Just purchased a used 98 Santana Arriva with Aerospoke wheels and Formula disc brake. The brake has to be rebuilt by Santana apparently. I have two questions: can Aerospokes accept different tire widths (we usually like a slightly wider tire than a true narrow road tire due to the sometimes rough roads in our area). Second, I have read the discussion about disc brakes and wondered if it was worth getting them rebuilt for the $100 Santana is charging or just go with hand brakes. Appreciate anyone's thoughts. (By the way, we are upgrading from a 10 yr. old Trek T-100 that we've put lots of miles on and has served us well.)
The Aerospoke wheels are presently built around Velocity's rims. I'm fairly certain that a 700x28 is an easy fit (I've seen them on plenty of Aerospokes) but you'd want to check the INSIDE diameter of your rims to confirm the proper tire size range. Here is a link to a width compatibility table at Sheldon Brown's Web site: http://www.sheldonbrown.com/tire_sizing.html#width
If for some reason a 28mm tire is borderline or over the limit, Avocet's 700x28 FasGrip K20's are actually more like 26mm wide and are also a good performance tire with "cushy" sidewalls; however, the soft sidewalls that make them cushy are easily cut if they get pinched or run-up against rocks and glass. Just something to keep in mind.
Brakes: How about spending that $100 and converting to a new Avid BB brake? Seriously, the Formula brakes are a double-edged sword. If you can get one properly adjusted it will work quite well. However, getting and keeping them properly adjusted is nearly a full-time job. Here is a link to a Web site that describes the conversion process. http://www.precisiontandems.com/avidconversion.htm
Regarding rim brakes, does that particular frame even have either bosses for the canti/v-brakes or a brake-bridge drilled for a brake caliper? I seem to recall that '98 was when the Formula first came on the scene and the initial production run bikes were devoid of the other brake fittings. Just something to check-on.
Bottom Line: For my $$, I'd rather take a flyer on the Avid (assuming you want to stay with the disc) versus going back to "rim" brakes -- noting that both are hand operated ;^)
I have used the following tires on Aerospoke tandem wheels:
Avocet Fasgrip 20K's in 700 X 28, 700 X 32, and 700 X 35. All of these with the kevlar belt. All of the wired-on variety. Sidewalls were too fragile for me. Stopped using them. Would be willing to use folders (if they exist) for racing-type special events.
Panaracer Paselas, 700 X 32. All of the wired-on variety. Tread delaminated on one, sidewall failure (railroad tracks, arguably my fault, pump gauge was reading 20 psi high, so the tire was 20 psi too low. pinch-flatted on tracks, then found defective pump gauge later. there is a lesson there...) on the other. Stopped using them.
Panaracer T-Serv for Messenger, size 700 X 32. Limited use so far, they seem to be sufficiently robust. Folders.
For some reason I always put in 120 psi. Don't know why that is....gross weight tends to run around 375-390 lbs, depending on how bad I've been lately. Experience suggests that wired-on tires will come off the rim after going flat and folders don't. I'm not using wired-on tires any more until I have a bad experience I can blame on folders. Bill McCready considers wired-on tires safer than folders because they are less likely to come off the rim and then flat when exposed to heat.
Is your question "What kind of brakes should I get for $100?"? I have no experience with disk brakes, so of V-brakes and cantilevers and double-pivot sidepulls, I would get sidepulls.
There has been one report on tandem@hobbes of an Arai drum brake melting the thermoplastic wheel around the hub of an Aerospoke. Probably not a good idea to use an Arai with an Aerospoke wheel. This shouldn't be a problem with disks.