Finite Element Analysis

It goes without saying that if you are going to design with composite materials you are going to have to use some form of computer modeling. We use finite element analysis (FEA) for our computer modeling. Composite materials are anisotropic (mechanical properties vary with orientation). Typically a frame is made up of 8 to 20 plies of carbon zxtfeafiber. Each one of these plies can have a different orientation and this greatly effects the stiffness and strength of the frame. Add to that the option of 180 degrees of orientation for each ply over the entire sculptured shape of the frame and it gets real complicated. You need a computer to keep tack of resultant material properties.

Further, you have to determine how these ply orientations will react to the loading conditions of the bicyclist. FEA is the only way to optimize a composite design.

The ZXT FEA model at the left is just an example of where some of the “hot” spots on the frame would be under one set of loading conditions. It takes many FEA iterations to get the design in the ballpark.

The same is true for the ZR frame shown on the right.

We look at stress plots and deflection plots to determine what is the best composite design we can offer. We use this information to design an efficient frame, which is light and stiff.

zrfeaThe FEA models below compare the ZR to an aluminum frame with the same geometry & loads. The tube set is an Easton Elite 7005. You can clearly see the excessive head tube twisting on the Al. frame as opposed to the very stable head tube on the ZR. The 7005 frame twists far more than the ZR. Excessive twisting basically sucks the energy out of your legs. Your energy is used to twist the frame rather than going forward.

ZR Carbon Fiber

ZR Bike


The ZR Carbon Fiber is the ultimate road bike. An aerodynamically sculpted custom carbon fiber frame definitely will lower your times in any event. We keep it slick by routing all the cables internally. Smooth riding and laterally stiff for excellent power translation is achieved both through the use of composites and the geometry of the frame.

The chain stay’s position is such that you’ll never have to worry about chain induced damage, there’s a clear path for the chain to bounce around all it wants. Other manufactures haven’t figured that out yet.

Carbon Fiber:

The best strength to weight ratio for the buck of any material in the world.


The advantages of the ZR are on par with the super bikes of the 1996 Olympics. Less tubes, less wind resistance, less drag, less effort.

Custom Frame:  zr3brk

Made to order geometry on a carbon fiber bike. You won’t get that kind of passion from a big company.

Internal Cables

  • Front derailleur
  • Rear derailleur

  • Rear Brake
  • Frt. & Rear Cable Tension adjusters

Above is our improved design for the 1999- 2000 bikes for routing the internal cables. We will be doing this on all the frames in the future. The shifting is improved as well as the aerodynamics.


We also improved the Front Derailleur cable routing. We had some trouble with road dirt and grime getting inside the area where the cable wrapped around the BB. Now it’s open, so it’s easy to clean and maintain.


1 inch or 1.125 inch DIAMETER HEADSETS

2001 – 2002 ZR Specifications

General Specification
Bicycle Type Road race & triathlon, 700C
Frame Weight 3.5 lbs
Sizes Custom, any size
Colors two-tone fade typical, Very custom call.
Geometry / Frame & Fork Specification
Frame Construction Carbon Fiber Composite, Patented Monocoque Beam Bike
Frame Angles 73.0 head, 73.0 seat
Chain Stay Length 41.5 cm, typical
Front Derailleur Braze-on, bottom pull road type
BB Shell Width 68mm, aluminum
Seatpost 26.8 mm dia.
Fork Rake/ brand – size 45 mm or 50mm, Wound-up, 1″ or 1.125″ dia. threadless
Fork Material Steel, AL or Carbon steer tube/ Carbon blades

ZXT Carbon Fiber

The ZXT Carbon Fiber is tomorrow’s tandem today. The custom hand built carbon fiber road tandem’s simplistic design results in an aerodynamically sleek ride. The Carbon fiber material allows for ample room for the stoker without sacrificing weight or frame flex. The frame is laterally stiff, yet vertically compliant which gives it unsurpassed comfort and climbing performance. All cables are internally routed to achieve the ultimate aero-art tandem design.

