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Comparing Tandem Frame Designs

by Bill McCready, 1996

(Eigenschaften von Tandemrahmen - sehr viel Hintergrundinfos und ein wenig Werbung. Aufbereitet aus der englischsprachigen Mailingliste vom 25.10.1996)

Part 1: The History of Comparative Tandem Testing

When I was out of the office in June preparing our Vermont rally, Steve saved some T@H postings for me to respond to. Unfortunately, I didn't find his stash until last week. (This is not a response to any recent postings).

Rather than respond to each item he saved, I'll simply share some insights we've gained from 23 years of comparative tandem testing. I say "we" because the testing was a team effort of various panels of riders I assembled.

The first expert panel was formed three years before the 1976 founding of Santana. This panel, made up of Bud's Bike Shop employees and various tandem owning friends, tested and evaluated three dozen tandems in as many months: I remember testing tandems produced by the following builders: T. Parsons, Schwinn, Jack Taylor, Mercian, Bob Jackson, Gitane, Alex Singer, Urago, Follis, Claude Butler, Mercier, Bruce Gordon, Fernwood, Southern Cross, Caylor, Colin Laing, Saturn, Atala, Le Jeune, Dave Moulton, Rixie, Jack Davis, Pogliaghi, Albert Eisentraut and Rene Herse. Some of these builders supplied Bud's with a number of different frame designs.

While only a few of these tandems were subjected to head-to-head testing (my shop was selling tandems faster than we could obtain frames and equip them), we often instructed custom builders to produce two nearly identical variations of the same design. After equipping both frames with the same components, it was easy for our testers to switch bikes and discover the better design while subjecting new tandems to our normal 50 mile burn-in rides.

Later, after I became "Associate Editor; Tandems" for BICYCLING, I gathered a half dozen tandems and the magazine's entire staff for a head-to-head one-day evaluation ride through Marin County ---the resulting "shoot-out" was the earliest publication of a tandem comparison test. Because back in 1976 Bicycling didn't have a dozen employees, we recruited some Marin County locals to help. One talented local rider who joined us that day, Gary Fisher, stayed on with Bicycling for many years after I resigned from the magazine to start Santana.

Through most of 1977 and 1978 Santana's six original employees built and evaluated 14 prototypes. Even though dozens of orders were piling up, delivery of the first Santana was delayed until after nearly two years of testing was completed. Because we then spent two additional years catching up with pent-up demand, Santana's first ads and catalogs didn't appear until 1982---six years after the company was started.

In 1981 Bicycling published a second tandem shoot-out. While I didn't perform the evaluation or write the article, I was responsible for collecting the comparison bikes and instructing Gary Fisher and John Schubert how to best discover various tandem frame attributes. The test originally included four tandems: a Santana, a Jack Taylor (winner of the earlier shoot-out), a custom-built Mike Melton and one other brand ("Schubley" will need to remind us). When, after a full day of testing, Schubert remarked that he and Fisher both thought the Santana was the best of the four and "nearly as good" as the Rodriguez tandem they had reviewed a few months earlier, I called a dealer in Santa Cruz and used my credit card to purchase a new Rodriguez off his showroom floor. I then paid one of his employees to skip a night's sleep and drive 400 miles to deliver the Rodriguez by dawn. When Schubert and Fisher showed up for the second day of testing, they were surprised to find a fifth tandem---which eventually placed second behind the Santana.

The following year Mike Melton, the conscientious builder of the third-place tandem, joined Santana (If you can't beat 'em...) and took over direction of our in-house testing program. During his eleven months at Santana we discovered the direct lateral design now favored by most tandem builders. When skeptics (who invariably owned or built a different style of tandem) insisted our new design was "hooey," Mike built a tandem version of the state-of-the-art "Tarantula" frame evaluation machine Gary Klein had just delivered to Bicycling. Ours was the original tandem-specific frame testing jig (and no one has yet bothered to build another). The world's first instrumented tandem frame test confirmed the superior efficiency of a direct lateral frame.

