Report by David Wilde
These brakes have been superceded by the hydraulic version, but are still available to order. They are designed to be fitted to Hope hubs using a spline fitting.
My Roberts tandem was specified with a rear disk brake. Cantilevers (before V brakes came out) were fitted to the front and to the rear. A front disk brake was added later.
Inititially it took quite a lot of messing about to get the brakes working effectively without dragging. Performance is very good - particularly for off-road use. We use the disks as the main brakes, operated by the steerer. The stoker can operate the rear cantilever.
The main problem is the brakes are set up to work with MTB levers, and my tandem has drop bars. The purchase of DiaCompe levers with the long cable pull (I think type 287 but check - mine came from George Longstaff) solved most of the problems.
Other members of the group use standard Shimano MTB levers with no problem (not V brake levers).
The position and length of the rear outer casing is critical. If it is too long or short it imposes a tension on the caliper effectively stopping it from floating correctly, which results in drag and rubbing noises.
The addition of rubber O rings on the caliper bushes (between the frame and the caliper) has also improved the centering of the caliper, and I can now adjust the brakes quite tight without rubbing when released.
Initially the brakes were fitted with pads where the friction material was glued to an aluminium back plate. These pads suffered from severe fade (very frightening and much more sudden than the fade experienced with rim brakes). During a tour in France the friction material became separated from the back plate, resulting in total loss of braking from the disk. Fortunately we also have a cantilever brake on the back operated by the stoker.
The same problems were experienced by two other teams in our group, again fortunately without incident.
The incident was reported to Hope, who were aware of the problem and were waiting for supplies of new pads. These pads offer improved performance, less fade and are bonded to a steel backplate in the same method as car disk pads such that separation is extremely unlikely. The new pads have a Green back plate. If you have the old aluminium pads, stop using them immediately and order replacements from Hope.
Fade can still be experienced with the new pads.
Despite all the problems mentioned above, the performance is much superior to standard cantilever brakes. During our touring holiday in France, before the total failure occurred, we were able to decend into the Gorges of the Lot and Tarn at high speed, with sharp braking before each hairpin. The comparison with the front cantilever persuaded me to fit a disk to the front wheel as well, once Hope had sorted out the new pads.
I have not tested the new V brakes. Reports indicate that they offer superior braking to the disks, but with less control and increased rim wear.
The main advantages are:
The main disadvantages are: