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  1. #1
    hors category TandemGeek's Avatar
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    Cowhorn Bars & Stoker Fitting - Some Thoughts

    I was going to tag this on as a reply to Steve's "Stoker Bar" thread but decided I'd just take the whole topic to a slightly broader level.....

    Cowhorn bars -- as best as I can tell -- only serve one real purpose; they lower the cost for producing a fully assembled tandem by a few bucks. Cowhorn bars are less expensive than drop bars and they eliminate the cost and labor associated with providing and attaching stoker pegs. The latter may have helped with keeping the cost of new tandems in check OR freeing up a little margin for the producer; I'm not exactly sure which was the real motivation or if there is even a distinction to be made. Cowhorns also reduce the weight of a tandem by a few grams -- also a marketing advantage -- which may or may not be more important than giving your stoker more hand position options depending on how you use your tandem (e.g., for racing, pain and discomfort is part of the game) or how concerned you are for your stoker's comfort (see additional comments for tandem captains regarding Stoker Comfort, below).

    So, just when did cowhorns become the default bar for stokers? A certain major producer of high-end tandems introduced the cowhorns back in the late 90's with the usual dubious techno-babble that accompanies each aspect of their product's features. Being the lead-dog in tandem producers (which admittedly is a position they earned and deserve), the major new-tandem buyer demographic (new empty nesters, one of who had been or was an active cyclist) bought into the latest "trend which, in turn, caused some of their competitors to follow suit so as not to lose a sale because they didn't offer the same features (and, well, they did reduce costs). Thus, a lot of stokers were put on tandems with handlebar "horns" that were way too wide for them @ 47cm -- not practical nor comfortable to use -- which relegated them to the flat section and a single, useable hand position. For a large number of teams, this arrangement "seems" to be quite fine. However, many astute teams have, instead, spent the $100 or so to replace the cowhorns with dropbars/stoker pegs/new bar tape and, thankfully, some of their competitors never did buy-in to the new trend and still sell their high performance road tandems with proper drop-bars and stoker pegs.

    Bonus Material For Tandem Captains:

    IMHO, most stokers who never rode a bicycle as an adult -- up and to the acquisition of a tandem -- don't know if they are comfortable or not because, lets face it, upright bicycles are not inherently "comfortable" machines.

    Therefore, many stokers merely learn to accept and sometimes even adapt to improper riding positions because they assume "that just the way it is" because no one ever took the time to work with them on their riding position and they're reluctant to complain. Well, that's not true. Many stokers ride in discomfort which can lead to "I'd just rather not ride today" or "honey, we need to stop again" or "honey, my _____ hurts when we ride" which is always a good indication that something isn't quite right: all of the foregoing can lead to an under or un-used tandem.

    Therefore, to all captains, PLEASE be sure that your stoker gets a proper bike fitting by a professional bike fitter, e.g., someone certified in the use of the "Fit Kit" or a Serotta Size Cycle either before you go shopping for your first tandem shopping, most certainly before having a custom frame made, and without question at the first sign of a fitting problem.

    As to whether or not the stoker's "optimum" personal bike riding position should be replicated on the tandem the answer is rather an easy one: just figure out how sub-optimum it will be and ask yourself if you'd be willing to ride thousands of miles over the next several years on a bike that was as proportionately mis-sized vs. your optimum riding position.

  2. #2
    SDS
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    Absolutely right (Mark).

    And shamelessly lifted wholesale and then adapted and edited for brevity and clarity from the thread "Stoker Handlebar Position":

    "Given that seat tubes will not vary much from 73 degrees, and that most stoker's horizontal-center-of-seatpost-to-center-of-handlebar spacing can be set on most tandems with the horizontal stoker stem length taking up the remaining distance between the seatposts, it is clear that the horizontal bottom bracket spacing sets rider spacing on a tandem.

    (this is not quite true. If the stoker runs out of clearance between her head and the captain's butt with her normal single bike riding position on the back of the tandem, then the single bike riding position is not set even if the seatpost and handlebar locations relative to the bottom bracket are the same as on her single bike)

    What is generally not clear in today's market is the answer to this question: what is the best rider spacing from the stoker's point of view, expressed as a multiple of the spacing between the stoker seatpost and handlebars, or as a fixed number of inches in excess of that, given no limitations set by materials?