Carbon Fiber:zxt
The advantages are even greater on a tandem frame.
Theadvantages are unsurpassed by any available tandem.
Custom Frame:
Custom geometry even on the carbon fiber tandem.

The frame geometry may look totally different from a typical triangular tandem, but the geometry is still the same. We design within the proven geometry that has worked for years. We just do it better.

Is this thing legal? Apparently, the UCI isn’t to concerned about tandems, but they do have a “No Technical Innovations Rule” which is real nice. It’s USCF legal.

Rider Testimony:

Pete & Mona Totman: LOTOJA tandem winners 1994. Very responsive, it’s unbelievable how easy it climbs hills. That’s a great bike.

Barry & Greg: 1999 Ride the Rockies tour. “Well, we hit 62 mph on one down hill section and we could drop every body like a rock when we wanted. It was amazing how many people would come around to look at the bike after the days ride.”

Details zxt4capstem2

Internal Cables

  • Stoker computer wires
  • Hydraulic rim brake
    Front derailleur,with barrel adjuster
  • Rear derailleur,
    with barrel adjuster


  • Your own cycling computer
  • Hard wired to the captain’s computerzxt4stokstem2
  • Rear Hydraulic disk brake control lever
  • Adjustable stem
  • Square tubing = no rotation
  • Lots of room (29″ top tube)

Front Derailleur

  • Different length Crank sets (175/170) available
  • Standard Braze-on type mount
  • Down Pull Cable

Brake Systemzxt4frtder2

  • Magura hydraulic Rim brakes, Front & Rear
  • Magura hydraulic rear disc
  • Internally routed cables
  • Hubs 40 or 48 hole
  • AeroSpoke Composite Wheels
  • 700C Rims


2001-2002 ZXT Specifications

General Specification
Bicycle Type Road , 700C
Frame Weight 8.5 lbs
Sizes Custom, any size
Colors two-tone fade standard, any thing else call.
Geometry /
Frame & Fork
Frame Construction Carbon Fiber Composite, Patented Monocoque Beam Bike
Internal cable routing front to rear computer cable ready, all cables internal
Drop Outs 6061-T6, CAS designed
Frame Angles 73.0 head, 73.0 Fseat, 73.0 Rseat
Front to Rear distance About 29 inches for a 56 cm x 48 cm frame.
Stand over height no problem, sloping main beam
Chain Stay Length 41.5 cm, typical
Rear Wheel Spacing 140 mm or 145 mm
Front Derailleur Braze-on, bottom pull road type
BB Shell Width rear 68mm aluminum, front 68mm steel shell /Al. eccentric
Seatposts front & rear 26.8 mm dia., 6061-T6 sleeve
Fork Rake/ brand – size 1 1/8″ dia. Threadless,
4130 steel- Co-Motion tandem
Carbon fiber – Wound-Up
Water bottle cages 4 locations
Component features
Brakeset Magura Hydraulic Rim Brakes, braze- on
Rear Disc Brake Option Hydraulic Disc brake, operated by stoker
Magura disc brake selection
Shift levers Magura road levers, Shimano bar ends Dura Ace
Front Derailleur Braze-on, bottom pull Shimano Ultegra Triple
Rear Derailleur 8 speed or 9 speed Shimano Ultegra long cage
Crankset Raceface 175 mm front / 170 mm rear 32 / 42 / 54t
Pedals Ultegra or Dura Ace (SPDR)
Rear Cogs 9-speed (Typical cog is 12-25)
Stoker Stem CAS design, 6061-T6 TIG welded square tubing, non-slipping
Handlebar Stem 120 mm typical
Hubs Shimano or Aerospoke or call
Rims 700C x 40 hole or 48 hole front & rear
Tires 700C x 28 c front & rear, IRC
Spoke Brand DT, straight 14 gauge
Spoke Nipples Brass

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