We have a Co-Mo Carrera with TRP Spyres and a Primera co-pilot with BB7. We too found braking not to our desired level of effectiveness - we’re a 400 lb team and ride very hilly terrain.

i am not sure exactly what your issue is, but take a look at this thread https://www.bikeforums.net/tandem-cy...rformance.html I found that the return spring of both the spyres and bb7s was not strong enough to overcome the slack in the Long cable run to the rear so I had to keep the pads opened up far enough to keep the pads from rubbing resulting in not enough pull range to apply strong braking. On a fellow forum members suggestion I added a secondary return spring to the TRPs which allowed me to set the pads closer and the braking performance is now fantastic. We obtained the primera later, experienced same, added the springs and all is good now.

I did read that thread. We initially had the same problem described by the OP in that thread--mushy brake lever, with pads adjusted just shy of the disk the lever would pull all the way to the bars. At that point, adding a spring probably would have helped. But I found the brake cables were kinked in several places. I put new cables in-- and totally got rid of the mush. Very crisp action at the lever. Now there's zero drag of the brake pads with lever released, and the brakes are fully engaged with about 3/4-inch pull of the lever (measured at the bottom tip of the lever), with plenty of room left before the lever would hit the bars if it could. But with the lever pulled as hard as it will go, the stopping power isn't any better than v-brakes. I certainly can't skid the back tire. Maybe I'm expecting too much of the disc brakes? (never had a bike with them before)

Our Carrera was our first bike with discs as well and I didn’t feel confident in them coming from an old Santana with canti’s and a drum brake.

i don’t believe you should have to be able to skid the rear wheel as the bike won’t lean forward as a half bike will. Others better schooled on the nuances of braking performance can comment.

after installing the spring I gained some confidence and now I am a true convert to disc brakes and feel more secure than I ever did with the old set up. I would suggest you give it some time. Try some aggressive braking tests with your stoker in safe situations to speed the development of the “feel” your bike will have.

Fully understand hydraulics and the ability of hydraulics to multiply force.

The downside to multiply hydraulic force is the requirement of piston A vs Piston B linear travel. Multiplied you no longer have short stroke, but longer stroke.

Avid BB7 brakes can work very well. Recently I just purchased a used single bike with them. The previous owner had done a poor and incorrect installation in regards to mounting the caliper brackets and the calipers to the frame / fork.

I assume the caliper brackets are installed correctly, are the correct size relative to the disc and are for the correct location.

Often, when installing the calipers themselves, the caliper is positioned too far outboard. Possible reasons are the frame or fork tab placement / location mandates a couple of shims to reposition the caliper bracket inboard more, or simply time was not taken in regards to endure the calipers inboard edge is not acting as the braking friction surface. In short, when the brake is applied, the disc could be rubbing the caliper and not truly contacting the brake pad itself.

As routine maintenance, regardless of hydraulic or mechanical brakes, it is advisable to clean the friction surfaces. I know that alcohol is often the recommended cleaner of choice, but honestly it is inferior to proper brake products such as Brake Cleaner from the auto parts store.

Use safety protection as needed.

Being lazy, you might try a clean cloth, dampened in brake cleaner, then wip the disc surface while rotating the the disc.

I may do the disc wipe at an event or as needed.

Ideally, and this is not difficult, learn to remove the brake pads, and without changing their locations, use the brake cleaner to wash the brake pads.

The best stopping power is from metalic pads. Organic pads can work, but are not as powerful. Over the years, I have tried / tested various pad setups, typically on our Ventana mountain tandem. I find that oem Avid pads work very well. Similar in performance are EBC metalic pads. Pretty certain the EBC is HH compound but I may have that confused with moto stuff.

If I had one complaint regarding Avid BB brakes, it is the spring that acts as an anti vibration / anti rattle device between the pads. As a spring it works fine. However, at the tip of each finger on the spring is an audible wear indicator. If you use the audible indicator to replace brake pads, they still retain a lot of life that is wasted. With that said, I typically use needle nose pliers and straigthen the audible indicator to disable it.

