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  1. #1
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    what are my choices

    HI,
    We've been tandeming for 3-4 years,...and we, well,..ok,..me primarily,...want to purchase a new lighter more modern bike. We are putting in consistently more miles,.. and we are going to start doing some longer rides. We'll get a non-lateral frame, and I will most likely build it up myself. I'm wondering who makes non-lateral frames. I'm familiar with Co-Motion's Macchiata (sp), but my preference would be to find a smaller builder. I know Bilenky makes great bikes, (our current bike)...but apparently he's still dedicated to the traditional design. Paketa will certainly be an option,..but are there others? I know Dave, on this forum,...sorry can't remember your last name.

    THANKS ahead of time if you have other ideas for me!!

    Rich

  2. #2
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    Search, in this part of Bike Forums, for "open frame" -- you'll find a few appropriate threads with makers' names.
    Bohemian, Co-mo, DaVinci, Paketa and others will likely come up

  3. #3
    hors category TandemGeek's Avatar
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    Calfee Tetra Tandem (Standard & Custom / Carbon)
    Paketa V2 (Standard & Custom / Magnesium)
    daVinci In-2-ition / joint-venture (Standard / Steel, Alum, Carbon)**
    Co-Motion Macchiato (Custom Only, Alum)
    Co-Motion Periscope Hammerheard (Small or Large, Alum)
    Bohemian (Custom Only, Steel, ???)

    ** Probably need to consult daVinci to determine which materials can be used for open frame design.

    There are obviously other builders who "could" fabricate a tandem without a lateral tube, but the over riding question will be related to your goals for that tandem and can be constrained by your intended use. For example, some of the open-framed designs have an upper weight limit and are not designed to support loaded touring, etc. so best to discuss your needs with a dealer or builder... which you have apparently done with Stephen or others at Bilenky.

    IMHO, an open frame design "could" provide a team with a lighter, more responsive, and less expensive tandem. Then again, if the design isn't well matched to the team's actual intended use or size, it "could" prove to be a less than ideal tandem. Within the next several months we'll be in a better position to comment on just how well a open framed, coupled tandem performs in contrast to two conventional steel tandems with internal tubes sharing similar dimensions: one with couplers and one without.
    Last edited by TandemGeek; 10-10-07 at 10:44 AM.

  4. #4
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    THANKS for the feedback TGeek. I'm familiar with the builders you mentioned, well, familiar in that I've seen them in previous posts and have seen most of their bikes. We are a 265-275lb team with absolutely no interest in self contained touring. I'm an older racer,...now riding in Masters,..although not really racing much the last couple of years, partly thanks to our enthusiasm for the tandem. We enjoy riding 30-60 miles, and like so many other on this forum, ride centuries occasionally. I figure a compact, open design would indeed save some weight and make for a pretty responsive bike.

    I'll look forward to your observations of the steel open designs you'll be riding.

    I was really just wondering if there are builders of tandems, experienced in tandems, I'm thinking Richard Sachs type builders. I'm sure David Bohm would fit,..and possibly he's the only small builder experienced in the tandem world.

    Anyway,...thanks for the feedback!!

    Rich

  5. #5
    Senior Member zonatandem's Avatar
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    Being a lighter team, any of the open framed tandems could work out.
    Calfee/Macchiatto/daVinci/Bohemian would be well under 30 lbs; Paketa around 22lbs. A newish builder is on the scene with the LUST.
    Athough weight cerrtainly is not the only criteria.
    Know David Bohm and his Bohemian bikes are custom only with incredile lugwork if you want it . . .every bit as good as Sachs'.
    Sadly our friend Bob Davis of Zona Tandems has quit taking orders due to health reasons; however he 'may' have an open frame still in stock.
    Pedal on TWOgether!
    Rudy and Kay/zonatandem
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  6. #6
    Senior Member
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    Thanks Rudy,...I'll send Bob an email.

    Really ridiculous,..but the name "LUST" just doesn't do it for me,..well,..at least for my bike.
    Of course I could always delete the decals.

