Advertise on Bikeforums.net



User Tag List

Page 9 of 17 FirstFirst ... 7891011 ... LastLast
Results 201 to 225 of 402
  1. #201
    PMK
    PMK is offline
    Senior Member PMK's Avatar
    Join Date
    May 2008
    Location
    Royal Palm Beach, Florida
    My Bikes
    2006 Co-Motion Roadster (Flat Bars, Discs, Carbon Fork), Some 1/2 bikes and a couple of KTM's
    Posts
    1,128
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Mirror polished is bad to the bone, if you don't mind the upkeep.

    Not our bike, but a polished Co-Motion would be nice...

    how much percentage does the stoker have in making these choices of paint or polish if they don't work on the bike. Could I just leave the tube sections she can see painted and polish the rest?

    PK
    Attached Images Attached Images
    2006 Co-Motion Roadster, flat bars, discs and carbon fibre fork, size 22 / 19
    2006 Ventana ECDM full suspension mountain tandem
    Some single bikes and a couple of KTM's
    And most important, someone special that enjoys them with me (except the KTM's)

  2. #202
    Senior Member
    Join Date
    Feb 2010
    Location
    Philadelphia area, Pa., USA
    My Bikes
    Santana Cabrio triplet, Santana Fusion S&S tandem, Co-Motion Mocha S&S tandem, Co-Motion Pangea S&S, Co-Motion Nor'wester S&S, C'dale F2000
    Posts
    717
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Unpacking our Santana Cabrio S&S triple from a recent trip, I decided to weigh the bag of chains alone: almost three pounds, just for the chains! Ugh. That's one rear drive train, two timing chains, and one connector chain for the stokid setup. Timing chains are OEM KHS brand, drive chain is Shimano Ultegra/XT level.

    [Edited for very stupid spelling error!]
    Last edited by briwasson; 06-29-10 at 12:42 PM.

  3. #203
    Senior Member
    Join Date
    Feb 2010
    Posts
    202
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Brad that looks GREAT!

    Quote Originally Posted by Brad Bedell View Post
    Total weight after the build: 26lbs 6oz

    Sorry about the fuzzy photo, was too lazy for the tripod and light was very low.

  4. #204
    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
    3,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Visited Calfee this weekend, a rest stop on the Strawberry Fields ride. Checked out their latest show bike.



    The one featured at the Calfee website:



    Ryan told me it was pretty light, so I asked to have it put on the scale.



    Yup, pretty light. It would have been in the 20's with just a non-adjustable stoker's stem.



    Geez, but this is light. I was trying to figure out how so light. There are savings in the double instead of triple, and no left side sync. Okay, but that wouldn't get it to 21 lbs.

    Ah, but it has No-Tube wheels. It turns out the wheels with the Stan No-Tube rims are really light, and there are no innertubes.



    The lightweight Rolf Prima's weigh 1815 grams, and innertubes add another 160 grams.

    (1815 + 160) - 1279 = 696 grams, 1.53 lbs. There is a 1-1/2 lbs weight reduction from otherwise lightweight wheelset and tires.

  5. #205
    Senior Member zonatandem's Avatar
    Join Date
    Dec 2003
    Location
    Tucson, AZ
    My Bikes
    ariZona carbon fiber tandem & single
    Posts
    10,193
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    _DSC3332.jpg
    This may be an old thread . . .
    . . . but we are still pedalin' our Zona tandem with 33,000+ miles on the odo now.

    Weight of tandem, as in this photo (May 30, 2011), custom rack (c/f), 'puter, pump, expandable rack trunk, assortment of tools (including 2 spare tubes), small medical kit, couple food bars, sunscreen, etc + 5 water bottle cages and 4 (empty) water bottles is 32 pounds.
    Our weight: Pilot 137, stoker 105 lbs. Ages 78/76.
    Can hardly wait 'til we get older!!!
    Pedal on TWOgether!
    Rudy and Kay/zonatandem

  6. #206
    Senior Member waynesulak's Avatar
    Join Date
    Jan 2008
    Location
    Ft Worth, TX
    My Bikes
    650B tandem converted from Santana Arriva, Santana Noventa, Boulder Bicycle 700C, Gunnar Sport, Trek TX700,
    Posts
    1,766
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Yeah was old but now it is restarted. Do you have a component listing to post? if not what type wheels? saddles? tires?

  7. #207
    Senior Member zonatandem's Avatar
    Join Date
    Dec 2003
    Location
    Tucson, AZ
    My Bikes
    ariZona carbon fiber tandem & single
    Posts
    10,193
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Compelete_Bike_crop_1.JPGHoK Stoker BB Flash.jpg07 adj stokerstem..jpg

    Zona stuff. . .
    Hubs: Chris King (32H front and 36H rear)
    Eccentric: custom Zona light weight
    BBs: CK
    Rims: Australian Velocity Aerohead
    Spokes: DT Revolution db
    Tires: Maxxis Re-Fuse (folding) 700x25
    Headset: CK No-Thread
    Crankset: FSA triple
    Front Der: Dura Ace
    Rear der: XTR
    Cassette: 11/34 9 speed
    Shifters: D/A barcons
    Front brake: D/A caliper
    Rear brake: Tektro Mini
    Chains: KMC 9 SL
    Pilot stem: Bontrager
    Stoker stem: Custom Zona carbon fiber/adjustable
    with custom bottle mount
    Handlebars: Easton EC90 carbon
    Stoker handrest: Round custom carbon fiber
    Pedals: pilot Shimano /road toeclips
    stoker: Wellgo/mt.bike toeclips
    Saddles: pilot Sella San Marco Integra
    stoker Serfas Curva
    Seatpost: captain Thompson Elite
    stoker c/f (non-suspension)
    QRs: Salsa
    Bottle cages: 3 American Classic; one Hi-E
    Rear rack: Custom carbon fiber
    Other specifics on the frame:
    Custom c/f tubing (made in USA)
    Wheelbase: 63 1/2 inches (about 6 inches shorter than production tandems)
    Handmade lugged frame; lugs have window cutouts.
    Drasctically sloping toptube (to accomodate Kay who is 4' 10 3/4")
    7 bottle mounts (including one each on pilot and stoker's handlebar)
    Custom mount for mini garage door opener on stoker's stem
    Custom pump mount on boobtube
    Custom mount under boobtube to ccarry 2 spare spokes
    Paint: Clearcoat, lugs have black/gold accents
    Builder: Bob Davis @ zonatandems.com in Peoria, AZ

    Photos includes:
    Full bike as delivered (made some minor changes later)
    Lugwork with window cutouts
    Adjustable stoker stem

    Pedal on TWOgether!
    Rudy and Kay/zonatandem

  8. #208
    PMK
    PMK is offline
    Senior Member PMK's Avatar
    Join Date
    May 2008
    Location
    Royal Palm Beach, Florida
    My Bikes
    2006 Co-Motion Roadster (Flat Bars, Discs, Carbon Fork), Some 1/2 bikes and a couple of KTM's
    Posts
    1,128
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    After reading about the tubeless setup, I was again curious about this.

    Pulled up the Stans sight and it appears the same as a while back.

    Anyone willing to admit converting and offer how it works.

    I have been removing some weight from our machine as time and money permits. The best has been reduction of each riders weight, but still I have removed a decent amount of weight for short money.

    Tubeless would be an easy swap and claims 12%, which I'm sure is an up to 12% faster roll.

    So anyone?

    PK
    2006 Co-Motion Roadster, flat bars, discs and carbon fibre fork, size 22 / 19
    2006 Ventana ECDM full suspension mountain tandem
    Some single bikes and a couple of KTM's
    And most important, someone special that enjoys them with me (except the KTM's)

  9. #209
    Senior Member waynesulak's Avatar
    Join Date
    Jan 2008
    Location
    Ft Worth, TX
    My Bikes
    650B tandem converted from Santana Arriva, Santana Noventa, Boulder Bicycle 700C, Gunnar Sport, Trek TX700,
    Posts
    1,766
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by zonatandem View Post
    Compelete_Bike_crop_1.JPGHoK Stoker BB Flash.jpg07 adj stokerstem..jpg

    Zona stuff. . .
    Hubs: Chris King (32H front and 36H rear)
    Eccentric: custom Zona light weight
    BBs: CK
    Rims: Australian Velocity Aerohead
    Spokes: DT Revolution db
    Tires: Maxxis Re-Fuse (folding) 700x25
    Headset: CK No-Thread
    Crankset: FSA triple
    Front Der: Dura Ace
    Rear der: XTR
    Cassette: 11/34 9 speed
    Shifters: D/A barcons
    Front brake: D/A caliper
    Rear brake: Tektro Mini
    Chains: KMC 9 SL
    Pilot stem: Bontrager
    Stoker stem: Custom Zona carbon fiber/adjustable
    with custom bottle mount
    Handlebars: Easton EC90 carbon
    Stoker handrest: Round custom carbon fiber
    Pedals: pilot Shimano /road toeclips
    stoker: Wellgo/mt.bike toeclips
    Saddles: pilot Sella San Marco Integra
    stoker Serfas Curva
    Seatpost: captain Thompson Elite
    stoker c/f (non-suspension)
    QRs: Salsa
    Bottle cages: 3 American Classic; one Hi-E
    Rear rack: Custom carbon fiber
    Other specifics on the frame:
    Custom c/f tubing (made in USA)
    Wheelbase: 63 1/2 inches (about 6 inches shorter than production tandems)
    Handmade lugged frame; lugs have window cutouts.
    Drasctically sloping toptube (to accomodate Kay who is 4' 10 3/4")
    7 bottle mounts (including one each on pilot and stoker's handlebar)
    Custom mount for mini garage door opener on stoker's stem
    Custom pump mount on boobtube
    Custom mount under boobtube to ccarry 2 spare spokes
    Paint: Clearcoat, lugs have black/gold accents
    Builder: Bob Davis @ zonatandems.com in Peoria, AZ

    Photos includes:
    Full bike as delivered (made some minor changes later)
    Lugwork with window cutouts
    Adjustable stoker stem

    Pedal on TWOgether!
    Rudy and Kay/zonatandem
    Thanks for the list. I see you save a lot of weight with your wheel choice. I like areohead rims but they are pretty light weight. Our team is about 50 lbs heavier than yours and we do have a tendency to try and maintain our speed even when the roads get rough so I am not sure we could get away with them. I do use 32 spoke areoheads on my single and feel they make a pretty good wheel.

    Looks like you have done a good job on taking advantage of your size to build a light setup that still is very practical.

    Wayne

  10. #210
    Senior Member
    Join Date
    Nov 2010
    Posts
    58
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Calfee Dragonfly vs. Paketa V2r chain line & wheel design

    There's an old cliche, "Imitation is the sincerest form of flattery." Compare the photo of the latest Dragonfly (above; link: http://www.calfeedesign.com/wp-conte...e-1024x683.jpg) to this photo of the V2r: http://www.bikeforums.net/showthread...528-Paketa-V2r.

    While the two bikes look quite similar, there's a couple of important differences to point out. First, while it might seem that there's not that much difference whether the timing belt is placed on the outside (Calfee) vs. inside (Paketa) of the drive chain rings, in fact it matters greatly. One of the key performance parameters with tandems is minimizing the boom tube flex under load. Lateral and torsional flex in the boom tube due to pedaling-induced forces translates directly into unpredictable handling as the front and back ends of the bike effectively "go in different directions." As a captain with 20+ years and 150,000+ miles of experience on dozens of tandems, I can tell you that it's rather disconcerting being on a tandem that exhibits this lack of stiffness! One tandem, which shall remain nameless, was so bad that the timing chain actually jammed up (more than once, actually, during a century ride) under hard pedaling when the chain tried to "climb off" the chain rings as the frame bowed sideways, nearly causing a very nasty crash as the cranks seized. Not fun.

    The amount of boom tube flex depends on the stiffness of the frame itself, obviously, but also the offset distance of the timing chain or belt from the frame center line. A cursory calculation of the belt lines on the two bikes shows that the Calfee's is about 53 mm from the center line of the frame to the center line of the belt, while the Paketa's is 31 mm. This is assuming the double-chain ring setup follows the standard 43.5 mm road double standard chain line and there's a 2.5 mm space between the belt sprocket and the neighboring chain ring in each case for clearance. That's a difference of [I]71% more bending load[I] on the Calfee as compared to the Paketa. All else being equal, one can build a frame that's lighter and more comfortable while still being durable if you don't have to increase the frame stiffness in order to compensate for higher pedaling-induced frame loads.

    The V2r on the Paketa web site at http://www.paketabikes.com/index.cfm?page=V2RTandem is 21.82 lbs. without pedals. It's no stretch to bring the weight down to under 21 lbs. if one is willing to make compromises on strength or durability in the component choices. A very light tandem team might be able to get away with using the ZTR Alpha 340 wheels, for example, but that's a stretch for anything other than a show bike (nothing wrong with that, by the way, but just realize that's what it is). The radial bending stiffness (there we go again with the engineering jargon, but in this case, too, it's pretty easily grasped) of the rim goes as the cube (3rd power) of the rim section depth, all else being equal. So, the 34 mm deep 420 rim on the V2r is about 340% stiffer than the 22.6 mm deep ZTR Alpha--and 32 spokes vs. 24 doesn't make up for this huge difference in rim stiffness.