    Material limitations in part led to current design. Older tandems made with less satisfactory tubing were reported to have flexible frames that tended to twist and oscillate due to aggressive steering and imperfectly coordinated riders. The solution was to make the rear end of the tandem as short as possible, thereby shortening the entire frameset, and keeping the frame flex to a minimum. Modern tubing and better frameset designs permit a wider range of fits, but the market still prefers tandems that look like all the other tandems, and with the average female height in the country being around 5'4", with a horizontal fit of 23" or so, tolerable (barely!) shorter-than-single-bike stoker fit can be had on a typical Santana with a stoker stem of 150mm or so. Bill McCready (Santana) absolutely insists on staying that short, saying that anything longer decreases the drafting effect of having the riders close and raises the power requirement. This sort of fit does impose some limitations on stoker position (can't put head down to prone because in many cases it won't clear captain's butt) and makes standing difficult.

    But....National tandem time trial championships are generally won on long wheelbase custom tandems with stoker compartments long enough to permit some kind of triathlon-type aerobars in addition to stoker single bike fit. This narrows the stoker position enough to improve aerodynamics, though on a few bikes, having achieved the narrow position, the stoker hand position at the forward end of the aerobars is set near the captain's seatpost to keep close rider spacing for better drafting.

    Given a blank sheet of paper, and a custom tandem budget, I would be inclined to set the bottom bracket spacing to accommodate the single bike seatpost to handlebar dimension of the most frequent stoker, plus room for aerobars set to fit as used on the most frequent stoker's single bike, plus three more inches to the back of the captain's seatpost, unless the stoker is definitely at the upper end of the contemplated stoker size range, in which case you do not need the additional three inches. Depending on your stoker size(s), this will put your bottom bracket spacing a lot closer to 40" (perhaps more) than the current 28-30". Production tandems like this do not currently exist.

    The neat thing about this sort of rule is that you can generously fit female stokers of average size, fit female stokers who are larger than average, and fit men of average size or a little larger with their normal single bike fit, though in that case the aerobars are backed up or removed. Instead of the limiting factor being the horizontal spacing in back, the limiting factor tends to be how far you can safely run the seatpost out. After you have spent a hunk of money on a tandem, surely it should fit as large a portion of the population as possible without consequent disadvantages?"

    Right at the beginning when you and your prospective stoker are thinking about taking up tandeming, it makes sense to try production tandems (which, I and some others say, are all too short horizontally in back, except when used with children), either by buying a new or used one or renting or borrowing, if you can get temporarily tolerable fit as defined by you.

    But the moment you think you might be beginning to contemplate a custom tandem purchase, it's time to start thinking about ideal stoker fit as defined by the stoker. And as Mark noted, if that means that professional fitting is required for a beginning adult cyclist, then you need to do that, and if at all possible, give her a chance (a couple of months) to see where the aerobars go on her single bike (worst case: stoker doesn't have single bike, so put tandem (or borrowed single bike) on resistance trainer, attach aerobars AROUND captain seatpost, remove captain and captain saddle (lower seatpost and raise stoker stem if the seatpost is close to the stoker's head), let stoker ride and adjust until aerobars set), before you set the dimensions of your custom tandem. What you are trying to do is to purchase a tandem that fits more like a car is intended to fit. Cars are not supposed to provide poor fit in the back seats for persons of 5'2", and no fit at all for persons larger than that (would you buy a car like that?), but that is what current production tandems provide, even though they can easily cost as much as a used car.

    Mark has been a leading proponent of better fitting (horizontally longer in back) tandems for a long time, and he has not given himself the credit he deserves here (or anywhere else! we owe him a bunch just for "The Tandem Link" website).

