We have a Dawes Galaxy Twin, we've had the bike a couple of years, but the rear brake has never seemed quite... right.
The tandem currently has Tektro 720 cantilevers with Shimano BL-R400 levers. The front brake works very well, I'm able to apply more than enough force to bring the tandem to a halt abruptly, but I'm concerned that I would not be able to bring the tandem to a stop using the rear brake in the event that the front brake fails.
The lever feels very soft and the braking force is so weak that I'm not able to lock the rear wheel even when riding solo. If I set the brake so that there is sufficient clearance for the wheel to rotate freely, the lever hits the bars before I get enough braking force.
I've replaced the brake cable and housing, but this had little effect. I know about setting the height of the yoke and length of the straddle cable in order to vary the mechanical advantage of the cantilever, but the geometry of the frame limits my options here, since the stoker half of the frame is very small to accommodate my 5"1' stoker:
The frame does have mounts for a disc brake, so I wouldn't mind fitting one if this might solve the problem. What should I do?