At 9:01 AM -0600 2/26/07, Mark Stonich wrote:
>But I've a caution for anyone with a Taylor tandem. Because the
>seat tubes extend well above the top tube joints, some people have
>damaged their frames by using period correct (ie, short) seat posts
>up to the limit lines at the top. This puts the bottom of the seat
>pin in the brazed joint, where IMHO you should have it at least a
>couple of inches below. Given the extra stresses fed into the
>captains seat pin by the stokers bars I strongly recommend an
>off-topic (ie, long) mountain bike seat post.
>
>I've repaired one that was damaged this way and know of at least one
>other. Strong riders in both cases.
Mark, you are correct about the dangers of extending seatposts too far. However, instead of using an off-topic mtb seatpost, I recommend sizing classic bikes the way they were sized in their heyday. For most of our CR-timeline bikes, the "fist-ful of seatpost showing" method is a good approximation, and that usually means above the top tube, not the extended seat tube... Often this means riding taller frames than are usual today. If you search the archives, you find this response to many questions of "why did the old riders have such long legs and short arms?" They didn't, they just sized their frames differently. (Once you go back 80+ years to the age of sloping top tubes, you get different sizing again...)
Of course, tandem sizing always is a compromise of many factors, but especially rear standover clearance is not an issue - the stoker never will be in that position. So buy them large (by today's standards).
Jan Heine
Editor
Bicycle Quarterly
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