas21

That actually might work, great idea!

Duo

Does JB stick to carbon good? How about aluminum and steel? thanks