20/32mm Adjustable MTB Bike Disc Brake Bracket Converter Frame Adapter Mounting Holder (31.8mm)

First of all for a little over $5 what did I expect? It's basically a shape cut out to go over the axle of the front wheel to accommodate a disc brake caliper set. First thing I had to modify is that I have an electric bike front wheel which has a larger diameter axle. This bracket would not go over the larger axle so I had to file the bracket slot about an eighth of an inch to accommodate a larger axle on an e-bike. Once the bracket is on you'll notice it doesn't go in line with the slot in the forks so you have to take the bracket off every time you take the wheel off to change your tire. This is going to be a real pain in the butt. The retaining clamp that goes around the fork is a thin piece of nothing. The fasteners that hold it to the main bracket are cheap screws that are tapped through into the clamp. Also the bracket was way too large for even my 30 mm forks. After some fooling around I managed to get the brake caliper to sit on properly. After using it I noticed that the breaking action would misalign the bracket assembly. I was continuously having to adjust the disc brake calipers to not scrape the disc. I wound up having to put quite a bit of clearance on the disc pads to the disc so that it wouldn't rub. I only use this brake and bracket when I'm not moving to keep the bike steady if I'm stopped. Otherwise my main coaster break in the back is what has to stop me.

I've given it 3 stars because it probably does what it is supposed to do, I just couldn't get it to work with the geometry of my specific frame.I read the reviews about the limitations of the design, so I knew what I was getting into. I have a Trek Y50, which has a very unusual frame. The rear frame elements leading to the dropouts have rectangular cross sections (no joke), but I was hopeful that the metal of this adapter would be just pliable enough to fit around them.The metal "loops" are a bit pliable, but the problem turned out to be just the location of the dropouts. As you can see from the photos, the rear triangle has a much larger weldsite than most "normal" bicycles, so the adapter couldn't reach from the attachment point to the axle. It was closer if I installed in on the lower frame element, but not close enough.It can be done, as shown in the final photo, by only using one of the two screws. I added the green electrical tape just to protect the aluminum frame while I tightened it on. That's obviously suboptimal. Another option would be to cut the closer loop, so that it sits closer to the axle. I'm taking a look at other possible solutions first, since one bolt and one loop strikes me as unlikely to be very sturdy (and also likely to damage the frame).For $9, it was worth a try. As many other reviewers note-- be prepared for some mechanical work, and the possibility that it just won't fit.

Speaking for myself of course, this adapter worked fine the first couple trips, but it was not easy to keep it aligned straight with the disc, maybe mainly because I had front fender stays & the left one crossed right over the caliper to get to its mounting screw hole location. The last trip ended in catastrophe, refer to my pic of the mangled adapter, & the bent disc. It's quite a sturdy steel disc, & astoundingly left the spokes, & the front wheel, unscathed. SO, I reinstalled an mtb fork, with a welded caliper mount 😀.

It's all in the name MTB. 31.8 mm is likely a common tube diameter for mountain bikes, front ant back. At that, keep in mind if you have fenders/racks something will have to be removed to switch to disk brakes. Also, when the brake is applied the caliper unit will be pushed into the mount tube. For the front this will be the fork tube. Any flex in the adaptor under braking may cause a twisting action on the disk. Not my idea of a good design. Some time back Phil Wood made a disk brake that fit the front or back without any adaptor needed. Wish Phil would update their design as it was much easier to deal with than any of todays disk brakes.

Works on my 24” Diamondback motorbikes before I was using caliper brakes

In the process of converting an ancient Trek mountain bike to E-pedal assist, needed bracket to mount a new front disk brake to replace the v-brake I had been using. Ordered this adapter and found that the angle of the dropout slot did not match my front fork, the metal band was not sized to match the front fork tube and the anchor slot that was supposed to be secured between the inside of the front fork and the axle boss would not work unless I changed the axle from quick release to bolt secured. So, I used this bracket as a template to fabricate a usable part from flat steel stock that would work on my bike. I used it to position the disk brake mounting holes and the holes for the metal band and built a bracket that would mount outside the fork axle dropout that I could actually secure with a bolt, and I fabricated a new mounting band as well. Bottom line, it is likely that you will have to do some modification to either the bracket or your bike for it to work.

I'm not sure if it was just the shape of my dropouts or what but the placement of the angle in relation to the cutout for the axle wouldn't allow for me to attach to the axle and still make it around the frame.I had another hole in the dropout that was in a good enough position to bolt through though. i just needed to find the right bushing. all said and done it worked great and for the price i don't think you can really expect a perfect universal fit out of the box.

Didn’t end up using it for its I tended purpose, I cut the lower half off to make a fender bracket adaptor for my springer forks to be able to use the stock nel lusso fender. Which it was great for. As a brake caliper bracket it’s ok but I wouldn’t use it where it was a primary brake as one bent on me and caused my caliper to fall into the disc and severely warp the disc rendering it useless.