    It's important to understand where it's safe to save weight without sacrificing performance.

    Dave Walker
    Paketa Cycles

  11. #211
    Senior Member
    Join Date
    Jul 2009
    Posts
    324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    2002 Burly Rumba, about 50# dry.

  12. #212
    Senior Member
    Join Date
    Jul 2009
    Posts
    324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Sorry, 04 Burley. Blue one with tool kit in back and handlebar bag. should be up to 55# or more with watter and full bag up front.

  13. #213
    Senior Member
    Join Date
    Mar 2011
    Posts
    137
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    37 pounds with 4 steel water bottle cages, pedals, and an Old Man Mountain rack.

  14. #214
    rebmeM roineS JanMM's Avatar
    Join Date
    Jan 2006
    Location
    Indiana
    My Bikes
    RANS V3, RANS V-Rex, RANS Screamer
    Posts
    12,034
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    RANS Screamer Summit (Hostel Shoppe version) claimed to be 49 pounds. That's a good thing downhill.
    RANS V3 (steel), RANS V-Rex, RANS Screamer

  15. #215
    Senior Member waynesulak's Avatar
    Join Date
    Jan 2008
    Location
    Ft Worth, TX
    My Bikes
    650B tandem converted from Santana Arriva, Santana Noventa, Boulder Bicycle 700C, Gunnar Sport, Trek TX700,
    Posts
    1,766
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by sixtiescycles View Post
    There's an old cliche, "Imitation is the sincerest form of flattery." Compare the photo of the latest Dragonfly (above; link: http://www.calfeedesign.com/wp-conte...e-1024x683.jpg) to this photo of the V2r: http://www.bikeforums.net/showthread...528-Paketa-V2r.

    While the two bikes look quite similar, there's a couple of important differences to point out. First, while it might seem that there's not that much difference whether the timing belt is placed on the outside (Calfee) vs. inside (Paketa) of the drive chain rings, in fact it matters greatly. One of the key performance parameters with tandems is minimizing the boom tube flex under load. Lateral and torsional flex in the boom tube due to pedaling-induced forces translates directly into unpredictable handling as the front and back ends of the bike effectively "go in different directions." As a captain with 20+ years and 150,000+ miles of experience on dozens of tandems, I can tell you that it's rather disconcerting being on a tandem that exhibits this lack of stiffness! One tandem, which shall remain nameless, was so bad that the timing chain actually jammed up (more than once, actually, during a century ride) under hard pedaling when the chain tried to "climb off" the chain rings as the frame bowed sideways, nearly causing a very nasty crash as the cranks seized. Not fun.

    The amount of boom tube flex depends on the stiffness of the frame itself, obviously, but also the offset distance of the timing chain or belt from the frame center line. A cursory calculation of the belt lines on the two bikes shows that the Calfee's is about 53 mm from the center line of the frame to the center line of the belt, while the Paketa's is 31 mm. This is assuming the double-chain ring setup follows the standard 43.5 mm road double standard chain line and there's a 2.5 mm space between the belt sprocket and the neighboring chain ring in each case for clearance. That's a difference of [I]71% more bending load[I] on the Calfee as compared to the Paketa. All else being equal, one can build a frame that's lighter and more comfortable while still being durable if you don't have to increase the frame stiffness in order to compensate for higher pedaling-induced frame loads.

    The V2r on the Paketa web site at http://www.paketabikes.com/index.cfm?page=V2RTandem is 21.82 lbs. without pedals. It's no stretch to bring the weight down to under 21 lbs. if one is willing to make compromises on strength or durability in the component choices. A very light tandem team might be able to get away with using the ZTR Alpha 340 wheels, for example, but that's a stretch for anything other than a show bike (nothing wrong with that, by the way, but just realize that's what it is). The radial bending stiffness (there we go again with the engineering jargon, but in this case, too, it's pretty easily grasped) of the rim goes as the cube (3rd power) of the rim section depth, all else being equal. So, the 34 mm deep 420 rim on the V2r is about 340% stiffer than the 22.6 mm deep ZTR Alpha--and 32 spokes vs. 24 doesn't make up for this huge difference in rim stiffness.

