Brake can't reach the rotor mounted on front motor

On my new front 14 mm hub motor with IS disc mount fork, I can't get standard shimano brake adapters to fit. If I use 180 mm rotor and adapter the brake will only be able to touch the edge of the rotor.

The fork has "lawyers lips" and the motor axle is 14mm. I have no normal wheel to compare with (maybe my fork is odd?) but I think the problem is that the 14 mm axle makes the center of the wheel axle to be off center enough to make this problem.

Is this a common problem or have I something very strange here?

I think my solution will be to but the brake adpter (IS to Post) upside down (making it to short) and then use longer bolts and a nut or similar as distance. And maybe I can file the inside of the fork edges to make the axle go a little deeper, but that will only give a mm or so.

I would call/write to the maker of the bike you have and tell them the situation. Is is a cargo bike or some other custom bike ?

Close up pictures here to show the problem, will be much better. Take pictures with a Real Camera, set the megapixels to 2mp or less.

Perhaps use a 160 rotor and some washers under the brake caliper / between the brake caliper and mount on the fork ? but not seeing pictures that is just a far out there guess.

Yes a cargo bike, bakfiets.

Your last idea about 160 mm adapter and washers was what I was thinking of (but need like 10 mm), but I felt that 180 mm adapter upside down was closer, but did not compare that much. There is a little difference in angle of how the caliper sits then but nothing extreme.

I can fix a picture of tomorrow.

Actually almost all thick axle hub motor should cause a slight offset from original center? But maybe most often it is just a couple of mm so it is no problem.

Looking like you got a standard 203mm adapter. Buy a rotor for it, or find the proper bracket for the rotor that you have.

I have all 3 sizes of adapters and rotors and all are shimano (not the 160 mm), caliper too.

I mean, instead of setting a bracket upside down and add 10mm of washers, it should be better to use a larger rotor that will make a better fit. Washers and spacers are not bad when little correction is required, but when you put a lot the brake alignment is not as reliable and might move pretty often. Also, you would have better brake with a larger rotor atop of a stiffer mount.

Here are som pictures describing. If I use the 203 mm adapter upside down I only need a couple of mm of spacer to make it fit good. Why not?

Picture of fork with 180 mm rotor:


Picture of axle in fork. Should I file the edges of fork to get the motor further in? Or will it only make the fork weaker? Edit: yes I should, se my new post below.


Picture of 180 mm adapter that should be the one to use since the rotor is 180 mm. But the caliper is too high upp and only touches the edge.


Picture of 203 mm adapter upside down. The caliper is all the way in (too far), but with a few mm spacer it should get clearence to rotate.

That looks sketchy as hell, Jesus. The fork leg, I mean. You expect it to handle all that torque with no problem or fatigue failure? Yeah, right...

That was the plan yes. 48V and 18-20A with two torque arms.

But sure it looked tiny when the fork and thick motor axle arrived... and you think it is crazy?

Swe said:

Should I file the edges of fork to get the motor further in? Or will it only make the fork weaker?

Click to expand...

Well I can answer my own question, yes I should file it to fit all way in. See topics below:

https://endless-sphere.com/forums/viewtopic.php?f=3&t=60065
and
https://endless-sphere.com/forums/viewtopic.php?f=2&t=43786