I first read about this on Sheldon Brown's website, but he doesn't show how to build them. This instructable fills that gap.
Please note - If you build them and your brakes fail, don't come after me. Your bike was built to use a certain size wheel with a certain size brake. Change these things at your own risk.
A note about wheel sizes: I am using a set of 26" mountain bike wheels on a frame designed for 27" road wheels. The long-reach brakes shown here will reach a set of 700c wheels from the stock mounting location, but I didn't have another "spare" set of 700c wheels lying around. I did, however, have a set of mountain bike wheels. This bike is primarily used for a trainer so I don't have to mess with taking my favorite road bike off the trainer every time I want to go for a ride in the real world. The smaller wheels drop the bottom bracket and increase the risk of striking a pedal on the ground during a turn. If you mount a set of smaller wheels, always be aware of this when making turns.
Step 1: Tools You Will Need
- Aluminum bar stock - I bought mine at the local hardware store for about $7. Don't go too narrow or too thin. It has to handle the force of stopping you!
- Bolts and lock nuts - be sure to measure the size of the bolt on your brakes and get the same size from the store.
- Aluminum tubing (not shown). It should be big enough to slide one of your bolts through and thick enough to handle the clamping force of the brake.
- A hacksaw (for cutting the bar stock)
- A drill and the right size drill bits (match it to the size of your bolts).
- A wrench or two.
- Some sandpaper or a file (not shown).
Step 2: How low should it go?
Step 3: Time to cut and drill
Once you know exactly where you want the first hole, use a punch to create a starting point and then mount the stock back into the vice. The punch isn't necessary, but it helps to keep the drill bit from wandering when starting the hole.
Double-check the second hole location before drilling it. Once two holes are drilled, triple check the hole locations by mounting the drop bolt on the bike and sliding the brake into place. The brake pads should align with the rim. If the holes are spaced incorrectly, there will not be enough pad adjustment on the brakes to make them align with the rim. If that happens, start over.
Step 4: Cut and drill the second drop plate
When you are finished, you should have two matching plates. These will have rough edges which need to be either filed or sanded down.
Step 5: Time to bolt it all together.
The next piece(s) to slide on are the spacer(s). It is probably best to cut a piece of aluminum tubing to the correct length, but a stack of washers or nuts will do. The only tubing I had on hand was too short, so I added a couple of nuts to fill in the gap. The idea is to make the stack long enough so the drop plates fit snugly against the fork.
After the spacers, slide on the second drop plate and the final anti-rotation washer with the grooves pointed toward the final nut. Place the final lock-nut and tighten, making sure everything is aligned.
Finally, slide the brake into position so the holes in the drop plates align with the brake mounting hole in the fork. Slide a bolt through and tighten with a lock nut.
Make sure the pads will reach the rim and align properly. Now install the brake cable and it is ready to go!