Break calipers too wide for hub motor

#1
Hey guys!

Just converted my first bike to an e-bike, everything went great except when trying to fit the hydraulic break caliper to the hub motor. The spacing between the hub and the brakes is way to small to fit my current calipers, and i've been searching the web to try and find something which will fit.

i found this on e-bike kit
https://www.ebikekit.com/products/narrow-disc-brake-calipers-f160-r140

but it's only mechanical, and when i try searching the web for hydraulic options im not finding what im looking for. Anyone know where i can find this or have experience with this ? If i bought the caliper from ebikekit, could i use this with my existing cables or how would i do this? The bike is great but i can't say i feel too safe driving only with front brakes
 

indianajo

Well-Known Member
#2
Try a bigger rotor & move your caliper mount up the strut. You may have to build a bracket out of a U of sheet metal with some holes drilled in it. Use safety glassses using a drill motor. I use 10-32 screws and elastic stop nuts, but you could alternately use 4 mm hardware. Clearance drill for 10-32 is #11. One long screw (1-1/2") tightens the U around the strut. The shorter screws mount the caliper to the bracket. I get such hardware from mcmaster.com but I make the brackets out of sheet metal from dead appliances - floor box fans for example. Use a file to blunt the edges after cutting a strip out with a weiss shear.
 
#3
Thank you for your quick reply, but unfortunatly i dont think i could pull that off! Im Looking for an easy option, prefferably something i can buy and just mount on the bike as im not that thecnichal And dont realt have any tools or experience with this
 

J.R.

Well-Known Member
#4
You might be able to convert to a larger rotor, 180mm or 203mm, using an adapter like this:

SHIMANO R203P/S Disc Brake Adaptor https://www.amazon.com/dp/B002F91TT0/ref=cm_sw_r_cp_apa_i_zKb8CbZM97XG7

You'd need frame clearance. I don't know if you have 160mm or 180mm now, or if your frame will accommodate a larger rotor? And will a larger rotor clear the hub? You should post the bike you have, brake system you're running and some detailed pics for precise recommendations.
 

Ebiker01

Active Member
#5
Hey guys!

Just converted my first bike to an e-bike, everything went great except when trying to fit the hydraulic break caliper to the hub motor. The spacing between the hub and the brakes is way to small to fit my current calipers, and i've been searching the web to try and find something which will fit.

i found this on e-bike kit
https://www.ebikekit.com/products/narrow-disc-brake-calipers-f160-r140

but it's only mechanical, and when i try searching the web for hydraulic options im not finding what im looking for. Anyone know where i can find this or have experience with this ? If i bought the caliper from ebikekit, could i use this with my existing cables or how would i do this? The bike is great but i can't say i feel too safe driving only with front brakes
It spells BRAKE not break, breaik or other forms...
 
#6
It spells BRAKE not break, breaik or other forms...
Thank you for your reply, although it was really unnecessary. English is not my First language but i try my best to make myself understood, but i guess you cant escape the grammar police.

If you have any other contribution to this thread which can help me with my bike i’ll gladly take it though, posting pictures inn a few hours when i Get off work
 

Ebiker01

Active Member
#7
Thank you for your reply, although it was really unnecessary. English is not my First language but i try my best to make myself understood, but i guess you cant escape the grammar police.

If you have any other contribution to this thread which can help me with my bike i’ll gladly take it though, posting pictures inn a few hours when i Get off work
Good logical thinking starts with good grammar and also front brakes supply 70% of total brake force. Most people they overbrake or brake at the wrong times in the wrong places.
I would put a bigger rotor for the front brake and that is enough unless you do downhill rides or your ebike is capable of 35mph+ speeds.
 
#8
Good logical thinking starts with good grammar and also front brakes supply 70% of total brake force. Most people they overbrake or brake at the wrong times in the wrong places.
I would put a bigger rotor for the front brake and that is enough unless you do downhill rides or your ebike is capable of 35mph+ speeds.
Very informative, Thank you!

My bike is 1500w 48 Ah, i installled it with two torque arms, but have read that only one is necessary, do you have any experience with this?
 

Ebiker01

Active Member
#9
Very informative, Thank you!

My bike is 1500w 48 Ah, i installled it with two torque arms, but have read that only one is necessary, do you have any experience with this?
.

SInce is a lot of power (1500watts) , that is the reason for the 2 Torque arms. So, leave that alone , it is needed as extra security...
And with this much power, try to get a big front rotor(200mm) , this way you have a powerfull front brake. And down the road , hopefully you can add a rear brake as well.
I’m not sure about the following idea, but you can also have 2 front brAkes(1 disc , 1rim brake). And the install would be on the right handlebar for one of them.
Just an idea...a bit crazy.
 

JohnT

Active Member
#10
The spacing between the hub and the brakes is way to small to fit my current calipers,
By this, do you mean that the brake rotor is too close to the hub motor for the caliper to fit between them? I hear this is a common problem. There are spacers available that fit under the rotor to make more room. You might need longer bolts. Sorry, I haven’t done this so I don’t have a part source to recommend.
 

JRA

Well-Known Member
#11
The problem is that, especially the “1000w” kit motors, diameter encroaches on the space that the brake caliper resides in and isn’t affected when used with a smaller hub motor or a conventional sized hub.

I have run into this on both my hub builds and ended up having luck with the TRP cable activated hydraulic calipers which fit with my need for cable type due to use with the existing drop bar type brifters.
 
#12
I have encountered this issue when building fatbike wheels on 110mm hubs. The solution has always been to move to a larger rotor size plus, on occasion, I filed away some of the brake caliper material. That said, brake calipers are all different — a Shimano XT caliper is much more narrow than, say, Magura MT5.