    As you can see by clicking on the link provided by Mark in the "Stoker Bars" thread, I have just such a tandem (Moby), though at the time we had it built we wanted single bike fit for a 6'4" stoker (center of seatpost to center of handlebars horizontal dimension of 30") and 8" of stoker stem, but with smaller stokers there was room for aerobars, and as such it has been a great "proof of concept" tandem. There is a slim chance it could be slightly slower with a front quartering headwind (we have not observed this), but the stokers are absolutely sure that in the hierarchy of tandem characteristics, stoker aerobar-length fit is much more important than a possible aerodynamic disadvantage in some operating regimes.

    I sent a note about Moby to a tandem buyer a few days ago:

    "The drag coefficient drops noticeably when the stokers get on the aerobars, the longer wheelbase gives a smoother ride, and the stokers can stand up, move forward, and lay down flat, all without ever worrying about where I am. A few months ago I took a woman out for a big club ride with an atrophied forearm after it was immobilized for a distal radius fracture. She'd never seen the tandem before (never heard of one with aerobars in back), and she was darn happy to snooze on the aerobars without much need to grip hard (her muscles were so weak they would cramp picking up a coffee mug). She'd gotten the pins out of her radius on Monday, and went out with me on the next Saturday."

    I highly recommend Meridian Tandems, particularly for custom tandem purchases.

    Someday I believe we will purchase production tandems with much longer stoker compartments. The reason we do not do that at present is because the first-time buyer market does not know to ask for them (though apparently there are a few veteran tandem riders who prefer short tandems). As they become more common and knowledge of them spreads, slowly the market will change. If you want one today, though, you will have to order a custom.

  3. #3
    hors category TandemGeek's Avatar
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    Quote Originally Posted by SDS
    Mark has been a leading proponent of better fitting (horizontally longer in back) tandems for a long time, and he has not given himself the credit he deserves here....
    I'm humbled and unworthy. Glenn Erickson is the guy who first understood that stoker comfort was the most important design feature to master on tandems, followed by handling, and all with a touch of style thrown in because -- after all -- with so few tandems being made who the heck wants one that looks just like the one next to it.

    However, I do feel I have accomplished some good in that I have earned an honorable but un-named mention by inference on page 12 (column 4, 2nd paragraph) of Santana's 2003 Tandems & Tandeming marketing brochure along with Glenn and his design philosophy and methods; "A final myth is the benefit of super-extended rear top tubes. While we have already explained (on page 11) that Santana pioneered roomy stoker compartments and currently features a comparative rear top tube length of 30", a couple of custom tandem builders (and a few of their enthusiastic customers) are promoting top tubes that are 2-6 inches longer."

    I still get all choked-up when I read it... Of note IS page 11's explanation of Santana's "comparative rear top tube length of 30 inches". It is another wonderful example of creative writing mixed with a lack of consideration for stoker comfort. Because, to get that extra 2" Santana pushes the stoker's saddle as far back as possible without regard for what the stoker's proper saddle set-back position "should be" and allows that their cowhorns provide an additional 1" of usable reach up front. Again, to actually use that additional 1" on the cowhorns the stoker's head ends up above the captain's back; very aero but not all that pleasant.

    Now, before I upset any Santana owners or friends of Bill, let me note that while I'm often times spun-up by Bill's marketing methods and carefree use of techno-babble, I still consider Bill to be a friend and genuinely nice guy. I've also been the happy owner of a Santana tandem, I think they are excellent products, and I truly believe that more people are riding tandems today BECAUSE of all that Bill has done. But, at the end of the day, there is no such thing as "the best tandem" or "the right way to build a tandem"; instead, let me suggest that there is only one thing that matters and that is finding the right tandem that is the best for each team's individual needs.

    "Mark climbs back off of his soap box".


    Quote Originally Posted by SDS
    I highly recommend Meridian Tandems, particularly for custom tandem purchases.
    I have also done so in the past but, of late, I'd:

    1. make a minimal deposit against a firm-fixed price for the final product,
    2. be sure to get a firm delivery commitment date;
    3. attach cost reduction penalties tied to late delivery, e.g., deduct $100 for each week past the delivery commitment, and
    4. would be clear that final payment would only be made upon delivery, less any price reductions for late delivery penalties.

