Originally Posted by Retro Grouch
Eccentric on the rear!
What is your drivetrain plan?
Was told that the placement of the eccentric at the rear was to add strength and stiffness to the rear bb where the loads are higher and this rear mounted bb seems to be a feature with Arvon tandems... and this is a very stiff frame. The boom and many of the other tubes are custom drawn "Mesa Oval" and Arvon jokes that he called them this because he does not mesa round. These also add stiffness and strength to the frame and the filet brazed frame also improves the frame quality... you won't find any rolls of dimes on these frames.
Some other features I like is that none of the joined tubes have any internal connection to each other so most are impervious to water contamination... the bb's are closed cyclinders and if you did get water in the seat tubes you'd have to flip the bike upside down to drain things out.
The quality of the brazing and machining tolerances are incredibly well done... I was a machinist and can really appreciate nice workmanship and the turned pieces are all done by hand and not on a cnc. The eccentric bb is hand built like the rest of the bike and is as perfect as can be... my 10 year old daughter could adjust it.
Will be using good old friction with Suntour thumbies (will be running a trekking bar up front) mated to a Suntour VX group and an 8 speed rear cassette... am still running the gear math in my head and will probably have to make some adjustments once the lady and I get to riding as on singles I tend to spin things out at high rpm's while she has exercise induced asthma and can't spin like a gerbil on crack.
But she has amazing stamina and great power... have not seen many people who can hammer from the saddle like she does and she is by no means a slow rider. We think that riding the tandem will allow her to do rides that are beyond her single capabilities while I have no problem hopping on a bike and riding 100 km.
Will have a 52:11 as my initial top gear so a cadence of 80, which is low for me, will still get us up to 28 mph... we are not going to be racing but will be using the bike for longer rides together as well as getting around the city as a couple and with the girls who think we already need a second tandem.
For now I am going to have to work with three stokers... my daughters are 10 and 12 and are strong riders so even with them we should be able to push some taller gears.
Will start by using the same set up as I do on my touring bike with a 28/40/52 and see how that works with a tighter spaced 8 speed and have been working out all kinds of combinations and have even been playing with using a half step and granny since I am such a curmudgeon.