Tandem Cycling - Drum Brake Adjustment

Our tandem has the rather conventional cantilevers + Arai drum braking system controlled via a bar-end shifter. I rarely use the drum brake but last weekend I set it to control our speed on a 2-3 mile downgrade with cross traffic, signals, and rather choppy pavement. Afterwards, I found that the bar-end lever had reached the end of its' range; I had to move it through about 45 degrees before the drum engaged and it wasn't fully engaged even pulling the lever all the way up. I figured that the brake shoes - having not had much use - had finally worn in and seated themselves. There was a lot of travel in the brake arm itself before the shoes contacted the drum, so I moved the little barrel at the brake end of the cable up about 1/2 inch to shorten the cable. Now the brake engages after only a few degrees of lever travel but fine adjustment of the brake tension seems to be gone. Now it seems to be either on or off: It goes from off to fully engaged in about 30 degrees of lever movement. Is this to be expected when the brake wears in? There doesn't appear to be any other adjustment to this brake unless it's inside the brake itself.

Sorry, no epiphany to offer. What you see is what you have to work with. The only thing internal to the brake that influences cable travel is the amount of pad wear; the more it wears the more travel it takes to engage.

If you haven't done so, just pull it apart and make sure nothing has contaminated the inner surface of the drum or brake shoes that may be influencing the grip, to include sanding off any glazing on the shoes, being mindful to wear a paper mask to keep brake dust out of your lungs.

Reassemble and readjust the cable pull on the actuation lever and see if that gives you any better performance.

I just read in another forum that the Arai drum brake is out of production. Does anyone know if this is true?

The Arai does not have adjusters as on a car brake drum (that compensate for wear). As the shoes wear, they have to travel farther to contact the drum. So, most of the cable travel is taken up by moving the shoes through air which does no braking. That's probably one major drawback to this simple drum brake.

Does anyone know if this is true?

Yes, this is a true statement. Mel @ TandemsEast.com mentioned this during the Expo back in March, noting that he had stockpiled as many as he could get his hands on from the remaining inventory.

However, it was implied that a product may be out there somewhere that would be a substitute for the Arai once the existing inventories are depleted.

On the bright side, there are A LOT of these things sitting around in people's garages so I suspect it would be many years before the entire market of new or used brakes dried up.

Got an answer to my problem:

I stopped at R+E yesterday to ask the mechanics about this and Scott was familiar with this issue - it turns out that you have to leave some play in the lever arm to have good brake modulation. (Actually, you don't have play because the arm will hold the cable tight with spring tension.) If you adjust the cable so that there is very little travel of the arm before the shoes contact the drum - even if the wheel turns without the brake dragging - you will lose modulation. I moved the cable anchor out a little (lengthening the cable) and now it works fine.