Advertise on Bikeforums.net



User Tag List

Results 1 to 24 of 24
  1. #1
    Senior Member
    Join Date
    Oct 2009
    Posts
    930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Speed of old tandems vs new?

    Has anyone done any testing, or noticed how the old tandems compare to the new for speed on a flat road.
    I am referring to the difference in the stoker top tube length. Some of the older tandems are much shorter here and I was wondering if they had better aero with the stoker closer to the captain. We have an old Bob Jackson racing tandem that we used for a long time (18yrs) but also got a C'dale RT3000 a couple of years ago. My wife likes the extra room back there and it is definitely stiffer in the bottom bracket, but I have a feeling the old BJ might be at least as fast or maybe faster. It is in parts at the moment but when it is back together I will do a bit of testing.

  2. #2
    Tandem Vincitur Ritterview's Avatar
    Join Date
    Sep 2005
    Location
    Northern California
    My Bikes
    BMC Pro Machine SLC01, Specialized Globe, Burley Rock 'N Roll tandem, Calfee Dragonfly tandem.
    Posts
    3,226
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Dean V View Post
    I am referring to the difference in the stoker top tube length. Some of the older tandems are much shorter here and I was wondering if they had better aero with the stoker closer to the captain.
    There are so many variables, knowing what to attribute any speed difference to would be difficult. Scrunching up the stoker might affect stoker contentment, which likely has a non-linear negative effect on stoker power output.

  3. #3
    Charles Ramsey
    Guest
    Tandems are roughly 1.2 times faster than singles. For a simple calculation if you double the horsepower this means the effective frontal area is multiplied by a factor of 1.1574. Here is the simple equation 1.2^3=2/1.1574 If you scrunch up together the effective frontal area is multiplied by 1 and you will only be going 1.26 times faster than singles. For a small change in top tube lenght say one inch a linear model will not produce too much error. Say you are 15.74 inches apart and you move to 16.74 inches apart then the frontal area is multiplied by 1.1674 this will mean you are going 1.196566 times as fast as a single. This is about .03 mph at 10 mph. Tailwind used to advertize their panniers effectivly reduced the frontal area of a single. Then someone did a test and found a lot of pannier brands did the same thing.
    Last edited by Charles Ramsey; 10-25-09 at 04:07 PM.

  4. #4
    Senior Member
    Join Date
    Oct 2009
    Posts
    930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    The stokers top tube on the Bob Jackson is 22.5" centre to centre. The C'dale is 28.25".

  5. #5
    MB1
    MB1 is offline
    DisMember
    Join Date
    Feb 2002
    Location
    Washington DC & Clermont FL
    My Bikes
    Waterford RS22 Gearie, Waterford RS22 Fixte, Rivendell Rambouillet, Trek Madone5.5, Santana Beyond, GT Zaskar
    Posts
    183
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Depends on how old or new the riders are.

  6. #6
    Senior Member rdtompki's Avatar
    Join Date
    Nov 2008
    Location
    Hollister, CA
    My Bikes
    Volagi, daVinci Joint Venture
    Posts
    3,941
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    My perception riding with my 6' tall son as stoker is a loss of aero advantage versus my 5'6" tall wife. Of course his extra power output more than makes up for the difference. My wife can't see around me at all, my son can see over my shoulder. I'm sure when I'm in the drops into a headwind he's catching a lot of air. I would think getting the stoker in the shadow of the captain is really the issue, not the top tube length (although they do interact).
    Rick T
    --------
    Volagi - Triple"ized" and Tubeless
    daVinci Joint Venture