    It's important to understand where it's safe to save weight without sacrificing performance.

    Dave Walker
    Paketa Cycles

    I am not following a couple of your points:

    Rim strength: I agree that a deeper section rim if much stronger and stiffer that a shallow one however would that relate only to vertical strength and stiffness (toward center of wheel)? Horizontal stiffness would appear to relate to the cross section of the rim which you do not mention and which is similar on both rims. A tacoed wheel would appear to me to have failed laterally not vertically. The number of spokes would however add some measure of additional lateral support. I may be wrong on this so feel free to educate me as this it not my area of expertise.

    I am afraid I don't follow your calculation of timing chain position. Both bikes use doubles with the gates drive located inside in what would be the granny position. Does the V2r use a different chainline? In any case the limiting factor to inboard lacation of teh gates drive seems to be the wide gates "sprockets" touching the chainstay. I suppose the V2r has 135mm spacing and the Calfee 145mm? That would account for only 5mm of the 22mm offset that you calculated. Is the chainstay of the V2r thinner and or longer than the Calfee?

    The Paketa looks like a innovative bike. Feel free to contact me off list if there is a way to test ride one in the Dallas-Fort Worth Texas area.

    Wayne


    Wayne

  16. #216
    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
    3,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by waynesulak View Post
    I am afraid I don't follow your calculation of timing chain position. Both bikes use doubles with the gates drive located inside in what would be the granny position.
    The Calfee has the Gates drive on the outside of the big ring, as seen here.


  17. #217
    Senior Member
    Join Date
    Sep 2009
    Location
    Central Illinois
    My Bikes
    Trek Speed Concept 9.9, 2011 Calfee Tetra Tandem
    Posts
    935
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)


    30 pounds as it sits. I still have to install the computers.

  18. #218
    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
    3,266
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by DubT View Post
    [/IMG]30 pounds as it sits. I still have to install the computers.
    Man, you got that put together fast!

    Did you get a frame weight before assembly?

  19. #219
    Senior Member
    Join Date
    Sep 2009
    Location
    Central Illinois
    My Bikes
    Trek Speed Concept 9.9, 2011 Calfee Tetra Tandem
    Posts
    935
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Ritterview View Post
    Man, you got that put together fast!

    Did you get a frame weight before assembly?
    That is the nice thing about being semi-retired (I work 2 days a week). I also had everything ready, did not have to go get anything, also the build went extremely well.

    I did weigh the frame before assembly, frame with Chris King headset, Bushnell Eccentric and seat post clamps weighed 3,183 grams.

  20. #220
    Senior Member waynesulak's Avatar
    Join Date
    Jan 2008
    Location
    Ft Worth, TX
    My Bikes
    650B tandem converted from Santana Arriva, Santana Noventa, Boulder Bicycle 700C, Gunnar Sport, Trek TX700,
    Posts
    1,766
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Ritterview View Post
    The Calfee has the Gates drive on the outside of the big ring, as seen here.


    Thanks, that is interesting. I have considered doing that with a chain drive but decided that if the drive chain ever went outboard of the chain ring we might have a long walk home.

  21. #221
    Senior Member
    Join Date
    Jan 2010
    Location
    UK
    My Bikes
    Canyon Dura ace, Pinarello Asolo Super Record, Holdsworth Nuovo Record, Ibis Tandem, Brompton
    Posts
    81
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Our tandem (Bill Phillbrook, 1970's, Reynolds 531) is 21kg (46 lbs).

    The cheapest way of reducing overall tandem weight is remove it from the riders. Our combined weight is now 69kg + 52kg = 121kg. A year ago (and at this point, we would not be considered to be overweight) it was 75kg + 55kg = 130kg. The 9kg cost nothing, just a bit of willpower and improving the diet, but to do this via reducing the tandem weight would have been horrific - '000's of 's.

    There's a morale in there somewhere - start with the riders, then attack the bike when you can't lean up anymore.

  22. #222
    PMK
    PMK is offline
    Senior Member PMK's Avatar
    Join Date
    May 2008
    Location
    Royal Palm Beach, Florida
    My Bikes
    2006 Co-Motion Roadster (Flat Bars, Discs, Carbon Fork), Some 1/2 bikes and a couple of KTM's
    Posts
    1,128
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by waynesulak View Post
    Thanks, that is interesting. I have considered doing that with a chain drive but decided that if the drive chain ever went outboard of the chain ring we might have a long walk home.
    I built one of our off-road tandems as a 2x9 with right side drive. When new and without a ramped and pinned large drive ring it worked good. With some miles on it, the setup became inconsistent. We never walked home, but on all but one ride important ride I carried tools to loosen the chainrings. Of course the ride when the tools were forgotten was a group event. After it jumped a couple times, we opted to not use the small front ring unless we absolutely needed it and had plenty of time to find the shift both down and back up.

    The bike now runs a left right setup and has not been a problem.

    Yes it weighs more, but is a much better bike with the added reliability.

    Always a compromise.

    PK
    Last edited by PMK; 05-29-11 at 06:28 AM.
    2006 Co-Motion Roadster, flat bars, discs and carbon fibre fork, size 22 / 19
    2006 Ventana ECDM full suspension mountain tandem
    Some single bikes and a couple of KTM's
    And most important, someone special that enjoys them with me (except the KTM's)

  23. #223
    Senior Member
    Join Date
    Oct 2009
    Posts
    965
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    1970's Bob Jackson, Reynolds 531. 35lb.

  24. #224
    Senior Member
    Join Date
    Nov 2010
    Posts
    58
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi, Wayne,

    Thanks for asking, and if I wasn't clear in my descriptions I apologize.

    To answer the first question about rims, what's interesting and perhaps not obvious to many people is that lateral wheel strength is very much a function of radial rim stiffness. Even though the two rims being compared (Stan's ZTR Alpha 340 and American Classic's 420) are the same width, the huge difference in radial stiffness (3.4 times greater for the 420 rim vs. the Alpha 340) will produce a wheel that's laterally stiffer, too. This was proven from first principles by Prof. Henri Gavin at Duke University about twenty years ago with some elegant theory and engineering analysis, and was one of the things that prompted me to build my first set of tandem wheels using deep-section rims in 1998. These are those wheels: http://sandsmachine.com/a_bil_t8.htm. I tested them side-by side against a pair of contemporary Santana Sovereign 48-spoke wheels built with Sun CR16II rims (a popular tandem rim at the time) and my 24-spoke wheels were much stiffer radially (as you’d expect) and just as stiff laterally as the Sovereign wheels, even though the Sun rims are wider than the FIR rims.

    To answer the second question about timing belt (or chain) placement, the Calfee has the timing belt on the outside of the double-chain ring drive, while the Paketa has the timing belt on the inside. The Paketa uses 130 mm rear axle spacing, so in order to make room for the inboard-mounted timing belt the chain stays and boom tube have reliefs for the Gates sprockets—the bike was designed and built with all this in mind. Take a look at the third photograph in this thread: http://www.bikeforums.net/showthread...528-Paketa-V2r. I don’t know what the rear spacing is on the Calfee; my timing chain line calculations above (31 mm Paketa; 53 mm Calfee) are assuming 130 mm rear spacing on both. If the Calfee spacing is more than 130 mm, this would mean the timing chain position is even further outboard and will create an even higher boom tube bending load. It's not obvious to me that the Calfee was designed with right-side timing in mind.

    If you choose to use 130 mm spacing on a road tandem, it’s almost imperative that you use deep section rims to maintain adequate wheel stiffness and strength, both radially and laterally. There’s nothing on the V2r that’s accidental: it all works very well as a system, but the system depends on judicious component selection. Inadequate wheel stiffness will be neither safe nor durable, even though the wheels might be fun to ride and really light. Safety and durability, high performance, and light weight—in that order.
    Last edited by sixtiescycles; 05-30-11 at 01:59 PM. Reason: save space!

  25. #225
    Member 40SpokeOD's Avatar
    Join Date
    Mar 2011
    Location
    Philadelphia, PA
    My Bikes
    Commuter, MB and road bike
    Posts
    40
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I'm new to "captaining" gonna hopefully pick up my new/used tandem tomorrow evening. After riding it today for the first time she was MUCH lighter than I anticipate being as the bike was steel from 1992. Anyone here ever hear of IronHorse tandems? The model is a Tango and it is a purple to blue fade. I want something nice for me and my mom to take on various rides around the area so speed isn't my first concern. Her comfort and safety is. This is a mountain bike style tandem. Anyone have any input on this tandem specifically, I'd love to hear it. Thanks in advance.

Page 9 of 17 FirstFirst ... 7891011 ... LastLast

Posting Permissions

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