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Discussion Starter · #1 ·
I'm not entirely sure which section to put this in because I'm not sure what I'm doing wrong, so please forgive my ignorance.

Some basic info, I'm not sure what all is relevant...

I've got a new wheelset for my fatbike. 135 QR hub. Avid BB7 brakes.

When I'm installing the front wheel it goes in the dropouts fine with a small gap on the brake caliper side of the wheel, when I tighten the QR it pulls the wheel to that side to the point the rotor is pushing up against the caliper. Even with the pads adjusted all the way out it's to the point where it is slightly bending the rotor from being too far over.

Obviously I'm doing something wrong, but I've not run into this before. Any thoughts?


Attaching a picture of the gap before tightening the wheel.
 

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remove caliper from bike

remount wheel make sure it is mounted correctly, centered, any spacers it needs are there (or not).

now back pads (widen the spacing) off the caliper with the red dials
install caliper hand-snug on the bolts...it's still a little loose...
and center it over the rotor, tighten up the pads on both sides with the adjusters to fix the caliper to the rotor with the pads too tight, now tighten the caliper bolts with a wrench, dial back the pads with the red dials, should be fine now

if that doesn't fix it, [cannot really tell from the pics]
but maybe the caliper mount on the fort is bent a bit ?
 

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Discussion Starter · #3 ·
Thanks, I will give that a shot.

Are spacers "normal" for wheels? I've got a handful of bikes and never noticed any when swapping tires or fixing flats. The stock wheels on the bike didn't use any, so I didn't think this would need any.
 

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spacers now are found in a lot of bikes since there are so many new hub standards and wheel or hub conversion. I don't know your specific setup so just said get brake out of the way so you can verify wheel in dropouts properly ....once that is confirmed then deal with brake alignment
 

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Discussion Starter · #5 ·
I had (wrongly) assumed that the brake calipers would be static in that there is only one spot to bolt them on, so there wouldn't be much in the way of adjustment there.

Like you said eliminating one variable at a time makes the most sense.
 

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I had (wrongly) assumed that the brake calipers would be static in that there is only one spot to bolt them on, so there wouldn't be much in the way of adjustment there.

Like you said eliminating one variable at a time makes the most sense.
There's a slot that allows in/out mounting location. Those special washers also allow slight adjustment as well so take care to mount it centered.
 

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Discussion Starter · #7 ·
Well I removed the caliper from the fork and the wheel drops in no problem. Used a square to make sure everything was even and it looked perfect.

Went to put the caliper back on and it's a no go, if the rotor fits into the slot the caliper itself is several mm off from being able to mount to the fork. Showed a photo to a couple bike mechanics and neither had any ideas, my have to bring it to the LBS in person because I'm stumped.
 

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Discussion Starter · #8 ·
Update, I believe the mystery is solved.

Turns out older fatbike forks are designed around rear hub disc spacing, which is about 5mm different from front spacing which is what current hubs are designed around after fatbikes had their 15 minutes of fame.

I don't have a solution yet, but at least I know what the problem is.
 
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