  7. #7
    Senior Member WebsterBikeMan's Avatar
    Join Date
    Jun 2008
    Location
    Just outside Kitchener, Ontario
    My Bikes
    Nishiki Continental, Bilenky custom travel tinker, home built winter bike based on Nashbar cross frrame
    Posts
    622
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by rdtompki View Post
    My perception riding with my 6' tall son as stoker is a loss of aero advantage versus my 5'6" tall wife. Of course his extra power output more than makes up for the difference. My wife can't see around me at all, my son can see over my shoulder. I'm sure when I'm in the drops into a headwind he's catching a lot of air. I would think getting the stoker in the shadow of the captain is really the issue, not the top tube length (although they do interact).
    Exactly. And the interaction may, for some stokers, be that if the top tube is too short, they can't get as low without the Pauli Exlcusion principle getting in the way (meaning their head and some part of the captain's body need to occupy the same space). I suspect that the optimum top tube length from a speed/wind resistance point of view, be the one that allows the stoker to get in a low tucked position without the need for inter-penetration.

  8. #8
    Senior Member
    Join Date
    Nov 2006
    Posts
    787
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It depends what distance you are riding and the the terrain.
    Short and flat maybe the Jackson is faster by a small amount.
    As distance and hills increase fatigue maybe become a big factor and the bike that the least stoker fatigue would win. I remember the first tandem I ever wanted was a Mercian. I saw one and thought it looked awesome. So I ordered one through my LBS and waited over a year and then was told Mercian was not building any until they got more orders. Sadly I had to cancel the order. My first tandem was built by Andy Gilmour in Arizona. I did own a Mercian single bike for a time and it was one the nicest rding steel bikes I ever had.

  9. #9
    pan y agua merlinextraligh's Avatar
    Join Date
    Aug 2005
    Location
    Jacksonville
    My Bikes
    Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er
    Posts
    27,363
    Mentioned
    10 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by WebsterBikeMan View Post
    Exactly. And the interaction may, for some stokers, be that if the top tube is too short, they can't get as low without the Pauli Exlcusion principle getting in the way (meaning their head and some part of the captain's body need to occupy the same space). I suspect that the optimum top tube length from a speed/wind resistance point of view, be the one that allows the stoker to get in a low tucked position without the need for inter-penetration.

    If you look at purpose built TT tandems, there appears to be some support for that belief. There's a picture posted here before with a tandem with a very long stoker top tube, and aero bars mounted to the top tube.

    Getting the stokers arms in and back flat in all likelyhood is going to be faster than a more up right position, even if that position is closer laterally to the captain.

    Just anecdotally, when my stoker gets down in the Cane creek speed bars, which give her a pretty flat back, and hands in just wider than the stem, it's worth about .5mph with the same perceived effort.
    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.

  10. #10
    Senior Member
    Join Date
    Mar 2008
    Posts
    53
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by merlinextraligh View Post
    ....................
    Getting the stokers arms in and back flat in all likelyhood is going to be faster than a more up right position, even if that position is closer laterally to the captain.

    Just anecdotally, when my stoker gets down in the Cane creek speed bars, which give her a pretty flat back, and hands in just wider than the stem, it's worth about .5mph with the same perceived effort.
    My stoker has back problems and can't get down into the flat back position. She does report that she has less wind noise in her ears with our short tandem. Besides she likes to look around and enjoy the scenery.

  11. #11
    Tandem Vincitur Ritterview's Avatar
    Join Date
    Sep 2005
    Location
    Northern California
    My Bikes
    BMC Pro Machine SLC01, Specialized Globe, Burley Rock 'N Roll tandem, Calfee Dragonfly tandem.
    Posts
    3,226
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by merlinextraligh View Post
    If you look at purpose built TT tandems, there appears to be some support for that belief. There's a picture posted here before with a tandem with a very long stoker top tube, and aero bars mounted to the top tube.
    I came across some interesting photo's on Flickr of purpose-built tandem track bikes, from the British Nationals. The top tubes don't look particularly long.







    Also, a tandem track video here.

  12. #12
    pan y agua merlinextraligh's Avatar
    Join Date
    Aug 2005
    Location
    Jacksonville
    My Bikes
    Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er
    Posts
    27,363
    Mentioned
    10 Post(s)
    Tagged
    0 Thread(s)
    These were the ones I was alluding to:





    I would think that a track tamdem, presumably used for different events, is going to have different design considerations, than a tandem built for the specific purpose of going fast over a 40k road tt.
    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.

