Are there any disk brake mount adaptors for ebikes?

ClintBX

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Hi EPFMs,

I've been running my 1200 watt, 48 volt ebike with rim brakes for a while and after burning through 4 sets of rim brakes in 2-3 months during the wet season, I've decided to make an effort to upgrade to disks.

I've been wanting to do this for a while but dreading what that was going to mean.

The biggest problem is finding a mounting adaptor that matches.

The first thing I tried was a cheap and nasty $5 bracket that turned out to be for horizontal dropouts only. I was foolish enough to try to make that work anyway. The caliper seemed to line up right to start with but after one sharp brake, it started scraping the disk pretty ferociously.

Since then, I manage to find a universal mount. Its an a2z DM-UN I'll post a pic. I just received it today but it turns out this is only suitable for quick axles. The holes in it are too small.

Is there anything on the market for ebikes or am I going to have to craft my own?

Guys, what are your thoughts and experiences?


Clinton
 
Here's the pic. It has 2 holes, so maybe it's not just for quick axles. But the bigger hole is still too small. Clearly not for an e-hub axle. And it's position would offset the caliper.
 
a frame really should be designed to take disk brakes to be honest. You might be able to bodge some adaptors to mount the caliper, but the spacing between the dropouts will be too small for the disks to fit.
 
Yep. The brake caliper should be held on the frame. Frames are made for disc brakes. Welding and facing a standard brake mount is the proper way to adapt disc brakes to a frame that is not made for them.
 
anth_85 said:
a frame really should be designed to take disk brakes to be honest. You might be able to bodge some adaptors to mount the caliper, but the spacing between the dropouts will be too small for the disks to fit.


The spacing isn't an issue (though it comes close).

Upon inspection, there are 2 holes extending from the frame of my bike but they're too close together to be for a caliper mount. If I can get this piece to work, I might have saw them off. Or at least sand the inside face level with the frame so the bracket can sit flat.

Also, I might be able to use the larger hole. It turns out that the alignment with caliper (with a 20mm adptor) aligns to the edge of the disk just right. I'm just eye balling it at this stage though. That bigger hole is still too small but I might be able to maybe use a cone file (what are those really called?) To make the hole just big enough. Its like 1-2 mm too small.
 
Welded is certainly best. One of these days I will learn how to weld. Here's what I am using til then. It's a bracket for adding disks to gas powered bike conversions.

$20 Aluminum disk brake bracket from Ebay

It's a round 12mm hole, so I had to make it into a slot to fit over the motor axle. It has an extrusion that's supposed to help hold it in the dropout, and I added an extra brace.

This is on a Walmart fatbike that had awful rim brakes. In the picture, you see that the caliper mounts on the bottom, and the cable has to loop around. The brace is screwed to the torque arm mount. I think it's a rigid arrangement. In the front, I replaced the fork with one that had caliper tabs. I'm using Avid BBS7 calipers.
 

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I was hunting down an adapter for a build some years back and came across this on eBay. It transfers the braking torque to the existing brake post and looked like the best of the bunch at the time, but that build project went away and I don't have any first hand experience with the unit.
Still looks pretty good...


$(KGrHqVHJE4E+Wco-yVrBP1sGtVLeQ~~60_12.jpg
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Anyhow, it's from Chaser Tech - http://www.chasertech.com/

They responded to a question with this info back in 2012:

Chaser Tech said:
Hello!

Attachments are photos of the installation diagram and actual item mounted on frame.

Please note this item may not fit some bikes w/ rear suspension due to the rear seat stays design are not standard (round tube shape) and it may not give enough clearance for the support rod and adapter plate. Also note the adapter plate mounts outside of the dropout so you will need to use the QR skewer that included in the package (no clearance issue like other brand that mounts at inside the drop out plate).

Hardware included bolts and nuts to secure the adapter plate and support rod. This listing is for 145mm and we also have a longer rod 170mm for special or large frame. Standard frame use with 145mm rod (frame measure length straight line from center brake boss to center drop out axle mount point around 10" or 254mm) from the center pillar ball mount (center to center) then the full rod length is 180mm.The inside bolt length at each end can extend to max 215mm (for 170mm rod will add additional 25mm at max 240mm). The plate measure from center of pillar bolt to the center of axle mount is 75mm.

Note: there are other ways to go around that 3rd point drill mount such as clamp down or weld or if the drop out has circle ring above (to drill on adapter plate to fit that ring with bolt and nut) if the drop out has small surface that can't be drilled .If you have any questions please send us ebay message or email us.

Thank you

Mizuhiro
 
teklektik said:
I was hunting down an adapter for a build some years back and came across this on eBay. It transfers the braking torque to the existing brake post and looked like the best of the bunch at the time, but that build project went away and I don't have any first hand experience with the unit.
Still looks pretty good...


View attachment 2
View attachment 1


Anyhow, it's from Chaser Tech - http://www.chasertech.com/

They responded to a question with this info back in 2012:

Chaser Tech said:
Hello!

Attachments are photos of the installation diagram and actual item mounted on frame.

Please note this item may not fit some bikes w/ rear suspension due to the rear seat stays design are not standard (round tube shape) and it may not give enough clearance for the support rod and adapter plate. Also note the adapter plate mounts outside of the dropout so you will need to use the QR skewer that included in the package (no clearance issue like other brand that mounts at inside the drop out plate).

Hardware included bolts and nuts to secure the adapter plate and support rod. This listing is for 145mm and we also have a longer rod 170mm for special or large frame. Standard frame use with 145mm rod (frame measure length straight line from center brake boss to center drop out axle mount point around 10" or 254mm) from the center pillar ball mount (center to center) then the full rod length is 180mm.The inside bolt length at each end can extend to max 215mm (for 170mm rod will add additional 25mm at max 240mm). The plate measure from center of pillar bolt to the center of axle mount is 75mm.

Note: there are other ways to go around that 3rd point drill mount such as clamp down or weld or if the drop out has circle ring above (to drill on adapter plate to fit that ring with bolt and nut) if the drop out has small surface that can't be drilled .If you have any questions please send us ebay message or email us.

Thank you

Mizuhiro

I like this one. With that long arm to slot right onto the old v-brake mount, this doubles as a very good torque arm.

But my frame is a dual suspension. Although, I don't see how having a rear suspension interferes. I have a spring coil mid frame on mine. I know that there are other frame with a sus cylinder somewhere below the seat post. Maybe that's the type of frame its not suited for.

I'd be interested to know if it fit w well on the hub axle or if you have to enlarge it to fit?
 
quick update. Agree enlarging the hole soit would fit over the axle, turns out that this bracket isnt going to work for my frame gor different reasons than I had expected. The tubing shape of my rear dropout makes it imposible. I thought I was going to just dremel off those rear rack mount holes.

The search continues.
 
Buy a big brake for the front, you can live with what you have on the rear already. You could add regen eventually. The rear brake is not that important. Or else, best is to do the real job. Find a pro welder to fit a standard brake mount to your swing arm.
 
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