But all this is ancient history, isn't it?

Well, sort of. Mike Melton left Santana in 1983 when Huffy / Raleigh recruited him to design and build the original Olympic Super-Bikes (and in case you don't remember, the 1984 U.S. team used these innovative bikes to win a record number of Olympic cycling medals). Mike's replacement was a novice framebuilder named Ross Shafer, who oversaw Santana's testing program before returning to Northern California to start his own company---Salsa Cycles. You probably don't need to be reminded of the name of the company Gary Fisher started. And Schubert went on to become the founding editor of Bicycle Guide (America's first cycling publication actually edited by a cyclist!). More recently Schubert finished his 2nd edition of The Tandem Scoop (an improved version of the best tandem book ever). All of these talented people (and dozens of others) who have worked with me on comparative tandem testing will confirm our testing revealed undeniable differences in comfort and performance.

We continue to test frames here at Santana. Our own frames AND frames built by others. When we state, for instance, that aluminum tandem frames built by others have a lower stiffness-to-weight ratio than a cromoly Santana, it is because we've purchased complete new tandems, removed the components and scientifically tested the bare frames. To this day I do not believe anyone else (magazine or builder) has performed these sorts of tests.

Part 2: A scientific way to compare tandems

In Santana's most extensive scientific tandem testing (published in 1993) we ranked the stiffness-to-weight ratio of every major brand of tandem then being sold in the U.S. The surprising answers: some tandem frames were twice as efficient as others (the range of efficiency among competing single bike frames is probably one-fourth as dramatic), high priced tandem frames sometimes scored worse than a budget frame from the same builder, and double-butted cromoly frames had significantly higher stiffness-to-weight scores than plain-gauge aluminum frames. Because we knew our published findings would be challenged, we saved the frames and invited retesting.

More revealing than lab-tests are comparative road tests. While all of us have learned to prefer objective "facts" over subjective "opinions," it is not yet possible to objectively measure such essential frame qualities as stability, handling, ergonomics or comfort with an instrumented test jig. And, because only an idiot would prefer stiffness or lightness (which can be measured) over stability (which can only be judged), subjective road tests are still the best way to determine overall frame performance.

Santana has developed a methodology to verify the accuracy of subjective scoring with subsequent lab tests. For instance, after a panel of testers develops seat-of-the-pants scores for stability, handling, comfort and stiffness, we remove the components and objectively test the stiffness of those same frames. And YES, we have established a conscientious panel of test-riders CAN accurately determine tandem frame stiffness. When objective lab results verify the accuracy of certain subjective scores (such as stiffness), the panel's scores for unverifiable results (such as stability) merit a high degree of credibility.

Unfortunately, the aforementioned seat-of-the-pants scoring is too-often unduly affected by the shape of the saddle. To accurately compare various tandem frames through subjective testing it is absolutely essential to equip the frames the identical seats, tires, inflation pressures, pedals, bars and tape. Because magazines usually skip this step, their reports have a diminished degree of validity.

It is also necessary to use comparably-sized frames. In a recent issue of TANDEM various teams evaluated a Santana against another brand. Only one captain preferred the other bike. Because I was curious as to why this one captain panned the Santana, I reached him by phone. His answer: "I just couldn't get comfortable." When I pressed further I learned the dissenting team's captain was a great deal taller than the other captains---and the tandem he preferred simply had a larger frame.

When we test tandems at Santana, we not only make sure all the frames are the same size, we go a step further. Because you can't accurately judge a tandem's overall performance until you've ridden both ends, every test rider must not only fall within a certain range of height, the heights of test partners must be similar enough to allow equal time in both seats.

Further, we have found scoring is haphazard unless the testers are first instructed on terminology and technique. For instance, most riders confuse stiffness with comfort (on a single bike---but not a tandem---there is a high degree of correlation). To obtain meaningful tandem evaluations we need to start by defining the terms on our score sheets. In the case of stiffness, we then put each tester on a tandem with an instructor and show them how to determine frame flex while standing and grinding up a steep incline. To gauge comfort we ask both riders to remain seated while coasting over a washboard surface. Once the testers know what to look for and how to find it, an amazing degree of scoring consistency emerges. As for the commonly expressed opinion that "...all tandems are about the same." Those who have participated in our panels know better.

And when I say "an amazing degree of scoring consistency," I don't mean testers should be allowed to compare observations in order to develop consensus. On the contrary; until every score sheet has been turned in, testers should not be allowed to discuss the testing with anyone other than their partner. And even test partners are separated while marking their individual score sheets.

Is our test program worthwhile? IMNSHO ongoing testing is the reason Santana's original tandems were the WORLD'S BEST, and why today's Santana tandems retain this distinction.

Too strong a claim? Need some independent proof? Over the past 15 years a number of head-to-head tandem comparison tests have been published by Bicycling, Bicycle Guide, Tandem and others---and until this past June, in every test where an overall ranking was determined, Santana triumphed over every other brand of tandem.

Part 3: Is Santana still #1?

This past summer Santana's 15-year old unbroken string of road-test victories came to an end when the CTC (a respected British cycling club that publishes a "Consumer Reports"-like magazine for its members) staged an elaborate off-pavement tandem test and pitted a Santana enduro-style (drop bar) 26" tandem against a field of mountain bike tandems with straight bars. The winning ATB tandem was produced by a UK custom builder (a CTC subscriber will need to supply the builder's name). Santana's enduro tandem finished second.

For the record, even though it would be interesting to know if a change of handlebars might have affected the outcome, I have considerable respect for CTC's testing. Unlike most reviews, in both of CTC's recent tandem shoot-outs (700c and 26-inch), every test team evaluated each tandem over the same course.

And why would I want to doubt the integrity of the CTC? After all, in CTC's same issue (published this summer) Santana's least-expensive 700c tandem, the often-overlooked Visa, handily outscored every other road tandem CTC tested, including current road models from Burley, Ibis, Cannondale and a Trek T-200.

For the past two years Santana has stated in writing what the CTC has now independently confirmed: today's Visa, Santana's least expensive road tandem, will outperform every other current tandem built elsewhere.

Will Santana stand behind this claim? You bet. If, in a fair and scientific ranking of overall tandem frame performance, the current model Santana you own now or purchase in the next year, loses to any non-Santana tandem produced prior to the date of this posting, Santana will refund your purchase price (limited to the first 10 Santana owners who apply).

If other builders really want to deliver superior tandems (as opposed to unverified claims) they'll need to initiate an in-house testing program.

Bill McCready

P.S. Because the end result will be better tandems for all tandem enthusiasts, Santana continues to offer assistance to other builders with a serious desire to "improve the breed" (i.e. we have never patented our designs and we have always made our tandem-specific frame materials available to all qualified builders). If you know a builder who wants to do better, encourage them to give us a call---Santana's goal remains better tandems, not market share.

P.P.S. While it's certainly possible to increase a frame's stiffness by plugging in one or more additional tubes, Santana has carefully tested these direct-lateral alternatives and confirmed a reduction in a tandem's stiffness-to-weight ratio (what we refer to as "efficiency"). And, to add injury to insult, uptube and tri-lateral frames are not only less efficient, they are decidedly less comfortable. To expound further I would need to overcome my reluctance to argue specific claims posted to this forum by the esteemed designers of uptube and tri-lateral tandems. Instead of a boring and pointless electronic debate, I propose they ship their best-effort frames to Santana for authoritative testing---I'll then invite Hobbesians to collectively appoint a testing witness who can post the results.

D. Bettge; 17.1.2004, letzte Änderung: 17.1.2004