  13. #13
    Tandem Vincitur Ritterview's Avatar
    Join Date
    Sep 2005
    Location
    Northern California
    My Bikes
    BMC Pro Machine SLC01, Specialized Globe, Burley Rock 'N Roll tandem, Calfee Dragonfly tandem.
    Posts
    3,226
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by merlinextraligh View Post
    I would think that a track tamdem, presumably used for different events, is going to have different design considerations, than a tandem built for the specific purpose of going fast over a 40k road tt.
    Those do look aerodynamic. We can also look at what appears to be a standard sized new Calfee ridden by Canadian Paralympian (VI) Brian Cowie (at Kona IronMan with a blazing cycling time) although I think he uses this for road races as well.






  14. #14
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,154
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Just some food for thought in terms of what might influence tandem frame design...

    1. You don't suppose that track tandem stoker compartments are short for some other reason such as frame stiffness?
    2. You don't suppose the very nature of a track tandem event places LESS emphasis on having a stoker position that affords long-term comfort and more on a stoker position that affords better power transfer over short duration maximum efforts.
    3. You don't suppose that sight or hearing impaired stokers might prefer to be closer to their captains so they can hear audible prompts or get a better feel for the captain's movement.

    There's a completely different set of "you don't supposes" that can be applied to dedicated time trial tandems as well as to why so many tandems that show up at events like the Co-Motion classic are simply stock tandems.

  15. #15
    pan y agua merlinextraligh's Avatar
    Join Date
    Aug 2005
    Location
    Jacksonville
    My Bikes
    Wilier Zero 7; Merlin Extralight; Co-Motion Robusta; Schwinn Paramount; Motobecane Phantom Cross; Cervelo P2; Motebecane Ti Fly 29er
    Posts
    27,363
    Mentioned
    10 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by TandemGeek View Post
    There's a completely different set of "you don't supposes" ... as well as to why so many tandems that show up at events like the Co-Motion classic are simply stock tandems.
    Not the least of which is money. You'd have to be pretty seriously into tandem racing to have a road racing tandem, and also have a second tandem specifically built as a TT bike.

    And having flown to the race, I could not imagine the logistical nightmare of getting 2 tandems there. and traveling from stage to stage with 2 tandems on a rental car.

    I think even at Master's nationals, for the most part people of using regular road tandems, with some aero add ons, such as clip on bars.
    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.

  16. #16
    Senior Member
    Join Date
    Oct 2009
    Posts
    930
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    There certainly are a lot of variables to consider. For both stoker and captain to be right down with their backs near horizontal like on the white TT tandem you do need a long bike. To my way of thinking this would be the most aero. But in saying that I have seen solo TT and pursuit riders at world class level that are not as low as this, say with their torso at about 15 deg from horizontal, and the position you are in most of the time for a road race is even higher again. On a tandem this would allow the stokers head to be above the captains backside/lower back, shortening the bike up somewhat.
    I definitely want to ride a few TTs on both our bikes and maybe some coast down tests as well. At least then I may find out what works for us.

  17. #17
    Tandem Vincitur Ritterview's Avatar
    Join Date
    Sep 2005
    Location
    Northern California
    My Bikes
    BMC Pro Machine SLC01, Specialized Globe, Burley Rock 'N Roll tandem, Calfee Dragonfly tandem.
    Posts
    3,226
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by TandemGeek View Post
    There's a completely different set of "you don't supposes" that can be applied to dedicated time trial tandems as well as to why so many tandems that show up at events like the Co-Motion classic are simply stock tandems.
    Even if this tandem was a dedicated time-trial /triathlon tandem , you'd need either the manufacturer (Calfee), or the purchaser, to push the idea of a long/aero stoker compartment, and so overcome the inertia of the stock frame design. This isn't usually likely to happen.

