Join Date: Mar 2003
Location: Grand Prairie, TX
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A tape measure and measurements off your single bikes are just about the most valuable things you can take with you tandem shopping.
You need transferable measurements. So you need the bottom bracket heights, handlebar heights, and seat top heights, off the ground. It's useful to have the measurement from the bottom bracket center to the top of the saddle, parallel to the seat tube, as a double check on the saddle height off the ground, and it is also independent of the bottom bracket height.
In addition, you should also have the horizontal measurements from both bikes, between the center of the seatpost and the center of the handlebars, parallel (yes I know that is redundant) to the ground.
When purchasing a tandem, the measurement that is often not considered, is the spacing of the riders. Given that the seat tubes are parallel, and that the horizontal bottom bracket spacing is greater than the stoker's single bike horizontal center-of-seatpost-to-center-of-handlebar measurement, the remainder of the distance is by deduction horizontal stoker stem length with single bike fit. This varies from maker to maker and size to size. On production tandems, there seems to be no exception to the rule that more horizontal bottom bracket spacing (for adult stokers at or above 5'2") is better, and your goal will of course be to get the most tandem for your budget. I would not accept a size on the front smaller than the captain's single bike fit, though I might be willing to go 3/8-1/2" higher (more leverage for wrestling the handlebars). With a stoker of 5'5", you might be looking at single bike post-bar c-t-c spacing of 23" or so, so then the question is, is the remaining space in back large enough to keep her happy, and what else is available and affordable? If you asked me, I would say the bare, bare minimum is 5" of horizontal stoker stem for a stoker that size (therefore 28" bottom bracket spacing), but others may have different opinions.
You can find a little more coverage of this in the thread entitled "Stoker Handlebar Position."
Don't know where you are in Texas, but the very best thing you could do would be to call Richardson Bike Mart and get an appointment to come tandem shopping. And you need to look the brands not carried by RBM too (Cannondale?). The idea is to practice shopping, and to get an idea of what is available.