  7. #7
    hors category TandemGeek's Avatar
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    It's not an open frame, I don't know squat about it, nor do I know if it is the right size, but I can tell you that just based on the asking price this Calfee Tetra looks pretty tasty:

    http://phoenix.craigslist.org/bik/440268336.html

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    Dang,..that would be really ideal,...although the size is way too small. My road bike has a 58cm top tube,...so I'd need to put some top tube extenders to make it work. I've never ridden a carbon bike,..well, never for any extended distance. I have packed up a couple,..and they definately feel really cool!

    Tgeek,..THANKS for the idea!

    Rich

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    Senior Member zonatandem's Avatar
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    . . . and carbon rides even nicer than it looks!
    Just our opinion/experience.

  10. #10
    Senior Member ftsoft's Avatar
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    Quote Originally Posted by TandemGeek View Post
    Although I didn't specify, the open framed tandem will be a coupled carbon model from Calfee.

    The baseline for comparison will be our two steel Erickson tandems with internal tubes: the non-coupled one which we still own and the coupled-one that we recently sold to help fund the Calfee. The Calfee will share similar dimensions and geometry with the Ericksons, although the Calfee will have shorter rear chainstays and we've also shortened the stoker compartment from 31.5" to 30". Aside from that, and less the internal tube, they'll have a very similar profile.

    We too are a smaller than average size team: I'm 5'8" and Debbie's 5'2" and we have a combined weight under 280lbs. Not exactly an acid test of the open frame design.
    TandemGeek - What exactly is an "open frame"? If it is, indeed, a frame without a lateral, then wouldn't it be less stiff? It seems to me that, just as with single bikes, weight is not that important (within reason), but with a tandem it would seem that stiffness is pretty important.

    Frank

  11. #11
    Senior Member swc7916's Avatar
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    Why are you fixated on a non-lateral frame? There's a reason for that tube - Doing without some kind of internal bracing will require beefing up the frame somewhere else, primarily through larger-diameter tubing.

  12. #12
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    Calfee Open Frame

    swc7916, done right, I think an open frame can be cheaper (particularly if you want couplers), lighter, and plenty stiff. I also think they look better, have posted this pic here before, but here again is a picture of our new Calfee tandem. Yes, top tubes and bottom boom are chunky, but you would have to have a very knock-kneed pedaling motion for that to be an issue.

    We are a 295 pound team, frame is a 64/52, and though we are not hard core cyclists we are both pretty fit and can put some decent power out occasionally, and I assure you that frame flex is not an issue. I do not have a lot of experience with tandems (200 miles now), but find the Calfee to be quite stable, and also quite responsive, climbing and zipping around turns.

    vtrich, I don't know if Calfee is smaller than Co-Motion, I do not think he has a huge operation, but I do think he knows bikes, including tandems, and you will get personal attention from him.

    If you don't care about couplers, one other builder we considered was Habanero. We have a couple of singles from him, they are straight gauge titanium, not the lightest in the world (my 62cm single is just under 20lbs, DA build, basic wheels), but sturdy and functional. He gets his frames made in China, but they look great and perform well. You could actually do a custom ti frame from him for less than kilobucks (but not an open frame, I suspect).
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  13. #13
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    Fixated,...yeah,..suppose I am. Aestetics,..they look much nicer, well to me. More efficient as well,..oh and lighter. Back in the 70s, I had a Colnago tandem, non-lateral bike, and it was certainly not the stiffest,..but deflection was never enough to be a problem,..and I figure with better materials etc., they should be fine.

    ...and mb,....your bike is really great looking,...and as Zona says,...it must ride great!

  14. #14
    hors category TandemGeek's Avatar
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    Quote Originally Posted by ftsoft View Post
    TandemGeek - What exactly is an "open frame"? If it is, indeed, a frame without a lateral, then wouldn't it be less stiff?
    Yes, open frame = no internal tube (aka, no lateral tube). As for stiffness, I guess we'll find out... and we sure do hope everyone appreciates our charity in taking on this experiment for y'all at great personal expense.

    Seriously, all other things being equal, if you simply removed the internal tube from a conventional tandem it should be a lot less stiff... which would be a bad thing. However, all things aren't always equal, to include rider weights / sizes and frame designs. Moreover, having an internal tube or other bracing doesn't guarantee a tandem will be stiff either. Remember, it's the skill and knowledge of the designer/builder + materials + material specs + design + the execution of the design against a known set of rider specifications that will yield a frame with the desired ride and handling characteristics.