    According to Brian, he likes the Calfee:

    Quote Originally Posted by Brian Cowie
    Our new custom carbon tandem by Calfee Design. This is the best tandem I have ever ridden. Very fast. We were easily cruising at 45 km/h [27.96 mph] today.
    On the actual 112 mile Kona route, their time was 5:14, averaging 21.4 mph. The fastest bike time was 4:25:11 (25.5 mph).

  18. #18
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,154
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by Ritterview View Post
    Even if this tandem was a dedicated time-trial /triathlon tandem , you'd need either the manufacturer (Calfee), or the purchaser, to push the idea of a long/aero stoker compartment, and so overcome the inertia of the stock frame design. This isn't usually likely to happen.
    Would you like to try running that by us once more, but this time in plain speak.

    I'm having a hard time connecting the dots from what you quoted in my earlier post, to the point you're trying to make which, on it's own merit, makes no sense, i.e., what the heck is 'the inertia of the stock frame design'?

    Moreover, what does that have to do with what appears to be the somewhat longer than stock Calfee that Cowie and his pilot ride? I'm pretty sure that to a person, we all like our Calfee tandems and think they are the best tandems we've ever ridden. Just looking at the 'team' bike he was riding in Beijing, I can only imagine how much more comfortable he is on the plastic-fantastic.
    Last edited by TandemGeek; 10-26-09 at 09:17 PM.

  19. #19
    Tandem Vincitur Ritterview's Avatar
    Join Date
    Sep 2005
    Location
    Northern California
    My Bikes
    BMC Pro Machine SLC01, Specialized Globe, Burley Rock 'N Roll tandem, Calfee Dragonfly tandem.
    Posts
    3,226
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Geez, it wasn't that cryptic. Since the long-stoker aero frame is out of the ordinary, if neither the manufacturer nor the customer initiates that the frame is to be different, the stock frame will likely be produced. There is inertia behind the stock frames.

    So, we can't conclude from the use of stock frames by dedicated racers, be they track or triathlon, etc., that the stock frame is aerodynamically ideal. It might just be all that is likely to be produced.

    I don't know if the Calfee that Cowie uses is any longer than usual. The obvious thing for a male stoker would be to order a large/large.

    When I was visiting the Calfee factory in May, I took some pictures of the frame as it was being shipped out. Can we tell anything from the numbers?




  20. #20
    Senior Member zonatandem's Avatar
    Join Date
    Dec 2003
    Location
    Tucson, AZ
    My Bikes
    ariZona carbon fiber tandem & single
    Posts
    10,035
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    jnbrown:
    Have ridden a couple of Andy Gilmour's tandems; he's had one of his custom tandems used in the Paralympics with a very tall blind stoker a few years back.

    Our first custom tandem in 1977 (60 and 1/4"" wheelbase, 34 lbs) was built for speed. Yes, we were faster on the flats then than we currently are, but heck that's over 3 decades ago! Our wheelbase is now a stretched out 63 1/2".
    Longer stoker compartments might be needed for some stokers, but Kay is 4' 10 3/4" tall does not need that.
    When we time-trialed she'd rest her head sideways against my backside and hammered.
    We always had a 'do-it-all tandem'; used for daily rides, centuries, tours, time trials and track.
    Specialization is nice but could not afford, or want, special tandems for each event.
    After all the advantages in equipment is the two riders that count the most.
    Pedal on TWOgether!
    Rudy and Kay/zonatandem

  21. #21
    hors category TandemGeek's Avatar
    Join Date
    Jan 2002
    Posts
    7,154
    Mentioned
    0 Post(s)
    Tagged
    1 Thread(s)
    Quote Originally Posted by Ritterview View Post
    Geez, it wasn't that cryptic. Since the long-stoker aero frame is out of the ordinary, if neither the manufacturer nor the customer initiates that the frame is to be different, the stock frame will likely be produced. There is inertia behind the stock frames.
    Good grief, that's even more cryptic. However, I believe what you're trying to say in some type of obscure techno-speak is:

    Since most stock tandems use a standard length rear stoker compartment, that's what most buyers will end up with unless the builder or the customer have figured out they may want or need a custom frame. Therefore, most tandems are sold in stock sizes as it's more cost effective for the builder and the average tandem buyer who really doesn't need a custom frame.

