Decisions, Decisions – Part 4

So what’s the good news? Well, there isn’t much at this point. I did have to rethink a few of the previous choices so to get everyone up to date here is where we are.

I have asked Brent if the rear OLD (Over Lock-nut Dimension) could be made 132.5 mm instead of the 130 mm I had previously specified. I felt if we could make this small change that we would be able to accommodate hubs of both road (130 mm OLD) and mountain bike (135 mm OLD) variety. This would mean that the rear triangle would only need to compress or stretch 2.5 mm about 2 pennies thickness, either direction. Brent says this is a practical solution and has noted it on my build sheet.

Seat post choice was also abandoned as the KCNC seat post has a weight limit of 90 Kg (about 198 pounds). So the original choice of Thomson Masterpiece seat posts have returned. The Thomson is strong and light enough for our needs. Besides that it looks good too!

I think that the color has been finally decided also. We are going to go with basically a clear finish with pearl in the clear coat. A lot of pearl in the front fading to none. This should allow us to customize the tandem with virtually any color we want in the future. But for right now it looks like we are going to go with white bar tape and brake hoods along with white saddles. There might be a small touch of an accent color on the front but we are not certain what that might actually be yet.

The crank set decision is still not made but we are currently leaning toward the FSA SLK Carbon as it is the only modern (outboard bearing) design currently available. I might, if I can find them cheap enough try to find some older Shimano Dura-Ace 7703 (triple) and 7700 (double) Octalink cranks and modify them by drilling out the pedal threads, re-tapping them and using coil inserts to get the pedal threads on correctly. In order to do this I actually need to buy three sets of cranks since you need three spiders (the part where the chain rings mount). I would have to drill and tap three arms to reverse the pedal threads. This would not be a job for the timid and I am just not sure how well a coiled insert would work with the power involved in propelling a tandem.

There are reports that older FSA cranks had issues with crank arms coming loose, but usually the use of a serviceable thread-locker (Loctite blue) and the proper torque on the bolts should be enough to remedy that issue. The other issue is bearing quality. Even now it seems like there just isn’t much life in the FSA bearings. Fortunately FSA and Shimano use the same size bearings and shim in their respective bottom brackets and swapping one for another is just a trivial matter. Or even better yet is to use some hybrid ceramic bearings like those from Enduro. They are built to specification and use bigger bearing balls and do not require the plastic shim like Shimano or FSA.

Still undecided about the front handlebars. I have an FSA K-Wing carbon bar in a 44 cm. Problem is that it is just too heavy, advertised as 240 grams and actual measurement is 284 grams. The slope of the flattened top is at a funny angle, limiting the mounting options of the bar. I have sanded out the FSA logos and resprayed the clear coat on it so at least it is stealth looking and will match up well with the carbon frame.

More later!