    I've had some great discussions with Jim in the past and his company turns out some outstanding products, but more recently he has been difficult to get a hold of and many customers, while very happy with their tandems, have experienced delays with little if any proactive notification by Meridian. Not sure what's going on, other than the burdens associated with running a small business in the bicycle industry.

    I've not purchased a Meridian, but have purchased several custom bikes and tandems and have gone through the waiting game coupled with a cash-strapped builder. It's not fun, but you never want to surrender leverage and your money is your leverage. Give as little of it up-front as possible when purchasing bikes (or anything else for that matter).
    Last edited by livngood; 01-01-04 at 02:12 PM.

  4. #4
    Senior Member Caval„o's Avatar
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    Wow, this is a great thread... I actually found it searching for something else but so glad I did. I would even recommend the meat of this thread be posted as a sticky...

    On our current tandem, the stoker compartment is far too small for my 5'6" stoker to get close to what I would call a fast road position (4+" drop to bars, flat back, etc.), even with ridiculous setback and a 100mm stem (and where would her head go?). I figure, no biggie we will deal with it for now and then upgrade to a newer tandem later (I use a 150mm stem and TT length is still short of ideal for me too). I want something that will fit me like my road racing singles, and be like the back car seat for the stoker... fits my stoker well, but could also accommodate a larger male stoker if needed.

    I started to look at the Co-Motion geometry for the 23/20 size closely... WTF, the stoker's effective TT is the same as what we already have? So then I notice it is the same for all sizes... oh must be a typo I figured. Now that I see this thread I look at some other builders and low and behold, they are pretty much all the same... why bother even listing a stoker "size" then...

    Well, looks like I will be sticking with Tsunami, or going custom eventually.

  5. #5
    Senior Member Caval„o's Avatar
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    This is more like it:



  6. #6
    Senior Member zonatandem's Avatar
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    After your team's first experience with tandem ownership, you learn some lessons. What you like/don't like and what to change.
    That's why after our first French production tandem in 1975, we decided to design our own tandems and have a qualified custom builder tackle the job. Have been happy tandemists ever since.
    To you have a twicer that fits the team properly is worth the xtra cost for custom; we've kept/ridden each of our 3 past custom tandems all for over 56,000+ plus miles and have 20,000+ on our present custom c/f 2-seater.
    As to the cowhorn bars, Kay always prefered drop bars with round handrests. While we used to ride lots in the drops decades ago, our older bods prefer a bit more upright position now.
    Have had folks tell us 'we like cowhorns for stoker instead of drops' they are usually at a loss to explain why. We've told more than one couple . . . 'easy; get out the hacksaw cut off the drops and flip the bar over.'
    Burley actually used chopped off alu drops when they first introduced cowhorns.
    Not too many tandemists get into time trialing on a regular basis.
    Just our observations . . .
    Pedal on TWOgether!
    Rudy and Kay/zonatandem

  7. #7
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    At a traffic light I have one foot clipped in and one foot on the ground. The bike is leaning against my leg. Lets call that the pivot point. Measure from the pivot point to the stokers seat post. Now, measure from the pivot point to above the front axle. The ratio of the distances is the mechanical advantage the weight of the stoker has. On a tandem where the stoker is close there is no problem. On a tandem where the stoker has a lot of room I some times have to push down on the handle bars to keep the front wheel on the ground. We like to have the stoker remain clipped in to make for a faster take off. We may have to change this for the tandem with more room.

    Every change in design is a trade off.

    We have one tandem with cow horns and one with dropped bars. My stoker still isn't shure which is better. Maybe next year we will change one, maybe not.
    Last edited by rfutscher; 09-12-08 at 09:59 AM.

  8. #8
    pan y agua merlinextraligh's Avatar
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    Cow horns give at least 3 effective positions.

    Drop bars essientally give one more postion (arguably 2).

    My experience riding a TT bike with cowhorns, I don't see the problem with the number of hand positions with cowhorns.

    As for aerodynamics, the stoker can bend their elbows and get as low with cowhorns, as with drop bars.

    And the weight difference is not inconsequential. The bars are lighter to start, and the Cane Creek stoker pegs that shipped with our bike are friggin heavy.