    Or, to be more succinct: Most tandems are built using stock sizing.

    Yes, that's absolutely true and it appears as though Cowie's Calfee may or may not be a custom, per se. I say that noting even 'stock' Calfee tandems are 'built to order' and it's rare for any two to be alike. The same is true for nearly all boutique tandems that are built to order.

    Quote Originally Posted by Ritterview View Post
    Can we tell anything from the numbers?
    There's that pedagogical-sounding 'we' again... but, yes: It would appear to be a Large/Medium Tetra & the 305th tandem built by Calfee, just two frames ahead of osurxbiker's custom-sized coupled Tetra #307 which was delivered in early June.
    Last edited by TandemGeek; 10-27-09 at 07:50 AM.

  22. #22
    Gear Combo Guru Chris_W's Avatar
    Join Date
    May 2007
    Location
    Switzerland
    My Bikes
    Spec' Tarmac (road), Spec' Secteur Disc (commuter & tourer), Salsa Mamasita (MTB), CoMo Speedster (tandem), Surly Big Dummy (cargo), Airnimal (folder), a train pass, and NO car :)
    Posts
    2,066
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    While debating how long the top tube should be to maximize aerodynamics, I'm surprised that no-one has mentioned that the way to make the fastest tandem would be to make a recumbent tandem. Recumbent singles can easily go faster than upright bikes, so I assume that it would be the same for tandems.

  23. #23
    Senior Member
    Join Date
    Dec 2005
    Location
    Brighton, UK
    My Bikes
    Rocky Mountain Solo, Specialised Sirrus Triple (quick road tourer), Santana Arriva Tandem
    Posts
    1,546
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Just to chime in, because I'm reading Bikeforums and don't know any better than to do so

    We started with a very short 'Orbit' which in its day was a good one. Discomfort and twiddly characteristics made our later 'Santana' seem much faster. In fact, though, on consecutive timed 60+ miles timed rides like London to Brighton or London to Oxford there was no discernable difference. Same legs, same routes, same speeds

    We were much happier and much less beaten up on the newer and longer one, though

    One consistent pattern though, which also presents with skiing

    Good breakfast - fast
    No beer halfway through - slow
    A pint or (for stoker) a marguerita half way through - fast
    More than the above - slow

    OK, this isn't about absolutes or extreme performance, just about a couple of reasonably paced enthusiasts

    To us, a bit more space equals a bit more comfort, and consequentially speed and distance

  24. #24
    Senior Member Homeyba's Avatar
    Join Date
    Jul 2009
    Location
    Central Coast, California
    My Bikes
    Colnago C-50, Calfee Dragonfly Tandem, Specialized Allez Pro, Peugeot Competition Light
    Posts
    3,370
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Chris_W View Post
    While debating how long the top tube should be to maximize aerodynamics, I'm surprised that no-one has mentioned that the way to make the fastest tandem would be to make a recumbent tandem. Recumbent singles can easily go faster than upright bikes, so I assume that it would be the same for tandems.
    To give you a serious answer, there are engineering issues with recumbent tandems. First, DF tandems are actually pretty aerodynamic compared to upright recumbents, more so than single DF bikes. There isn't that big of an advantage. Look at the pics above of racing tandems and look at a racing recumbent tandem (if you can find one). To get some kind of significant aero advantage you'd need to make a lowracer type of tandem. Recumbent tandems are extremely long and very heavy to begin with, a recumbent lowracer would be the better part of 15ft long! That creates all sorts of strength and rigidity issues. Maybe someone has tried to overcome the difficulties and has already built one but I haven't seen it. If you have pics I'm sure w'd like to see one. Personally, I doubt that you will find a tandem recumbent that comes anywhere near the performance of a standard racing tandem.
    It doesn't get harder, you just go slower.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •