Moving the brake caliper inwards

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Dumsterdave   100 W

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Moving the brake caliper inwards

Post by Dumsterdave » Dec 23 2019 8:40am

I just put a rear hub onto a fat bike, but I have a problem... The existing caliper needs to move inwards (closer to the hub) by about 2 centimeters. Is there an adapter that will allow for this?

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Skorohod   100 W

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Re: Moving the brake caliper inwards

Post by Skorohod » Dec 24 2019 6:22am

Dumsterdave wrote:
Dec 23 2019 8:40am
Is there an adapter that will allow for this?
I've been in similar situation (not a fat bike and not a two centimeters, though). I've decided not to search for adapter but use a right amount of washers instead:
washers2.jpg
washers2.jpg (153.38 KiB) Viewed 1125 times
washers1.jpg
washers1.jpg (156.72 KiB) Viewed 1125 times
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goatman   100 kW

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Re: Moving the brake caliper inwards

Post by goatman » Dec 24 2019 1:11pm

you can use a chunk of 3/4x3/4 aluminum bar or square tube, cut to length and drill 2 holes. you can machine aluminum with a skill saw and carbide blade. so if you have a chunk of aluminum, a drill and a skill saw and a belt sander, you can machine, plane, sand any shape you want

Voltron   10 MW

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Re: Moving the brake caliper inwards

Post by Voltron » Dec 24 2019 1:37pm

Sometimes it's better to move the rotor out with a spacer, but you may need slightly longer bolts too. Don't use a plastic spacer that comes with some motors.. That's just to keep the bolts from going in too far to the motor case while no rotor is mounted... It's too mushy for actual spacer-ing.
s-l300.jpg
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Edit...I just reread 2cm... Maybe some of both... Spacer the caliper in and the rotor out?

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amberwolf   100 GW

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Re: Moving the brake caliper inwards

Post by amberwolf » Dec 25 2019 2:16am

Moving the caliper away from the frame with washers means repeated shear loading on the bolts. Depending on the bolts, etc., the repeated bending back and forth has the potential to break them and leave you unable to brake (or to have the caliper get tangled up in the rotor and lockup the wheel).


Spacing the rotor away from the motor, with the right kind of spacer and sufficient bolt pressure, has a different kind of loading on that extension, which is unlikely to fail in the same way. Spacers for this purpose specifically are commonly available, as are longer bolts.


So if I were doing it, I'd put the spacers on the rotor, not the caliper, though 2cm is quite a distance.

Punx0r   100 GW

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Re: Moving the brake caliper inwards

Post by Punx0r » Dec 25 2019 9:21am

In my experince 1cm spacing on both rotor and caliper works fine on a back disc brake.

Dumsterdave   100 W

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Re: Moving the brake caliper inwards

Post by Dumsterdave » Dec 26 2019 4:42pm

Voltron wrote:
Dec 24 2019 1:37pm
Sometimes it's better to move the rotor out with a spacer, but you may need slightly longer bolts too. Don't use a plastic spacer that comes with some motors.. That's just to keep the bolts from going in too far to the motor case while no rotor is mounted... It's too mushy for actual spacer-ing.s-l300.jpg

Edit...I just reread 2cm... Maybe some of both... Spacer the caliper in and the rotor out?
Where can I find that 7mm spacer

Voltron   10 MW

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Re: Moving the brake caliper inwards

Post by Voltron » Dec 26 2019 5:42pm

That was some random Google image... I've never needed to order one that big.

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Re: Moving the brake caliper inwards

Post by billvon » Dec 26 2019 6:43pm

Dumsterdave wrote:
Dec 26 2019 4:42pm
Where can I find that 7mm spacer
I would note that some rotors (when adequately cut down) make excellent spacers.
--bill von

Punx0r   100 GW

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Re: Moving the brake caliper inwards

Post by Punx0r » Dec 27 2019 4:54am

Fiddly, but stacks of washers (preferably taped together) will work. I'd rather use a spacer of some kind though.

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Re: Moving the brake caliper inwards

Post by aroundqube » Dec 28 2019 5:40pm

Dumsterdave wrote:
Dec 26 2019 4:42pm
Voltron wrote:
Dec 24 2019 1:37pm
Sometimes it's better to move the rotor out with a spacer, but you may need slightly longer bolts too. Don't use a plastic spacer that comes with some motors.. That's just to keep the bolts from going in too far to the motor case while no rotor is mounted... It's too mushy for actual spacer-ing.s-l300.jpg

Edit...I just reread 2cm... Maybe some of both... Spacer the caliper in and the rotor out?
Where can I find that 7mm spacer
Disc rotor spacers here : https://mbrebel.com/bike-parts/

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