    We're fortunate in that, as already stated, we're smaller than average sized adults. So, in some respects, a stock production tandem that is built to handle a a pair of 6'2" adults with a combined weight of 450lb is certainly over-built for us. This was true for riders in the 1890's and remains true for many folks today. Therefore, the challenge for the tandem frame designer and builder was, and still is, achieving a sufficient amount of frame stiffness for a given client.

    Now, if you build several hundred to nearly 1,000 tandems a year, you'll want as little variability as possible in your materials and designs so that you can leverage the economies of scale. Therefore, your "baseline" specifications for your production tandems will have to be robust enough to address the full-range of possible riders who could end up buying one of your tandems. Hence, a notional 280lb team will end up riding a tandem designed for the aforementioned notional 450lb team (plus safety margin on top of that), regardless of whether they needed that internal bracing and other robustness or not, i.e., one size fits all. This is a smart way to build your tandems if you're using mass production / batch building and it's really not a bad thing for buyers either. Sure, small teams end up with tandems that are over-built, but that's better than putting teams that are too large on tandems that aren't beefy enough, and the costs / waiting time for buyers are usually less than they would be for a custom built bike.

    Now, once you enter the realm of the semi-custom or custom bike things can become a bit different. The designer/builder now has the advantage of knowing exactly what the size and weight of the riders will be, along with information about how the bike will be used. If the team is small, won't be doing loaded touring, nor even attaching mud guards or a rear trunk rack, chances are the designer will build the frame differently than he would for a much larger team who intends to do fully loaded, self-supported touring and who needs eyelets for racks, mud guards, and the kitchen sink. For example, given the very long stoker compartment we have asked for, we were faced with the prospects of a 2" top tube vs. the standard 1 3/4" that is used on the Tetra Tandem. However, as we played around withthe specifications, some give and take yielded a workable solution for the standard size. In other words, more often than not, high-end custom frame design is a bit more precise than scoring in horseshoes and hand grenades.

    So, getting back to your question, will it be "less stiff"? No, it will be exactly as stiff as Craig intends it to be to deliver the ride characteristics that he thinks will suit our size, stated needs, wants, and desires. If we find it to our liking and we don't find ourselves thowing the sync chain honking out of the saddles on a steep climb or, conversely, knocking our fillings out on cobbles, then it really doesn't matter if it's more or less "stiff" than our current tandem or any other tandems we could have acquired in its stead. And, here's the really cool thing about Craig's frames: if for some reason it is simply too whippy or too stiff, it can be reworked. Now, to be frank, based on what I know about Craig's design for our tandem and his ability to execute that design, I'm quite confident it will be just fine 'right out of the box'.
    Last edited by TandemGeek; 10-12-07 at 05:47 AM.

  15. #15
    Senior Member ftsoft's Avatar
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    Thanks for the info.

  16. #16
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    TG, your description of the new bike is precisely what I am aiming to do, sans the couplers.
    Looking forward to your observations. What do you think you'll see as a weight difference between the two? Recognizing there will be a weight difference,..will that influence your choice for gearing and will your components be pretty much the same? My current Bilenky weighs in at 42lb, that 12 - 14lb. difference is really appealling, especially recalling our slug up some of our local "hills."

  17. #17
    hors category TandemGeek's Avatar
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    Quote Originally Posted by vtrich View Post
    What do you think you'll see as a weight difference between the two? Recognizing there will be a weight difference,..will that influence your choice for gearing and will your components be pretty much the same?
    With pedals, saddles, and water bottle cages attached, our smallish coupled steel Erickson was 38 lbs and the uncoupled Erickson is 35 lbs, both have Alpha Q carbon forks which shaved about 1.2 lbs off of each bike. I'm guessing the equally smallish tandem which will also have the Alpha Q fork will be around 30 lbs, but that's just a conservative guess based on back-of-the-envelope analysis. Of course, those weights are rendered somewhat meaningless once you strap seatpacks with a multi-tool, spare tube, spare tire, a frame pump, and four water bottles to the bike, never mind excess rider weight.

    The components will be similar to our current tandems.
    Last edited by TandemGeek; 06-09-08 at 05:38 PM.

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