    To me, I think it's largely a personal preference. But if the stoker is comfortable with the cowhorns, there's a definite weight advantage.
    You could fall off a cliff and die.
    You could get lost and die.
    You could hit a tree and die.
    OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.

  9. #9
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    My wife and I rode MTR over Labor Day weekend and I noticed how most of the stokers sat up on their tandem and probably did not duplicate their single bike positions. It is also apparent in the MTR pictures. Yet, tandem frame builders seem hesitate to build longer stoker compartments. Bicycle frame construction has many compromises but cost and tube availability may be the underlying reasons.
    Sheldon
    Greenfield, IN

  10. #10
    Senior Member swc7916's Avatar
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    Quote Originally Posted by rfutscher View Post
    At a traffic light I have one foot clipped in and one foot on the ground. The bike is leaning against my leg. Lets call that the pivot point. Measure from the pivot point to the stokers seat post. Now, measure from the pivot point to above the front axle. The ratio of the distances is the mechanical advantage the weight of the stoker has. On a tandem where the stoker is close there is no problem. On a tandem where the stoker has a lot of room I some times have to push down on the handle bars to keep the front wheel on the ground. We like to have the stoker remain clipped in to make for a faster take off. We may have to change this for the tandem with more room.
    What?!?!?!?

    How short does the stoker compartment have to be for there to be "no problem"? And: Are you saying that the front wheel comes off of the ground if the stoker compartment is too long? I don't think that stoker compartment length has anything to do with it; otherwise, how does the captain of a triplet or longer hold the front wheel on the ground?

    The main mechanical advantage that the weight of stoker has is the height from the ground; that is, a higher center of gravity will tend to cause the the bike to rotate along an axis front-to-back and parallel to the ground (in the airplane biz we call this roll.) This will cause the front wheel to feel like it's lifting up and moving away from you.

    I stop in a similar way, but along with leaning the toptube against my leg (in my case, the left) I also jam the nose of the seat into my hip (butt, actually) so that I am kind of wedged in and I don't have to depend on arm or leg strength to deal with any movements my stoker may make while we're waiting.

    Edit: I wrote this kind of hastely and upon thinking more about it, realized that because the weight bias is so far to the rear (after all, the only one sitting on the bike is the stoker) the front wheel will lift if the stoker leans too far either way because the only two supporting points are the captain's leg and the rear wheel. This makes my statement regarding triplets invalid, since the weight is distributed more evenly fore and aft. With a shorter rear top tube, the stoker stem is shorter and in some cases is actually under the captain's seat. This forces the stoker forward and down, lowering the center of gravity. When the rear top tube is lengthened, the stoker's bar can be positioned further back and up. This allows the stoker to sit up higher and raises the center of gravity, which in turn affects how difficult it is to hold the tandem up at a stop. On our tandem, the stoker's bars are about 3 inches in back of and level with or slightly higher than the captain's seat.
    Last edited by swc7916; 09-12-08 at 01:55 PM.

  11. #11
    Senior Member 72andsunny's Avatar
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    Quote Originally Posted by zonatandem View Post
    Have had folks tell us 'we like cowhorns for stoker instead of drops' they are usually at a loss to explain why. We've told more than one couple . . . 'easy; get out the hacksaw cut off the drops and flip the bar over.'
    Our first (used) Santana came with these 80s style drop bars. I'm not sure how to describe them: they were narrow at the top ("inside" the hoods) and wider in the drops. The stoker's bars had no pegs. I was having a little work done on it shortly after buying it, and was surprised to see that the tandem friendly bike shop had stoker pegs...the owner convinced me how uncomfortable the old handlebars would be. I ended up replacing the front bars with a new set (and also new brake levers because aero is cool), and the shop cut the stoker bars into cowhorns. My $500 bike became a $700 very quickly...it was never terribly comfortable for either of us, but we managed a few thousand miles before taking the plunge.

  12. #12
    Senior Member zonatandem's Avatar
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    72andsunny
    The bars you describe were likely Nitto Randonneurs.

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