Conventional wisdom says that 90% of solo mountain bikes sold never leave the pavement. Serious off-road cycling is very demanding of skill and fortitude on the part of the riders. The greater length of a tandem seriously reduces its maneuverability. The bumpier surfaces encountered off-road are much more punishing to the stoker's rear end than the mere potholes encountered on pavement.
For these reasons, I would not look for off-road tandeming to ever become a major niche in cycling. Does this mean that "mountain-bike" type tandems are doomed to be an esoteric fringe of the tandem scene? I don't think so.
Who buys tandems, anyway? Some people buy tandems because they are so fast. Two vigorous, enthusiastic tandemists who are prepared to hammer can blow the doors off of anybody on a solo bike...but these matched pairs of "sportif" cyclists are not the usual first-time tandem buyers.
Typical tandem purchasers are married couples. Pat is a serious cyclist, Chris isn't. Perhaps Pat feels guilty about going cycling without Chris, perhaps Chris is jealous of Pat's time spent cycling. They have tried cycling together on solos, but Pat hates having to constantly slow down to wait for Chris and Chris feels pressured to go too far and too fast. The tandem is the obvious solution to the problem, so they buy one. Pat becomes the captain, Chris the stoker. Sometimes this solves their problems, and they become active tandemists and live happily ever after...
Unfortunately this fairy-tale ending doesn't always happen. Too many tandem buyers ride together a few times, then put the bike in the garage, usually because the stoker doesn't like it. There are two major things that turn potential stokers off: fear and pain.
If Pat is a speed demon and takes full advantage of the speed potential of a tandem right off the bat, Chris is likely to be terrified. Chris, remember, is not a serious cyclist, and has no experience in high-speed cycling even when in control of the bike. Traveling at high speeds, with no control of the bike, no forward visibility, and an inexperienced captain--this can be so traumatic that the first ride may be the last.
Even if Pat is a considerate and experienced pilot, Chris is going to suffer from sore buns. Pat's legs are strong enough to carry more body weight, so Pat doesn't sit so hard on the saddle as Chris will. To make matters much worse, Chris can't see the bumps coming, so Chris is constantly getting whacked in the rear end by the saddle without warning.
If Pat and Chris, as beginning tandem purchasers, start out with a mountain bike type tandem, they have a better chance of making it work out and getting past these early pitfalls. The reasons are the handlebars and the tires.
Captaining a tandem is much more demanding on the upper body than riding a solo. With a solo, most of the steering and balancing is done by weight shifts. With a tandem, particularly with an inexperienced stoker, the weight is greater and less under the captain's control. This requires much more forceful use of the handlebars. For this reason, tandems generally come with wider handlebars than solos, but even 44 or 46 cm drop bars give much less leverage than straight bars.
A novice captain (even though an experienced solo cyclist) will have much better control with straight bars. The stoker will feel this increased level of control, and will feel safer and more relaxed as a result. In addition, the bike will be a bit slower, a definite plus for a nervous stoker. If the captain misses the multiple hand positions of drop bars, bar ends may be added.
The problem of stoker saddle discomfort is very real, and many approaches have been used to deal with it, including wider saddles, sprung saddles, sprung seatposts, and combinations of these. An additional line of attack that works very well is to use a wider, lower pressure rear tire. Road type tandems with 622 mm (700c) of 630 mm (27") wheels cannot compare with 559 mm (26") mountain bike type wheels for availability of wide tires with street type tread. A wider tire not only gives a much softer ride, it also increases the stability of the bike on imperfect road surfaces.
Thus, a mountain-bike type tandem will be more comfortable and less scary for the stoker.
A further plus of mountain bike wheels is their greater durability and reliability. Skinny tired tandems are often called "tantrums" because of the incidence of tire, rim and spoke problems. Quality skinny-tire tandems always have to use at least 40 spoke wheels or more often 48's. The natural cushioning of a mountain-bike tire allows the use of ordinary 36 spoke wheels with excellent reliability.
One should note that there is one major difference in frame geometry between tandems that are "mountain-bike type" and those that are built for real off-road use, and that is the bottom bracket height. Tandems in general need higher bottom brackets than comparable solos because their longer wheelbase brings the bottom bracket closer to the road when cresting a hill. Tandems made for serious off-road riding need extra-high bottom brackets even by mountain-bike standards. This type of bike is not as good a choice for road use, because the extra high bottom bracket makes it much harder to start and stop, especially for less experienced tandemists.
I don't mean to say that high-performance, road-type tandems are obsolete, by any means. My point is that for most couples buying their first tandem, a "mountain bike" model is more likely to give them a positive start, and less likely to gather dust for lack of a contented stoker. For those who develop as tandemists to the point that they are bothered by the limitations of this type of tandem, they can always trade up later, since used tandems hold a much higher percentage of their value than solo bikes do.
Last Updated: by Harriet Fell