VeloBuild major issue

[electrolux]

Hi all,

I recently started building my Velobuild GF-002 frame and have ran into a major issue with the rear brake mount. The top faces of these appear to be unmachined and are not level.

This means my 140mm rotor rubs directly on the caliper housing and the rear wheel is seized. No amount of 'hold the brake while torqueing the bolts' prevents this.

I have measured the angle the best I can and it seems to be around 3 degrees off.

To verify I added some shims (knife blades) which allowed the caliper to remain level when torqued down. This solved the rubbing and the wheel spins freely.

Am I correct in my diagnosis? Any suggestions?

Grateful for any help.

[jefflinde]

I have had this on frames a few times.  You can manually file them flat or take it to bike shop and they can face the mounting holes.  Usually $20-$40.  Then just use some m4 or m5 washers between the caliper and the frame to build up the distance to clear the rotor.  The facing can also be done by hand if you want.  Pretty easy fix either way. 

[jonathanf2]

GRX hydro calipers already have very little leeway when it comes to alignment. You can try shims on the disc rotors or possibly use thin washers on the brake caliper mount. A somewhat ghetto solution is not to fully tighten one of the screws on your brake calipers. This will give it a bit of leeway and once the pads start to wear in, you can tighten later on.

[coffeebreak]

GRX hydro calipers already have very little leeway when it comes to alignment.

GRX 400 series calipers are the worst in this regard.

[mattgolt]

You are most likely correct in your findings. Many of us had this problem, me included (on a vb-218). However, 3° is very very excessive.

I had approximately 1.5° misalignment on the rear brake
My solution was: I got post-mount brake calipers and aluminium adapters. I then machined down the adapters to compensate for the misalignment. But you need a mill for that.. 

Next cheap Chinese frame I buy will have rim brakes. Or I buy that hilariously expensive facing tool from parktool and rent it to people with the same problem
 

[Serge_K]

I recently built 2 of these frames and didn't have the problem, but disc rub is super annoying. For reasons i dont understand, sometimes i would remove the wheel, put it back, before no rub, after, rub. Without changing anything, just removing the wheel and putting it back on, front or rear. The clearance between no rub and rub is a fraction of a millimeter, it is so irritating!
These are the 1st bikes i build / use with discs, so idk if that's because of the frame, the brakes (mechanincal), the wheels, and how much of it is my own incompetence (probably a good amount, to be fair).
I found that using a business card on the side that tends to rub can help. There seems to be micro adjustment when you tighten the thru axle, and there's ofc a lot of play when you tighten the caliper. I've also been cute and sometimes tried to limit the default pad spacing to have the levers brake sooner, but that's so likely to rub that you have to be a ninja for that to work (i'm not a ninja).

[electrolux]

Thank you everyone for the replies. More helpful than Velobuild who haven't replied!

I will take it to a local bike shop and have them face the mount.

I did try some cup and cone washers, they allowed clearance but the caliper sits quite high which reduces contact with the pads.

[Liter]

Thank you everyone for the replies. More helpful than Velobuild who haven't replied!

I will take it to a local bike shop and have them face the mount.

I did try some cup and cone washers, they allowed clearance but the caliper sits quite high which reduces contact with the pads.

had this on one of their forks, they actually shipped a second fork and had the same issue, mechanic had to make new holes use helicoil

[hazzer19]

Thank you everyone for the replies. More helpful than Velobuild who haven't replied!

I will take it to a local bike shop and have them face the mount.

I did try some cup and cone washers, they allowed clearance but the caliper sits quite high which reduces contact with the pads.

Try them on social for help. They often provide an answer quickly, unless it's a more complex query.