As a last consideration, understand that there are differences between Avid BB brakes. Avid offers BB7m or even the newer series BB75m for mountain bikes.

BB7r is the road version. The difference is the helix that actuates the brakes. The helix profile determines the brake lever to be used.

The very early Avid brakes, and you may have these tended to like an added return spring. My opinion is they are not as nice as the later versions. Newer versions also have adjustable spring force capability and do not require added springs provided the cable is good / clean.

My reply was not focused on a manufacturer selecting the proper ratio of piston diameters, but rather in reference to your reference material of how hydraulics operate and you representing how hydraulics operate with no downside.

Hydraulic brakes on bicycles have improved many levels since the early production versions in the 1990s. Not saying hydraulic brakes are superior or inferior, simply another choice to get you stopped.

Each design and method of actuating, plus each manufacturer has their quirks. Properly setup, Avid BBs are very worthy, The Avid RS brakes on my inspired trials bicycle are a good match for the levers to my fingers ergonomics and accoplish powerful braking. The Shimano XT brakes on my wifes LIV Advanced Pique 1, she loves, where I find the rate linkage notchy and do not like the feel when I am on that bike. My Scorpa has AJP brakes, my KTM uses Brembos, and the Can Am Spyder uses Brembos. Each setup and system has its own merits and demerits. Not so much quoted from a magazine article, but relative to riding and using the brakes.

Not important to you, both our Co-Motion and Ventana both use Avid BB series brakes, and when adjusted well, never leak fluid and have more than enough stopping capability with good modulation at the levers.

Pretty certain, with a touch of effort, minimal if no expense, and care setting up, the original post will have very good brakes.

Agree. Attention to a few details gets results. Acetone does well to clean the surfaces of metalic pads also. Not a fan to read when people substitute acetone based nail polish remover for true acetone.

The tool for truing the discs works well. Sadly, with non floating discs, we often induce small amounts of wobble from heat and distortion. Unless truly bent, I leave well enough alone.

Not sure how you cut your cable housings, I typically rough cut to length with Park cable cutters, then final cut with a cut off wheel or ensure the ends are flat on a belt sander or similar. Obviously, reopening the inner liner with a scribe after cutting and squaring.

Deglazing the discs work very well to help burnish the pads quickly. Also after burnishing, the remaing texture reduces, even prevents shudder from the disc being too polished.

Everything you posted is great advice.

I use a dedicated cable cutter and dress the ends with a Dremel. Flaring the end of the liner is important too as it's very stiff on these housings.

Pay attention to cable routing, too, on our Cannondale the cable housing was routed outside and over the chainstay, which put a severe bend to it right as it got to the caliper. Re-routing it inside the chainstay straightened things out.

While you have it apart, ensure you have metalic brake pads and not organic or semi metallics.

Sanding the discs, your sander, if electric and for woodworking, it may not be best. If you have an automotive type random orbital sander that may work better. Ideally, your finished surface will get a texture similar to honeing a cylinder in an engine. Doubtful you will get the pattern, but the roughness matters.

Without using the powered sander, my suggestion is a sanding block. Avoid hand sanding without the block, the finish will be inconsistent.

Read up on how to initially position the fixed pad. Many people start with the fixed pad incorrectly positioned, and have calipers in the less than ideal location left to right.

Dealing with the spherical alignment washers is kind of a pain and takes time. On both the off road and road tandems I found that even when aligned well, with use the caliper can ever so slowly move. For us, I have gone to a flat washer stack of matching height. This may or may not be best for you, how well they aligned the caliper mount during manufacture of the frame plays into this.

Also, realize that the brake pads and rotors need to bed in, so initially braking may seem soft and less effective. Usually, ten or so hard stops and then make minor pad adjustments gets you dialed in.

Two avid rotors came with this tandem. Pix below. Condition being equal, is one model preferable?